I have pale text rendering in Linux with freetype2-infinality and custom FIR filter (INFINALITY_FT_FILTER_PARAMS="06 18 33 18 06"). This behaviour was introduces in the Qt5, the Qt4 is not affected. The screenshot is attached (Qt4 assistant and Qt5 assistant are shown side by side). I found that problem is related to the gamma tables. So I've made a hack, which fixes this issue by disabling the text gamma correction completely (patch is attached). Maybe someone knows, how to make a correct fix?