but it seems to have been more in common a decade or so ago than now. I haven't found a good rationale for a linear ramp on the front or matrix spaces. I checked the ProPhoto RGB profile Adobe uses as well and it is also a pure gamma profile! But I also recall ROMM had a linear ramp as well so I don't know why that has filtered into Adobe stuff. Different implementations may use different slope limits. Note that the above slope limit is an implementation aspect, not an attribute of the Adobe RGB (1998) color space encoding. see graphic equation in PDF - my one line equiv: max(pow(C,2.19921875), C/32) for C The effective inverse transfer function for Adobe RGB (1998) when used with ACE thus becomes: At the time of writing, the Adobe color conversion engine, ACE, included with Adobe Photoshop and other products from Adobe Systems, imposes a slope limit of 1/32. A slope limit of 1/32 affects 8-bit integer values 1 to 14. When used with the Adobe RGB (1998) ICC profile, the slope limit should not be greater than 1/32. For an arbitrary slope limit of x (where x < 1), the effective gamma curve as used in the color converter has a slope of x or greater. Many color converters and products impose slope limits on gamma curves found in the rTRC, gTRC, and bTRC tags of ICC profiles.
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