Lab Color model question

JG
Posted By
Justin_Giovanetti
Jul 15, 2004
Views
310
Replies
1
Status
Closed
2 things. In the L*a*b mode L=Luminance, and it states that Luminance at 100% equals white. But if you pick for instance the color: 0072B0 and set the L (Luminance) to 100% you end up with the color: 94FFFF, not white. The second thing, notice what happens to the "H" numbers in the HSB model when you drag the luminance up and down. The H (Hue) changes. The problem is, the Lab model is supposed to use the "a" and "b" for the Hue and the "L" is only supposed to effect the Luminance/brightness, it’s not supposed to effect the Hue. So why is the hue being effected and why don’t I get the color white when I set the Luminance field to 100.
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George_Austin
Jul 15, 2004
Justin,

To say that Lab contains no chrominance data is not to say that HSB hue does not contain luminance data. It does. Luminance affects hue. Remember that hue is defined in a different color system. Although Lab Luminance contains no chrominance data, chrominance data is spread across all three HSB channels. And HSB brightness does NOT correspond to Lab luminance, as you seem to imply.

George

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