[QUOTE="Andrew Reilly"] JPEG is 8 bits per colour, but that is *after* gamma correction, which is something of the same sort of logarithmic encoding as u-law or A-law in telephone systems. So JPEG's 8 bits (can) represent about 12 bits of linear dynamic range (RAW). Modern digital cameras often have some pre- jpeg processing that can boost shadows a bit, so the recorded dynamic range can be a good bit higher.[/QUOTE] That is basically correct, and a very good comparison. However, the particular gamma correction with JPEG gets a bit over 9 stops of dynamic range. That compares with u-Law encoding of telecommuncations voice frequency circuits, where the SNR of a voice channel cannot be greater than 37 dB. Which says that if, for example, u-Law were used for the gamma correction in JPEG it would result in only about 6 stops of dynamic range.