Diffuse and Sharpen module and Noise

I have noticed this before, and it seems that I read a closely related topic a little while back, but I could not find it.

With today’s Play Raw with the flooded bridge (by @lphilpot ), I decided I wanted to add some sharpness to the wood of the bridge. When I used the Diffuse and Sharpen module and its Sharpness preset, a tremendous amount of noise was seemingly added. So, I removed that module and posted my edit without the sharpness that I thought the image needs.

Anyway, the post I read a few weeks ago seemed to have general agreement that the processing modules cannot add noise. If what I was seeing was not noise, it certainly looked like it. So, I’m requesting further discussion and advice.

I think you might want to clarify “add” vs “enhance.”

Certainly DoS can enhance noise that is already present.


That’s exactly my experience with DoS too. I tried all deblur/sharpen presents and they all added some noise/grain to my images under close inspection. This happens with photos from both Nikon Z6 and Sony A7IV. Some of presets from the discussion about ART did not produce that much noise, but for me results were still not as good as from ART.

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Just tweak the threshold sliders… a small change will often remove the grain…But go to far and then you will start to lose the sharpening…

I didn’t really even attempt to edit this mostly just defaults and a pretty harsh DorS preset that I use sometimes… I will tweak it by moving one of the threshold sliders and or opacity…

If there is a bump in noise let me know where you see it the most… I can use that feedback to experiment with this further…

Relative and Perceptual Renders with set to HQR=no
IMG_4659.CR3.xmp (11.2 KB)

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Ok, I played with the sliders. If I change the speed sliders, I can reduce the apparent noise, but it loses the sharpness.

The anisotropy sliders don’t change the noise one way or the other.

The luminance masking treshold helps reduce the noise, but also at a loss of sharpness.

But increasing the edge threshold to about 0.25 (from zero) seems to help the noise and retain the added sharpness. At least with this image.

There are so many sliders in this module, I guess you just have to play and play. Thanks.

Edge threshold is a good one to use when noise or grain appears but I think pixel peeping can often result in over smoothing…if you take all the grain out of the image it will for sure be less sharp esp when zoomed out so its always a trade off here and the destination or intent of your image may dictate the balance you choose…


The slider that you want to adjust is the details threshold slider in the masking option. I use this often. A positive value on the slider limits sharpening to the details (see image below) so the noise is not sharpened in the image. A negative value protects details from the softening effects of denoising. This is critical to my work flow with high ISO images.

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Thank you. That works pretty well. It seems kind of strange to adjust the masking of a mask that is not used, though.

I learnt about this on the forum. Possibly from @priort. I shoot a lot of high ISO images and the feature is brilliant. Also in the denoise (profiled) there is a slider to preserve shadows. It reduces the shadow noise in noisy images when it is set to a lower value than default. It is important as well.


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You have to watch it as you can create harsh transitions…

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Here’s my two-penny bit of D&S and DeNoise modules. I learnt about its usage from two videos, One by BorisH, and the other by BruceW. Take some time out and watch how they use them. Most queries are likey to get solved


@nwinspeare Actually has 2 that are very good and both easy to understand or mostly and well presented…They should be on any video list for that module

What you were seeing was noise, but noise enhanced by the module:
you are using DorS to sharpen, i.e. to enhance any edges. Noise creates lots of edges, and can cause very steep gradients. Now, you can compare diffusion with balls rolling down a slope: the steeper the slope, the faster the balls will move. So the further they will move in a given time.
In terms of DorS, that means that on sharpening, a steep edge will get enhanced more.

What doesn’t help is that the sharpen presets use very small radii, so the influence of the fine-detail layers is very strong. Those are the layers with the noise…
Personally, I find the “lens deblur” presets more pleasant in their effect. Or, if I need much sharpening, the contrast equaliser “sharpen” preset works well.

But with any preset, at their default settings I do not get a “tremendous amount of noise” visible, unless I increase the number of iterations (at least double the number). Then again, I almost automatically use profiled denoise…


So I presume you are talking about the details threshold slider adjustment to sharpening and denoising. I have never noticed harsh transitions, but will look more carefully in the future. How big a problem is this and how often do you observe this?

I often use the lens deblur presets as part of my sharpening strategy in combination with an instance of antialaising sharpening preset.

The denoise presets of fine, medium or course in the DorS module are also very good, but I use snapshots to compare the effect between the various presets. The DorS module is another great module in DT.

I saw it when you told me about the control and I played with it. I just had to hold back on the adjustment.

That is what I was getting at or use some blur, feather contrast if necessary … There is a natural gradient to some edges and pushing the details to the extreme and then sharpening them can create artifact in some random area… but its a nice additional tool to refine the area of masking

I will keep an eye on that problem. I use a 43 inch monitor so I would have expected to see any problems. Also maybe I am not pushing too hard on the effects anyway. The ability to feather masks is a godsend for getting smooth transitions.