I'm trying to minimize the VRAM usage, and since the DXTn compressor is still produces artifacts on higher mip levels, I thought of using 16-bit textures as a fallback. I'm using GL_RGBA4 and GL_RGB5 internal formats to be specific. The problem is that I don't see any difference in VRAM usage and visually the textures look the same, which suggest that they are still in RGB/RGBA. I also tried setting the TGLLOWQTEXTURES environment variable, which used to force every texture into 16-bit, but it didn't have any effect either. My question is, was the 16-bit texture support removed, or is there some bug that prevents the resampling of the texture into the requested format?