A Simple CMOS Camera for Itsy
Contents
1. Cn and Rn are capacitors and resistors whose value is as shown on the schematic Com ponents labeled JPn are test points The rest of the com ponents are as follows Sensor Circuit Board CONI Hirose 30 pin 0 5mm top contact connector ICI PB 0300CCC L1 amp L2 600 ohm 100MHz ferrite beads join split power and ground planes DC FIFO Circuit Board CONI Hirose 30 pin 0 5mm bottom contact connector DC daughter card connector IC 7ALCX373EN octal D type latch IC2 IDT72V83L15PA dual 2 048 x 9 FIFO IC3 74LCX14FN hex Schmitt inverter IC9 SG636 PCE 24MHz oscillator IC10 TC1015_33VCT regulator IC11 7ALCX32EN quad 2 input or IC12 74LCX74FN dual D flip flop L1 600 ohm 100MHz ferrite bead R1 amp R3 0 1 ohm precision resistors for power measurement A SIMPLE CMOS CAMERA FOR ITSY WRL TECHNICAL NOTE TN 58 17 T 13945 AOSUSS 23n 33n A8UNUIS in3dud 3 99N 8dl1S Z1nod 33n JIN LnoG nod UNO nod od N9 od od N9 N9 eLnoa NI UN QIQ3NTI HI UN 19S X I9XId aNd dol zZ 0 1002 2141 HEH ASqunw iusunoo AOSUSS 31111 ebewl euswej As1 AN IS in3dud Y dl 2inod e1nod NDA IO UNI HI ATIS Aja SF LO NO IN cd 0 A 19XId RIES UNI peeq I3 LC 21 Deag I3 C T1 i i E al A 19X Id vuEV 8d Z1noa 91noad an2. Figure 1 Three Itsy Pocket Computers At the top of the picture is an unmodified Itsy It is 118mm x 65mm x 16mm and weighs including battery 130g with a molded plastic case Below it are two units with the camera extension that are 147mm x 64mm x 20 5mm and weigh including battery 195g with a SLA epoxy case or 267g with a NC tooled aluminum case Itsy s reflective gray scale display is used as the view finder displaying in real time the scene in front of the lens Typically when the camera is used the photographer holds the display horizontally in their hand at a good viewing angle The lens imager assembly is then rotated into a ver tical position so the lens points forward middle of Figure 1 at the subject The hinge allows smooth motion through 180 so the display viewing angle need not be compro mised to correctly position the lens When the camera is not in use the lens imager assembly is folded flat bottom WRL TECHNICAL NOTE TN 58 of Figure 1 and the camera is easily stored in a purse or pocket There is minimal interference with other Itsy function as the unit fits as well in the hand as an unmodified Itsy The least objectionable way to increase the size of Itsy is to lengthen it as has been done here The camera has a mini mal impact on the unit s width and height This view camera inspired design has a number of ad vantages First since the reflective display is illuminated by ambient light that is typical
3. 24 MHz clock supplies power to the PB 0300 and enables the daughter card mem ory interface The application starts by issuing an ioctl I O control command to reset the camera The driver implements this operation by pulsing RSTPB This initializes the PB 0300 and runs it in its default configuration where it sup plies the StrongARM with 30 VGA size images second Before taking pictures the application may need to make configuration changes on the PB 0300 This is done by issuing a number of ioctl requests to read and write the PB 0300 s registers The driver performs these functions via a software implementation of the SHIP protocol using the SCLK and SDATA GPIOs The Itsy is the protocol master and it provides the clock via SCLK a dedicated output pin Clock pulse duration is controlled by busy wait ing in the driver using the StrongARM s 3 6864 MHz op erating system timer Both Itsy and the PB 0300 use the SDATA line to transfer data a bit at a time Typically SDATA is configured by the driver as an input pin so its value is either driven by the PB 0300 or driven to 1 by the pull up resistor The only time Itsy drives this signal is when the protocol requires the driver to write a O data value in which case it forces SDATA to 0 by configuring it as an output pin with a value of 0 for one bit time Addi tion ioctl commands are used to allocate image buffers in the driver and select the mode of operation still picture or video
4. WRU s research partners at EPFL integrated a mobile cam era 7 into Itsy Their electronics were more complex than those described in this paper as they were interfacing two sensor chips with less integrated functions that the PB 0300 Two commercially available cameras for handheld sys tems are the Kodak PalmPix for Palm and the eyemod ule for the Handspring Visor M The PalmPix image sensor is the same size as Itsy s but the display must be held vertically in a poor viewing position in front of the user s face in order to operate it The eyemodule s display is held in a horizontal position like Itsy s for good viewing but its image sensor is only 320x240 pixels The major limitations of each of these designs are processor perform ance and camera to memory bandwidth The low perform ance processors in both handhelds require that the camera extensions provide dedicated image processing electronics The camera is in turn connected to the processor on both systems by a 115 200 bit second serial interface Contrast this with Itsy where the camera is directly connected to the StrongARM memory bus and is capable of sustained trans fers at 8 8Mbytes second 640x480 pixel frames at 30 frames second This bandwidth is clearly required for taking video clips but it is also desirable to provide real time updates to the viewfinder While this camera is centered on the Photobit PB 0300 the design could be easily adapted to a number of
5. enough to the level of Itsy s system power to allow signals but not power connections to freely cross between the image sensor and the rest of the system The sensor power is noticeably cleaner than the Itsy system power and this helps improve picture quality Not obvious on the sche matic are the separate analog and digital power and ground planes that are provided on the image sensor s circuit board to further reduce noise 5 Itsy Daughter Card Interface The interface to the Itsy daughter card 9 provides ac cess to all the unused StrongARM 1100 3 GPIOs general purpose I O pins and to the full memory address and data buses In the interest of building the simplest interface possible the only control logic on the daughter card is for functions that could not be handled by the Linux driver The STANDBY RSTB FRAMEVLD SCLK and SDATA signals from the PB 0300 are directly connected to dedicated GPIO pins The flexibility of the StrongARM GPIOs allows the Serial Host Interface Port M SHIP pro tocol compatible with PCTM to be implemented entirely by the driver The bulk of the logic on the daughter card is dedicated to moving data from the PB 0300 to the StrongARM mem ory bus The FIFO is two 8 bit pixels wide and is imple mented by a dual 2 048 x 9 IDT72V83 asynchronous FIFO that is directly connected to bits 0 15 of the memory bus Since the FIFO is the only register that need be read or written a minimal control design suf
6. other CMOS image sensors For example the Agilent HDCS 2030 the Kodak KAC 0310 and the Zoran Pixel cam PCS2112 all are powered at 3 3V have PC compatible controls and provide digital image output data Minimal changes to the electronics would be required to control any of these chips 10 Conclusions The camera extension of Itsy is a success The changes to the base Itsy unit have been minimized yet the resulting object is pleasing to the eye and encourages users to pick it up It produces pictures of acceptable quality and the utility and power of the system are demonstrated by the initial computer vision experiments The positive results and the simplicity of the design should encourage others to integrate cameras into their off the desktop systems WRL TECHNICAL NOTE TN 58 Acknowledgements This work would not have been possible without the skills and interest of my colleagues at WRL William Hamburgen Marc Viredaz Wayne Mack Deborah A Wallach Lawrence Brakmo and Andreas Nowatzyk Stu dio Red turned the project s unfocused ideas about a view camera into a striking design and functional prototype packages Jim Rehg and Uli Kremer provided the neural network based face detector Wendy Bartlett provided edi torial assistance for this technical note I thank you all References 1 Jim Adams Kevin Parulski and Kevin Spaulding Color Processing in Digital Cameras IEEE Micro November December 1998 pp 20 29 2
7. 33n S22 te Edf O ajo Lo o s o 10 74 199UuS d 6 0Z 280 1002 2141 exeg JSQUAN aiuesunoog OjTjOp 3 1111 0313 20 e4aweg Asx A SIMPLE CMOS CAMERA FOR ITSY WRL TECHNICAL NOTE TN 58 Yun Yun ASNUIS OTININVI 4 gun LG LNOG Yun uN nod oa N9 00 00 N9 Od od N9 N9 od 19 N9 n HIH UN RRE A79X Id UN UNO idezy T GIBTOL dAH NOHS D UNO 1non NIN T1L28d AGONYLS E Oz OTN3NYa 4 1 8d1S8 LZ a11nod ZHWrc 9 99S Uds G I03NT 1 HIHOS RRE kel Lal M SF LO SOP IN CO ATX Id HOH UNO pesq_IW4 L 1 vaa OTNINTT_ TI jul Q 113 IW zo Qusard 11 A SIMPLE CMOS CAMERA FOR ITSY WRL TECHNICAL NOTE TN 58 E7E 2188YS drG Qz 8 1002 2141 exeg 48qunwN aiueunoog dE JILIL 0313 20 e48uej fisil ST IXId Qc SE 3H_ 0X_ 33 43 ZE SCH t 8 ee ar ees D Ra Dac zz 9E sz RER Cer 9 amp 7 St SR ES Ss SG Bes D Be O4IJLlSu 2 XIdM O4IJlSu 8df O03141S 8_ I 441 g I An O4IJlSu LZ 010413010 QINANT T ATX Id 6T s 1 42 t per LS LZ 0 IL LNO 12
8. February 2001 WRL Technical Note TN 58 A Simple CMOS Camera for Itsy Joel F Bartlett COMPAQ Western Research Laboratory 250 University Avenue Palo Alto California 94301 USA The Western Research Laboratory WRL located in Palo Alto California is part of Compaq s Corporate Research group WRL was founded by Digital Equipment Corporation in 1982 We focus on information tech nology that is relevant to the technical strategy of the Corporation and that has the potential to open new business opportunities Research at WRL includes Internet protocol design and implementation tools to optimize com piled binary code files hardware and software mechanisms to support scalable shared memory graphics VLSI ICs handheld computing and more As part of WRL tradition we test our ideas by extensive software or hard ware prototyping We publish the results of our work in a variety of journals conferences research reports and technical notes This document is a technical note We use technical notes for rapid distribution of technical material usually this represents research in progress Research reports are normally accounts of completed research and may include material from earlier technical notes conference papers or magazine articles You can retrieve research reports and technical notes via the World Wide Web at http www research compaq com wrl You can request research reports and technical notes from us by mailing you
9. Joel F Bartlett Lawrence S Brakmo Keith I Farkas William R Hamburgen Timothy Mann Marc A Viredaz Carl A Waldspurger and Deborah Wallach The Itsy Pocket Computer Research report 2000 6 WRL Compaq Palo Alto CA USA October 2000 3 Intel Intel SA 1100 Microprocessor Technical Ref erence Manual September 1998 available via www intel com 4 Shoji Kawamua Capturing Images with Digital Still Cameras IEEE Micro November December 1998 pp 14 19 5 Photobit Corporation PB 0300 1 3 inch CMOS Ac tive Pixel Digital Image Sensor March 2000 Version 3 0 available via www photobit com 6 H A Rowley S Baluja and T Kanade Neural Net work Based Face Detection IEEE Transactions on Pattern Analysis and Machine Intelligence Vol 20 No 1 1998 pp 23 38 7 Olivier Saudan Interfacing a mobile camera with the Itsy pocket computer 7 semester project LAMI EPFL Lausanne CH February 1999 8 Thad Starner Jake Auxier Daniel Ashbrook and Maribeth Gandy The Gesture Pendant A Self A SIMPLE CMOS CAMERA FOR ITSY illuminating Wearable Infrared Computer Vision System for Home Automation Control and Medical Monitoring In The Fourth International Symposium on Wearable Computers IEEE October 2000 pp 87 94 9 Marc A Viredaz The Itsy Pocket Computer Version 1 5 User s Manual Technical Note TN 54 WRL Compaq Palo Alto CA USA July 1988 Bill of Materials Components labeled
10. clip Once PB 0300 configuration is complete the applica tion issues a read request to the device to take a picture This is posted in the driver but no action is taken until a falling edge on FRAMEVLD causes an interrupt The PB 0300 is now between frames and not trying to transfer any data into the FIFO so the FIFO can be reset by pulsing RSTFIFO The interrupt handler completes by enabling falling edge interrupts on FULL and HALF As pixel values are generated by the PB 0300 they are moved into memory in the following manner see the DC FIFO schematic When PIXCLK falls to 0 and LINEVLD is 1 pixel data is available at DOUT O 7 and WRITE falls to 0 When WRITE falls data is latched in the octal D type latch IC1 74373 and either WRITEO7 or WRITE815 falls to O which starts the transfer of the latched data into the appropriate half of the FIFO When WRITE rises to 1 the value of the D type flip flop IC12A 7474 is inverted which results in the other half of the FIFO being selected for holding the next pixel A SIMPLE CMOS CAMERA FOR ITSY When the FIFO become half full HALF falls to 0 which interrupts the processor The interrupt handler then reads 2048 pixels from the FIFO and stores them into memory The FIFO is visible to the processor as static memory bank 3 Each load from a virtual address mapped to this bank causes DCCS3 to fall to 0 and the FIFO places two pixels of data 16 bits onto the memory da
11. fices The FIFO is visible to the StrongARM as static memory bank 3 and the static memory control register is configured as follows as suming a 100 MHz memory clock RTx 0 nonburst ROM or Flash EPROM RBWx 0 32 bit ROM bus width RDFx 1 2 clocks from address to data valid RDNx 0 ignored as device is not written RRRx 1 2 clocks to get off the bus When configured this way any read or write access to any physical address in static memory bank 3 results in DCCS3 an active low selecting the memory back being asserted by the StrongARM which starts the read cycle on the FIFO and two pixels are transferred to the memory bus The FIFO is reset and status information is communi cated to the StrongARM by four dedicated GPIO pins RSTFIFO active low that resets both FIFOs FULL active low on FIFO overflow EMPTY active low on FIFO empty HALF active low on FIFO half full The final GPIO control signal to the daughter card is CAMERA This is an active low that turns on the clock and linear regulator for the PB 0300 and enables the WRL TECHNICAL NOTE TN 58 daughter card memory interface When the camera is not in use this signal is high to disable these components and save power With these signals defined attention will now shift to using them to take a picture 6 Taking a Picture The camera is visible to application programs as the device dev pb0300 When it is opened the driver sets CAMERA to 0 This starts the
12. gy sinoqa UNO 1N00 1no d XIdUUn Z1noa T1noa Hun ginod Uun 100312 NDMO ND412 QTn3WUHi ASONUIS ABUNUIS OMNIA 19S ATIS U1UdS vlas TS S8dlSH AX Id A SIMPLE CMOS CAMERA FOR ITSY WRL TECHNICAL NOTE TN 58 dorop 1082 2141 Laien Z1 1188ug 49qunwN aiueunoog HOH dE 0313 20 e48uej fisil JILIL e LS1 01XId ONG NNIL dNIL UN 13SHO490 N320 e BEd 1 030 ee a3d 6za30 ON9 80390 e BEd 22090 92090 Sca3d c020 ezau zza 1030 ONG ecza3a e BEd 61090 81020 1000 91090 e BEd aadd 30490 UN MOId2GQ dodod 0r8Ed z33d30 143d30 M30 3020 SUd2 ONG csuad2 TSud2 esuda3ad e BEd SU22 cSU22 190220 0S U0220 N3 Ond UN staga 1090 1090 z1000 B BEd 11090 gI 50 6090 80390 ON 2090 9030 Saad 030 BrE e090 zaad 1030 a30 UN Qr Ed e axa ONG e axi JASAMA Taxa ASUMA T axi 3usand 1IUMda20 91SIOI20 cS22 0 UNO 938d20 113S1ASd90 ScuU2 2900 DOC d cuU2 224900 12990 aN9 YA Jel 61930 81930 1900 91990 DOC d tyad 1990 122 UNO lt 1N90 1noli3s3u T1430 8150 6430 8430 Q Ed 2990 9930 DN geod 430 430 ZU2 1990 eu2 DOC d es390 15490 UNO HIH 3113 ASONU L dd1sd 0313154 QYAWYI_ Ee ALdH3 tdf G1nawed 4 IUH TINA gay ASUMA T30 NN033q
13. he camera Based on experience with other cam eras and electronics users have an expectation about how things should move freely without overshoot yet hold their position when stopped This is accomplished by lu bricating the joint with the appropriate grade of damping WRL TECHNICAL NOTE TN 58 grease Nyogel 774VL on the lens threads and Nyogel PG 44A on the body hinge With this overview of the package design and electron ics segmentation complete attention can now turn to the details of the electronics 4 Photobit PB 0300 CMOS Image Sensor The design of the electronics was driven by the capa bilities and requirements of the PB 0300 5 image sensor With only a few digital controls and external VCC and clock this camera on a chip can produce digital output at up to 30 frames second with VGA 640H x 480V reso lution Unlike earlier CCD image sensors this sensor re quires no external control circuitry analog to digital con verters or non standard reference voltages as these functions are integrated into the sensor chip The sensor s integral gain and exposure controls allow pictures to be taken under widely varying lighting conditions without the need for an adjustable aperture lens or a mechanical shut ter The Image Sensor schematic details the interface to the PB 0300 Signal names are shown in a sans serif font and those signals that are active low have a as the first character of their name The s
14. ignals of interest are GND ground VCC analog and digital power CLKIN 24 MHz master clock input STANDBY active high to set chip on standby RSTPB active low to reset the chip SDATA Serial Host Interface Port data SCLK Serial Host Interface Port M clock PIXCLK pixel clock for output data LINEVLD active high on image data output FRAMEVLD active high during image processing DOUTO data output bit 0 LSB DOUT data output bit 1 DOUT2 data output bit 2 DOUT3 data output bit 3 DOUT4 data output bit 4 DOUT5 data output bit 5 DOUT6 data output bit 6 DOUT7 data output bit 7 MSB Finding an appropriate method for supplying power to the PB 0300 required some experimentation as analog and digital power levels for the chip are specified at 5 0V While it will produce acceptable pictures at lower voltages it cannot produce them when powered by Itsy s 3 05V sys tem power One solution would be to use a charge pump to produce 5 0V power This was rejected because it was expected that future 3 3V camera on a chip devices would be available from Photobit and other vendors and that signal level conversions required in a mixed voltage system would complicate the system Instead a linear regulator is used to convert the raw battery voltage to 3 3V that is used to power both the ana A SIMPLE CMOS CAMERA FOR ITSY log and digital portions of the image sensor This provides a high enough voltage to provide good pictures yet is close
15. ly overhead the preferred viewing position is approximately horizontal which is how the camera uses it Like a camcorder with an LCD viewer the camera de sign allows the photographer to remain in eye contact with the subject and allows others to look over the photogra pher s shoulder while they are composing the picture Finally the camera can be used in a variety of ways It can be placed on a table in front of the photographer for unobtrusive candid shots The lens imager assembly can be rotated up to 180 for use in making greater than 1 1 close up shots or not rotated at all bottom of Figure 1 and the camera used for self portraits 3 Inside the Package In order to implement this design the camera s elec tronics are segmented into two circuit boards as shown in Figure 2 The board on the left contains the CMOS image sensor and the lens In order to minimize the width of this board a conventional lens mount that surrounds the image sensor was not used Instead an aluminum tube is glued directly to the glass cover of the image sensor and the lens is threaded into it Opaque plastic tape is applied around the tube to prevent extraneous light from entering the im age sensor as shown in Figure 4 9906 rm TH damn E SLL Figure 2 Image sensor and daughter card electronics The lens was chosen with the idea of using the camera for snapshots The lens is a Sunex DSL900C f 3 0 9 9mm lens It can be focused fr
16. n public interest in Itsy has exposed project members to some opportunities for powerful camera centric handheld devices With this motivation an effort was started to add a snapshot camera to Itsy with an eye towards demonstrating an innovative way to integrate a camera into a handheld device and encouraging its use The goal of this effort was to minimally impact the Itsy base system yet not compro mise the image sensor s performance While many digital cameras use specialized image processing electronics 4 this camera would use Itsy s existing processor and mem ory for all image processing and control functions In the sections that follow the package and electronics design will be discussed and the paper will close with a few sam ple images and comparisons to other systems 2 Package Design The starting point for the design was the base Itsy sys tem shown at the top of Figure 1 Working with the exist ing base electronics and minimizing redesign of the case Studio Red created the design shown at the center and bot Compaq Computer Corporation Western Research Labo ratory 250 University Avenue Palo Alto CA 94301 joel bartlett 9 compaq com 2001 Compaq Computer Corporation tom of Figure 1 The CMOS imager and lens are contained in a hinged extension to the left end of the case that length ens it by 29mm The rest of the electronics are contained on a daughter card that thickens the case by 4 5mm
17. om infinity to closer than 2 by rotating it Quality color images require an infrared filter so the final component of the lens assembly is a Sunex IRC21 8R IR cut off filter that is directly bonded to the glass cover of the image sensor Since there is no variable aperture or auto focus system the camera operates silently A SIMPLE CMOS CAMERA FOR ITSY The rest of the electronics that control the image sen sor and provide the datapath to memory are located on the daughter card shown on the right side of Figure 2 The camera is assembled as shown in Figures 3 and 4 In Figure 3 the daughter card is attached to the Itsy moth erboard The daughter card s impact on the thickness of the camera is minimized by careful selection and placement of its components so that they fit in the space available between the daughter card and the motherboard A thirty wire 0 5mm flat flex cable connects the daughter card and the image sensor In order to thread this cable through the hinge two wires are removed and the cable split as show in Figures 3 and 4 Figure 3 Itsy shown face down with the case back off the daughter card installed and cabled to the image sensor card orn e Figure 4 Itsy shown face up with the front of the im age sensor case removed Even the simplest cameras have moving parts Here the lens is rotated in its mount to focus it and the image sensor lens arm rotates on a hinge connecting it to the main body of t
18. r order to Technical Report Distribution Compaq Western Research Laboratory 250 University Avenue Palo Alto CA 94301 U S A You can also request reports and notes via e mail For detailed instructions put the word Help in the sub ject line of your message and mail it to WRL techreports pa dec com A Simple CMOS Camera for Itsy Joel F Bartlett Abstract Itsy is a high performance platform for research in off the desktop computing One of the attributes of the base hardware is that it can easily be extended through the use of daughter cards This technical note describes the packaging and electronics for one such extension a simple CMOS camera 1 Introduction Itsy 2 is a flexible high performance handheld com puter designed for research in off the desktop computing Approximately the size of a Palm V it has a 200MHz Intel StrongARM 1100 processor 32 MB of RAM 32 MB of flash memory and runs Linux Hardware extension is done by building daughter cards that interface directly to the memory bus and the StrongARM GPIOs As CMOS camera on a chip image sensors have be come available there has been significant interest in inte grating cameras into handheld devices Itsy s memory size and performance also suggest that it could be more than just a simple camera It could act as a handheld computer vision platform capable of significant image processing at the time a picture is taken In additio
19. ta bus After the PB 0300 outputs the last pixel of the image FRAMEVLD drops to 0 which interrupts the processor The FIFO is emptied into the driver s buffer and then the read completes If the driver is configured to record a video clip then the interrupt handler will start the next read so no frames are lost Otherwise it will disable the FIFO interrupts as the PB 0300 images are being ignored 7 Processing the Image Data A picture appears to the application program as a VGA sized 640 x 480 array of unsigned bytes Cameras im plemented using the monochrome version of the PB 0300 require no further processing as this array is the gray scale image Color cameras require additional processing as the image sensor is covered by a color filter array as shown in Figure 5 Each pixel in the image sensor looks through a red blue or green color filter and returns that value When printed as color image since each pixel has only a red green or blue value the result is like that shown in Figure 6 In order to produce RGB values for each pixel the miss ing color values are recovered by interpolation 1 and the result is shown in Figure 7 Since the camera does not have dedicated image proc essing electronics in camera color recovery is application dependent or can be deferred until after the images have been removed from the camera Figure 5 A portion of the Bayer Pattern of the PB 0300 color filter array where each colored sq
20. uare is a color filter covering one pixel WRL TECHNICAL NOTE TN 58 A SIMPLE CMOS CAMERA FOR ITSY frames second are possible One example is a short feature called The Break Figure 10 where CIF size images 352W x 288H were shot at 60 frames second in two two second long bursts A slow motion QuickTime movie was then assembled using Adobe ImageReady Figure 6 A magnified portion of an image returned by a color PB 0300 where each pixel has only a red green or blue value Figure 7 Image color recovery from the image data of Figure 6 using a simple pixel averaging algorithm 8 Initial Applications Software to implement simple still and video cameras has been implemented Three still pictures taken by the camera are displayed in Figure 9 They demonstrate the picture quality available from the camera and its ability to take close ups Since the camera is capable of recording successive SE images short video sequences limited only by the size of Figure 9 Three sample still images an outdoor scene Itsy s memory can also be recorded By selecting an im a shop window and a well worn quarter age size smaller than VGA frame rates faster than 30 WRL TECHNICAL NOTE TN 58 Figure 10 The Break shows a pool break at 1 12 real time In this frame the cue ball has just hit the head of the rack The most interesting application for the Itsy camera is handheld computer vision To demonstrate this o
21. ur col leagues at Compaq s Cambridge Research Laboratory sup plied a neural network based face detector 6 that detects any number of frontal upright faces in an image The de tector was paired with the Itsy still camera code and the result is a face finding camera whose results are shown in Figure 11 Figure 11 After taking a picture the face finding camera draws a rectangle around each frontal upright face it finds in the image Another application that could easily be hosted on an Itsy with a camera is the gesture pendant 8 designed at Georgia Tech This is a wearable camera that contains sufficient processing power to recognize hand signals and convert them into control commands to nearby appliances It was prototyped using a video camera a 900MHz video A SIMPLE CMOS CAMERA FOR ITSY transmitter receiver pair and a desktop computer Since Itsy has sufficient processing power and memory to recog nize a gesture its camera could capture the gesture and its IRDA link could directly control the desired appliance Lest one think the power required for such a device is impossible in a wearable device the Itsy still camera soft ware that uses the display as a real time viewfinder is able to continuously run for three hours before discharging the standard 2 2 watt hour battery 9 Related Work and Extensions With the Itsy camera s design in mind attention can now turn to putting it in context with related work One of
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