Not as far as I know. I suppose the amount of desaturation will depend on both the cause of the noise, and the denoising method. But I suspect that denoising of ordinary photos (which have low saturation) generally results in saturation decrease.
When a photo has high saturation, I get virtually no change in saturation. See examples at Camera noise.
As I mentioned, I generally denoise the R,G0,G1,B channels independently, before demosaicing. With DSC09955.ARW, going through the process but with no denoising, we get:
I have cropped to some bricks near top-left. For this, the C channel of HCL has a mean of 0.148742. The Cz channel of JzCzhz has mean 0.00341112.
With my dnsePsh2Mn denoising, we get:
The C channel of HCL has a mean of 0.111013. The Cz channel of JzCzhz has mean 0.00283577. So chroma has decreased by denoising. We can always boost chroma if we want:
%IMG7%magick ^
c_bdp_den.png ^
-colorspace HCL ^
-channel 1 -evaluate Multiply %%[fx:0.148742/0.111013] +channel ^
-colorspace sRGB ^
c_bdp_den2.png
EDIT: Bother, the images aren’t showing. They are at:
Non denoised:
http://snibgo.com/imforums/c_bay_deg
Denoised:
http://snibgo.com/imforums/c_bdp_den
Denoised, with adjusted chroma:
http://snibgo.com/imforums/c_bdp_den2
… but put “.png” at the end of each.
EDIT2: Uploaded images with drag-drop.
EDIT3: Now the original images show. I’ve been notified: “system 1 hour — downloaded local copies of images”. Hooray. Perhaps it was a sidekiq problem, as mentioned on [Friendly reminder] Limit JPEGs to maybe full HD resolution - #40 by Thomas_Do , and now fixed.