Demosaicing with Fuji X100T, color filter removed

I’ve got the color filter removed for my X100T to make it a monochrome camera.

Then I got this problem with demosaicing in raw processing in RT 5.8 WIN.

I follow the RT documentation to

  1. set INPUT PROFILE = NO PROFILE

  2. set Demosaicing = Mono

Then I got picture 1 (zoom in) below. This is absolutely what I want with a monochrom camera.

If I change Demosaicing to 3-pass, then I got picture 2 which is not actually 100% black and white.

Is there anyone can help?

Thanks!

What do you want to demosaic if the colour filter is removed?

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The problem is that you have to choose something under “demosaic” to get the raw file proceseed.

The choice of “none” is not in consideration. So I have to choose “mono” to tell RT the raw file is from a X-Trans with color filter removed.

Sure, mono is the correct one for your case. I just wondered why you wanted to use 3-pass

I used 3-pass just to compare, which I am sure is not the correct soultion.

But the problem is that the result from “mono” is not acceptable. Any idea?

Why do you find the result from ‘mono’ unacceptable?

That seems contradictory…

Can you provide a raw file?

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Have you set a custom white balance (which should have 1-1-1 multipliers)?

I set thew WB as “Customized”, which is a white paper I shot.

I am afraid that either the removal of color filter or the setting of RT is wrong.

Because “picture 1” above is normally seen by a camera with color filter. When the color filter removed, the sharpness and image quality are supposed to be improved.

If I mannually turn ”picture 2" into black and white. The quality seems to be better than “picture 1”.

So I am not sure what is wrong.

Sure. But the file is not with me now. I will upload tomorrow.

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Maybe I did not describe clear here.

The bright part of Picture 1 is supposed to be with similar color, not with so many mixing black and white pixels.

If Fuji is doing some processing (like dark current or read noise subtraction or white balance pre-copnditioning) to their raw files, it will show up as a faint mosaic pattern on debayered camera with no demosaicing. This is a common problem with black and white modified Nikon cameras (I had one of those back in the day).