I think you may be secretly sneaking a step whereby the adjustment layers all run with more bits then only collapse back out to 8-bit at the end to get their higher quality. If you've fixed your code to work with the adjustment layers, you might as well fix it to work that way in general, which I think what GEGL is . It's still not the "adjustment layers" that are fixing anything, it's the fact that you're actually retaining the bits. Pure 8-bit adjustment layers will still look bad, and 12/14/16/8+-bit normal layers will look much better with and without adjustment layers. You can't escape from the fact that computing with too few bits necessarily entails information loss.