i use: double inv_map_ab(double ab) { return (ab+128)*256/UINT16_MAX; } interested to know your results: please let me know if it works for you! regards, edward
On Apr 9, 2015, at 2:26 PM, 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?
Thanks, Mike
-- *Mike Pucher* *Sr. Image Capture Specialist* *Animation Research Library*
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