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Internet Graphics

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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 = 1,310,720VGA: 640 x 480Your monitor can be modified

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Representing Images

RGB: monitor, each pixel Intensity: 0 (dark) – 255 (bright) Representing Color: # - # - #

255-255-255 = white100-0-0 = scarlet16,777,216 = 16 million colors

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Representing Images

Light media: RGB Opaque media: paint

Red, blue, yellow Printers

Cyan, yellow, magentaMust have conversion software for

translating monitor to printer

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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

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Reducing Color Depth

Reduce the number of colorsDepth: measured by bits/pixelTrue color = 3 bytes = 24 bits

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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 + 768 bytes to define the palette

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Other Color Depths

1-bit - Black & White 4-bit = 16 colors

Simple drawings, iconsWindows, but can change paletteStart; Settings; Control Panel;

Display; Appearance; Scheme

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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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