csu - dce 0723 - advanced perl web images - fort collins, co copyright © xtr systems, llc...

CSU - DCE 0723 - Advanced PerlWeb Images - Fort Collins, CO

Copyright © XTR Systems, LLC

Introduction toImaging on the

World Wide Web

Instructor: Joseph DiVerdi, Ph.D.



Core Imaging Concepts

• Graphics Models– Raster vs. Vector

• Image Types– “Photograph” vs. “Cartoon”

• Color Models– Black-White, Monochrome, RGB, HSL, HSV, ...



Graphics Models

• Raster Environment– Space is defined using a fixed number of points

called “pixels” which possess a color• images are made up of arrays of pixels• Adobe PhotoShop



Raster Examples

Magnified View ofTV or Monitor Screen

Magnified View ofPrinted Magazine



Raster Examples

Magnified View of Image ofTV or Monitor Screen



Graphics Models

• Vector Environment– “Objects” are defined using mathematical

operations• line: start_point, end_point• patch: top_left_point, bottom_right_point, color• Adobe Illustrator, PostScript



Vector Examples



Importance of Resolution



Graphics Models

• Vector Environment– Requires considerable processing power to

“render” or display image– Objects can be manipulated at any time– Image is scalable, always rendered at the output

device’s resolution

• Raster Environment– Images have intrinsic resolution– Objects do not exist– Data size depends on pixel count– WWW is “primarily” but not exclusively raster



Image Types

• “Pictures”– Continuous gradations of

color– Think photographs



Image Types

• “Cartoons”– Relatively large patches

of constant color– Gradients can be

simulated or approximated

– Think cartoons



Color Models - Color Wheel



Color Models - RGB



Color Models - HSL



Color Models



Storage Formats

Photoshop compressed internal use only, supports layers

GIF compressed, pallette only

cartoons, interlacing, transparency, animation, proprietary

JPEG compressed, RGB or pallette

photorealistic, cartoons, high compression

PNG compressed non-proprietary



Storage Formats

Saved as JPEG Saved as GIF

csu - dce 0723 - advanced perl web images - fort collins, co copyright © xtr systems, llc...

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