Re: Colorimetric Accuracy in the Field
Re: Colorimetric Accuracy in the Field
- Subject: Re: Colorimetric Accuracy in the Field
- From: Ben Goren <email@hidden>
- Date: Wed, 05 Jun 2013 13:41:11 -0700
On Jun 5, 2013, at 1:30 PM, Robin Myers <email@hidden> wrote:
> Since they are slightly yellow, their XYZ values lie on an axis defined by D50 but shifted slightly by their amount of yellow reflectance.
Yes, exactly.
But, to my mind, a more clear way of stating that is that the N{whatever} patches on the ColorChecker aren't actually neutral; they just have very low saturation.
Which means that you want them to be rendered into an RGB file not as neutral R=G=B patches (as Bruce Fraser did) but instead as patches with (specific) RGB values very close to each other but not actually equal.
Would you agree that a spectrophotometer is very unlikely to measure the N9.5 patch on Mr. Fraser's chart as L*=96.14 a*=0.00 b*=0.00, and yet Mr. Fraser's profile incorrectly rendered that patch as ProPhoto RGB = 241,241,241 = L*=96.14 a*=0.00 b*=0.00?
Cheers,
b&
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