I use RawTherapee for sometime now. Before I use noise reduction mostly by enable it and with 2-slider : luminance and detail recovery then leave the chrominance is automatic global. Never touch median filter until recently after read more about “noise reduction” : Noise Reduction - RawPedia
Now I start using median filter to remove something left-over form noise reduction. And I use noise reduction + median filter every picture mostly on 3x3soft. Even with jpg file. Before noise reduction jpg file with digikam but now only noise reduction in rawtherapee because more control and output quality is better than noise reduction from digikam. Happy but have question.
Question is , it is good to use median filter in every picture after use noise reduction? Without using it I can see something left or none smooth left after noise reduction. With it I will lose some detail isn’t it? So what should I do, when it use or not to use it? - median filter.
Generally, I find luminance median filtering to be too aggressive and destructive, but chroma median filter can sometimes come in handy with certain speckles of color that seem to not ‘go away’ with modest chroma nr.
As an alternative to median filtering, I suggest you experiment with the impulse noise reduction slider. It is like the median filter, but only removes the most extreme and objectionable single pixel noise bumps, but less variation than defined in the threshold is left intact. This generally is good at removing some of the excess noise still remaining after the noise reduction module.
Finally, it is important to be open to at least leaving a little noise, as when you try to go for the extreme of total noise removal, rather than noise reduction, you end up losing so much detail that the image becomes a blotchy waxy mess, like a cell phone pic.
Luminance median filter tends to ‘rubberize’ the image, but is fine to use when you are going to downsize on export anyway. Chrominance median filter is often unneeded when the chroma denoise is already enabled, but can be useful if there are still errant specks of color, from noise or aliasing. Chroma median filter tends to not have as many problems, as the eye is less sensitive to fine chroma detail than fine luminance detail.
I like the idea of the median filter as a final touchup for denoise but i found it too much strong even with the 3x3 kernel.
Just wonder how it perform in real image the weighted median filter, basically for what i understand it’s just a median but the central pixel is counted two or more times.
It should preserve better the details