50% Gray in RGB, Lab ang Gray-gamma 2.2: why are different?

Started Jan 15, 2013 | Discussions thread
OP NeroMetalliko Regular Member • Posts: 237

technoid wrote:

Pretty good improvement. Keep us updated.

I took a look at Argyll and there are a ton of things in it but didn't see anything dealing with B&W only. That would be a great addition and really pretty easy. I suppose I could download the source but am not really motivated. Matlab hack works well and most of my work is color and I get good results with X-rite's stuff.

Currently I'm really busy learning and implementing/testing the L*a*b* to Adobe RGB (and inverse) calculations functions in the spreadsheet (thanks to the great Bruce Lindbloom website).

In this way I think I could achieve the goal to build the curve directly in Adobe RGB (256 values instead of 101).

With Argyll I suppose I can create a wedge with up to 256 gray patches, printing and reading it, building then a (RGB) .icc profile with only the gray information. This will allow me to convert the gamma 2.2 BW source image to the Argyll RGB (gray based) .icc profile and then, by assigning a Gray gamma 2.2 profile the job should be done.

I will keep you updated.


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