Hello, I'm using a DPT-94 colorimeter, dispcalGUI, and argyllcms to neutralize and improve the greyscale response of my notebook's LCD screen (dispcal reports a typical 8-bit LUT response). It works well using the small 127-patch measurement chart to produce a small, medium quality LUT profile. Switching from a gamma 2.4 power curve to the sRGB curve slightly improved the tonal separation in the RGB(0, 0, 0) to RGB(5,5,5) range, so I'm using that curve (without any view condition compensation, however). Matrix profiles just don't seem to lead to a result as good as the LUT profiles. I'm a beginner at color management, the motivation for switching over from a profile using the 100-patch LUT profile option of the bundled Monaco software was that while the Monaco software produced a profile with good separation in highlights and shadows, there was a small amount of banding at any target temperature, including native--which for this LCD is around 6000K, a little too warm. Also, the Monaco software was still producing a small amount of variable colour casts visible on grey ramps, although less with the LUT profile. The Argllycms LUT profiles are distinctly better on the banding and colour temperature issues--even just using the 127-patch chart. My preference is for a slightly cooler temperature, and the 6500K nominal temperature setting works out to 6300K in the actual measured profile, with no sign that the LUT curves are bashing the tones on the LCD, and the grey ramps at 6500K are even more neutral than the Monaco profile at native LCD temperature. Anyway, the one remaining issue is tonal separation in the RGB(1, 1, 1) to RGB(5,5,5) range: RGB(3,3,3) is output at RGB(12,7,5), barely distinguishable from the input of RGB(0,0,0) output at RGB(9,1,1), while the Monaco profiles seem to have a deliberately steep curve in that range: deep shadow tones are easily distinguished from total black, for a very pleasing separation: this is something that must be part of the Monaco "secret sauce", tweaking the curve in that area, argyllcms adheres much more closely to the mathematical definition of the curves. Still, the Monaco profile manages to squeeze out some differences from the typical medium quality matte LCD notebook screen which argyllcms does not. I'm attaching jpegs of the different curves, as well as the profiles (the Monaco profile includes some kind of measurement data, hence the larger size). The argyllcms options were dispcal -v -d1 -c1 -yl -qm -m -t6500 -gs -f0 -k0 colprof -v -qm -al Now, what argyllcms options would allow either 1) steepening the curve in that deep shadow range, or perhaps 2) slightly raising the profile curve output at the RGB(0.0.0) end of the curve so that an input of RGB(0,0,0) is translated to something the next step up in the output greyscale? I can't quite figure out how to use the -f or -k options of dispcal to do this, or should I be using the view condition option -a? Can anyone help?
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