Black & white: high noise high iso

Software RawTherapee
1

RT 5.6 appimage.

I have a iso 6400 fuji-x image, that I converted to B&W. It’s high noise (yeah 6400).

I have looked at rawpedia: https://rawpedia.rawtherapee.com/Noise_Reduction

Almosat all of these things are for non-fuji and colors.

Any suggestions and where to look. I’m not doing a good enough job with the noise.

Thanks

Syv

2

As usual, give us some examples and pp3s. We don’t know where you are at, unless you show us.

1 Like
3

pp3: https://drive.google.com/open?id=1gH2ykuHWkD_ifn2b_5R75TFdJMWl57Hc
raf file: https://drive.google.com/open?id=1Y1UvsIPBK8-VvyQxfL7jEIRfo9sxDzCr

Thank you

4

Being a Fuji, noise shouldn’t be a problem. I cannot go anywhere above 1600 ISO on the 550D and even 1600 is stretching it. :sweat_smile:

5

Sorry,

But you are missing the point of my question. Rawpedia shows how to deal with high iso & noise for color only. It doesn’t deal with B&W.

That’s what I was asking about, and I gave the image as an example.

They suggest to use: LMMSE and IGV for demosaicing which is not available with fuji.

I’d like to smooth the grain without loosing to much of the details.

Thanks

6

@foto For this file I suggest to try this demosaic settings, which at least give a much better oof background:

grafik

7

Try these 2 PP3 files.

https://drive.google.com/open?id=151RzntQJ5pTr2-_D_1-2-wN_qfGExkua
^ With luminance curve & median filter

https://drive.google.com/open?id=1rtYyucNaZmjhr_-PyUmjYcO7ZdQmDw43
^ No luminance curve or median filter.

8

@foto I understand your question. While waiting for others to respond, I was just commenting on how inadequate my camera was. :stuck_out_tongue_winking_eye:  BTW, dual demosaicing is awesome.

9

These really help, thanks but I don’t understand:

  • Why set the chrominance red-green & blue-yellow to minuses? This is a b&w photo
  • I don’t understand the purpose of the median filter

It’s a great improvement over my settings, but I’m trying to understand…

Thanks

Syv

10

It’s not b&w. It’s raw, means it still has colours. You can make it b&w, but that b&w conversion is applied after denoise in rt

1 Like
11

I have a specialized set of PP3 files that I use all the time on my Pentax cameras. I have my RawTherapee set to automaticaly pick the appropriate PP3 file for each ISO setting. I’ve been playing with RawTherapee for many years now & have kind of figured out how much I can tweak the noise reduction settings to reduce color noise, but still keep most of the color, hence the funny looking NR settings.

The median filter basically smooths out the image a bit more. Sometimes if will kinda of smudge fine detail. It’s a matter of zooming in 100% & seeing if you need it or not.

I have a thread on Pentax Forums where I explain a bit more. Feel free to take a look at it. There are some PP3 files that you can download. You can also download a slightly modified RawTherapee build with the PP3 files already included.

1 Like
12

You can try wavelets too, although it is yet undocumented (at least not up to date).

ppoc-20190621-7423.png.out.pp3 (11.2 KB)

  • Noise reduction (general tool) is only used to automatically remove color noise (chroma noise)
  • Defringe is used to remove purple and green fringing present in the image (look at the papers on the wall)
  • White balance taken from the paper hanging on the wall
  • Wavelets: there’s a lot to play with. If you don’t understand anything, just ask (if it’s allowed to explain things in this thread, that is, if it’s not offtopic)
  • Demosaicing kept as you chose it
  • B&W just turned on

This is a before/after detail (I have chosen not to show faces here): upper half with noise, lower half denoised

ppoc-20190621-7423_partial
ppoc-20190621-7423_partial1089×622 312 KB

You can completely remove noise if you wish, although in a B&W image I’d rather see some noise.

13

No worries, it would definitely be on-topic.

Same here.

14

For sure it is allowed :+1:

15

Try the settings I mentioned above :wink:

16

Thanks,

Excellent: The XavAL + a little bit of “Mafia” + the demosaic from heckflosse and what a world of improvements.

Now I have to try to understand it, especially the wavelets. I have seen: https://rawtherapeewavelets.wordpress.com/2015/07/05/wavelets-part-2-treating-noise/ but I will have to try to understand it.

Thanks

Syv

1 Like
17

You’re right! :open_mouth:

Just that simple change in my processing and the result is smoother, with better-looking noise :smiley:

1 Like
18

It’s not too bad a tutorial if you already know what you’re doing, but I guess this is not the case. The wavelets tool is really complex and you may loose yourself on all those sliders: if you want to follow it, just center on the Denoise part, and play with it.

My approach is entirely different, though:

  • set image zoom at least at 100% (I usually denoise with zoom at 300%-400%)
  • choose some part of the image without many details
  • at the top of the tool, choose Strength: 100 and Edge performance: D10 (or D14). Then Background: Residual (you will soon see color patches coming from the image without details). Process: One level and Level 1 will show you the finest details (level 1) over the residual image.
  • activate Denoise and Refine and uncheck Link with Edge Sharpness Strength
  • now the fun part: on the Level 1 dual slider, set Strength (the lower slider) at 100. The noise will try to get off the screen. Don’t worry. Set the upper slider (Denoise) to a value you like while looking at the preview. Don’t forget to check that your finest details don’t disappear. It’s better if you don’t completely remove noise, as you will send back Strength to a reasonable value.
  • if you have heavily denoised the level noise, set Strength to a value around 30-50 and see if you like it. If not, just play with other values. Strength will increase or decrease (with negative values) the local contrast on the level you’re working on.
  • in your image, level 1 is mostly noise, so I would go for a mild denoising and a negative value on Strength (actually lowering the noise contrast without fully removing it)
  • select Process: One level and Level 2, and start the process again with those details/noise
  • when you have finished denoising all pertinent levels, go back to the general Strength (at the beginning of the tool), and lower its value to something like 85 (it has more or less the same effect as the Layer opacity in Gimp), or any value you like.
  • don’t forget to return Process: to All levels in all directions

The wonderful thing with this tool is that you can denoise and sharpen the image at the same time :smile:

3 Likes