Whenever I look into changing illuminants or colorspaces of an image my head explodes because the tutorials out there aren’t as straightforward as I hope. In particular, I am interested in how we arrive at these matrices and would like an easy to follow step by step explanation so that I can make more.
From https://github.com/Beep6581/RawTherapee/blob/dev/rtengine/iccmatrices.h; e.g., how do we get to this?
constexpr double xyz_rec2020[3][3] = {
{0.6734241, 0.1656411, 0.1251286},
{0.2790177, 0.6753402, 0.0456377},
{ -0.0019300, 0.0299784, 0.7973330}
};
PS Future: once clarified, I or someone could make G’MIC more capable in this area.