I have been trying to get a handle on noise reduction in RT. I have processed the following image as good as I can. I wonder if I can get the noise down any more.
I followed along in the Rawpedia (RT Documentation) in the section on noise reduction. I still do not know the difference between luminance and chrominance noise. I basically move sliders around (while reading the manual) until I like the result.
Could I have done better with this picture? How?
Camera: Canon G7X Mark 2.
I’m not an expert, so forgive my sloppy terminology, but you can think of chrominance noise as the “coloured stains” that you see when opening an underexposed image without any noise reducion. Luminance noise is essentially the “grain” that you see also when looking at a black-and-white picture.
that’s perfectly fine, I think
Better is subjective, but here are couple of things I would do with your picture, FWIW:
use a dual-illuminant dcp profile for your camera. I generated one from dpreview’s studio scene (see this thread)
turn off “auto CA correction” in the raw tab. Unfortunately in my experience this setting has a negative effect in colour, which is especially visible in underexposed/high iso shots
use “colour propagation” for highlight reconstruction instead of blend, as it seems to work better here.
I also made a couple more tweaks to the noise reduction settings, because I don’t mind a bit of grain, but I don’t think this is that important.
Depending on what you want to achieve is what will measure the final processed version. Are you trying to go for as little noise as possible, or recovering of colour contrast definition?
There is a noise reduction module in Wavelet Tab too. I used that and also changed the tone curve and reduced the contrast. Used Color Propagation Highlight recovery to get this:
To be honest, I have never tried to fight the noise too much… if I have a noisy image, I very often go for a B&W version and try to turn the noise into “grain-like texture”.
Wavelet noise reduction is my preferred way of removing noise . I don’t really understand it but I move the sliders around ( viewing at 100 percent) until I get a nice result. I always tend to do another edit after rawtherapee in GIMP , usually a tad bit of sharpening and if i want a mono I tend to use GMIC black and white enabling pseudo greys too