Texture compression

Is the texture compression on NVIDIA GPUs lossy or lossless ?

How to specify a lossless texture compression in OpenGL ?

I am not aware of any lossless compression scheme that still allow efficient random acces of texels…

All of the current texture compression methods on GPU’s are lossy, all losseless compressions to date have a way to high preformance cost to be practical.
One can only hope they will add something like that, but i am not gonna hold my breath.