|Image Processing Toolbox User's Guide|
Reducing Colors in an Indexed Image
imapprox when you need to reduce the number of colors in an indexed image.
imapprox is based on
rgb2ind and uses the same approximation methods. Essentially,
imapprox first calls
ind2rgb to convert the image to RGB format, and then calls
rgb2ind to return a new indexed image with fewer colors.
For example, these commands create a version of the
trees image with 64 colors, rather than the original 128.
The quality of the resulting image depends on the approximation method you use, the range of colors in the input image, and whether or not you use dithering. Note that different methods work better for different images. See Dithering for a description of dithering and how to enable or disable it.
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