On Tue, Nov 13, 2012 at 9:14 PM, Paul Geraskin <paul_geraskin@xxxxxxx> wrote: > I had some experience in converting sRGB to linear RGB. When I coded in > GLSL. I have taken this code from blender GLSL shader. > The main idea is: convert all inputs to linear RGB, then make formula > calculation, then convert output to sRGB. > > The methods from blender GLSL shader (it works per channel): in GIMP and GEGL code pixel format conversion between well defined standard color models and pixel formats is the responsibility of babl, http://gegl.org/babl/ Converting from 8bits per component sRGB to 32 bit floating point with the same RGB primaries as sRGB but with a linear gamma ramp is done like this: babl_process (babl_format ("R'G'B'A u8"), babl_format ("RGBA float"), source_buffer, destination_buffer, n_pixels); Other predefined babl_formats of interest could be "RaGaBaA half" which is 16bit floats in linear light with premultiplied alpha. Or "Y' u8" which is 8bit grayscale like you'd find in a grayscale JPG or PNG. You can extend babls vocabulary of data types and pixel formats at runtime as well as register optimized fast-paths, that can be combined for pairs of formats without their own fast paths (possible conversions are precision and performance profiled at runtime). /Øyvind K. -- @hodefoting _______________________________________________ gimp-developer-list mailing list gimp-developer-list@xxxxxxxxx https://mail.gnome.org/mailman/listinfo/gimp-developer-list
