Hello all, in the interest of clarity, I am seeking information with _citations_ for the coefficients used in the first rgb_to_bw conversion.
If you don't have a citation from a reliable source, please don't post and muddle this thread up any further. I believe the following conversion is a "ITU-R BT.601-2 to Luma" conversion. This should be likely labeled in the code and _not_ used for the majority of situations as it A) Implies 601 primaries, B) assumes a tone curve where A.1) Blender has an assumed BT.709/sRGB primaries base and B.1) linearized tone curve. Citation: http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC11 > float rgb_to_grayscale(const float rgb[3]) >> { >> return 0.3f * rgb[0] + 0.58f * rgb[1] + 0.12f * rgb[2]; >> } I am requesting a citation of the coefficients used in the following formula: >> float rgb_to_bw(const float rgb[3]) >> { >> return 0.35f * rgb[0] + 0.45f * rgb[1] + 0.2f * rgb[2]; >> } >> Oddly luminance BT.709 / sRGB primaries on a radiometric linear source set of RGB values is not listed: "CIE Luminance from linear ITU-R BT.709/sRGB" Citation: http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9 float 709rgb_to_luminance(const float rgb[3]) { return 0.2126f * rgb[0] + 0.7152f * rgb[1] + 0.0722f * rgb[2]; } And finally, there has been some rather exhaustive perceptual research on the various weights here: http://dcgi.felk.cvut.cz/home/cadikm/color_to_gray_evaluation/ With respect, TJS _______________________________________________ Bf-committers mailing list [email protected] http://lists.blender.org/mailman/listinfo/bf-committers
