Re: 12 bit images The problem is that Real Life™ has a contrast ratio well in excess of 12bits (72dBs) and if you add any exposure error (human error or fooled software) then you may find quite a bit of your exposure is crushed or burnt out.
This is why people use 14bit scanners running at 4096dpi and the like, only to downsample to 640x480x8bit. You will always get better results if you throw away resolution cleanly using well designed digital filter than to use a low-res scanner directly. I have seen several comparisons of SD vs HD TV down-converted, and the latter wins every time. my 2¢ -Steve
