Message
Re: [colorvision_group] Re: GretagMacbeth Mini ColorChecker - Delta-E?
2006-03-02 by CDTobie@aol.com
In a message dated 3/2/06 9:07:55 AM, ttrostel@... writes:
Yes .. I thought so also. One question which occured to me was how
important is it to measure the complete spectrum returned by a sample
vs the several LED lights used in the 1005. Technicaly if the LEDs
have a spectral distribution which mimics the bell shaped spectral
response curves to which our eyes cone receptors are sensitive ... it
shouldn't make a difference (clever though on the part of ColorVision).
Its not necessary for the LEDs to mimic the spectral response curve; that can be taken care of in firmware. After all, such devices work by CIE XYZ matching, which involves such factors.
On the other hand if some of the pigments in the ColorChecker chart do
not merely reflect spectral energy but in fact absorb and re-emit them
in different wavelengths (like optical brighteners do) then those 4-5
delta-e measurements would make a lot of sense.
Which is why more expensive BCRA tiles are used for actual testing. The ColorChecker seems more determined to fill out the bright corners of the colro range, which would lead to more fluorescence. I can send you EyeOne and 1005 measurements of the same ColorChecker for comparison. Measurement differences between the two average less than one L, a, or b unit; haven't coverted that to Delta-E98 yet...
C. David Tobie
Product Technology Manager
ColorVision Business Unit
Datacolor Inc.
CDTobie@...
www.colorvision.com