Raw Denoise Nind - Hot Pixel issue

Software darktable
1

I was noticing if I have some hot pixels on high ISO images, if I use the AI raw denoise nind process to reduce the noise down. The hot pixels are not removable. It’s almost like the DNG copies them over from the raw photo and they cannot be removed with the hot pixel module. But if I leverage the normal raw photo the hot pixel module can get rid of them.

Has anyone else found a way around this issue besides using the traditional denoise module and not leveraging the AI process? I’ve found the AI module can work for about half of the scenarios as long as I don’t have heavy shadows, no one wearing black etc while in a high ISO photo. Otherwise, I’ll wind up with hot pixels that cannot be removed in the DNG file.

2

I’m having issues with the site.

I get very bright red or green spots larger than one pixel. Used retouch on those.

Here is an example:

image
image422×676 24.3 KB

3

Hi Adam, welcome to the forum. I only ever reach for AI denoising as a last desperate resort. Many of the non-AI options work well for me in Darktable. However, very occasionally I use AI denoising. Most times I use the denoise option after editing which provides a tiff file. This option would allow you to apply hot pixels module and non-AI denoising before AI gets involved. As you can see from my screen shot I tend to run at very low values.

image
image369×106 2.13 KB

However, getting back to your original question. I just tested the DNG produced by RAW denoise and the hot pixels module still works. To prove the point I have maxed the controls out. Maybe you need to increase the strength and or lower the threshold to get detection.

image
image392×138 2.59 KB

I also often use detect by three neighbors and this might help detection in your case.

4

Thanks @Terry I have the pixels being marked and they fade but don’t go away. For example, -

DNG after AI noise cleanup and pixels marked:

image
image1803×1294 133 KB

Then when I turn off “Mark fixed pixelsfixed” it looks like

image
image1453×1282 95 KB

Whereas in the actual raw photo it looks like this -

Before:

image
image2050×1512 625 KB

And after disabling “Mark Fixed pixelsfixed”

image
image1660×1564 522 KB

This was shot at 3200 ISO, pretty extreme example with a Panasonic GX85, I however noticed it across many more photos as well.

Your flow on this is Raw to tiff to AI denoiser (non raw) then from what I am seeing in your screenshots?

5

Thanks @Doug-Phoenix I’ve used retouch on a few of the photos that I used the AI denoiser on. Some of them had gradient patterns and so I opted back to the denoiser module since the retouch module left me with a color oddity. But it is a good way about it and yes, they look exactly like your hot pixels.

6

Would you have an image you can share. I suspect AI denoising may not be necessary or if it is maybe the post edit denoise option might be best or maybe something could be done to get rid of the remaining hot pixels. I max out my Canon R7 often and don’t need to resort to AI denoising.

7

Thanks for the feedback @Terry I am in agreement with you and will switch up my workflow. I have the default denoise, retouch and other methods to help me get around some of the noise and keep things looking okay. I got bitten by the AI hype. Thanks for the help.

2 Likes
8

I feel the AI denoise was offered as another tool and not a simple replacement of non-AI denoising.

1 Like