I have a hardware product that relies upon receiving pixel values over an HDMI link, exactly as they are coloured no the desktop. For example if a pixel had the 24-bit colour 0x57505F, then the hardware needs tor receive the exact same 24-bit value. I have just started using an AMD Radeon HD 6250 chipset, with Catalyst Control Center 2013.0705.1415.23716 and the values of the pixels are not being reproduced exactly. For example when I have an area (say 100x100 pixels) of the same value (0x57505F) and I look at the HDMI stream the values (seemingly randomly) drift around the desired pixel value, for example I will see some 0x58505F, 0x57515F, 0x585060, 0x575160, etc as well as the correct pixel value. All the Control Center options are default and I have tried tuning the settings, but without any success.
Is anyone able to explain what is happening to have the pixel values change like this. I do not believe it is an error on the HDMI bus (I would be seeing bit-shifts in the 8b/10b encoded data, not 1-bit value shifts), but rather an artefact of some filtering, or rendering that is happening somewhere in the graphics driver/chipset combination.