the image of monochrome debayer is very soft

Hi, the camera I used is Fuji XT-1 with removing the Color Filter Array (CFA). I follow the instruction to choose method of demosaicing as MONO and color input profile as no profile. But the image is very soft.
The mac system is 10.15.4. The rawtherapee version is 5.8.
Do I need any path on it?
Thank you.

Hi @Ming_Li! That’s an interesting situation. Could you maybe share the RAW file so that others can take a look what might be going on?

Dear Thanatomanic,

Here are the raw files for your information.

Thanks for your kind help.


_DSF6020.RAF (32.2 MB) _DSF6057.RAF (32.0 MB)

Removing the bayer filter is only for the bravest of the brave!

To me the output looks fine. darktable didn’t really work for me, but RawTherapee (5.8) looks good. I only set the demosaic to Mono.

But I believe debayering RAW need some more special handling.

I agree with @st.raw. The image looks sharp to me. It is actually a great example to test out the Capture sharpening tool. Have you tried that?
Also, have you looked at the raw on 100% zoom level? And have you tried exporting it? Because the preview inside RT is usually a little softer than the image in reality is.

100% Crop from the JPEG output (Mono, Capture sharpening on, +50 on Contrast)

As a side-note: if you use Mono the selected Input profile has no effect. So no need to change that.

Thank you very much. I totally agree with you. Actually, the debayering raw can be tuned by RGB channel that means it is still been calculated instead of as mono luminar channel.

Thank you very much. The image is improved a lot after turning on the Capture sharping.

Oooh, downloaded both of your raws, makes me want to scrape that pesky Bayer CFA off one of my cameras… :smile:

Really, to make best use of these raws, I don’t think you don’t want anything called demosaic going on. You want to open it, scale it to the black and white points, and apply whatever tone curve is needed to accommodate the linear sensor response.

Here’s one of the raws with just such processing in my hack software:

Note the toolchain in the top-left pane; just the data scale and right to the tone curve, no demosaic.

The image is nice and sharp as-is, with really good tonality all the way down to dark, very little discernible noise. I used a control point curve just to show the lift, but I also tried a filmic curve and it really worked better to do the lift while preserving the darks.

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Amazing! thanks a lot.

Just to clarify, the demosaic method called Mono in RT does not demosaic the data. It’s just in the Demosaic selection, because there was no other place for it.


Does it do anything else?

Not that I know, though there might be further differences in RT processing pipeline when using Mono instead of a demosaicer. Have to check that. There might be even differences between using Mono compared to using a Sensor which is known to have no CFA. Have to check this as well…