Bit depth = levels of gradient?

Started 2 months ago | Discussions thread
J A C S
J A C S Forum Pro • Posts: 14,421
Re: Bit depth = levels of gradient?
1

filmrescue wrote:

Another poster suggested that the reason I sometimes get banding is because of noise and not because of bit depth when capturing very low contrast B&W negatives with a DSLR. I'm not fully understanding that though. The banding goes away when I scan it with an actual film scanner at 16 bit but maybe he's right and that's not a bit depth issue.

Why don't you post some scans. Who knows what your scanner is doing under the hood. It might not use your bits efficiently or it might convert to low quality JPEGs, etc.

My own scans show enough grain to think that posterization should not be a problem but on some of them, I do see posterization. Most likely a poor conversion (Nikon Coolscan 4000ED if I remember well, 14 bit).

BTW, the tonal range calculations are valid at a reference resolution for the highest frequencies only, roughly speaking. In large low frequency areas, like sky, etc., the extra bits might help.

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