Quote:Why use 16-Bits-per-channel all the time? Isn't this a total waste?

Not when you take compression into account. To make this clearer, assume a paletted image with 5 colors and no transparency. So the data is only a set of regular chunks (color1, ..., color5) in a certain order. Compression algorithms have been designed to recognize those chunks and can even look at how these chunks interact.Local tests have shown that farbfeld easily beats paletted PNG-images. Try for yourself and look at the bzipped results! There is no need for special grayscale, palette, RGB, 1-, 2-, 4-, 8-, 16-Bit subformats. Just use 16-Bit RGBA all the time and let compression take care of the rest.