>>4212900>TIFF?Yes, indeed TIFF supports grayscale image with a single 16-bit channel. Same with PNG. I tested it by converting this cell phone snap into a monochrome image. Let's see if 4chan supports 16-b mono PNG.
It seems like only lossless formats support high bit depth (>8 bits/pixel) images. On the video side lossy 10-bit colour depth has been available for a long time and I was wondering why something similar doesn't exist for photos.