Join GitHub today
GitHub is home to over 28 million developers working together to host and review code, manage projects, and build software together.Sign up
Update grain.c: grain blending using photographic-paper response. Fixes #11335 #1386
A sigmoidal function is used to model a the exposure-density characteristic curve of photographic paper, and the lightness channel is used to modulate the grain accordingly to the characteristic curve. A LUT is used for computational efficiency. The main effect is a fall off of the grain in shadows and highlights accompanied by the skewing of grain distribution (for further info see the discussion on discuss.pixls.us: https://discuss.pixls.us/t/lets-improve-grain/2709/22). A "midtones bias" slider has been added, at 0% the added grain is indistinguishable from the old implementation.
Looks promising, not too intrusive, but changes are needed.
I've tested it but I cannot see a difference when using the midtone-bias slider. I've looked at the image closely in different location. It seems that the image is not changed. The histogram moves a bit, so I suppose that there is some changes done to the image. Where should I looked? How this slider is working? Thanks.