Bit depth = levels of gradient?

Started 2 months ago | Discussions thread
John Sheehy Forum Pro • Posts: 21,886
Re: I think you're getting misleading/unhelpful advice here

knickerhawk wrote:

filmrescue wrote:

I've been searching around to find some sort of chart or list that tells me how many levels of gradient there is for different single channel bit depths but I'm not having a lot of luck. Can anyone fill me in or link me to the info I'm looking for. I'd like to see from 2 all the way up to 20 or so.

Your problem isn't about too much noise in the deep shadows limiting the dynamic range of the image. Indeed, more noise would actually reduce the appearance of posterization/banding that you're seeing. And since you're scanning negatives and presumably inverting them to positives, most of the image noise should be present in the highlights, not the shadows, of the output image. The dithering effect of the noise should actually mask posterization, not make it worse. Noise is NOT the enemy here!

No, but excess noise is.  Most cameras have excess noise in most of their tonal ranges.  Ideal noise is equally distributed noise over a range of 1 DN, with no spatial correlation or low-frequency content at all.  Real noise is a bit worse than that, and mostly unnecessary.

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