Hi all,
For two XYZ1 and XYZ2 values, if I choose a reference white W_200 with
Luminance=200cd/m and then convert both XYZ1 and XYZ2 to CIE Lab, I
obtain the difference err1 in Delta E.
Now if I choose another common reference white W_100 which has the
same chromatricity coordinates as W_200 above but the Luminance=100 cd/
m^2, then I compute the difference of two stimuli in Delta E, I obtan
the err2.
My confusion is that err1 (with W_200) will be smaller than err2 (with
W_100).
With a high lumiance white reference (200cd/m^2) , the XYZ1 and XYZ2
will be considered darker than those when we use lower- luminance-
white reference (100cd/m2). The Human Visual System is more sensitive
to the difference in the darker range than that in the highlight
(brighter) range. So I expected the difference between XYZ1 and XYZ2
in Delta E units when 200cd/cm^2 white reference is used should be
larger than that when 100cd/cm^2-reference-white is used. However,
from the mathematical conversion formular, it it converse. Can you
tell me what is my missing point?
Thank you
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