What is the name of a algorithm implemented in gamma_curve of dcraw?

Dcraw contains a following algorithm to process image colors: https://gist.github.com/1047302.

Is it a formal (named) image processing algorithm?

If not, what sh开发者_运维百科ould I read to understand reasoning behind it?

It's not processing an image. It's generating a lookup table (curve[]) used to perform gamma correction.