Digital Still ImagesDigital Still Images

ETT 555ETT 555

14 June 2004 14 June 2004

Digital ImagesDigital Images Uses

Multimedia projects Email Prints Web CBL ?

Digital Image Digital Image CategoriesCategories

““Artsy”Artsy” Drawings (create)Drawings (create) Clip art (get, don’t create)Clip art (get, don’t create)

RegularRegular AnimatedAnimated

““Realistic”Realistic” PhotosPhotos

Image Technical Image Technical DetailsDetails

Digital Graphics Types (+ / -)Digital Graphics Types (+ / -) Bitmap (aka “raster”)Bitmap (aka “raster”)

= Pixels (picture elements)= Pixels (picture elements) Used for detailed art / photosUsed for detailed art / photos

VectorVector =Formulas for component =Formulas for component objectsobjects Used for clip art, CAD, etcUsed for clip art, CAD, etc

Cf. fontsCf. fonts

Digital Image Digital Image CreationCreation

Draw / Paint SoftwareDraw / Paint Software Create drawings, clip artCreate drawings, clip art Bitmap or vectorBitmap or vector Time consumingTime consuming Need artistic talentNeed artistic talent

Tools, e.g. graphics tabletsTools, e.g. graphics tablets Examples: Examples: Paint, FreehandPaint, Freehand

Digital Image Digital Image CreationCreation

Direct “Copies”Direct “Copies” Scanner (prints, slides, Scanner (prints, slides, strips)strips)

Digital camerasDigital cameras Digitizing boards (video)Digitizing boards (video) Bitmaps onlyBitmaps only

Digital Image Digital Image CreationCreation

““Borrow” from web pagesBorrow” from web pages Right-click; save (target) as Right-click; save (target) as . . .. . .

Legal issues?Legal issues? See copyright section on webSee copyright section on web

Digital Image Digital Image ManipulationManipulation

Graphics softwareGraphics software ““Fix” problemsFix” problems

Light / darkLight / dark ColorColor ““Retouch” (hair, red eye, etc.)Retouch” (hair, red eye, etc.)

Add interestAdd interest Special effects (“filters”)Special effects (“filters”) Combine for “new” imagesCombine for “new” images

Still Image Still Image HardwareHardware

Digital Camera Precursors “Xapshot” (analog) Apple QuickTake

Still Image Still Image HardwareHardware

Digital Camera Features Resolution (megapixels)

How many do you need? Zoom type and ratio

Optical vs Digital More __X is better

Still Image Still Image HardwareHardware

Digital Camera Features Storage medium

Capacity Flexibility Speed of save Card types

Transfer to computer methods Cable (issues) Card reader

Still Image Still Image HardwareHardware

Scanner Types / Features Flat bed

Bed size Transparency Adapters ADF

Sheet Convenient, but limited

Slide Auto feeder?

Still Image Still Image HardwareHardware

Scanner Features Interface method

Early Now

Scanners & Resolution What do you “need”?

Digital Image Size Digital Image Size FactorsFactors

Physical Size (on screen)Physical Size (on screen) Initial size (in/cm, if scanned)Initial size (in/cm, if scanned) Screen resolution (variable)Screen resolution (variable) Image resolution (variable)Image resolution (variable) Scaling (not all software has)Scaling (not all software has)

MS Viewer = YMS Viewer = Y PowerPoint = Y/NPowerPoint = Y/N Browsers = NBrowsers = N

Digital Image Size Digital Image Size FactorsFactors

Physical Size (printer Physical Size (printer output)output) Image file dimensionsImage file dimensions Printer resolution (dpi)Printer resolution (dpi) Printer vs image resolutionPrinter vs image resolution Software “scaling”Software “scaling”

Your softwareYour software Photo finishersPhoto finishers

Digital Image Size Digital Image Size FactorsFactors

Physical Size (screen, print)Physical Size (screen, print) File SizeFile Size

Image pixel dimensionsImage pixel dimensions Color depth (1-24 bits)Color depth (1-24 bits)

Calculate base examplesCalculate base examples File format impactFile format impact

CompressionCompression Preserve a HQ originalPreserve a HQ original

Impact of File SizeImpact of File Size

K/sec 100K 1MB

28.8K 3.0 33 sec 6 min

56K 6.0 17 sec 3 min

T1 Cable / DSL

150 variable

0.7 sec 7 sec

Digital Image Size Digital Image Size FactorsFactors

Physical Size Physical Size File SizeFile Size Graphic file formats Graphic file formats

(examples)(examples) jpg, gif, bmp, png = bitmapsjpg, gif, bmp, png = bitmaps tif, tga, bmp = top qualitytif, tga, bmp = top quality wmf, cgm = vectorwmf, cgm = vector pcx/pct/pict pcx/pct/pict = obsolete= obsolete

Format Format CharacteristicsCharacteristics Color potential

“true” color (24-bit) B&W (gray scale, 8-bit) Line art (B or W, 1-bit)

File size “Raw” Compression

In digital cameras = “quality”

Format Format CharacteristicsCharacteristics(http://www.webopedia.com)(http://www.webopedia.com) JPG

Full, subtle color Compact, but “lossy”

GIF Limited color (#, areas) B&W (gray scale) Compact & lossless

PNG (http://www.w3.org/Graphics/PNG/) May equal quality of tif Flexibility of color depth, etc Not patented (as gif is)

Format Format CharacteristicsCharacteristics TIF

Full color Limited compression

BMP Full color Little/no compression

Format Format CharacteristicsCharacteristics WMF

Vector Microsoft clip art

CGM Some clip art

PCX Old clip art format

Typical Format Typical Format ChoicesChoices For best prints / “archive”

tif bmp psd (Photoshop)

For on-screen display gif jpg png

Working with Image Working with Image FormatsFormats

Load image Manipulate

Original Quality is the KEY Crop / Resize / Orientation Colors / Brightness / Contrast Color Depth Effects (“filters”)

Save as . . . (choose format)

Assignment & DemosAssignment & Demos