Introducing color calibration module (formerly known as channel mixer rgb)

[anon41087856]

@Thanatomanic

However, in some situations I get a worse white balancing results than by simply using the white balance module. This has probably to do with the CAT. But if someone can tell me how I can improve this with the color calibration module, I look forward to learn. (My minor gripe with this poorer result is that the module is called ‘color calibration ’ which implies things should be very / more accurate).

I just tried that image. The CAT relies on the usual white balance to correct the image to D65, so that the color input profile gets predictable. But for the Sony from that picture, the red white-balance coeff is 2.67, which is massive and probably wrong (most sensors are between 2 and 2.33). If you force a red coeff of 2.0 in white balance module, then retry the color calibration sampling from any grey patch, then it will work.

Problem here is we stack the color calibration on top of white balance and input color profile, so we expect/pray for anything else having been profiled properly.

I got the smell of the red factor issue because cyan is the opponent color.

@kofa

It’s a bit confusing why the ‘temperature’ readings are different from the WB module (e.g. for a daylight shot I got 5527 K in the WB module (‘legacy’ mode); I get CCT = 4467 K in the ‘colour calibration’ (‘modern’ mode) and at the same time temperature = 4466 K on the slider; if I select ‘as shot’ in the ‘illuminant’ drop-down, the CCT changes slightly to 4466 K, the value previously shown on the slider. I know they’re just numbers and I don’t really care, but I do notice the inconsistencies and some may get confused (well, I’m also confused, but I just ignore it for now).

All the CCT computations there are approximations. The temperature slider of color calibration computes the XYZ coordinates of the illuminant from an approximation based on temperature input. Then the CCT display tries to find the best temperature match from an approximation based on XYZ input. Having only 1 K of error in the roundtrip is actually impressive. And you get rounded to 1 K, so a visible difference of 1K could be an actual difference of 0.5 K.

Don’t even try to compare temperature readings from both modules. Again, color calibration takes an input that is already pre-corrected by white balance and input profile.

@MarcoNex

The gamut compression is nice, but I would like to have more range in the slider, to fix led blue lights etc.

Right click on slider, input value on keyboard up to 10.