I'm trying to use LibRaw to convert CR2 files from Canon 80D, and when I use rgb_cam combined with pre_mul, I get some not quite realistic colors. In particular, it looks too orange to me. It appears as if the old Canon 1100D got it more "right" than the new 80D.
I then took some photos of my monitor showing RGBCMYK colors and lighter versions of them with 80D, and also measured these colors with SpyderX. After I made my own camera-to-sRGB color conversion matrix using these data, I got some better results.
I'm quite sure that I'm using the matrix correctly, at least because the calculation of sRGB2XYZ*rgb_cam*diag(pre_mul) gives me a very close matrix to inverse(cam_xyz), so this seems sane.
My question is now: where is rgb_cam taken from? Is it some official Canon-supplied matrix, or was it derived somehow by LibRaw developers?