Pixel Dust Removal
Add a module for removing "pixel dust" from an image. This is different from luma noise. If this is the purpose of the raw denoise module, can it be perhaps improved so that it catches more of the artifacts and destroys less detail? It seems that raw denoise tries to do some slight chroma noise reduction too so maybe that's not the right tool.
Aftershot Pro has "raw impulse noise removal" for hot pixels and "raw noise" for pixel noise. I believe the open source former plugin "pixie" addressed this as well.
#2 Updated by Rick Gabriel almost 7 years ago
- File ASP Sample with Pixel Dust Reduction.png added
- File ASP Sample without Pixel Dust Reduction.png added
"Pixel dust" is some patterns or "salt & pepper" variation/noise in raw images. It's not luma or chroma noise per say and it's different from hot pixels (aka. impulse). Sometimes noise reduction algorithms can also fix pixel dust but their values would have to be so high that they would destroy lots of detail in the process. By addressing pixel dust separately, you can keep your noise reduction to minimal levels and preserve detail while getting rid of the noise. Perhaps DT "raw denoise" does this type of optimization?
I have attached screenshots from ASP with their pixel dust removal enabled and disabled at 100% zoom. I used PNGs so you won't be confused by JPG artifacts. On this image, the effect is subtle so look closely.
#3 Updated by Rick Gabriel almost 7 years ago
Here is a better example. Both of these images have noise reduction applied, but one also has pixel dust removed. It should be more obvious what it is if you look at these at 100%. Without this type of filter, you might tend to apply more luma noise reduction to try to combat the pixel dust and it would obscure more of the details than necessary.