Applying denoise on dark area only?

questions about practical use of Neat Image
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lansing
Posts: 67
Joined: Sat Apr 21, 2012 6:52 am

Applying denoise on dark area only?

Post by lansing »

I have scans of color prints and after descreen, a lot of paper texture noises were revealed. Those noises are only visible in darker area of the image so I'm looking for a way to remove them with Neat Image. How do I apply my denoise only on the dark area?

Right now I'm doing:
  1. duplicate the base layer and run denoise on the new layer
  2. set the blend mode of the denoised layer to "darken"
This method kind of worked, replacing the noise on the darker area with my denoised layer while not touching the lighter area, but the problem with this is that it will create an non smoothed result. If my base layer has a lot of uneven spots in the those areas, I would end up a lot of uneven black spots after the blend.
NITeam
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Joined: Sat Feb 01, 2003 4:43 pm
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Re: Applying denoise on dark area only?

Post by NITeam »

One possible way to achieve more smooth results would be to smooth out the mask you apply to the denoised layer in PS. That is perhaps the easiest way.

Another option would be to manipulate the graphs in the noise equalizer of Neat Image (in the Device Noise Profile tab) to manually turn down the graph nodes corresponding to light part of the brightness range. That would also reduce the strength of the noise reduction applied to that part of the range.

Vlad
lansing
Posts: 67
Joined: Sat Apr 21, 2012 6:52 am

Re: Applying denoise on dark area only?

Post by lansing »

NITeam wrote: Sun Dec 27, 2020 8:41 am One possible way to achieve more smooth results would be to smooth out the mask you apply to the denoised layer in PS. That is perhaps the easiest way.

Another option would be to manipulate the graphs in the noise equalizer of Neat Image (in the Device Noise Profile tab) to manually turn down the graph nodes corresponding to light part of the brightness range. That would also reduce the strength of the noise reduction applied to that part of the range.

Vlad
Hi I tried the graph manipulated method, I dragged the lighter nodes all to the bottom of the graph, the result doesn't look good though as the transition between denoised and uptouched area looked so weird.

I did found an article on how to create luminosity mask for shadow using channel and applied that to my denoised layer. The result looks pretty good as the lighter part of the image were untouched and the transition between light and dark area doesn't look weird.
NITeam
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Joined: Sat Feb 01, 2003 4:43 pm
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Re: Applying denoise on dark area only?

Post by NITeam »

> I dragged the lighter nodes all to the bottom

Perhaps you could do that in a bit more gradual way for better results.

> I did found an article on how to create luminosity mask for shadow using channel and applied that to my denoised layer.

This probably achieves the same smooth transition result.

Vlad
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