Digital Imaging Basics - School of Information
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1. extension D E mmddyy date W A 3 Starting serial 1 Compatibility M Windows V Mac OS M Unix Errors f Log Errors To File HA Figure 14 Digital Imaging Basics 14 Removing Red eye There is a common need to retouch photos of people or animals to remove the red eye that occurs when using the flash on the camera Since there are lots of tools out there to do this PH just briefly explain the basics of removing red eye and give you links to more software specific information Whatever tool you are using you will basically be performing these tasks e open your image file zoom in on the eye or eyes you want to fix e configure the remove red eye tool with some settings best suited to your image e choose a replacement color for the red you wish to replace e drag or paint over the red with the mouse replacing the red with the color you chose After you have done this once or twice you Il be a pro Remember you can always go to the Help menu in your image editor and type remove red eye to find helpful information Here are some links to software specific instructions and more detailed information about the how and why of red eye e Removing Red Eye from Digital Photos http graphicssoft about com od redeyeremoval e ACD Digital Photo Software Tips http www acdsystems com English Community ColumnsArticles SoftwareTips software 2005 05 11 htm2. e Removing Red Eye with the GIMP http gimpeuru org Tutorials RedEye2 File Management You might find that thoughtful file naming conventions as discussed in the Best Practices section of this tutorial just aren t enough you need help organizing your ever growing digital image collection Here are a few examples of software applications that can help you find organize and share your digital images Some of these offer basic editing functions as well e ACDSee 7 http www acdsystems com nr acdsee7 EN homelife index htm e Picasa http picasa google com index html e Apple iPhoto http www apple com ilife iphoto Digital Imaging Basics 15 Additional Resources There are lots of digital imaging resources on the Web for amateurs experts or the mildly curious Here are some suggested additional resources to help you on your way to becoming a digital imaging whiz General Digital Imaging Resources e About com Working with Digital Photos and Scanned Images http graphicssoft about com od digitalphotography e Art Support com http art support com creatingsites2 htm Scanning Resoutces Scanning Software Tips and Help http graphicssoft about com od scanning e All Graphic Design Scanning Tips http www alleraphicdesign com scanning html e Tutorials Guide Scanning Tutorials http www tutorialguide net computers scanning Image Editing Resources e An Intro
3. never seeing all of it at once You downloaded all the images from your digital camera onto your computer and then tried to burn them onto a cd to give to someone You have dozens of pictures and only a few will fit on a cd before it is full This is going to take FX You tried to print a digital image that looks great on your computer monitor We M only to realize that the image file prints really small looks really bad and you don t know how to fix that Objectives of this tutorial Review basic concepts in digital imaging including e Digital image production e Resolution amp File size e Image editing e File management Digital imaging concepts pertinent to Conservation students in the School of Information can be found at http www ischool utexas edu technology tutorials graphics dig_img dig_img_kcpcer pdf Digital Imaging Basics 1 Definitions of Terms Resolution Refers to the sharpness and clarity of an image measured in terms of ppi and dpi PPI pixels per inch Measurement used for images displayed on screen Pixel A word invented from picture element the basic unit of programmable color on a computer display or in a computer image from http searchsmb techtarget com Lossy A term meaning with losses used to describe image file formats that discard data due to compression RGB Red Green Blue The color model for display devices monitors digital projectors etc Each di
4. submissions make sure you know what s required before you start digitizing Computer display Images intended primarily for display on a computer monitor such as email attachments or images on a Web page really only need a 72ppi to 96ppi resolution as that is what computer monitors are capable of displaying A higher resolution will not make your image appear any better on the screen In fact if you don t expect folks to print out your images these images should be optimized which means making them as small and compressed a file as possible while still retaining the appropriate visual clarity so that they load quickly and do not take up too much space on the hard drive TIP if you need to make high resolution large files available via the Web or computer create thumbnail versions of your images that then link to the larger images This prevents your viewer from enduring slow loading times for images they are not interested in seeing TIP Optimizing images for computer Web display involves compression which throws out some pixel data You cannot then enlarge the images without encountering pixelation example on pg 7 Digital Imaging Basics 5 Resolution Examples images courtesy of author Format TIFF DPI 400 Pixel Dimensions 2000 x 1193 Print Dimensions 5 x 3 File Size 6 59MB Ideal for Print Use Format JPG DPI 72 Pixel Dimensions 361 x 210 Print Dimensions 5 x 3 F
5. file sizes significantly so that you can fit more files onto a disk or attach more to an email message without exceeding the disk storage or file size limits Inserting images into presentations or other documents Resizing images on the screen after inserting them into your PowerPoint presentation or Word document does not reduce the file size of that image this only changes the dimensional display size of the image in that document Presentations and other documents that contain numerous images can become very large in total cumulative file size In order to keep such presentation and document files at a reasonable size you should appropriately resize your image files in an image editor before inserting them into your final document Best Practices Start Big When in doubt about how you might end up using your images opt for the highest resolution possible It is always better to start out with the most information possible and then scale down as necessary If you start out with low resolution you cannot get a higher resolution without scanning or taking the picture again with higher resolution settings and you may not get that chance Protect Originals Keep the original high resolution versions of your images which should be in TIFF format if possible in a separate place from your working documents or optimized Web images Back up your important documents on some kind of external storage medium CD Rom or fire wire drive for examp
6. or resolution Some cameras have options such as good better and best while others actually have numbered pixel dimensions such as 640x480 or 1600x1200 What it boils down to is this the better the quality or higher the numbers the bigger the file size for each image and the less total number of images you can fit on the memory card or disk So you have to decide do you want fewer but higher resolution pictures or are you a shutterbug that needs to take 100 shots just to get a few that look good Your situation and your skill may help determine this decision Part of this includes your intended use of the pictures once you get them off the camera which we will discuss in more detail later in this tutorial If need be you can purchase a memory card with larger storage capacity to hold more pictures Digital Imaging Basics 4 2 Some digital cameras will let you choose which format you want your images saved in All cameras will offer JPG or JPEG format and some will offer TIFF format for high quality high resolution images Additionally some cameras may have a proprietary format option that only works with the software that came with the camera 3 Certain settings on your camera may return to default settings after turning the camera off This can be especially annoying if you are trying to conserve the battery but have to navigate through the menus and reset your desired quality or format settings ea
7. the pixel dimension width box and click OK I could continue to edit my document but for purposes of this example I ll stop here by clicking the Stop button in the action pane Figure 13 History Actions FT OE Water RETECTION Trypey JB p gt Custom RGB to Grayscale 4 P Molten Lead gt Make Clip Path selection gt Sepia Toning layer gt Quadrant Colors p gt Save As Photoshop PDF gt Gradient Map wy _duck action relate ls Figure 13 Step 2 Batch Process Now that I have an action recorded I can proceed to batch process my other documents using that action I will go to File gt gt Automate gt gt Batch and in the dialog box that opens I will choose to play my duck action Figure 14A For the Source section I need to define the source files upon which the action will be performed I organized all my source images into one folder which I now designate by clicking the Choose button Figure 14B navigating to that folder and clicking Choose again Next is the Destination section in which I designate where my edited files will be saved This should be a separate location from my original or source files I select Folder from the Destination drop down menu then click the Choose button and navigate to and choose an appropriate folder In the File Naming section I have many choices of combining the document name derived from the original source file plus the do
8. 1 inches Ea g Height 3 917 inches re Resolution 72 pixels inch HA v Scale Styles M Constrain Proportions v Resample Image Bicubic Figure 10 Batch Processing You may find that you need to resize many many images to the same pixel dimensions in order to create a digital portfolio or otherwise prepare your digital images for Web display or print To save time on such routine tasks you can use a function called batch processing Basically you decide ona set of steps which you record as an action You then tell Photoshop to perform that action on the many image files saving you time and effort Step 1 Record Action Display the Actions pane in Photoshop by going to Window gt gt Actions Then click the New Actions button in the lower left of that window Figure 11 Type a name for your action in the dialog box that appears and click the Record button Figure 12 Then perform the operations that you wish to perform on all of your images 000 History Actions v Aj 3 Default Actions atn New Action Name Action 1 E Record Set Default Actions atn x Cancel Function Key None Hy Shift Command Color _ None HJ Figure 11 Figure 12 Digital Imaging Basics 12 For example before I created my new action I had the file Ducky tif open After clicking Record I click the Ducky tif document window to activate it then go to Image gt gt Resize and type 200 into
9. Digital Imaging Basics by Melanie Cofield Information Technology Lab School of Information The University of Texas at Austin Summer 2005 Introduction Digital imaging has become more than just a popular pastime in contemporary culture Personal computers in addition to a plethora of hand held electronic devices have become the preferred mode of communication for increasingly large portions of the population Digital cameras and camera phones have made taking processing and sharing photos almost instantaneous making digital images a common component of hi tech communications With all this fast paced instant gratification going around one might not notice the extent to which professional industries also rely on digital imaging Publishers of both print and web materials depend heavily on the quality and accessibility of their images Attention to the details of how an image is created how it is stored who will be using or accessing it and how is crucial to successful digital imaging An understanding of these details can also be useful to the average consumer who just wants to shoot some pictures and email them to friends or post them on a Web site Frustrating scenarios that can be avoided after learning digital imaging basics a You get a picture emailed to you from a friend and when you open the image file it takes forever to open and when it does you have to scroll around on Se your computer screen to see the whole thing
10. ch time you want to take a picture Again familiarity with these particular features on your camera will help a lot towards achieving better results Photo CDs You may obtain a collection of digital images from your photo processor along with your developed prints or slides Many photo processing services now provide photo CDs with jpg images on them If you are unfamiliar yet curious about the nature of these images this tutorial should help you figure out what you can and can t do with them and will give you suggestions for software that can help you manipulate or organize them Image Size Resolution As mentioned in the definition of terms earlier in this tutorial resolution refers to the sharpness and clarity of your image Of course the sharpness and clarity vary depending on the context of the image Are you scanning or viewing your image Are you viewing it on a computer monitor or are you looking at a printed page Scanning When scanning your images you are usually prompted to choose what resolution you would like your images scanned at The intended use or display of your images will help you make this choice Printing Images intended for high quality printing should be scanned in at no less than 150dpi preferably 300dpi Remember dpi is dots per inch and the more dots per inch the sharper and crisper your images will look on the printed page Many publishers have minimum resolution requirements for digital image
11. cument extension also derived from the original source file unless saving in a new format was included in the action plus date stamps or serial numbers to help me keep track of various edited versions of the same image ll choose Document Name extension mmddyy Figure 14C and PH select all the compatibility options available Figure 14D If there are errors I don t want the batch processing to stop so Pll choose Log Errors to File from the Errors drop down menu Figure 14E and specify what I want that log file to be called and where it should be saved Now I m ready and PI click OR After some brief flickering and flashing of document windows that may occur while the batch processing action is running you will end up with caboodles of images edited to your specifications and saved to the location of your choice all before you can say I love batch processing Digital Imaging Basics 13 Batch Play As Set Default Actions atn H4 Action duck action B Source Folder Macintosh HD Users tutorials digital imaging images l Override Action Open Commands Include All Subfolders l Suppress File Open Options Dialogs Suppress Color Profile Warnings Destination Folder HH Macintosh HD Users melanie Desktop personal_docs l Override Action Save As Commands File Naming Example MyFilegif071205 C Document Name
12. duction to the Gimp http www ischool utexas edu technology tutorials graphics gimp index html e Getting Started with Adobe Photoshop http www ischool utexas edu technology tutorials graphics photoshop7 e Photoshop Tips amp Tricks http www graphic design com Photoshop Digital Imaging Resources for Library Preservation amp Conservation Professionals e Moving Theory into Practice Digital Imaging Tutorial from Cornell University http www library cornell edu preservation tutorial contents html e Conservation Online Stanford University http palimpsest stanford edu bytopic imaging Digital Imaging Basics 16
13. ile Size 222KB Ideal for Computer Web Use Notice the difference in sharpness amp clarity between these two printed images Digital Imaging Basics 6 Resolution Examples Format TIFF DPI 400 Pixel Dimensions 2000 x 1193 Print Dimensions 5 x 3 File Size 6 59MB Enlarged Format JPG DPI 72 Pixel Dimensions 361 x 210 Print Dimensions 5 x 3 File Size 222KB Enlarged The difference is more pronounced when you try to enlarge the JPG image the individual pixels become visible Digital Imaging Basics 7 Image Size File size File size is proportional to the pixel dimensions of an image is partially determined by the file format and it specifically refers to how much disk space your file occupies either on the hard drive CD or other storage medium Image files normally range in sizes measured in Kilobytes KB or K and Megabytes MB or M extremely large files may be measure in Gigabytes GB Images for print will have larger file sizes since higher resolution more data stored in the file Images for Web or computer display will have smaller file sizes As a general rule and there are appropriate times and places to break it Web images should fall between 10 and 200K images with larger file sizes will load more slowly and generally be too cumbersome for effective computer distribution and display Saving your images in JPG or GIF format will automatically compress and reduce your
14. le This will help to ensure that you have something to go back to and work from should something unfortunate happen to the other files Name Files Accurately Develop a file naming convention that will help you accurately identify your files Names that include descriptive information version or size information or intended use information can be helpful when managing large digital image collections Digital Imaging Basics 8 Viewing File Information There are various ways to view the file types and sizes of your image files the most common are demonstrated in the three bulleted examples below e Right click on your file in Windows Explorer or Mac OSX Finder Choose Properties or Get Info Figure 4 respectively to see the file type or Kind file size and other information Figure Open Open With Print Get Info Move to Trash Duplicate Make Alias Create Archive of A70 jpg Slideshow Copy A70 jpg Color Label x 80e88680 06 Figure 4 O A70jpg Info qa A70jpg 212 KB c Modified Jun 28 2005 11 22 AM gt Spotlight Comments Y General Kind JPEG Image Size 212 KB on disk 214 533 bytes Where Users melanie Desktop Created Tuesday June 28 2005 11 22 AM Modified Tuesday June 28 2005 11 22 AM Color label x 0 Stationery Pad C Locked gt More Info gt Name amp Extension gt Open with gt Preview gt O
15. oc 288 3K 288 3K gt Figure 7 File size Digital Imaging Basics 10 Common Image Editing Tasks Three of the most common image editing tasks are cropping resizing and removing red eye from photos Pll briefly explain the basics of each using Adobe Photoshop CS These basic processes should be applicable to most other image editing programs ll also go over batch processing a valuable time saver when applying the same edits to large numbers of files Other common editing tasks such as adjustments to exposure or color balance can be performed either when you scan the image or later when you use an image editor Cropping Often the digital image you are working with includes more visual information than what you really want The process of selecting what you do want and then deleting the rest of the image is called cropping This is akin to trimming printed photos with scissors to fit into a frame or remove unwanted details NOTE The difference between the Crop function and the Cut function is this Crop removes what is outside your selection marquee Cut removes what is nside your selection marquee To crop an image select the portion of the image you wish to keep by using one of the marquee tools from the toolbox Then go to Image gt gt Crop Figure 8 Your image will be reduced to what was inside your selection or in the case of using the elliptical marquee as in this example it is reduced to what rectangular forma
16. ormation each time that they are compressed The lossless and compressed file format that is preferred for graphics because it keeps edges and lines sharp GIFs are limited to 256 or fewer colors and are not recommended for photographs but rather for images with flat fields of color such as clip art GIFs can be static or animated Portable Network Graphics format an open source substitute for GIFs PNGs provide a higher lossless compression rate than GIFs and help to reduce cross platform differences in image display quality among other technical advantages PNG provides a useful format for the storage of images during intermediate stages of editing See http www libpng org pub png for mote info All of the formats detailed above are readable in both Windows and Mac OS operating systems and are supported by most image viewing and editing applications Digital Imaging Basics 3 Production of Digital Images Digital images can be produced in a number of ways the most common of which are detailed below Scanning You can take pretty much any printed material and scan it to obtain a digital copy of it Readily available scanners make scanning images on paper printed photos slides and negatives a fairly simple process Many of these scanners are plug and play which means that soon after you unpack and plug your scanner into your computer you can scan away without much delay Flatbed scanners Figure 1 operate in a
17. splayed color is determined by a combination of RGB Bit mapped or Raster images Images that have data that describe the color of each pixel Larger display sizes equal larger file sizes in this type of image Bitmapped images cannot be rescaled without resulting in pixilation or loss of definition in the details JPEG and GIF images are examples of bitmapped images Proprietary Denotes ownership and non disclosure of details regarding format or programming code In the context of this tutorial proprietary refers to file formats that require a certain software application to read open that file For example psd is the proprietary file format for Adobe Photoshop files DPI dots per inch Measurement used in printing images Megapixel A megapixel that is a million pixels is a unit of image sensing capacity in a digital camera In general the more megapixels in a camera the better the resolution when printing an image in a given size from http searchsmb techtarget com Lossless A term used to describe an image file format that retains all the data from the initial image file CMYK Cyan Magenta Yellow and Black The color model for printing If you are printing something in color be sure you have saved it in CMYK Vector images Vector images have data that describe lines and curves These images can be enlarged and still maintain their smooth edges not pixilated like bitmap images Artis
18. t most closely approaches the edges of the selection circle Figure 9 Image Layer Select Filter View Window Help Mode gt W weer E Heo 3 irune Fool Presets Adjustments Duplicate Apply Image Calculations Image Size Canvas Size Pixel Aspect Ratio Rotate Canvas Ducky tif 100 RGB 8 Doc 799 8K 799 8K Figure 8 Figure 9 Digital Imaging Basics 11 Resizing In order to change the display or print dimensions of your image you need to resize it Do this by going to Image gt gt Image Size and entering the desired dimensions in either the pixel dimension for computer display or document size for print area of the dialog box Figure 10 You will notice when you adjust the numbers in the pixel dimension area the document size numbers adjust automatically and vice versa This is because pixel and print size are related and affect one another You may find it necessary to have one image sized optimally for computer display from the original and another copy of the image sized optimally for print also from the original Selecting Constrain Proportions will ensure that adjustments to width will automatically adjust the height proportionally and vice versa so that your image doesn t become distorted Image Size Pixel Dimensions 233 8K e a Width 283 pixels HA 3 Cancel Height 282 pixels HA f E O E Document Size Width 3 93
19. ts and designers will often work with vector images and then rasterize the finalized version for distribution and display Adobe Illustrator files ai and CorelDraw files cdr are examples of vector images Open Source Denotes a more accessible way to share improve and distribute resources requiring that licensing not be specific to a particular product See http www opensource org for more info Digital Imaging Basics 2 Explanation of File Formats It is also helpful to understand the common image file formats of digital images how these file formats differ and what their recommended use is TIFF tif JPG jpg jpeg GIF gif and PNG png are file formats and their respective file extensions that you are likely to encounter Other image file formats are used to a lesser extent these formats are often proprietary such as Photoshop psd files TIFF JPG or JPEG GIF PNG A lossless file format that can be compressed This format is widely supported across operating systems TIFF is the best file format for archiving high quality images The JPG file format was specifically created for photographs and can contain millions of colors JPGs are automatically compressed you can choose the level of compression to match your desired image quality resulting in a relatively small file size while still retaining quality For this reason JPGs are ideal for email and Web use JPGs are lossy discarding inf
20. way similar to photocopier you raise the lid put the image face down on the glass close the lid and scan Some of these flatbed scanners even have feeder trays to quickly scan multiple pages EEE ey we 4 4 Figure 1 Figure 2 Figure 3 Www epson com www photographic com www canon com Photo print slide and negative scanners sometimes these are all combined into one scanner as in Figure 2 usually have a slot into which you feed the item you want scanned You can scan these types of materials on a flatbed scanner but the raising and lowering of the lid often shifts or turns the items slightly resulting in unexpectedly crooked or off centered scans A small piece of tape across your item and the edge of the scanner NOT the glass can help to alleviate this problem Digital Cameras Digital cameras Figure 3 and camera phones are probably the fastest easiest way to produce digital images Keep in mind that there is quite a wide range of performance differences among brands models by the same brand and between consumer vs professional grade equipment What you really need to know is how to navigate through the function menu on your particular piece of equipment The user manual will be very helpful in explaining what all those weird abbreviations codes and acronyms mean At this point I want to point out a few notable settings on the digital camera 1 All digital cameras have variable settings for image quality
21. wnership amp Permissions Figure 5 Digital Imaging Basics 9 e Inthe Windows Explorer or Mac OSX Finder choose to view a list of your files with details by clicking View gt gt Details or the button respectively This will display your detailed file information in columns In Mac OSX these are labeled file Name Date Modified file Size and file Kind Figure 6 e eX images a 88 SE te Q Network Date Modified Size Kind Ia canon_powershotA70 jpg Jul 10 2005 3 08 PM 116 KB JPEG Image D 3 en cdrom gif Jul 10 2005 2 41 PM 8 KB Graphics Interchange Format Image E Desktop epson4870 jpg Jul 10 2005 3 00 PM 4KB JPEG Image A get_info Today 2 19 PM 152 KB TIFF Document melanie nee lel hpphotosmart jpg Jul 10 2005 3 17 PM 8 KB JPEG Image A Applications info_details Today 2 22 PM 52KB TIFF Document J Documents mac_detail_btn Today 12 07 PM 764 KB TIFF Document amp Movies mac_detail_btn tif Today 12 10 PM 44 KB Adobe Photoshop TIFF file 6 Music Pictures J an 8 items 92 48 GB available A Figure 6 e While working in a photo editor such as Adobe Photoshop you can see the file type and size information in either the bottom border of the application window Windows or the top and bottom borders of the document window Mac OS Figure 7 Q Q Ducky tif 100 RGB 8 File type as indicated by the tif extension 100 D
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