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National Instruments Image Acquisition Software User's Manual

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1. Figure A 2 StillColor Decoding Fr Note You can find color versions of the illustrations in this appendix in the online version of this document included with your NI IMAQ software kit Both pictures are approximately 80 by 80 pixels in size and are acquired using an NTSC composite video signal Figure A 1 uses classic decoding algorithms including bandpass bandstop and comb filtering Figure A 2 was acquired using the PCI PXI 1408 and the StillColor algorithm NI IMAQ User Manual A 4 National Instruments Corporation Appendix A StillColor Why StillColor StillColor is optimized for single frame acquisition A StillColor Composite acquisition acquires multiple consecutive frames Assuming that all frames represent the same scene of still objects the algorithm then uses knowledge about the composite color format to perfectly separate the color and the luminance information In an NTSC video signal two consecutive frames representing the same object will contain the same luminance information but will have chroma signals that are opposite in phase By adding the two frames together the chroma information is cancelled and by subtracting the two frames from each other the luminance signal is cancelled The resulting separation is now perfect as shown in Figure A 2 Color and luminance separation is more complex in a PAL video signal The IMAQ device must acquire three consecutive frames but the same perfect separation of the c
2. 3 14 to 3 15 status signals 3 5 to 3 6 StillColor A 1 to A 6 advantages A 5 composite color acquisition A 5 composite color video signals A 2 to A 4 overview A 1 purpose and use A 2 RGB color acquisition A 6 snap programming example 3 16 to 3 17 traditional color decoding A 2 to A 3 NI IMAQ User Manual T technical support B 1 to B 2 telephone and fax support numbers B 2 U utility functions 2 7 V video cameras for color acquisition A 1 visible spectrum A 6 to A 7 W white light A 7 National Instruments Corporation
3. A 8 to A 9 import libraries IMAQ LIB required for application development 1 3 location table 1 3 purpose and use 1 2 intensity A 7 intensity planes A 8 to A 9 interface functions interface naming convention table 3 2 generic functions 2 2 grab acquisition 3 1 grab functions list of functions 2 2 to 2 3 programming examples L high level functions 3 8 to 3 9 low level functions 3 15 list of functions 2 7 programming considerations 3 2 to 3 3 low level functions 2 5 to 2 7 acquisition functions 2 5 advanced programming examples 3 14 to 3 17 grab functions 3 15 ring functions 3 16 NI IMAQ User Manual l 2 National Instruments Corporation sequence functions 3 15 to 3 16 snap functions 3 14 to 3 15 attribute functions 2 6 buffer management functions 2 6 to 2 7 3 4 interface functions 2 7 3 2 to 3 3 programming considerations 3 2 utility functions 2 7 luminance A 7 luminance planes A 8 to A 9 manual See documentation miscellaneous high level functions 2 4 NI IMAQ header files 1 3 NI IMAQ libraries 1 2 NI IMAQ software See also functions application development 1 2 to 1 4 application development environments 1 2 features and overview 1 1 NI IMAQ libraries 1 2 sample programs 1 4 _NIWIN constant 1 3 P programming advanced examples 3 14 to 3 17 low level grab functions 3 15 low level ring functions 3 16 low level sequence functions 3 15 to 3 16 low level
4. U and V representing the coordinates in a color plane National Instruments Corporation G 13 NI IMAQ User Manual Index A acquisition functions 2 5 application development 1 2 to 1 4 creating applications 1 3 NI IMAQ libraries 1 2 attribute functions 2 6 buffer management functions list of functions 2 6 to 2 7 programming considerations 3 4 bulletin board support B 1 C camera attributes 3 4 to 3 5 color A 6 to A 9 See also StillColor definition A 6 hue A 7 image representations A 8 to A 9 32 bit HSL and HSI A 9 color planes A 8 hue saturation luminance and intensity planes A 8 to A 9 RGB A 8 intensity A 7 luminance A 7 perception of color A 7 saturation A 7 white light and visible spectrum figure A 2 composite color cameras A 1 customer communication xi B 1 to B 2 National Instruments Corporation D documentation conventions used in manual x how to use NI IMAQ manual set ix National Instruments documentation xi organization of manual ix x related documentation xi dynamic link libraries DLLs 1 2 E electronic support services B 1 to B 2 e mail support B 2 example programs advanced programming examples 3 14 to 3 17 low level grab functions 3 15 low level ring functions 3 16 low level sequence functions 3 15 to 3 16 low level snap functions 3 14 to 3 15 StillColor snap programming 3 16 to 3 17 introductory programming examples 3 6 to 3 14 h
5. perfect reconstruction of the original color image is not possible A 2 National Instruments Corporation Appendix A StillColor All of the traditional ways to separate the two signals result in visual artifacts on the final picture Techniques such as frequency band filtering or comb filtering can minimize some of these artifacts but most techniques are optimized to obtain the best picture for visualization of a continuous acquisition The composite color formats are designed so that artifacts resulting from one frame are almost cancelled by artifacts in following frames This system takes advantage of the slow response time of the human eye to obscure most of these problems The situation is different in a single frame acquisition where a single image is needed A single image usually clearly shows the result of a bad color luminance separation Typical weakness of traditional separation techniques are e Reduced luminance bandwidth resulting in a blurry image e Cross color modulation where rapidly changing colors affect the luminance of the image as shown on the edges of the parrot s head in Figure A 1 e Cross luminance modulation where rapidly changing luminance stripes results in irritating random color patterns as shown on the black and white stripes around the parrot s eye in Figure A 1 National Instruments Corporation A 3 NI IMAQ User Manual Appendix A StillColor Figure A 1 Classical Decoding
6. valid session handle When you invoke a snap it initializes the board and acquires the next incoming video frame or field to a buffer A snap is appropriate for low speed or single capture applications where ease of programming is essential Figure 3 2 illustrates a typical snap programming order imgInterfaceOpen opens imgInterfaceOpen and configures the interface according to the file setup by the IMAQ Configuration Utility y lagg Fono imgSessionOpen opens a session that RR e will be used for all acquisition and configuration y imgSnap acquires an image into a buffer The buffer may be passed into imgSnap or automatically imgSnap allocated by NI IMAQ If no buffer is passed into imgSnap it will automatically snap into a new buffer and return a pointer to the buffer y User Specific Functions User specific image processing y l imgClose imgClose closes the interface and session Figure 3 2 Snap Programming Flowchart The hlsnap c example demonstrates how to perform a single snap using imgSnap The example opens an interface and a session and then performs a single snap The buffer pointer that is passed to imgSnap is initialized to NULL which instructs imgSnap to automatically allocate a buffer for the image The size of the buffer is calculated based on the region of interest ROI and the rowPixel attributes ROI height multiplied by rowPixel multiplied by the number of bytes per pixel When you o
7. NI IMAQ RTSI and StillColor are trademarks of National Instruments Corporation Product and company names listed are trademarks or trade names of their respective companies WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS National Instruments products are not designed with components and testing intended to ensure a level of reliability suitable for use in treatment and diagnosis of humans Applications of National Instruments products involving medical or clinical treatment can create a potential for accidental injury caused by product failure or by errors on the part of the user or application designer Any use or application of National Instruments products for or involving medical or clinical treatment must be performed by properly trained and qualified medical personnel and all traditional medical safeguards equipment and procedures that are appropriate in the particular situation to prevent serious injury or death should always continue to be used when National Instruments products are being used National Instruments products are NOT intended to be a substitute for any form of established process procedure or equipment used to monitor or safeguard human health and safety in medical or clinical treatment Contents About This Manual How to Use the NI IMAQ Manual Set cccecescccessececescecesseceseeeceseecenssseecseaeesneaeens ix Organization of This Manual se seseeeesseeesserese
8. and configures the interface according to the file setup by the IMAQ Configuration Utility y a inas ne imgSessionOpen opens a session that TARPS SOTERA will be used for all acquisition and configuration y imgRingSetup sets up a ring acquisition to a a naat programmable number of buffers These buffers ie orate ome a can be created either by the driver using imgCreateBuffer or passing a NULL or by you y y y f POENA imgSessionStartAcquisition starts aa ewer duces Ar EA AUS TETON the acquisition into a driver buffer a imgSessionStatus gives the current status of the ring including the buffer number of the last buffer imgSessionStatus that was successfully transferred With this information you can determine which buffer you want to process y or copy to a private location ai User Specific Functions User specific image processing eee Loop e y A PE imgSessionStopAcquisition imgSessionStopAcquisition stops the ring function y Va imgClose imgClose closes the interface and session NI IMAQ User Manual Figure 3 5 Ring Programming Flowchart The HLRing c example demonstrates how to perform a ring acquisition using imgRingSetup The example sets up a ring containing six buffers and sets the skip count to three which causes the program to acquire on every third frame Unlike the sequence example the skip count is set to the same value for every buffer in the ring A skip cou
9. boards in your system These names observe the convention shown in Table 3 1 Table 3 1 Interface Naming Convention Interface Name Board Installed img0 Board 0 imgl Board 1 imgn Board n You can edit existing or create new interfaces by using the IMAQ Configuration Utility You also can use the IMAQ Configuration Utility to configure the board serial number and the default state of a particular interface 3 2 National Instruments Corporation Chapter 3 Programming with NI IMAQ Before you can acquire image data successfully you must open an interface by using the imgInterfaceOpen function imgInterfaceOpen requires an interface name and returns a handle to this interface NI IMAQ then uses this handle to reference this interface when using other NI IMAQ functions To establish a connection to the first board in your system use the following program example INTERFACE_ID interfaceID if imgInterfaceOpen img0 amp interfaceID IMG_ERR_GOOD user code imgClose interfaceID FALSE This example opens an interface to img0 When the program is finished with the interface it closes the interface using the imgClose function For a complete list of the available interface functions refer to the NI IMAQ Function Reference Manual Session Functions Use session functions to configure the type of acquisition you want to perform on a particular interface After you have establi
10. buffer pointer you can use this pointer in successive calls For greater control of the acquisition buffers such as creating buffers larger than the image size for adding borders you can create them by calling a memory allocation routine for example malloc or using the low level function imgCreateBuf fer When creating buffers using either approach dispose of the buffers using free or imgDisposeBuf fer when applicable to free PC memory for maximum performance Camera Attributes CF Note NI IMAQ User Manual The camera attributes allow you to control camera functions such as integration time and pixel binning directly from NI IMAQ These camera attributes are camera specific and can also be set in the IMAQ Configuration Utility on the Advanced tab Information about specific attributes for your camera is contained in lt my camera gt txt which can be found in the ni imag camera info directory For more information about camera attributes and their uses please consult your camera documentation Currently camera attributes are supported only by the IMAQ PCI 1424 The camera attribute file lists all attributes for the camera Each attribute description contains four fields Attribute Name Description Data Type and Possible Values The Attribute Name field contains the name of the attribute in quotes The Data Type field contains the data type of the attribute String Integer or Float String indicates that there are se
11. buffers Next the program sets the ROI to the acquisition window width The program calculates the correct memory requirements of the frame buffer However this is not necessary if you choose to use the default acquisition window width rowPixels and ROI In this case NI IMAQ will allocate the correct size buffer if you pass a NULL as the size parameter to imgCreateBuffer The buffer is created and the buffer list is configured for each buffer element in the ring The memory is locked and the image acquisition is started asynchronously The main processing loop of the code shows how to wait for the first buffer to be filled and subsequently processed NI IMAQ returns a value of OxFFFFFFFF as the IMG_ATTR_LAST_VALID_BUFFER attribute until the successful acquisition of the first buffer To guarantee that you wait for the acquisition of a new buffer in a ring with more than one buffer you can loop on the attribute IMG_ATTR_LAST_VALID_BUFFER until it changes If your buffer analysis requires many computations call imgSessionExamineBuf fer to extract the desired buffer from the live sequence When using imgSessionExamineBuf fer the buffer requested is literally pulled from the looping sequence for the duration of the analysis Use imgSessionReleaseBuf fer to return the buffer to the continuous sequence StillColor Snap Programming NI IMAQ User Manual You can use the high level snap function to acquire StillColor images from ei
12. description of the directories produced by the install programs and the names and purposes of the uncompressed files consult the readme txt file on your installation CD or diskettes Fundamentals of Building Applications with NI IMAQ The NI IMAQ Libraries NI IMAQ User Manual The NI IMAQ for Windows 95 NT function libraries are dynamic link libraries DLLs which means that NI IMAQ routines are not linked into the executable files of applications Only the information about the NI IMAQ routines in the NI IMAQ import libraries is stored in the executable files Import libraries contain information about their DLL exported functions They indicate the presence and location of the DLL routines Depending on the development tools you are using you may give the DLL routines information through import libraries or through function declarations Your NI IMAQ software kit contains function prototypes for all routines 1 2 National Instruments Corporation Chapter 1 Introduction to NI IMAQ Creating an Application This section outlines the process for developing NI IMAQ applications using C for Windows 95 and Windows NT Detailed instructions on creating project and source files are not included For information on creating and managing project files consult the documentation included with your particular development environment When programming use the following guidelines National Instruments Corporation You must define
13. documentation These documents have detailed information about the IMAQ hardware that plugs into or is connected to your computer Use these manuals for hardware installation and configuration instructions hardware specification information and application hints e Software documentation Examples of software documentation you might have are the LabVIEW and LabWindows CVI documentation the ComponentWorks documentation the IMAQ Vision documentation and the NI IMAQ documentation After you have set up your hardware system use either the application software LabVIEW or LabWindows CVI or the NI IMAQ documentation to help you write your application If you have a large and complicated system it is worthwhile to look through the software documentation before you configure your hardware e Accessory installation guide or manuals If you are using accessory products read the installation guides They explain how to physically connect the relevant pieces of the system Consult these guides when you are making your connections Related Documentation The following document contains information you may find useful as you read this manual e Microsoft Visual C User Guide to Programming Customer Communication National Instruments wants to receive your comments on our products and manuals We are interested in the applications you develop with our products and we want to help if you have problems with them To make it easy for y
14. live acquisition lets you lock a buffer out of a continuous loop sequence for processing when you are performing a ring continuous acquisition imgSessionReleaseBuffer Releases a buffer that was previously held with imgSessionExamineBuf fer National Instruments Corporation 2 5 NI IMAQ User Manual Chapter 2 Software Overview Attribute Functions Use attribute functions to examine and change NI IMAQ or camera attributes imgGetAttribute Returns an attribute for an interface or session imgGetCameraAttributeNumeric Gets the value of numeric camera attributes imgGetCameraAttributeString Gets the value of camera attributes imgSessionGetLostFramesList Gets information about frames that were overwritten during a continuous acquisition imgSetAttribute Sets an attribute for an interface or session imgSetCameraAttributeNumeric Sets the value of numeric camera attributes imgSetCameraAttributeString Sets the value of camera attributes Buffer Management Functions NI IMAQ User Manual Use buffer management functions to set up objects such as buffer lists and buffers imgCreateBuffer Creates a user frame buffer based on the geometric definitions of the associated session imgCreateBufList Creates a buffer list that is passed to imgSessionConfigure imgDisposeBuffer Disposes of a user frame buffer imgDisposeBufList Purges all image buffers associated with this buffer list 2 6 National Instr
15. phase locked loop circuitry that provides a very stable pixel clock that is referenced to another signal for example an incoming HSYNC signal the exact sequence of bits characters and control codes used to transfer data between computers and peripherals through a communications channel points random access memory a property of an event or system in which data is processed as it is acquired instead of being accumulated and processed at a later time a measure in LSB of the accuracy of an ADC it includes all nonlinearity and quantization errors but does not include offset and gain errors of the circuitry feeding the ADC G 10 National Instruments Corporation resolution RGB ribbon cable ROI ROM RS 170 RTSI bus S S saturation scaling down circuitry scatter gather DMA SRAM StillColor sync National Instruments Corporation G 11 Glossary the smallest signal increment that can be detected by a measurement system resolution can be expressed in bits in proportions or in percent of full scale For example a system has 12 bit resolution one part in 4 096 resolution and 0 0244 percent of full scale red green and blue the three primary colors used to represent a color picture An RGB camera is a camera that deliver three signals one for each primary a flat cable in which the conductors are side by side region of interest a hardware programmable rectangular portion of the acquis
16. technical support centers which are staffed by applications engineers Electronic Services Bulletin Board Support National Instruments has BBS and FTP sites dedicated for 24 hour support with a collection of files and documents to answer most common customer questions From these sites you can also download the latest instrument drivers updates and example programs For recorded instructions on how to use the bulletin board and FTP services and for BBS automated information call 512 795 6990 You can access these services at United States 512 794 5422 Up to 14 400 baud 8 data bits 1 stop bit no parity United Kingdom 01635 551422 Up to 9 600 baud 8 data bits 1 stop bit no parity France 01 48 65 15 59 Up to 9 600 baud 8 data bits 1 stop bit no parity FTP Support To access our FTP site log on to our Internet host ftp natinst com aS anonymous and use your Internet address such as joesmith anywhere com as your password The support files and documents are located in the support directories National Instruments Corporation B 1 NI IMAQ User Manual Fax on Demand Support Fax on Demand is a 24 hour information retrieval system containing a library of documents on a wide range of technical information You can access Fax on Demand from a touch tone telephone at 512 418 1111 E Mail Support Currently USA Only You can submit technical support questions to the applications engineering team through e mail at the In
17. the constant _NIWIN prior to including any NI IMAQ header files You can define this constant in your source files by using the define directive that is define _NIWIN Or you can add the definition to your project file s preprocessor definitions if your environment supports this feature All C source files that use NI IMAQ functions must include the NIIMAQ H header file Add this file to the top of your source files You must add the IMAQ LIB import library to your project Some environments allow you to add import libraries simply by inserting them into your list of project files Other environments allow you to specify import libraries under the linker settings portion of the project file When compiling you will need to indicate where the compiler can find the NI IMAQ header files and shared libraries Most of the files you need for development are located under the NI IMAQ target installation directory If you choose the default directory during installation the target installation directory is C Program Files National Instruments NI IMAQ The include files are located under the include subdirectory The import libraries are located under the 1ib lt environment gt subdirectory for the following platforms Table 1 1 Import Libraries Development Environment Directory Microsoft Visual C lib msc Borland C lib be 1 3 NI IMAQ User Manual Chapter 1 Introduction to NI IMAQ Sample Programs Pl
18. used with units of measure such as volts and hertz 2 mega the prefix for 1 048 576 or 22 when used with B to quantify data or computer memory megabytes of memory a unit for data transfer that means 1 million or 10 bytes s G 8 National Instruments Corporation memory buffer memory window MSB MTBF mux N NI IMAQ noninterlaced NTSC NVRAM 0 operating system PAL PCI PCLK National Instruments Corporation G 9 Glossary See buffer continuous blocks of memory that can be accessed quickly by changing addresses on the local processor most significant bit mean time between failure multiplexer a switching device with multiple inputs that selectively connects one of its inputs to its output driver software for National Instruments IMAQ hardware a video frame where all the lines are scanned sequentially instead of divided into two frames as in an interlaced video frame National Television Standards Committee the committee that developed the color video standard used primarily in North America which uses 525 lines per frame See also PAL nonvolatile RAM RAM that is not erased when a device loses power or is turned off base level software that controls a computer runs programs interacts with users and communicates with installed hardware or peripheral devices Phase Alternation Line one of the European video color standards uses 625 lines per frame See also NTSC Per
19. 0 299 x Red 0 587 x Green 0 114 x Blue Intensity Red Green Blue 3 Hue ATN2 Y X where Y Green Blue 2 and X 2 x Red Green Blue 6 Saturation lx xY where Y Green Blue 2 and X 2 x Red Green Blue 6 32 Bit HSL and HSI You can also pack the three 8 bit Hue Saturation and Luminance planes HSL or the three Hue Saturation and Intensity planes HSI in one array of 32 bit integers which is equivalent to the 32 bit RGB representation National Instruments Corporation A 9 NI IMAQ User Manual Customer Communication For your convenience this appendix contains forms to help you gather the information necessary to help us solve your technical problems and a form you can use to comment on the product documentation When you contact us we need the information on the Technical Support Form and the configuration form if your manual contains one about your system configuration to answer your questions as quickly as possible National Instruments has technical assistance through electronic fax and telephone systems to quickly provide the information you need Our electronic services include a bulletin board service an FTP site a fax on demand system and e mail support If you have a hardware or software problem first try the electronic support systems If the information available on these systems does not answer your questions we offer fax and telephone support through our
20. D BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER NATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA PROFITS USE OF PRODUCTS OR INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF ADVISED OF THE POSSIBILITY THEREOF This limitation of the liability of National Instruments will apply regardless of the form of action whether in contract or tort including negligence Any action against National Instruments must be brought within one year after the cause of action accrues National Instruments shall not be liable for any delay in performance due to causes beyond its reasonable control The warranty provided herein does not cover damages defects malfunctions or service failures caused by owner s failure to follow the National Instruments installation operation or maintenance instructions owner s modification of the product owner s abuse misuse or negligent acts and power failure or surges fire flood accident actions of third parties or other events outside reasonable control Under the copyright laws this publication may not be reproduced or transmitted in any form electronic or mechanical including photocopying recording storing in an information retrieval system or translating in whole or in part without the prior written consent of National Instruments Corporation Bridge VIEW ComponentWorks CVI IMAQ LabVIEW
21. EREE ERNES 3 8 High Level Sequence Functions 2 0 0 cece eceseesecseecseceseesececeseceseeseeeeeeaeeees 3 10 High Level Ring Functions eee ceceseeeeeeeeeeeeeseeceecaeecaecssesseceseeseeneeees 3 11 High Level Signal I O Functions cies ceeceseceeceseceeeeseceseeeeeeeeeeeneeees 3 13 Advanced Programming Examples 00 ceseecceeeecceseeeeecseeesecaeesaecaeeaecneceseeeeeeeeaeenes 3 14 Performing a Snap Using Low Level Functions cece ee eeeeeeseeeeceeeeeeees 3 14 Performing a Grab Using Low Level Functions cece eeeeseceseceeeeseeeeees 3 15 Performing a Sequence Acquisition Using Low Level Functions 3 15 Performing a Ring Acquisition Using Low Level Functions 0 ee 3 16 StillColor Snap Programming 00 eee cece cee ceseeseceseeseceeceeeseeeeeeseaeesaeeneenaes 3 16 Appendix A StillColor Appendix B Customer Communication Glossary Index NI IMAQ User Manual vi National Instruments Corporation Figures Figure 3 1 Figure 3 2 Figure 3 3 Figure 3 4 Figure 3 5 Figure 3 6 Figure 3 7 Figure A 1 Figure A 2 Figure A 3 Tables Table 1 1 Table 3 1 Contents NEIMAQ Stats Signals sseni nnie a 3 6 Snap Programming Flowchart eee cee cesecseessececeseceseeseensensees 3 7 Grab Programming FlOWchalt ect eeeeseceeceseeesceseeeeeeeeeeeseneeeneenees 3 9 Sequence Programming Flowchart 0 ceeeeeceseeeeceeeceeeeeeseeeeeeeenes 3 10 Ring Programming Flowchart 0 0 0 0 s
22. IMAQ NI IMAQ User Manual Image Acquisition Software Sinstrumenrs June 1998 Edition Part Number 371443A 01 Internet Support E mail support natinst com FTP Site ftp natinst com Web Address http www natinst com Bulletin Board Support BBS United States 512 794 5422 BBS United Kingdom 01635 551422 BBS France 01 48 65 15 59 Fax on Demand Support 512418 1111 Telephone Support USA Tel 512 795 8248 Fax 512 794 5678 International Offices Australia 03 9879 5166 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Brazil 011 288 3336 Canada Ontario 905 785 0085 Canada Qu bec 514 694 8521 Denmark 45 76 26 00 Finland 09 725 725 11 France 01 48 14 24 24 Germany 089 741 31 30 Hong Kong 2645 3186 Israel 03 6120092 Italy 02 413091 Japan 03 5472 2970 Korea 02 596 7456 Mexico 5 520 2635 Netherlands 0348 433466 Norway 32 84 84 00 Singapore 2265886 Spain 91 640 0085 Sweden 08 730 49 70 Switzerland 056 200 51 51 Taiwan 02 377 1200 United Kingdom 01635 523545 National Instruments Corporate Headquarters 6504 Bridge Point Parkway Austin Texas 78730 5039 USA Tel 512 794 0100 Copyright 1996 1998 National Instruments Corporation All rights reserved Important Information Warranty Copyright Trademarks The media on which you receive National Instruments software are warranted not to fail to execute programming instructions due to defects in materials and workmanship for a period of 90 da
23. ONE Board Initiates Acquisition A l i Buffer 0 Buffer 1 Buffer 2 Data In Data In Data In l Memory Memory Memory I All Image Data In Memory Figure 3 1 NI IMAQ Status Signals You can use the NI IMAQ status signals for many purposes Pulses can be generated based on the assertion of any of these signals This allows you to generate specific timing pulses based on acquisitions to control other aspects of your system such as a strobe light Furthermore you can configure callback functions that are invoked based on any of these signals For example you may want to initiate an image processing routine as soon as an image is in memory You can configure a callback containing image processing code to be invoked when Buffer Complete is asserted Introductory Programming Examples CF7 Note NI IMAQ User Manual This section introduces some examples for performing the different types of image acquisition The error codes that NI IMAQ returns are not included in the examples In your programs always check the return code for errors You can find these code examples in the ni imaq samples directory 3 6 National Instruments Corporation Chapter 3 Programming with NI IMAQ High Level Snap Functions A snap acquires a single image into a memory buffer Snap functions include imgSnap and imgSnapArea Use these functions to acquire a single frame or field to a buffer To use these functions you must have a
24. abetical list of key terms and topics in this manual including the page where you can find each one Conventions Used in This Manual cP bold bold italic italic italic monospace monospace NI IMAQ User Manual The following conventions are used in this manual This icon to the left of bold italicized text denotes a note which alerts you to important information Bold text denotes menus menu items or dialog box buttons or options Bold italic text denotes a note caution or warning Italic text denotes emphasis a cross reference or an introduction to a key concept Italic text in this font denotes that you must supply the appropriate words or values in the place of these items Lowercase text in this font denotes text or characters that are to be literally input from the keyboard sections of code programming examples and syntax examples This font is also used for the proper names of disk drives paths directories programs subprograms subroutines device names functions variables filenames and extensions and for statements and comments taken from program code X National Instruments Corporation About This Manual National Instruments Documentation The NI IMAQ User Manual is one piece of the documentation set for your system You could have any of several types of documents depending on the hardware and software in your system Use the documents you have as follows e Your IMAQ hardware
25. al goes TRUE when the last piece of data is transferred to memory indicating that the acquisition has completed Frame Start and Frame Stop indicate the status of an acquisition on a buffer basis Frame Start indicates that a buffer is being acquired This signal goes TRUE when the first valid pixel is detected by the board even if this pixel is not in the current region of interest The signal goes FALSE when the last valid pixel is detected by the board If the acquisition is a sequence or a ring Frame Start will pulse for every buffer in the acquisition Frame Done is the reverse of Frame Start and indicates when the image is transferred from the camera to the IMAQ board Buffer Complete indicates when the image data has been transferred to memory and is available for image processing Buffer Complete will go TRUE when the data in an image buffer has been transferred to memory either onboard or system memory depending on the acquisition National Instruments Corporation 3 5 NI IMAQ User Manual Chapter 3 Programming with NI IMAQ Figure 3 1 illustrates the values of the signals during a three buffer sequence acquisition AQ_IN_PROGRESS _ AN Board Initiates Acquisition FRAME_START FRAME_DONE BUF_COMPLETE E I All Image Data In Memory l X Last Valid Pixel Acquired ya By Board SE a Jh l First Valid Pixel Acquired s By Board AQ_D
26. an acquisition that loops continually on a specified number of buffers The high level function set also allows simple triggered acquisitions and the generation of external signals on the trigger lines National Instruments Corporation 3 1 NI IMAQ User Manual Chapter 3 Programming with NI IMAQ Low Level Functions The low level function set supports all types of acquisition and can be used to e Create a custom acquisition sequence or ring e Create and manage your own buffers e Set session and interface attributes to adjust image quality and size e Start a synchronous or asynchronous acquisition e Extract buffers out of a live acquisition for analysis e Set up and control triggered acquisitions Establishing Interface Connections and Sessions To acquire images using the high level or low level functions you must first learn how to establish a connection to an interface and create a session See the Interface Functions and Session Functions sections in this chapter for information on how to manage interfaces and sessions then refer to the high level or low level samples for information on acquiring images Interface Functions NI IMAQ User Manual Use interface functions to query the number of available interfaces establish a connection to control access to and initialize hardware such as the PCI PXI 1408 All interfaces in NI IMAQ are specified by a name By default the system creates default names for the number of
27. as a standard monochrome video signal such as RS 170 NTSC or CCIR 601 PAL e A modulated signal that contains the color information from the image The format of this signal depends on your camera The three main color standards are as follows M NTSC also called NTSC which is used mainly in the US and Japan B G PAL also called PAL which is used mainly in Europe India and Australia SECAM which is used mainly in France and the former Soviet Republics SECAM is only used for broadcasting so SECAM countries often use PAL as the local color image format National Instruments Corporation A 1 NI IMAQ User Manual Appendix A StillColor StillColor StillColor is a technique you can use to acquire color images from composite color video or RGB cameras using the PCI PXI 1408 monochrome device Use StillColor Composite mode to acquire color images from a composite color video camera Use StillColor RGB mode to acquire color images from an RGB camera StillColor composite acquisition results in an image of much higher quality than the traditional color decoding that can be obtained with a color image acquisition board To acquire a color image the PCI PXI 1408 acquires multiple frames from the camera Your computer CPU then processes the frames using the StillColor algorithm and creates a single color image Because StillColor uses your computer CPU to process the image the acquisition time for a single image depend
28. by the session ID imgSessionStopAcquisition Stops a session acquisition identified by the session ID Signal 1 0 Functions Signal I O functions control the trigger lines on IMAQ devices imgSessionTriggerConfigure Configures an acquisition to start based on an external trigger imgSessionLineTrigSource Configures triggering per line for acquisition from a line scan camera imgSessionTriggerClear Disables all triggers on the session imgSessionTriggerDrive Configures the specified trigger line to drive a signal out imgSessionTriggerRead Reads the current value of the specified trigger line imgSessionWaitSignal Waits for a signal to be asserted This function will return when the specified signal is asserted National Instruments Corporation 2 3 NI IMAQ User Manual Chapter 2 Software Overview imgSessionWaitSignalAsync imgPulseCreate imgPulseDispose imgPulseRate imgPulseStart imgPulseStop Miscellaneous Functions Monitors for a signal to be asserted and invokes a user defined callback when the signal is asserted Configures the attributes of a pulse A single pulse consists of a delay phase phase 1 followed by a pulse phase phase 2 and then a return to the phase 1 level Disposes of a pulse ID Converts delay and width into delay width and timebase values needed by imgPulseCreate Starts the generation of a pulse You must call imgPulseCreate first to configure the pulse Sto
29. ctions c ccesecessececceceeceesceeeecesaeceneeceeeecsaeecaeeneeeeneceseeeea 2 4 Low Level F NCHUONS isei enee ens n a a a a E 2 5 Acquisition Functions essseeesseeesssresrsresrrresrtrteseeresretesrsesresesrrsreersreeresrereses 2 5 Attib te FUNCTIONS eiren a ee A E E A E 2 6 Buffer Management Functions esesesssseseessseessseeerrrrererrereerssrrrrsreersreresreereens 2 6 Interface FUNCIONS onse esnea eire iaiia ne ar E EE Easa 2 7 Utility Functions ae ao A A E E AR 2 7 National Instruments Corporation v NI IMAQ User Manual Contents Chapter 3 Programming with NI IMAQ Introduction eyer n nanen i Ea EE eaten a Sieve Bosra ETE EEES 3 1 High Level F nctions isen ri eaa a tah E AE AN 3 1 Low Level Functions 000 0 en e nr a a 3 2 Establishing Interface Connections and Sessions ssseeesseeesseresrsresesersreereresreresressee 3 2 Interface Functions smsni a e S E E REE N 3 2 Session FUNCTIONS eens ree e S RE A E E 3 3 Managing Butters ane enin Shia A A E ARE 3 4 Camera Atri DUtes ieee eere ae EE E EA O EA NOEN O eatvondes SEAE EESE ERES 3 4 NI IMAQ Status Signals iiie e airosa ens enn e EEE EE Ei rR I eaii 3 5 Introductory Programming Examples esessesesessesesssstereseesrrreersrrsrerrsseresseeesrenenreererenes 3 6 High Level Snap Functions ssssssseesseeeseesssrssssteesrerrsresrsrteserrnenrssrerrsresesreeene 3 7 High Level Grab FUNCIONS seses 2 5 soshseveepestevteseietensaiesh esse alee eed
30. de NI IMAQ User Manual Programming with NI IMAQ This chapter contains an overview of the NI IMAQ library a description of the programming flow of NI IMAQ and programming examples Flowcharts are included for the following operations snap grab sequence ring and StillColor acquisitions Introduction The NI IMAQ API is divided into two groups the high level functions and the low level functions With the high level functions you can write programs quickly without having to learn the details of the low level API and driver The low level functions give you finer granularity and control over your image acquisition process but you must understand the API and driver in greater detail CF Note The high level functions call low level functions and use certain attributes that are listed in the high level function description in the NI IMAQ Function Reference Manual Changing the value of these attributes while using low level functions will affect the operation of the high level functions High Level Functions The high level function set supports four basic types of image acquisition e Snap acquires a single frame or field to a buffer e Grab performs an acquisition that loops continually on one buffer you obtain a copy of the acquisition buffer by grabbing a copy to a separate buffer that can be used for analysis e Sequence performs an acquisition that acquires a specified number of buffers then stops e Ring performs
31. e Manual which contains detailed descriptions of the NI IMAQ functions Organization of This Manual The NJ IMAQ User Manual is organized as follows e Chapter 1 Introduction to NI IMAQ describes the NI IMAQ software and lists the application development environments compatible with NI IMAQ describes the fundamentals of creating NI IMAQ applications for Windows 95 and Windows NT describes the files used to build these applications and tells you where to find sample programs e Chapter 2 Software Overview describes the classes of NI IMAQ functions and briefly describes each function e Chapter 3 Programming with NI IMAQ contains an overview of the NI IMAQ library a description of the programming flow of NI IMAQ and programming examples e Appendix A StillColor describes the different methods you can use to acquire a color image using the IMAQ PCI PXI 1408 and National Instruments StillColor technology explains basic color theories and describes the different output options supported by StillColor National Instruments Corporation ix NI IMAQ User Manual About This Manual e Appendix B Customer Communication contains forms you can use to request help from National Instruments or to comment on our products and manuals e The Glossary contains an alphabetical list and description of terms used in this manual including abbreviations acronyms metric prefixes mnemonics and symbols e The Jndex contains an alph
32. ease refer to the readme txt file located in your target installation directory for the latest details on NI IMAQ sample programs These programs are installed in the sample subdirectory under the target installation folder if you elected to install the sample files NI IMAQ User Manual 1 4 National Instruments Corporation Software Overview This chapter describes the classes of NI IMAQ functions and briefly describes each function Introduction NI IMAQ functions are grouped according to the following classes e Generic functions e High level functions Snap functions Grab functions Ring and sequence functions Signal I O functions Miscellaneous functions e Low level functions Acquisition functions Attribute functions Buffer management functions Interface functions Utility functions The generic and high level functions appear within each function class in the logical order you might need to use them The low level functions appear within each function class in alphabetical order National Instruments Corporation 2 1 NI IMAQ User Manual Chapter 2 Software Overview Generic Functions Use generic functions in both high level and low level applications imgInterfaceOpen imgSessionOpen imgClose High Level Functions Opens by name an interface as specified in the IMAQ Configuration Utility Opens a session of an unknown type and returns a session ID Closes a session or interface a
33. ee ceeeseceeceseeeseeseeeeceeeeeeeeneeeeeenees 3 12 Signal I O Function Programming Flowchart sees eseeeeecteeeeee 3 14 Composite StillColor Snap Programming Flowchatt eee 3 17 Classical Decoding sssini eneore tr eaer EErEE eE E aS EEEE EE A 4 S llColor Decoding ascii eeo neeesa eai oa Enese ke SEE reke oneik A 4 White Light and the Visible Spectrum ssssessseeerseserseresrersereresrreesrees A 7 Import Libraries sennior otn eer rE an ES r E E ETs 1 3 Interface Naming Convention ssesssseeseseeeeseereresrerrsrssesresrerrereneesrereses 3 2 National Instruments Corporation vii NI IMAQ User Manual About This Manual NI IMAQ software is a powerful application programming interface API between your image acquisition application and the National Instruments image acquisition IMAQ devices This manual explains how to use your NI IMAQ software How to Use the NI IMAQ Manual Set To install your software and documentation set you should begin by reading the setup and test document included with your hardware and the NI IMAQ release notes These documents contain information about how to install your software and hardware Then read Chapter 1 Introduction of the your hardware user manual which contains a flowchart that illustrates the sequence of steps you should take to learn about and get started with NI IMAQ When you are familiar with the material in this manual you can use the NI IMAQ Function Referenc
34. ence acquisition to multiple buffers allocated by NI IMAQ As described in the low level snap example the program retrieves the acquisition window width of the selected camera and aligns it on a 32 bit boundary It creates a buffer list to describe the acquisition buffers Next the program sets the ROI to the acquisition window width The program calculates the correct memory requirements of the frame buffer However this is not necessary if you choose to use the default acquisition window width rowPixels and ROI In this case NI IMAQ will allocate the correct size buffer if you pass a NULL as the size parameter to imgCreateBuf fer The program creates the buffer and configures the buffer list for each buffer element in the ring The program locks the memory and starts the image acquisition asynchronously National Instruments Corporation 3 15 NI IMAQ User Manual Chapter 3 Programming with NI IMAQ The main processing loop of the code shows how to process each buffer acquired in sequential order Performing a Ring Acquisition Using Low Level Functions The LLRing c example demonstrates how to perform a ring acquisition using low level calls The example sets up a continuous acquisition to multiple buffers allocated by NI IMAQ As described in the low level snap example the program retrieves the acquisition window width of the selected camera and aligns it on a 32 bit boundary It then creates a buffer list to describe the acquisition
35. er of scans read or updates written per second G 6 National Instruments Corporation IC ID IEEE INL instrument driver interlaced interpreter interrupt interrupt level T O IRE IRQ National Instruments Corporation G 7 Glossary integrated circuit identification Institute of Electrical and Electronics Engineers inches integral nonlinearity A measure in LSB of the worst case deviation from the ideal A D or D A transfer characteristic of the analog I O circuitry a set of high level software functions such as NI IMAQ that controls specific plug in computer boards instrument drivers are available in several forms ranging from a function callable from a programming language to a virtual instrument VI in LabVIEW a video frame composed of two interleaved fields the number of lines in a field are half the number of lines in an interlaced frame a software utility that executes source code from a high level language such as Basic C or Pascal by reading one line at a time and executing the specified operation See also compiler a computer signal indicating that the CPU should suspend its current task to service a designated activity the relative priority at which a device can interrupt input output the transfer of data to from a computer system involving communications channels operator interface devices and or data acquisition and control interfaces a relative unit of measure named fo
36. eresesrssrerrsrerrsresrerenseressreresreresresesrrereersre ix Conventions Used in This Mantial cccccccccccsssccccesesssecececenseceececesseaececceessaseeseseneaees x National Instruments Documentation cccccccccecesssseceececesaececcecsessceseeceessaeeeeeseneaeees xi Related DoE O aa e E S E xi Customer Communication cccccccceesssccececesssceececsenseeceeceessaececeecsensceceeceesssesecesessseeeeees xi Chapter 1 Introduction to NI IMAQ About the NI IMAQ Software enee e e E E O a i aee 1 1 Application Development Environments essesssessesrseseesesersesererrerererreresessee 1 2 Fundamentals of Building Applications with NI IMAQ ssesessseessssessrssrrsressrrsrrssresres 1 2 The NI IMAQ Libraries ccccccccssccccecesssceececeececeeceessceceeceessseseceeensaeeeeees 1 2 Creating an Application eee eeeeceseecseceecaecaesaeceecesecsceeeeeeseneeaeeeaes 1 3 Sample Programs lt ssse d csosssessssevessusdatediagsssvsssesesoed sas EE ea TEETE Ep SESS iE roa 1 4 Chapter 2 Software Overview TMTFOCUCUION Sron e a e i i A T el ees 2 1 Generi FUN ction ss 3 c see i A A idles ed E E E 2 2 High Level Functions arasin e EE ENEE 2 2 Snap Functions esee see E E EE E ERE EAE 2 2 Grab FUN CUONS e aeree eria nE e evan nea aiei 2 2 Ring and Sequence Functions sesesseeeseeetseeeeeesestereseeresreesrsserrrseerrsreresreereees 2 3 Signal O Functions e ees a be hell R a E E A S 2 3 Miscellaneous Fun
37. essed in decibels electrically erasable programmable read only memory ROM that can be erased with an electrical signal and reprogrammed a voltage pulse from an external source that triggers an event such as A D conversion For an interlaced video signal a field is half the number of horizontal lines needed to represent a frame of video the first field of a frame contains all the odd numbered lines the second field contains all of the even numbered lines first in first out memory buffer the first data stored is the first data sent to the acceptor FIFOs are used on IMAQ devices to temporarily store incoming data until that data can be retrieved For example an analog input FIFO stores the results of A D conversions until the data can be retrieved into system memory a process that requires the servicing of interrupts and often the programming of the DMA controller This process can take several milliseconds in some cases During this time data accumulates in the FIFO for future retrieval an ADC whose output code is determined in a single step by a bank of comparators and encoding logic a complete image in interlaced formats a frame is composed of two fields the area of a video signal between the start of the horizontal blank and the start of the horizontal sync feet NI IMAQ User Manual Glossary function G gamma genlock GND GUI hardware HSYNC HSYNCIN hue NI IMAQ User Manual a set of sof
38. et up operations the maximum rate at which the hardware can operate trigger signal any event that causes or starts some form of data capture circuitry that routes monitors and drives the external and RTSI bus trigger lines you can configure each of these lines to start or stop acquisition on a rising or falling edge transistor transistor logic See YUV volts voltage controlled oscillator an oscillator that changes frequency depending on a control signal used in a PLL to generate a stable pixel clock Virtual Instrument 1 a combination of hardware and or software elements typically used with a PC that has the functionality of a classic stand alone instrument 2 a LabVIEW software module VI which consists of a front panel user interface and a block diagram program a video line consists of a HSYNC back porch active pixel region and a front porch G 12 National Instruments Corporation VSYNC VSYNCIN W white reference level YUV Glossary vertical sync signal the synchronization pulse generated at the beginning of each video field that tells the video monitor when to start a new field vertical sync in signal the level that defines what is white for a particular video system See also black reference level a representation of a color image used for the coding of NTSC or PAL video signals The luminance information is called Y while the chrominance information is represented by two components
39. fers commonly used instructions or data to increase processing throughput Comite Consultatif International des Radiocommunications a committee that developed standards for color video signals the color information in a video signal complementary metal oxide semiconductor a software utility that converts a source program in a high level programming language such as Basic C or Pascal into an object or compiled program in machine language Compiled programs run 10 to 1 000 times faster than interpreted programs See also Interpreter device that transforms a signal from one form to another for example analog to digital converters ADCs for analog input and digital to analog converters DACs for analog output central processing unit composite sync signal a combination of the horizontal and vertical sync pulses composite sync in signal composite sync out signal NI IMAQ User Manual Glossary D A DAC DAQ dB DC default setting DIN DLL DMA DRAM drivers NI IMAQ User Manual digital to analog digital to analog converter an electronic device often an integrated circuit that converts a digital number into a corresponding analog voltage or current data acquisition 1 collecting and measuring electrical signals from sensors transducers and test probes or fixtures and inputting them to a computer for processing 2 collecting and measuring the same kinds of electrical signals with A D o
40. ge The acquisition is started at setup time and the setup call is synchronous High Level Ring Functions Ring and sequence functions include imgRingSetup imgSessionStartAcquisition and imgStopAcquisition Use these functions to perform a continuous acquisition that loops or stops after a certain number of images have been captured A ring initiates a continuous high speed acquisition to multiple buffers Calling imgRingSet up initiates a ring imgRingSetup specifies both the buffer list that will be used for transfers and the number of buffers After imgRingSetup is called you can monitor the status of the transfer and perform processing on any of the buffers in the ring A ring is appropriate for high speed applications where you need to perform processing on every image You must use multiple buffers because processing times may vary depending on other applications and processing results You can configure a ring to acquire every frame or to skip a fixed number of frames between each acquisition For certain applications you can temporarily extract a buffer from the ring to prevent it from being overwritten during the ring s next pass Use the imgSessionExamineBuffer and imgSessionReleaseBuffer functions to do this Figure 3 5 illustrates a typical ring programming order National Instruments Corporation 3 11 NI IMAQ User Manual Chapter 3 Programming with NI IMAQ 7 imgInterfaceOpen opens imgInterfaceOpen
41. he image If you choose to plot the image using the imgP1ot function you must align the image width on a 32 bit boundary as well Performing a Grab Using Low Level Functions The LLGrab c example demonstrates how to perform a grab acquisition using low level calls The example sets up a continuous acquisition to a single user allocated buffer As described in the low level snap example the program retrieves the acquisition window width of the selected camera and aligns it on a 32 bit boundary The program creates a buffer list to describe the acquisition buffers Next the program sets the ROI to the acquisition window width The program performs a calculation to determine the correct memory requirements of the user buffer The program creates the buffer and configures buffer element 0 for a single continuous acquisition The program then locks the memory and starts the image acquisition asynchronously The main processing loop of the code shows how to wait for vertical blank and copy the buffer to an analysis buffer Keep your analysis code fast to minimize the number of missed frames during analysis If you need more time to examine a buffer set up a multiple buffer ring and call imgSessionExamineBuf fer to extract the desired buffer from the live sequence Performing a Sequence Acquisition Using Low Level Functions The LLSeq c example demonstrates how to perform a sequence acquisition using low level calls The example sets up a sequ
42. igh level grab functions 3 8 to 3 9 high level ring functions 3 11 to 3 13 high level sequence functions 3 10 to 3 11 high level signal I O functions 3 13 to 3 14 high level snap functions 3 7 to 3 8 location note 3 6 location of files 1 4 NI IMAQ User Manual Index F H header files 1 3 high level functions 2 2 to 2 4 grab functions 2 2 to 2 3 introductory programming examples 3 6 to 3 14 fax and telephone support numbers B 2 Fax on Demand support B 2 files required for application development 1 3 FTP support B 1 functions generic functions 2 2 high level functions 2 2 to 2 4 grab functions 2 2 to 2 3 miscellaneous functions 2 4 programming considerations 3 1 programming examples 3 6 to 3 14 ring and sequence functions 2 3 session functions 2 4 3 3 to 3 4 signal I O functions 2 3 to 2 4 snap functions 2 2 low level functions 2 5 to 2 7 acquisition functions 2 5 attribute functions 2 6 buffer management functions 2 6 to 2 7 3 4 interface functions 2 7 3 2 programming considerations 3 2 programming examples 3 14 to 3 17 utility functions 2 7 overview 2 1 grab functions 3 8 to 3 9 ring functions 3 11 to 3 13 sequence functions 3 10 to 3 11 signal I O functions 3 13 to 3 14 snap functions 3 7 to 3 8 miscellaneous functions 2 4 programming considerations 3 1 ring and sequence functions 2 3 signal I O functions 2 3 to 2 4 snap functions 2 2 hue A 7 hue planes
43. ion Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently National Instruments Products IMAQ hardware Interrupt level of hardware Address of hardware Programming choice NI IMAQ IMAQ Vision LabVIEW BridgeVIEW or ComponentWorks version Other boards in system Base I O address of other boards DMA channels of other boards Interrupt level of other boards Other Products Computer make and model Microprocessor Clock frequency or speed PCI chipset Type of video board installed Operating system version Operating system mode Programming language Programming language version Other boards in system Base I O address of other boards DMA channels of other boards Interrupt level of other boards Documentation Comment Form National Instruments encourages you to comment on the documentation supplied with our products This information helps us provide quality products to meet your needs Title NI IMAQ User Manual Edition Date June 1998 Part Number 371443A 01 Please comment on the completeness clarity and organization of the manual If you find errors in the manual please record the page numbers and describe the errors Thank you for your help Name Title Company Address E Mai
44. ipheral Component Interconnect a high performance expansion bus architecture originally developed by Intel to replace ISA and EISA it is achieving widespread acceptance as a standard for PCs and workstations and offers a theoretical maximum transfer rate of 132 Mbytes s pixel clock signal times the sampling of pixels on a video line NI IMAQ User Manual Glossary PCLKIN PFI PGIA picture aspect ratio pixel pixel aspect ratio pixel clock pixel count PLL protocol pts R RAM real time relative accuracy NI IMAQ User Manual pixel clock in signal programmable function input programmable gain instrumentation amplifier the ratio of the active pixel region to the active line region for standard video signals like RS 170 or CCIR the full size picture aspect ratio normally is 4 3 1 33 picture element the smallest division that makes up the video scan line for display on a computer monitor a pixel s optimum dimension is square aspect ratio of 1 1 or the width equal to the height the ratio between the physical horizontal size and the vertical size of the region covered by the pixel an acquired pixel should optimally be square thus the optimal value is 1 0 but typically it falls between 0 95 and 1 05 depending on camera quality divides the incoming horizontal video line into pixels the total number of pixels between two HYSNCs the pixel count determines the frequency of the pixel clock
45. ition window read only memory the U S standard used for black and white television Real Time System Integration Bus the National Instruments timing bus that connects IMAQ and DAQ boards directly by means of connectors on top of the boards for precise synchronization of functions seconds the richness of a color A saturation of zero corresponds to no color that is a gray pixel Pink is a red with low saturation circuitry that scales down the resolution of a video signal a type of DMA that allows the DMA controller to reconfigure on the fly static RAM a post processing algorithm that allows the acquisition of high quality color images generated either by an RGB or composite NTSC or PAL camera using a monochrome video acquisition board tells the display where to put a video picture the horizontal sync indicates the picture s left to right placement and the vertical sync indicates top to bottom placement NI IMAQ User Manual Glossary syntax system RAM T transfer rate TRIG trigger trigger control and mapping circuitry TTL U UV plane V y VCO VI video line NI IMAQ User Manual the set of rules to which statements must conform in a particular programming language RAM installed on a personal computer and used by the operating system as contrasted with onboard RAM the rate measured in bytes s at which data is moved from source to destination after software initialization and s
46. itude varies in proportion to the brightness of the video signal and corresponds exactly to the monochrome picture e Intensity which is the brightness of a color and which is usually expressed as light or dark For example orange and brown may have the same hue and saturation however orange has a greater intensity than brown National Instruments Corporation A 7 NI IMAQ User Manual Appendix A StillColor Image Representations NI IMAQ User Manual Color images can be represented in several different formats These formats can contain all color information from the image or they can consist of just one aspect of the color information such as hue or luminance The following image representations can be produced using NI IMAQ and StillColor RGB The most common image representation is 32 bit RGB format In this representation the three 8 bit color planes red green and blue are packed into an array of 32 bit integers This representation is useful for displaying the image on your monitor The 32 bit integer organized as 0 RED GREEN BLUE where the high order byte is not used and blue is the low order byte The system also supports a 24 bit and a 16 bit representation of the RGB image The 24 bit representation is equivalent to the 32 bit representation however there is no unused byte For the 16 bit representation the image is packed into an array of 16 bit integers where each 16 bit pixel contai
47. l Address Phone Fax Mail to Technical Publications Faxto Technical Publications National Instruments Corporation National Instruments Corporation 6504 Bridge Point Parkway 512 794 5678 Austin Texas 78730 5039 Glossary Prefix Meanings Value p pico 10 2 n nano 10 9 u micro 10 6 m milli 10 3 k kilo 103 M mega 10 G giga 10 Numbers Symbols 5V 5 V signal negative of or minus Q ohm per percent plus or minus positive of or plus A amperes AC alternating current acquisition window the image size specific to a video standard or camera resolution National Instruments Corporation G 1 NI IMAQ User Manual Glossary active line region active pixel region A D ADC address ANSI antichrominance filter API AQ_ DONE AQ_IN_PROGRESS area array ASIC aspect ratio back porch NI IMAQ User Manual the region of lines actively being stored defined by a line start relative to VSYNC and a line count the region of pixels actively being stored defined by a pixel start relative to HSYNC and a pixel count analog to digital analog to digital converter an electronic device often an integrated circuit that converts an analog voltage to a digital number character code that identifies a specific location or series of locations in memory American National Standards Institute removes the color i
48. l grab programming order 3 8 National Instruments Corporation Chapter 3 Programming with NI IMAQ va imgInterfaceOpen opens imgInterfaceOpen and configures the interface according to the file setup by the IMAQ Configuration Utility Vv a ias Pen imgSessionOpen opens a session that STO AR will be used for all acquisition and configuration y imgGrabSetup configures the interface for a Tmgerab cup continuous acquisition Yy a 5 EEEN faded imgSessionStartAcquisition starts poral ba energy ete ean dearer the acquisition into a driver buffer imgGrab copies the contents of the driver buffer to a user buffer This function can be synchronized to a vertical blank or initiated asynchronously The buffer can be passed into imgGrab or automatically allocated by NI IMAQ imgGrab can be called multiple times for high speed acquisition y ra User Specific Functions User specific image processing imgSessionStopAcquisition imgSessionStopAcquisition stops the grab function fa imgClose imgClose closes the interface and session Figure 3 3 Grab Programming Flowchart The hlgrab c example demonstrates how to perform a grab using imgGrabArea The example performs multiple grabs until an appropriate condition is met The program configures the session to perform a grab operation by calling the imgGrabSetup function The program then calculates the area to grab using the cur
49. nd unlocks and releases all buffers associated with the data type Use high level functions to quickly and easily capture images If you need more advanced functionality you can mix high level functions with low level functions Snap Functions Snap functions program the session to capture all or a portion of a single frame or field to the user buffer imgSnap imgSnapArea Grab Functions Performs a single frame and field acquisition Performs an area specific frame or field acquisition Grab functions start a continuous image acquisition to a user buffer Any frame or field can be copied from the grab buffer to another user buffer imgGrabSetup imgGrab NI IMAQ User Manual 2 2 Configures and optionally starts a continuous acquisition Performs a transfer from a continuous acquisition session Call this function only after calling imgGrabSetup National Instruments Corporation Chapter 2 Software Overview imgGrabArea Performs a transfer from a continuous acquisition Call this function only after calling imgGrabSetup Ring and Sequence Functions Ring and sequence functions start and stop a continuous acquisition of multiple fields or frames imgRingSetup Prepares a session for acquiring continuously and looping into a buffer list imgSequenceSetup Prepares a session for acquiring a full sequence into the buffer list imgSessionStartAcquisition Starts a session acquisition identified
50. nformation from the video signal application programming interface signals that the acquisition of a frame or field is completed signals that the acquisition of video data is in progress a rectangular portion of an acquisition window or frame that is controlled and defined by software ordered indexed set of data elements of the same type Application Specific Integrated Circuit a proprietary semiconductor component designed and manufactured to perform a set of specific functions for a specific customer the ratio of a picture or image s width to its height bit one binary digit either 0 or 1 byte eight related bits of data an eight bit binary number also used to denote the amount of memory required to store one byte of data the area of the video signal between the rising edge of the horizontal sync signal and the active video information G 2 National Instruments Corporation black reference level buffer bus cache CCIR chrominance CMOS compiler conversion device CPU CSYNC CSYNCIN CSYNCOUT National Instruments Corporation G 3 Glossary the level that represents the darkest an image can get See also white reference level temporary storage for acquired data the group of conductors that interconnect individual circuitry in a computer such as the PCI bus typically the expansion vehicle to which I O or other devices are connected Celsius high speed processor memory that buf
51. ns red green and blue encoded with only five bits each The most significant bit of the integer is always 0 Color Planes Each color plane can be returned individually The red green or blue plane is extracted from the RGB image and represented as an array of 8 bit integers Hue Saturation Luminance and Intensity Planes The hue saturation luminance and intensity planes can also be returned individually if you want to analyze the image You can retrieve the data in 8 bit format to reduce the amount of data to be processed or in 16 bit format to take advantage of the higher precision available when using averaging The 16 bit image representation is scaled so that the pixel values are always positive The value range is 0 to 32 767 so it is compatible with both 16 bit signed and 16 bit unsigned integers On average the 16 bit representation of a plane is equal to 128 times the 8 bit representation of the plane from the same image The 16 bit representation is generally only A 8 National Instruments Corporation Appendix A StillColor used if you are performing averaging on your image For example averaging an image 16 times requires four extra bits 16 hd to represent the increased dynamic range In this case using the 16 bit representation may increase the dynamic range of your image Luminance Intensity Hue or Saturation are defined using the Red Green and Blue values in the following formulas Luminance
52. nstruments Corporation Technical Support Form Photocopy this form and update it each time you make changes to your software or hardware and use the completed copy of this form as a reference for your current configuration Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently If you are using any National Instruments hardware or software products related to this problem include the configuration forms from their user manuals Include additional pages if necessary Name Company Address Fax Phone Computer brand Model Processor Operating system include version number Clock speed MHz RAM MB Display adapter Mouse ___ yes ___no___ Other adapters installed Hard disk capacity MB Brand Instruments used National Instruments hardware product model Revision Configuration National Instruments software product Version Configuration The problem is List any error messages The following steps reproduce the problem NI IMAQ Hardware and Software Configuration Form Record the settings and revisions of your hardware and software on the line to the right of each item Complete a new copy of this form each time you revise your software or hardware configuration and use this form as a reference for your current configurat
53. nt is the number of frames skipped prior to acquiring an image to a buffer The program then loops waiting for the next buffer to be acquired The imgSessionStatus function queries NI IMAQ for the buffer number of the last valid buffer that has been acquired The last valid buffer is defined as the buffer that contains 3 12 National Instruments Corporation Chapter 3 Programming with NI IMAQ the most recent video image This process will continue until a designated condition is met and then the acquisition stops High Level Signal 1 0 Functions The signal I O functions fall into two categories triggering acquisitions and driving the external trigger lines Triggered acquisitions allow images to be acquired precisely when an external event occurs such as a sensor activating The driving of external trigger lines allows external devices to be controlled in sync with the image acquisition For example a strobe light could be fired when a sequence acquisition begins Any of the four types of acquisitions can be initiated from an external trigger source by using imgSessionTriggerConfigure For sequence and ring just the first buffer in the list can be triggered or each buffer in the list can be triggered After using this function to set up the trigger any acquisition performed on the session will wait for a trigger Use imgSessionTriggerClear to remove the trigger settings from the session Some applications need to send signals out fr
54. olor and luminance information can be achieved after manipulation of these images After separating the color and luminance signals the StillColor algorithm then decodes and rebuilds the color image As shown in Figure A 2 the result does not show any of the artifacts encountered in traditional color decoding methods Composite Color Acquisition The PCI PXI 1408 in conjunction with NI IMAQ supports acquisition of color images from an NTSC or PAL composite color video camera NI IMAQ can acquire the multiple frames decode the color information and rebuild the image automatically The output image can be a simple RGB color image or one of many image representations supported by NI IMAQ See the Jntroduction to Color section later in this appendix for more information on image representations You can connect the composite video signal to any of the four input channels on the PCI PX I 1408 Since StillColor is used for still scenes you can perform only a snap a single image acquisition National Instruments Corporation A 5 NI IMAQ User Manual Appendix A StillColor StillColor RGB RGB cameras output a color image using three lines StillColor RGB will acquire the three signals and construct a color image The three lines are connected to three channels on the PCI PXI 1408 One frame is acquired from each of the three channels which represent the red green and blue planes of the image StillColor combines these frames to cons
55. om the IMAQ hardware to an external device Many types of signals can be driven out of the trigger lines by using imgSessionTriggerDrive This function takes a trigger line number the polarity the line should be driven and what to drive on the line This can be a steady state value of high or low or it can be one of the internal state signals of the hardware such as acquisition in progress When specific pulses need to be generated imgPulseCreate and imgPulseStart can be used Figure 3 6 shows the outline of a program that waits for an external trigger on line before acquiring a single image It also configures the driver to assert RTSI trigger line 3 when the acquisition is finished The trigsnap c example contains C code that implements this program National Instruments Corporation 3 13 NI IMAQ User Manual Chapter 3 Programming with NI IMAQ imgInterfaceOpen y imgSessionOpen y imgSessionTriggerConfigure y imgSessionTriggerDrive y imgSnap y User Specific Functions y imgClose imgInterfaceOpen opens and configures the interface according to the file set up by the IMAQ Configuration Utility imgSessionOpen opens a session that will be used for an acquisition imgSessionTriggerConfigure configures the session so that an acquisition will not occur until a trigger is received on external trigger line 1 imgSessionTriggerDrive configures the session so tha
56. ou to contact us this manual contains comment and configuration forms for you to complete These forms are in Appendix B Customer Communication at the end of this manual National Instruments Corporation xi NI IMAQ User Manual Introduction to NI IMAQ This chapter describes the NI IMAQ software and lists the application development environments compatible with NI IMAQ describes the fundamentals of creating NI IMAQ applications for Windows 95 and Windows NT describes the files used to build these applications and tells you where to find sample programs About the NI IMAQ Software Thank you for buying a National Instruments image acquisition IMAQ device which includes NI IMAQ software NI IMAQ is a set of functions that controls the National Instruments plug in IMAQ devices for image acquisition and Real Time System Integration RTSI bus multiboard synchronization NI IMAQ has both high level I O functions for maximum ease of use and low level I O functions for maximum flexibility and performance Examples of high level functions are snap and grab image acquisition Examples of low level functions are buffer setup and video configuration NI IMAQ enhances the performance of National Instruments IMAQ devices because it lets multiple devices operate at their peak performance NI IMAQ includes a buffer and data manager that uses sophisticated techniques for handling and managing image acquisition buffers so that you can simul
57. pen a session the ROI values are initialized from the acquisition window ACQWINDOW dimensions that are configured in the IMAQ Configuration Utility The ACQWINDOW dimensions will vary depending on the type of camera you are using National Instruments Corporation 3 7 NI IMAQ User Manual Chapter 3 Programming with NI IMAQ The sample then calls a process function to analyze the image When the program is finished it calls imgClose with the interface handle and sets the freeResources flag to TRUE This instructs NI IMAQ to free all of the resources associated with this interface which releases the session as well as the memory buffer allocated by imgSnap High Level Grab Functions NI IMAQ User Manual A grab is a continuous high speed acquisition of data to a single buffer in host memory Grab functions include imgGrabSetup imgGrab and imgGrabArea You can use these functions to perform an acquisition that loops continually on one buffer A copy of the acquisition buffer is obtained by grabbing a copy to a separate buffer To use these functions you must have a valid session handle Calling imgGrabSetup initializes a session for a grab acquisition After imgGrabSetup each successive grab will copy the last acquired buffer into a user buffer where you can perform processing on the image A grab is appropriate for high speed applications where you need processing performed on only one image at a time Figure 3 3 illustrates a typica
58. ps the generation of a pulse Miscellaneous functions set and get the acquisition window s region of interest and return information such as session status and buffer sizes imgSessionStatus imgSessionSetROI imgSessionGetROI imgSessionGetBufferSiz NI IMAQ User Manual 2 4 Gets the current session status Sets acquisition origin and dimension Gets acquisition origin and dimension Gets the minimum buffer size needed for frame buffer allocation National Instruments Corporation Chapter 2 Software Overview Low Level Functions Use low level functions when you require more direct hardware control Acquisition Functions Use acquisition functions to configure start and abort an image acquisition or examine a buffer during an acquisition imgMemLock Locks all session associated image buffers in memory in preparation for an acquisition imgMemUnlock Unlocks all session associated buffers imgSessionAbort Stops an asynchronous acquisition or synchronous continuous acquisition immediately imgSessionAcquire Starts acquisition synchronously or asynchronously to the frame buffers in the associated session buffer list imgSessionConfigure Specifies the buffer list to use with this session imgSessionCopyArea Copies an area of a session s buffer to a user specified buffer imgSessionCopyBuffer Copies a session s image data to a user buffer format imgSessionExamineBuffer Extracts a buffer from a
59. r DIO boards plugged into a computer and possibly generating control signals with D A and or DIO boards in the same computer decibel the unit for expressing a logarithmic measure of the ratio of two signal levels dB 20log10 V1 V2 for signals in volts direct current a default parameter value recorded in the driver in many cases the default input of a control is a certain value often 0 that means use the current default setting Deutsche Industrie Norme dynamic link library a software module in Microsoft Windows containing executable code and data that can be called or used by Windows applications or other DLLs functions and data in a DLL are loaded and linked at run time when they are referenced by a Windows application or other DLLs direct memory access a method by which data can be transferred to and from computer memory from and to a device or memory on the bus while the processor does something else DMA is the fastest method of transferring data to from computer memory dynamic RAM software that controls a specific hardware device such as an IMAQ or DAQ device G 4 National Instruments Corporation dynamic range E EEPROM external trigger field FIFO flash ADC frame front porch ft National Instruments Corporation G 5 Glossary the ratio of the largest signal level a circuit can handle to the smallest signal level it can handle usually taken to be the noise level normally expr
60. r the Institute of Radio Engineers 0 IRE corresponds to the blanking level of a video signal 100 IRE to the white level Note that for CIR PAL video the black level is equal to the blanking level or 0 IRE while for RS 170 NTSC video the black level is at 7 5 IRE interrupt request NI IMAQ User Manual Glossary kbytes s Kword L library line count LSB luminance LUT MB Mbytes s NI IMAQ User Manual kilo the standard metric prefix for 1 000 or 10 used with units of measure such as volts hertz and meters kilo the prefix for 1 024 or 2 used with B in quantifying data or computer memory a unit for data transfer that means 1 000 or 10 bytes s 1 024 words of memory a file containing compiled object modules each comprised of one of more functions that can be linked to other object modules that make use of these functions the total number of horizontal lines in the picture least significant bit the brightness information in the video picture The luminance signal amplitude varies in proportion to the brightness of the video signal and corresponds exactly to the monochrome picture look up table a selection in the IMAQ Configuration Utility that contains formulas that let you implement simple imaging operations such as contrast enhancement data inversion gamma manipulation or other nonlinear transfer functions meters 1 Mega the standard metric prefix for 1 million or 10 when
61. rent ROI rowPixels and BYTESPERPIXEL and the acquisition is started by calling imgSessionStartAcquisition In this example we allocate our own user buffer for grabbing and pass this buffer to imgGrabArea When the acquisition is complete it stops The program then frees the user buffer and all of the resources associated with this interface by calling imgClose National Instruments Corporation 3 9 NI IMAQ User Manual Chapter 3 Programming with NI IMAQ High Level Sequence Functions Sequence functions include imgSequenceSetup imgSessionStartAcquisition and imgStopAcquisition A sequence initiates a variable length and variable delay transfer to multiple buffers You can configure the delay between acquisitions with SequenceSetup and specify both the buffer list that will be used for transfers and the number of buffers After imgSequenceSetup you can monitor the status of the transfer and perform processing on any of the buffers in the sequence or you can wait until the acquisition completes and process all buffers simultaneously A sequence is appropriate for applications where you need to perform processing on multiple images You can configure a sequence to acquire every frame or skip a variable number of frames between each image Figure 3 4 illustrates a typical sequence programming order imgInterfaceOpen y imgSessionOpen y Buffer list setup y imgSequenceSetup r y imgSessionStatu
62. s y User Specific Functions N 1 1 1 1 1 i 1 1 i j 1 1i 1 1 i 1 1 i 1 imgClose e eee eee beets eee Loop ___ imgInterfaceOpen opens and configures the interface according to the file setup by the IMAQ Configuration Utility imgSessionOpen opens a session that will be used for all acquisition and configuration You must set up your buffer list and the number of the frames fields that need to be skipped between each acquisition imgSequenceSet up initiates a sequence toa programmable number of buffers These buffers can be created either by the driver using imgCreateBuffer or passing a NULL or by you imgSessionStatus gives the current status of the sequence including the buffer number of the last buffer that was successfully transferred With this information you can determine which buffer you want to process User specific image processing imgClose closes the interface and session NI IMAQ User Manual Figure 3 4 Sequence Programming Flowchart 3 10 National Instruments Corporation Chapter 3 Programming with NI IMAQ The HLSeq c example demonstrates how to perform a sequence acquisition using imgSequenceSetup The example sets up a sequence that uses 10 user allocated buffers Unlike the ring example each buffer in the sequence has its own skip count associated with it The skip count is the number of frames to skip prior to acquiring the next ima
63. s on your system performance You can acquire StillColor composite images at rates of up to 2 frames s and StillColor RGB images at rates of up to 10 frames s You can use StillColor in applications that require high quality images of still or very slowly moving objects StillColor supports many different image representations used in scientific or industrial applications such as RGB bitmap and single plane hue saturation luminance and intensity StillColor also supports image averaging of up to 128 frames to increase the dynamic range of the StillColor image See the Introduction to Color section later in this appendix for more information on image representations StillColor Composite NI IMAQ User Manual In a composite color video signal the color information chroma is modulated in phase and amplitude around a sub carrier frequency of 3 58 MHz NTSC or 4 43 MHz PAL The modulated signal is then added to the luminance information and the entire signal including synchronization pulses is transmitted on a single line Traditional Color Decoding On the receiver side or in your IMAQ board the luminance and the chroma signals must be separated before the color image can be decoded and rebuilt However the modulated color information and some of the high frequency luminance information share the same frequency range around the sub carrier frequency This sharing makes it impossible to separate the two signals perfectly and therefore
64. shed a connection to an interface you need to create a session and configure it to perform the type of acquisition you require To create a session call the imgSessionOpen function This function requires a valid interface handle and returns a handle to a session NI IMAQ then uses this session handle to reference this session when using other NI IMAQ calls To create a session use the following example program INTERFACE_ID interfaceID SESSION_ID sessionID if imgInterfaceOpen img0 amp interfaceID IMG_ERR_GOOD if imgSessionOpen interfaceID amp sessionID IMG_ERR_GOOD user code imgClose sessionID FALSE imgClose interfaceID FALSE National Instruments Corporation 3 3 NI IMAQ User Manual Chapter 3 Programming with NI IMAQ This example opens an interface to img0 and then creates a session to acquire images When the program is finished with the interface and session it then closes both handles using the imgClose function For a complete list of the available session functions refer to the NI IMA Q Function Reference Manual Managing Buffers Buffer management can be performed either by you or automatically by NI IMAQ If the high level acquisition routines imgSnap imgGrab imgSequenceSetup and imgRingSetup are initiated with NULL pointers for buffer addresses NI IMAQ will automatically allocate a buffer and return the value of the buffer pointer to you After you have a
65. snap functions 3 14 to 3 15 StillColor snap programming 3 16 to 3 17 National Instruments Corporation l 3 Index buffer management 3 4 camera attributes 3 4 to 3 5 high level functions 3 1 interface functions 3 2 to 3 3 introductory examples 3 6 to 3 14 high level grab functions 3 8 to 3 9 high level ring functions 3 11 to 3 13 high level sequence functions 3 10 to 3 11 high level signal I O functions 3 13 to 3 14 high level snap functions 3 7 to 3 8 location note 3 6 low level functions 3 2 session functions 3 3 to 3 4 status signals 3 5 to 3 6 programming environments supported by NI IMAQ software 1 2 R RGB cameras A 1 RGB image representations A 8 ring functions See also sequence functions list of functions 2 3 programming example high level functions 3 11 to 3 13 low level functions 3 16 S sample programs See example programs saturation A 7 saturation planes A 8 to A 9 sequence acquisition 3 1 sequence functions See also ring functions list of functions 2 3 programming example high level functions 3 10 to 3 11 low level functions 3 15 to 3 16 NI IMAQ User Manual Index session functions list of functions 2 4 programming considerations 3 3 to 3 4 signal I O functions list of functions 2 3 to 2 4 programming example 3 13 to 3 14 snap acquisition 3 1 snap functions list of functions 2 2 programming example high level functions 3 7 to 3 8 low level functions
66. t RTSI trigger line 3 will be driven high when the acquisition has completed imgSnap starts the acquisition The actual snap will not occur until the trigger is received User specific image processing imgClose closes the session and interface Figure 3 6 Signal I O Function Programming Flowchart Advanced Programming Examples You can use low level functions or combine high and low level functions for more advanced programming techniques including snap grab sequence ring and color image acquisitions Performing a Snap Using Low Level Functions The LLSnap c example demonstrates how to perform a snap acquisition using low level calls The example sets up a single frame acquisition to a buffer allocated by NI IMAQ The program retrieves the acquisition window width of the selected camera and aligns it on a 32 bit boundary You must align both the acquisition window width and rowPixels on a 32 bit boundary to ensure that your image is acquired properly The software does not perform this alignment for you unless you select a scaling option Although the IMAQ Configuration Utility performs this alignment NI IMAQ User Manual 3 14 National Instruments Corporation Chapter 3 Programming with NI IMAQ for you when you acquire an image with it you must perform the alignment yourself if you use window widths not aligned on a 32 bit boundary After the program sets the ROI it locks the memory and acquires t
67. taneously acquire and process data NI IMAQ uses direct memory access DMA to transfer all data NI IMAQ is a library of routines that work with National Instruments IMAQ devices NI IMAQ contains methods for overcoming difficulties ranging from simple device initialization to advanced high speed real time image acquisition The number of services you need for your applications depends on the types of IMAQ devices you have and the complexity of your applications National Instruments Corporation 1 1 NI IMAQ User Manual Chapter 1 Introduction to NI IMAQ Application Development Environments Note This release of NI IMAQ supports the following Application Development Environments ADEs for Windows 95 and Windows NT e LabVIEW version 4 x and higher e LabWindows CVI version 4 x and higher e BridgeVIEW version 1 x and higher e Borland C C version 4 0 and higher e Microsoft Visual C C version 2 0 and higher e Microsoft Visual Basic version 4 0 and higher Although NI IMAQ has been tested and found to work with these ADEs other ADEs or higher versions of the ADEs listed above may also work If you are using Visual Basic NI IMAQ support is provided by the ComponentWorks IMAQ hardware interface control Please consult the ComponentWorks IMAQ Vision documentation for more information Files on the NI IMAQ software media may be compressed Always run the NI IMAQ installation utility to extract the files you want For a brief
68. terface and a session The example then uses imgSetAttribute to enable and configure StillColor mode to acquire a composite image The example also configures the image data representation to 32 bit RGB mode imgSnap acquires a StillColor image and returns the image data in the buffer After the example processes the image it calls imgClose to close the handles and free all of the resources associated with the interface National Instruments Corporation 3 17 NI IMAQ User Manual StillColor This appendix describes the different methods you can use to acquire a color image using the IMAQ PCI PXI 1408 and National Instruments StillColor technology explains basic color theories and describes the different output options supported by StillColor Introduction You can use two basic video camera types for color acquisition RGB cameras and composite color video cameras An RGB camera delivers the three basic color components red green and blue on three different wires This type of camera often uses three independent CCD sensors to acquire the three color signals RGB cameras are used for very accurate color acquisition A composite color camera transmits the video signal on a single wire The signal is composed of two components that are added together These components are e A monochrome video signal that contains the gray level information from the image and the composite synchronization signals This signal is the same
69. ternet address listed below Remember to include your name address and phone number so we can contact you with solutions and suggestions support natinst com Telephone and Fax Support National Instruments has branch offices all over the world Use the list below to find the technical support number for your country If there is no National Instruments office in your country contact the source from which you purchased your software to obtain support Country Australia Austria Belgium Brazil Canada Ontario Canada Qu bec Denmark Finland France Germany Hong Kong Israel Italy Japan Korea Mexico Netherlands Norway Singapore Spain Sweden Switzerland Taiwan United Kingdom United States NI IMAQ User Manual Telephone 03 9879 5166 0662 45 79 90 0 02 757 00 20 011 288 3336 905 785 0085 514 694 8521 45 76 26 00 09 725 725 11 01 48 14 24 24 089 741 31 30 2645 3186 03 6120092 02 413091 03 5472 2970 02 596 7456 5 520 2635 0348 433466 32 84 84 00 2265886 91 640 0085 08 730 49 70 056 200 51 51 02 377 1200 01635 523545 512 795 8248 B 2 Fax 03 9879 6277 0662 45 79 90 19 02 757 03 11 O11 288 8528 905 785 0086 514 694 4399 45 76 26 02 09 725 725 55 01 48 14 24 14 089 714 60 35 2686 8505 03 6120095 02 41309215 03 5472 2977 02 596 7455 5 520 3282 0348 430673 32 84 86 00 2265887 91 640 0533 08 730 43 70 056 200 51 55 02 737 4644 01635 523154 512 794 5678 National I
70. ther composite or RGB video sources As shown in Figure 4 6 acquiring a StillColor image is identical to acquiring a monochrome image except for two session attribute settings For more information on StillColor see Appendix A StillColor 3 16 National Instruments Corporation Chapter 3 Programming with NI IMAQ imgInterfaceOpen opens imgInterfaceOpen and configures the interface according to the file setup by the IMAQ Configuration Utility mos T imgSessionOpen opens a session that Seo en ee will be used for all acquisition and configuration y imgSetAttribute configures the StillColor imgSetAttribute mode to acquire a StillColor image from a composite source using the attribute IMG_ATTR_COLOR_MODE y imgSetAttribute configures the image imgSetAttribute representation for 32 bit RGB mode using the attribute IMG_ATTR_COLOR_IMAGE_REP y imgSnap acquires an image into a buffer The buffer may be passed into imgSnap or automatically imgSnap allocated by NI IMAQ If no buffer is passed into imgSnap then imgSnap will automatically snap into a new buffer and return a pointer to the buffer User Specific Functions User specific image processing imgClose imgClose closes the interface and session Figure 3 7 Composite StillColor Snap Programming Flowchart The SCSnap c example demonstrates how to perform a single composite StillColor snap The example first opens an in
71. tion that goes from the red edge of infrared light the longest wavelength to the blue edge of ultraviolet light the shortest wavelength This continuous spectrum is called the visible spectrum as shown in Figure A 3 A 6 National Instruments Corporation Appendix A StillColor Figure A 3 White Light and the Visible Spectrum White light is a combination of all colors at once The spectrum of white light is continuous and goes from ultraviolet to infrared in a smooth transition You can represent a good approximation of white light by selecting a few reference colors and weighting them appropriately The most common way to represent white light is to use three reference components such as red green and blue R G and B primaries You can simulate most colors of the visible spectrum using these primaries For example video projectors use red green and blue light generators and an RGB camera uses red green and blue sensors The perception of a color depends on many factors such as e Hue which is the perceived dominant color Hue depends directly on the wavelength of a color e Saturation which is dependent on the amount of white light present in a color Pastels typically have a low saturation while very rich colors have a high saturation For example pink typically has a red hue but has a low saturation e Luminance which is the brightness information in the video picture The luminance signal ampl
72. truct the color image RGB Color Acquisition The PCI PXI 1408 in conjunction with NI IMAQ supports acquisition of color images from an RGB camera The NI IMAQ driver can acquire the three frames and rebuild the image automatically The output image can be a simple RGB color image or one of many image representations supported by the driver See the Introduction to Color section later in this appendix for more information on image representations For a StillColor RGB snap connect the three camera channels tred green and blue to Video 1 Video 2 and Video 3 respectively on the PCI PXI 1408 device Specify a channel for the video synchronization signal by selecting that channel as the sync source using the Operating Mode tab in the IMAQ Configuration Utility A typical RGB camera includes the composite video synchronization signal in the green signal You can also use other synchronization sources such as an external composite video signal that can be connected to Video 0 or an external TTL composite synchronization signal that can be connected to the CSYNCIN pin of the DSUB connector See Chapter 4 Signal Connections of your hardware user manual for signal connection information Introduction to Color NI IMAQ User Manual Color is the wavelength of the light we receive in our eye when we look at an object In theory the color spectrum is infinite Humans however can see only a small portion of this spectrum the por
73. tware instructions executed by a single line of code that may have input and or output parameters and returns a value when executed examples of functions are y COS x status AO_config board channel range the nonlinear change in the difference between the video signal s brightness level and the voltage level needed to produce that brightness circuitry that aligns the video timing signals by locking together the horizontal vertical and color subcarrier frequencies and phases and generates a pixel clock to clock pixel data into memory for display or into another circuit for processing ground signal graphical user interface an intuitive easy to use means of communicating information to and from a computer program by means of graphical screen displays GUIs can resemble the front panels of instruments or other objects associated with a computer program hour the physical components of a computer system such as the circuit boards plug in boards chassis enclosures peripherals cables and so on horizontal sync signal the synchronization pulse signal produced at the beginning of each video scan line that keeps a video monitor s horizontal scan rate in step with the transmission of each new line horizontal sync input signal represents the dominant color of a pixel The hue function is a continuous function that covers all the possible colors generated using the R G and B primaries See also RGB hertz the numb
74. uments Corporation imgGetBufferElement imgSessionClearBuffe imgSetArrayPointerValue imgSetBufferElement Interface Functions R Chapter 2 Software Overview Gets an element of a specific type from a buffer list Clears a session s image data to the specified pixel value Constructs an array of 32 bit pointers a Visual Basic helper function Sets a buffer list element of a given type to a specific value Interface functions load and control the selected IMAQ device and cameras These functions use information stored by the IMAQ Configuration Utility imgInterfaceLock imgInterfaceQueryNam imgInterfaceReset imgInterfaceUnlock Utility Functions S Locks a logical interface so that another process cannot use it Returns the interface name identified by the index parameter Performs a hardware reset on the interface type and returns a status either good or bad Unlocks a logical interface allowing another process to use it Use utility functions to display an image in a window save an image to a file or to get detailed error information imgPlot imgSessionSaveBuf fer imgShowError National Instruments Corporation 2 7 Plots a buffer to a window given a native window handle Saves a buffer of a session to disk in a native operating system specific format such as bitmap or tag image file format TIFF Returns a null terminated string describing the error co
75. veral valid values for this attribute that are expressed as strings The list of valid values is indicated in Possible Values Integer indicates that the 3 4 National Instruments Corporation Chapter 3 Programming with NI IMAQ attribute value is a numeric value of type integer Float indicates that the attribute value is a numeric value of type floating point The valid integer and float values are indicated in Possible Values Use the imgSetCameraAttributeString and imgGetCameraAttributeString functions to set and get the value of String Float and Integer attributes Use the imgSetCameraAttributeNumeric and imgGetCameraAttributeNumeric functions to set and get the value of Float and Integer attributes CF Note The spelling and syntax of the Attribute Name and string values must match the camera attribute file exactly NI IMAQ Status Signals NI IMAQ has several status signals that can be used to trigger the generation of a pulse or invoke a callback function Acquisition in Progress indicates that the board is acquiring image data This signal goes TRUE when the board initiates the acquisition either through a software or hardware triggered start When the last piece of image data is transferred to memory this signal goes FALSE If the acquisition is a sequence acquisition in progress will stay TRUE throughout the acquisition until the entire sequence is completed Acquisition Done is the reverse of Acquisition in Progress This sign
76. ys from date of shipment as evidenced by receipts or other documentation National Instruments will at its option repair or replace software media that do not execute programming instructions if National Instruments receives notice of such defects during the warranty period National Instruments does not warrant that the operation of the software shall be uninterrupted or error free A Return Material Authorization RMA number must be obtained from the factory and clearly marked on the outside of the package before any equipment will be accepted for warranty work National Instruments will pay the shipping costs of returning to the owner parts which are covered by warranty National Instruments believes that the information in this manual is accurate The document has been carefully reviewed for technical accuracy In the event that technical or typographical errors exist National Instruments reserves the right to make changes to subsequent editions of this document without prior notice to holders of this edition The reader should consult National Instruments if errors are suspected In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it EXCEPT AS SPECIFIED HEREIN NATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES CAUSE

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