"Alan Browne" wrote in message
...
How is an 8 bit file "1-2 stops less" than a 12-13 bit one?

A good JPG doesn't "lose" dynamic range because of the number of bits, it
is a log compressed format and as such can potentially represent the full
DR of an image - it does lose fine dynamic resolution, of course.

I'm unaware of any camera that can adjust curves before saving to jpeg, and
I sure as hell find it easier to do it at my leasure afterwards, than try to
do it with each shot as I take it, even if they did, so I don't have any use
for saving 8 bit jpeg only files in camera. They *WILL* lose DR.


Where JPG does lose DR is when it maps to a colorspace. JPG's created in
camera are mapped to a colorspace (and most cameras provide at least a few
choices). Such colorspaces have comparatively narrower DR.

Since many only map Jpeg to Srgb, that is indeed true.

Trevor.