Nicolas Robidoux wrote: > I stand to be corrected on this, but I believe that there is more than > one sRGB standard. I also vaguely remember reading that the formulas > are slightly different for 8 and 16 bit sRGB, meaning that they don't > exactly agree at the common (scaled) values. Hi, it appears that the util.h values are from a draft of the IEC sRGB standard, not the final one. Elle Stone wrote: > The standard values are: 0.04045 and 0.0031308. > The util.h values are: 0.03928 and 0.0030402477. Nicolas Robidoux wrote: > Again from fading memory, I believe that the original formulas failed > to be perfectly smooth, which was completely irrelevant in 8-bit but > could be argued to be significant in 16-bit. I also would not be > surprised if some 16-bit sRGBs have a slightly wider gamut. > These tweaks would break the "alignment" of 8-bit sRGB with 16-bit sRGB. Let's see: Current IEC specification values: 0.04045 / 12.92 = 0.003130804954 ((0.04045 + 0.055)/1.055)^2.4 = 0.003130807229 continuity error of 1 part in 1.3e6 Draft IEC sRGB & util.h values 0.03928 / 12.92 = 0.003040247678 ((0.03928 + 0.055)/1.055)^2.4 = 0.003039492412 continuity error of 1 part in 4e3 So the util.h values are a lot less smooth than the sRGB standard values. Graeme Gill _______________________________________________ gimp-developer-list mailing list gimp-developer-list@xxxxxxxxx https://mail.gnome.org/mailman/listinfo/gimp-developer-list
