32. Color image quantization - 2011

32. Color image quantization - 2011 - EE 638: Principles of...

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EE 638: Principles of Digital Color Imaging Systems Lecture 30: Color Image Quantization
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Color Image Palettization With 24 bits/pixel of video memory, color images may be displayed directly without artifacts. Many color displays have only 8 bits of video memory which are mapped into a lookup table (LUT) with 24 bits at the output 24 bits entrance
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Techniques for palette design Question: how to find 8 bits quantization to represent? The output color s are spaced non-uniformly to yield equal steps in L*. In L* uniform space, damage to color image could have minimum perception impact. 3 bits 3 bits 2 bits
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Scalar Quantization of R, G, B --- R, G are quantized to 7 levels and B is quantized to 4 levels for a total 7x7x4=196 colors. If no color value falls in this level, it is a waste. Splitting could be done along the coordinate axes of color space. - Medium cut - variance based
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Application of image-dependent techniques to a uniform histogram (R. S. Gentile , J. P. Allebach , and E. Walowit , "Quantization of color images based on uniform color spaces,” 1990).
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This note was uploaded on 02/19/2012 for the course ECE 638 taught by Professor Staff during the Fall '08 term at Purdue University-West Lafayette.

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32. Color image quantization - 2011 - EE 638: Principles of...

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