Let's talk about the rgb sensitivity in raw.

Started Dec 23, 2012 | Discussions thread
crames
Regular MemberPosts: 192
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Re: How RAW RGB Channel Data is derived from RGB Photosite Image Data
In reply to Iliah Borg, Dec 28, 2012

Iliah Borg wrote:

If the color ratios are constant

Define colour And do not loop

I'm talking about "psychophysical color" as defined in Wyszecki & Stiles.

So, what are the Munsell values, no renotation?

Since you insist, here are Munsell Hue, Chroma, and Value for your hypothetical colors, converted from the Lab coordinates you provided, assuming D50 Lab reference white in the Babelcolor CT&A utility. They are probably renotated, as is apparently all Munsell data since 1946:

7.8BG 8.4/14.7
6.9BG 6.3/11.8

This is interesting, because it shows that a simple change in luminance causes all three of the Munsell coordinates to change. This makes it less than useful for predicting the effects of exposure or luminance changes in real scenes. How would one know just by looking at HCV that those two colors are part of a "shadow series," with the same chromaticity? The exaggerated differences in Munsell coordinates offer no insight that the spectra of the two colors are very similar.

If one had Munsell paint chips with the above HCVs, however, colorimetry predicts that the two chips will visually match it you were to illuminate the darker chip with twice as much light, or view the lighter chip thru a 1-stop neutral density filter.

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