Graphics

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Graphics

• Problem Solving with Computers

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What is a Color Model?

• A method for representing colors
• Each color is normally represented by a triple
• Color models include
• RGB
• CMYK
• HLS

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Some terms ...

• complimentary colorstwo colors that make white
  light
• primary colorsbasic set of 3 colors for a model
• color gamutrange of colors derived from models
  primary colors

• dominant frequency (or wavelength)hue
• brightnessintensity of a color
• saturationpurity of a color
• chromaticitypurity and dominant frequency
  combined

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How do we see color?

• In the eye
• Rods sense the intensity light at low intensities
• Cones sense the intensity of light at moderate to
  high levels
• Cones exist for red, green and blue light

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RGB

• Red Green - Blue

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CMYK

• Cyan, Magenta, Yellow , Black
• Subtractive color model
• Used in printing

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HLS
L 1

• Hue
• Lightness
• Saturation

Green 120?
L 0.5
Red 0?
Blue 240?
H
L 0
S
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Bit-mapped Images

• Pixel
• Smallest directly addressable part of an image
• Generally rectangular
• Arranged in rows and columns
• Resolution
• Relative density of pixels

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Bit-mapped Images
Both of these images have the same number of
pixels