摘要 |
Color is edited using a color representation including digital values B (brightness), e and f such that B=√{square root over (D<SUP>2</SUP>+E<SUP>2</SUP>+F<SUP>2</SUP>)}, e=E/B; f=F/B, where DEF is a linear color coordinate system. Alternatively, color is represented using digital values B, C (chroma) and H (hue), where cos C=D/B and tan H=E/F. Brightness can be changed without a color shift by changing the B coordinate and leaving unchanged the other coordinates e and f or C and H. Other features are also provided. Brightness coding methods are provided to reduced the size of image data for storage and/or network transmission. The coding methods include logarithmic coding. Some embodiments use logarithmic or linear coding depending on the brightness at a particular pixel.
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