Terms
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Definitions
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Approximation
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The method by which the software chooses replacement colors in the event that direct matches cannot be found. The methods of approximation discussed in this chapter are colormap mapping, uniform quantization, and minimum variance quantization.
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Indexed image
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An image whose pixel values are direct indices into an RGB colormap. In MATLAB, an indexed image is represented by an array of class uint8, uint16, or double. The colormap is always an m-by-3 array of class double. We often use the variable name X to represent an indexed image in memory, and map to represent the colormap.
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Intensity image
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An image consisting of intensity (grayscale) values. In MATLAB, intensity images are represented by an array of class uint8, uint16, or double. While intensity images are not stored with colormaps, MATLAB uses a system colormap to display them. We often use the variable name I to represent an intensity image in memory. This term is synonymous with the term grayscale.
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RGB image
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An image in which each pixel is specified by three values -- one each for the red, blue, and green components of the pixel's color. In MATLAB, an RGB image is represented by an m-by-n-by-3 array of class uint8, uint16, or double. We often use the variable name RGB to represent an RGB image in memory.
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Screen bit depth
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The number of bits per screen pixel.
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Screen color resolution
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The number of distinct colors that can be produced by the screen.
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