That bug is really bugging! The treatment of colors in Blender is partly still a mystery to me as for example the “Color Management’s” transformation for converting your rendered image into a specific display device’s color space. There’s a gamma correction but I’m not sure whether this is all. The “Blender Manual” isn’t very precise there. At least I know that as soon as I save my rendering as .exr-file, no “Color Management” is applied by Blender.
