X-Trans demosaic algorithms differences

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sluggy_warrior Senior Member • Posts: 1,241
X-Trans demosaic algorithms differences

I feel bad hijacking the other thread, so I'm moving the content to a new thread.

What I found so far, from the fact that both Fuji SOOC and LR output look a little problematic, and Fuji worked closely with Adobe, I'm thinking that Fuji goofed up and didn't have a good demosaic to begin with (and gave that to Adobe).

Thanks to Frank Markesteijn for coming up with a demosaic algorithm for X-Trans, most open-source softwares using his algorithm (RawTherapee, darktable, UFRAW, ...) output perfectly fine JPGs, even with sharpening cranked all the way up (and the more you crank, the more details you see).

One feature to distinguish between the two algorithms is in small details, Fuji/Adobe output tend to loose the true color of the details, mixing in the color of the surrounding, resulting in flat and false colors. This usually see in (small) teeth being yellow/pink, or the (small) white part of the eyes become darker. Here are some samples I've collected.

(I've put all the related files here: https://drive.google.com/drive/folders/1tLELuxj5zs-EoafXbQC1sTim9pXJ0Yxo?usp=sharing)

SOOC JPG, small details lost their colors with surrounding colors blended in

darktable output, small details retain their colors, and thus better micro-contrast

LR output, the light pole got the blue from surrounding sign, and Chinese characters has some hollow strokes. This is from a wormy sample shared by Marco1971

darktable output, the light pole retains its color, the Chinese character strokes completely filled

darktable output, at max sharpening


And from the familiar DPR test scene, X-T20 at ISO6400

DPR default sample, from ACR?

darktable output, from same RAW

Fujifilm X-T20
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