X-Trans demosaic algorithms differences

Started 4 months ago | Discussions thread
OP sluggy_warrior Contributing Member • Posts: 884
Re: X-Trans demosaic algorithms differences
1

BryceM wrote:

FWIW, I found a DTStyle file that corresponds closely to your settings here: https://dtstyle.net/download.php/391/Denoise%20-%20profiled.dtstyle

I played with it some as well as another one from the same source that, while a little more processor intensive (9-steps), seemed to render cleaner detail in the test files I examined: https://dtstyle.net/download.php/392/00-Denoise.dtstyle

Thanks for confirming my finding. I've been playing around with other modules as well, and found that Dithering, Equalizer, Denoise - bilateral filter, and Raw Denoise complicated my tweaking with more variables but yet don't seem to help with denoising, that's why I stick to just three instances of Profiled Denoise.

I applied the two styles you mentioned to the same signs scene, while the outputs are cleaner, the little details are also discarded together with the noise, loosing that "extra-sharpness" that we got. Again, it's just my personal taste to retain details over noise-suppression.

Also, too-aggressive noise-suppressing leads to loosing colors in small details (I ran into the same problem while tweaking mine as well, and had to dial back). This can be seen as the red circle around the wheel chair becoming black instead of staying red.

Using your first mentioned style (Denoise - Profiled)

Using your second mentioned style (00 -Denoise)

.

What really interesting is, I downloaded NEF files from Nikon D7500, compared the outputs with and without my denoise combo, and there's no difference in sharpness. So, whatever the magic that denoising does to add the extra sharpness to X-Trans doesn't work on Bayer. I guess Markesteijn algorithm could have provided extra data that wavelet/NLM algorithm somehow can use to reconstruct tiny details around edges.

Or, if we look at it the other way, X-Trans is really tricky to work with, we do need some extra processing to make use of the details resolved by the lens, whereas Bayer doesn't need that

I'm so wishing that a darktable dev or Fuji engineer could drop in here and give us an explanation, the thirst to know what's going on with demosaic and denoising and their effects is killing me ...

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