I'm running into an oddity with the gamma I'm hoping someone can offer up some advise on.
I have a flat grayscale (de < 3) from 5-100%. I am measuring in normal lamp mode with the iris fully open (0). My lamp has 270 hours on it.
When I measure with a default custom gamma with the correction set to 2.2, it measures an average gamma of 1.99. When I set the correction to 2.3, it measures 2.10. When I set to 2.4, it measures 2.18.
In all cases, instead of showing a near-flat horizontal line, the gamma graph starts out high from 0-30%, then flattens out around the average, then drops off quite a bit at the end from about 80-95%.
When my lamp was new, I didn't have this issue, and only needed to use gamma correction of 2.3 to reach a 2.2 curve, and without the wild swings.
At any rate, after another 7 hours of meticulous tweaking last night, I managed to use the white point and RGB points in the custom gamma settings to dial in a flat gamma of 2.2 that follows a horizontal line from 5-90% and then drops off (to like 2.0) at 95%.
However the challenge I am having is that skin tones have a bit or red push that is a bit bothersome, when compared to using the default gamma or a normal gamma.
I can't figure out what is causing this. I double checked my grayscale with the custom gamma a few times and it is flat from 5-100% (dE < 3). And the CMS settings are dialed in with a dE of < 2 for all colors.
Again, when I use the normal gamma or a default custom gamma the skin tones do not have the red push. But with my custom gamma it does.
What do you think can be causing this? How can I go about tracking this down and resolving it? I would think that my work to get a flat gamma of 2.2 across the range would have been worth it - but now I am questioning whether it was the right thing to do.
Any ideas would be greatly appreciated. Thanks!