How can I check if .dds texture is gamma-corrected? It seems to be gamma-corrected since after manual gamma correction in fragment shader image is too bright. But I wanted to be sure.
If the data is only 8bbit per channel, then sRGB is the likely choice but...
If the DDS texture is mip-mapped, perhaps you could see if the downsampled pixels indicate if it's in sRGB or linear format, since the filtering process for sRGB should be done as sRGB->linear, filter/downsample, linear->sRGB, which should lead to reasonably different results. EG average of 0xFF and 0x00 in sRGB is around, IIRC, 0xB4 not 0x80.