darktable's filmic FAQ

[priort (Todd Prior)]

Gone but archived … @stuntflyer he has been asked a few times

How to determine 'middle grey' in image processing?

Nobody cares about the value of middle grey. It’s just a math anchor to unroll image processing algos. There is no truth in it. Normalized small dynamic range RGB spaces place it between 18 and 20% luminance, display-referred. Normalized spaces are useful when dealing with non-normalized input and output spaces, so they serve as connection spaces. Middle-grey is just a concept of an average luminance value, at equal distance between “white” (or max luminance) and “black” (or min luminance). And…

How to determine 'middle grey' in image processing?

Numbers are there because pixels are represented by some value. So we can’t escape doing maths on pixels. However, whatever value you read is code for something. Math is a language, numbers are representations of some quantity. Bothering about numbers is like bothering about words in a text. You don’t care about individual words, you care about their meaning. We are tackling fundamental epistemology here. Image processing uses models, like science does. Models represent something real in an a…