noise reduction compared to rawtherapee

Processing
1

Hi,
I know that this topic has been discussed multiple times already, but I am still struggling with it. I am a long time darktable user. I have read multiple tutorials about noise reduction. Most of them recommend profiled denoising in one or the other way. What I am looking for is noise reduction in darktable without profiles and compare this to rawtherapee.

I tried this today again with rawtherapee 5.4 and darktable 2.4.4. As always when I try this rawtherapee gives good results with just the regular noise reduction while I struggle to get any decent result with DT and non-local-means noise reduction + raw noise reduction.

See this comparison. Left side is rawtherappe, right side is darktable:

Bildschirmfoto%20vom%202018-12-19%2007-51-59
Bildschirmfoto%20vom%202018-12-19%2007-51-592504Ă—1410 6.55 MB

I did not spend time on the color. So dont bother about the slightly different colors. This is only about the noise level.

Any idea how to improve the darktable result without using profiled denoise?

The RAW can be downloaded here: Dropbox - File Deleted
The PP3 is here: Dropbox - File Deleted
The XMP is here: Dropbox - File Deleted

Thank you very much for your help!
Matthias

2

Why not use profiled denoise?

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Because I want to compare generic denoise algorithm and not camera specific profiles.

4

The thing is non local means is not generic: it is supposed to fight gaussian noise, while the noise we get in real life is usually not gaussian.
The “profiled denoise” module apply an anscombe transform to make the noise gaussian, so that the algorithm can work well.
The profile is only here to set correct parameters for the anscombe transform.

Apart of that, you can try playing with the equalizer, or with bilateral denoise modules.

In addition, rawdenoise and wavelets mode of profile denoise will be more flexible in 2.6. You may want to try them using the release candidates.

2 Likes
5

So what is rawtherappe then doing to give such good results with basically just one slider?

6

You might still compare apples and oranges as you dont know what the underlying code does.

Personally I would only use another module than “profiled denoise” if the camera is not supported. otherwise profiled denoise will give me the best results.

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I am afraid I don’t know. I did not took time to study rawtherapee’s code yet

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Even a simple raw denoise looks good to me in darktable.

IMG_0334
IMG_03341365Ă—1433 2 MB

IMG_0334.CR2.xmp (3,8 KB)

3 Likes
9

I agree that RT’s noise reduction is better than any noise reduction filter in dt. I think RT has the best noise reduction I know, but I am not claiming that I know every program that can do noise reduction. Actually I think that dt is only nr 3 - 2 is Lr/ACR. At least in terms of noise reduction. (I have the Photography Plan again, although I do not need it - “gift” from Adobe).
I wonder whether the noise reduction filters in G’MIC are better than dt.

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“I agree that RT’s noise reduction is better than any noise reduction filter in dt.” You are correct, but it’s because RT’s noise reduction is several filters wrapped with a border and labeled Noise Reduction.

Disclaimer: I didn’t read the code, so I may not be 100% correct with all the statements below.

I have RT 5.3 on my system, so that is what I’ll reference. If you go down the detail tab you find Impulse Noise Reduction. The darktable equivalent module would be hot pixels.

In the Noise Reduction section you first reduce luminance noise. The darktable equivalent module is denoise module of your choice, blend mode lightness.

Next is chrominance noise. The darkktable equivalent module is denoise module of your choice, blend mode color.

Next you come to Gamma. The darktable equivalent is a parametric mask based on luminance.

Finally you come to the median filter. The darktable eqivalent is denoise module of your choice, blend mode average, or the lowpass filter.

Is denoising in RT easier? Yes. It doesn’t require an understanding of noise and all the tools are right in front of you. Just move the sliders until you’re happy. Most of the time it works just fine and yields good results.

Darktable gives you many more tools to deal with the noise, but you have to understand noise and how to apply the tools.

I have styles set up in darktable to apply a sequence of denoise modules with specific blend modes and opacities. I’ve set up styles for low, medium, high, and very high ISOs. The strength and opacity of the modules change as the noise increases. I also add additional modules such as lowpass, hot pixels, and demosaic as the noise increases. When I denoise, I assess the noise and apply a style. If I don’t get satisfactory results, then I apply the next style. One or two clicks and I’m done. I shoot sports, so sometimes I’m dealing with hundreds of images. The noise usually remains constant, so I can select hundreds of images in lighttable and denoise them with one click.

6 Likes
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Hello Bill,

can you share those styles? I would like to have a look.

1 Like
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Here they are. NR 1, 2, 3, and 4 are the regular ones. The rest are experiments and alternatives.

Enjoy,

Bill
NR - 1 Low ISO.dtstyle (1.2 KB)
NR - 2 Medium ISO.dtstyle (1.9 KB)
NR - 3A - High ISO Alt.dtstyle (1.9 KB)
NR - 3 High ISO .dtstyle (2.2 KB)
NR - 4 Very High ISO.dtstyle (2.2 KB)
NR - LAB 10px.dtstyle (2.2 KB)
NR - LAB 2.5px.dtstyle (1.5 KB)
NR - LAB 5px.dtstyle (2.2 KB)
NR - Very High ISO Alt 1.dtstyle (2.5 KB)

12 Likes
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Thank you, Bill!

Claes in Lund, Sweden

1 Like
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Thanks a lot. This is good for testing during the christmas break :+1:

1 Like
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@wpferguson Hi Bill,

I am playing with your dtstyles. Great fun & they are quite effective.
Thank you.

@Thomas_Do If you have the time, try them on the img above :slight_smile:

Have fun!
Claes in Lund, Sweden

1 Like
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It would be great to have a better interface on dtstyle.net so that such things can be shared with a good descriptions, but I’m not a web developer …

2 Likes
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I did. These styles work well :blush:. The results are slightly better than what I could achieve doing a fast denoise “freehand”. So, I will keep them, thanks to @wpferguson!

2 Likes
18

@wpferguson many thanks for sharing!
Tested and more than approved.
Added to my style collection.
Just in case you guys want to do another test round, I bring this extremely noisy picture, taken with ISO 6.4K, licensed under CC BY-NC-SA 4.0
Neutral jpg:

IMG_1652_01
IMG_1652_011900Ă—1436 4.95 MB

IMG_1652.CR2 (23.4 MB)

EDIT: This one is hard, even with those excelent styles

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I would do it this way:

IMG_1652
IMG_16524384Ă—3314 4.11 MB

IMG_1652.CR2.xmp (4,7 KB)

1 Like
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Oh, @gadolf,

That is a very difficult image.
No, I will not publish my “result”, because it is too terrible :grimacing:

By the way: isn’t #2 the famous Brazilian player Senhor Arte Fato?

Have fun!
Claes in Lund, Sweden