1 Internet Graphics

2 Representing Images  Raster Image: Images consist of “dots” of color, not lines  Pixel: Picture element-tiny rectangle  Resolution: Number of pixels SVGA: 1280 x 1024 = 1,310,720 VGA: 640 x 480 Your monitor can be modified

3 Representing Images  RGB: monitor, each pixel  Intensity: 0 (dark) – 255 (bright)  Representing Color: # - # - # = white = scarlet 16,777,216 = 16 million colors

4 Representing Images  Light media: RGB  Opaque media: paint Red, blue, yellow  Printers Cyan, yellow, magenta Must have conversion software for translating monitor to printer

5 Storage of Images  1 byte = 8 bits = 255 values  Images are memory hogs  Causes problems with transmission  e.g. Image: 5 million pixels = 14 Mb  Solutions Less “accuracy” Compression

6 Reducing Color Depth  Reduce the number of colors  Depth: measured by bits/pixel  True color = 3 bytes = 24 bits

7 8-bit Color  1 byte = 8 bits = 256 colors  Color Palette – 256 colors Multiple palettes are available  8-bit number represents the particular color in the palette – not the mix of RGB  Uses 1/3 storage space bytes to define the palette

8 Other Color Depths  1-bit - Black & White  4-bit = 16 colors Simple drawings, icons Windows, but can change palette Start; Settings; Control Panel; Display; Appearance; Scheme

9 Color Depth Tradeoff  Color depth vs. Resolution  Due to storage requirements, must reduce one  1280 x 1024  256 colors  16 M colors  640 x 480  Photos: need more than 256 colors

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