Thread: Two basic questions about debayering

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  1. #11  
    Moderator Phil Holland's Avatar
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    One of the best cameras in recent history on the still side of things and one I use often for B&W is indeed the Canon 5DsR and certainly works well for IR/Full Spectrum Conversion or using an IR/UV Filter for normal imaging. Which you can snag for a hell of a deal used right now.

    A fun one to even comare straight away to the Leica Monochrome offerings.

    RED Monstro Monochrome is a seductive concept and honestly if I was doing more pure B&W work I would consider grabbing one. I think once Komodo is in full swing and the world is spinning again, I imagine a Monochrome Komodo would cost a slight premium, but likely a very low entry price considering all that could provide. That one I am eyeballing the hardest.
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  2. #12  
    Quote Originally Posted by Michael Tiemann View Post
    As to re-bayering...it is well-known that many colors are not uniquely represented by tristimulus values. So there are many inconsistent ways to re-bayer. And there is no way to know whether one re-bayer is correct vs another.
    this is incorrect. A tristimulus value (derived from a SPD) is a unique color - it represents the human vision perceived equivalent as per the implemented CMF.

    but you cannot create a spectrum from a tristimulus value, since various SPDs can result in the same tristimulus value - so it would be inconclusive/unknown what the original SPD was.

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  3. #13  
    REDuser Sponsor Andy Jarosz's Avatar
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    Quote Originally Posted by Karim D. Ghantous View Post
    1. What would happen if you debayered a monochrome RAW file? What kind of funky results would you get? Would you get any actual colour?

    2. Can you REbayer a debayered image? I assume you can, but could you tell the difference between the original RAW file and the rebayered RAW file? This goes for monochrome as well as RGB.

    There are reasons why I'm asking. The second question in particular is important.
    Just to answer the question, I ran a monochrome DNG RAW image, from a Leica M10 Monochrom through ImageJ using the Debayer2sx plugin. Using a bilinear demosaic algorithm, which is about as basic as it gets, yields this result:



    Which appears that nothing has happened, but when zooming in, does show some strange color changes:



    To answer the second question, yes, you can of course rebayer a debayered image--assuming the file isn't compressed. Here's that photo, that was debayed, and then rebayered:



    Of course, by doing this all in ImageJ, I'm just "pushing numbers around," not losing any info. If I tried to rebayer the .jpg, it would of course look different.
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  4. #14  
    Moderator Phil Holland's Avatar
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    ^Andy as you've illustrated, remember to still desaturate after your debayer if intent is monochrome from a B&W source.

    And also as you've illustrated, at least with this method, it's likely just better to add a blur :)
    Phil Holland - Cinematographer - Los Angeles
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  5. #15  
    Senior Member Karim D. Ghantous's Avatar
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    Quote Originally Posted by Andy Jarosz View Post
    Just to answer the question, I ran a monochrome DNG RAW image, from a Leica M10 Monochrom through ImageJ using the Debayer2sx plugin. Using a bilinear demosaic algorithm, which is about as basic as it gets, yields this result:

    Which appears that nothing has happened, but when zooming in, does show some strange color changes:

    Strange indeed. I also note the loss in detail.

    Quote Originally Posted by Phil Holland View Post
    I imagine a Monochrome Komodo would cost a slight premium, but likely a very low entry price considering all that could provide. That one I am eyeballing the hardest.
    I technically could buy one... but my budget is somewhat strict, until my investments start to yield serious growth. It may very well be the best DSMC camera out there, if you're aiming primarily at photographers.

    Eventually all cameras will be DSMCs. Photographers will resist, and they will strongly object, especially those who switched to digital early (more than one pardigm shift is not allowed!). Those who shoot film will just keep doing their thing.
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