Hello,

are there any plans to support LAB and CMYK colorspaces in Gimp?

Currently the only option in vanilla Gimp is to decompose RGB image into LAB or CMYK layers, then operate on each layer, and finally recompose them into RGB again - and see result.

There are plugins which allows to apply curves or mix in LAB colorspace - for instance gmic and mmcurves. However, they are very limited, it's not possible to read A or B value from given pixel and set it as control point on curve (just like it works in Gimp curves).

I am fan of Dan Margulis techniques, they all can be applied to GImp, but the problem is lack of realtime preview, you have to work on decomposed layers and imagine yourself what will be result - and it's not trivial in LAB colorspace.

I think the simples way to introduce such feature would be to give image kind of "display type" value. When one want to convert RGB image into LAB, already existing code could decompose RGB image into L+A+B layers, but these layers would be placed into 3 channels of new image. This new image will work just like RGB image, with the only exception - display code instead using 3 channels for R, G, B, will take L, A, B values, then calculate R, G, B values, and then show them on screen. To switch back from LAB to RGB, already existing code could just take 3 image channels and use them as 3 layers and recompose from LAB to RGB.

Would it work?