I am trying to verify that I am doing L*a*b* conversion to sRGB correctly.
The issue I find is that when I do the transformation the results are
always the same for each colorspace. I am trying to compare the converted
Lab in D50 2 degrees to sRGB to that of Labs in D65 2 degrees to sRGB. I
have taken the following steps:
1) I get a White Point for D50 2 degrees using {96.422, 100.0, 82.521}
xyY = {0.3456, 0.3585, 100.0}
2) I get a White Point for D65 2 degrees using {95.047, 100.0, 108.883}
xyY = { 0.3127, 0.329, 100.0 }
3) Create input profiles using white points above (cmsCreateLabProfile)
4) Create output profile using cmsCreate_sRGBProfile
5) Create transforms one for Lab D50 to sRGB and other for Lab D65 to sRGB
6) Call cmsDoTransform -
7) Also use cmsLab2XYZ to view the XYZs
L*a*b* 50, 20, 30
D50 2 deg XYZ = 21.7748, 18.4187, 6.06875
D50 2 deg RGB = 161, 105, 69
D65 2 deg XYZ = 21.46429, 18.41865, 8.007
D65 2 deg RGB = 161, 105, 69
Each set of Labs I use produces the same RGBs for both D50 and D65 which
is not what I would think it would do. I have compared my results with
the BruceLindbloom.com site and the values for D50s are different than
D65s. The XYZs are different for the two and agree with the Lindbloom
calculation. Am I missing a step. It seems to me that the conversion
always produces D50 2 degree results.
Thanks,
Bob
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