I am currently working on a MPC-HC patch which tries to improve the quality and give more control to the user over the CMS settings. Some people believe that a custom scaled Inverse-Rec709-Encode curve is better for viewing Rec709 materials than the good-old pure-power curves. There are three existing "Ambient Light" options: Bright, Dim, Dark and they currently represents pure-power TRCs wit gamma: 2.2, 2.35, 2.4 I don't want to change that. But I want to add three differently scaled Rec709 curves beside the currently available pure-power curves. The users who like the scaled curve (for example cyberbeing from forum.doom9.org) says I should try to simulate the ArgyllCMS/dispcal behavior. MPC-HC works with lcms2.1 and I don't want to change that either (at least for now). So, I want to ask for three parameter sets to construct "Type 4" tone curves with lcms. I think this is the exact inverse encode curve: exponent = 2.2; coefficient_exponential = 1/1.099; constant = 0.099; coefficient_linear = 1/4.5; constant_linear_range_length = 0.018; But it looks very bad on the screen and I am not sure how to change them to match with ArgyllCMS/dispcal. (My short "trial and error" caused errors only.) Here is the current test buid: http://www.mediafire.com/?enacumt92xh78cq (Right click on the middle, Renderer settings, Color Management)