On Apr 9, 2015, at 11:26 AM, Mike Pucher <michael.pucher@disneyanimation.com> wrote:
I have a set of L*a*b* measurements of color charts that I created with a i1Pro2 spectrophotometer. The Xrite software exports L*a*b* values on a scale of L*:0-100 and *a*b*: -100 to +100*.
I've written a script for Photoshop to automate the calculation of specific metrics of captures of those charts, but there's one snag: Photoshop displays L*a*b* values on a scale of L*:0-100 and *a*b*: -128 to +127*.
I assume, but I haven't been able to find confirmation, that it is a mathematically linear conversion (mapping) from the *-100 to +100 a*b* scale* to the *-128 to +127 a*b* scale.* Can anyone verify this? Or point me in the direction of the proper way to map the values between the two scales?
Hi Mike, How do you know the range from the “X-Rite Software” is -100 to +100 for a* and b*? I see no reason to believe that you should scale anything. I would think you are safer thinking of your -100->100 data as simply range limited and you should encode it to the same values in Photoshop regards, Steve