Bit depth = levels of gradient?

Started 2 months ago | Discussions thread
57even Forum Pro • Posts: 13,569
Re: Bit depth = levels of gradient?

John Sheehy wrote:

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.

It's a lack of noise that gives contour banding. Lack in the original RAW digitization is possible, but only in the deepest shadows in or near base ISO of just a few cameras. Most contour banding comes from smoothing an image in post-capture processing.

You need noise up to a certain point, and only after that does it become problematic.

If the lightness difference of the tones is less than the JND we should not see any posterisation, even if there is no noise at all.

That would require about 9.5-10 bits at a display contrast of 800:1.

8-bit media devices are a bind. Prints are usually OK thanks to dither and a lower contrast range, but displays are a real issue, especially if you adjust contrast - even when the image has noise.

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