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How does On1 PhotoRAW deal with the demosaicing of images taken using Pixel shift?

Answered
Peter Smith
My Pentax K-3 II cameras have pixel shift capability. Basically it records 4 separate images, each after shifting the sensor one pixel in a circular pattern and saves them all in one file, hence the massive 150Mb'ish file size. It's then the job of the RAW developer to combine those 4 images into one demosaic'd file.
So how does On1 PhotoRAW deal with any motion that might occur between each of the 4 images being recorded, as might be the case in a landscape scene (plants, animals, people etc.)?
Other camera marques besides Pentax use pixel shift technology so hopefully On1's engine has some intelligence to detect and correct motion between the frames.
I can find no mention of pixel shift in the user guide.
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4 comments

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  • Brian Lawson Community moderator
    The Pentax K-3 II camera is on ON1's list of Tier 1 supported cameras which means that the program is doing its own demosaicing. I don't have any experience with the pixel-shift cameras so I can't speak to how good a job it does.
     
    Have you tried processing any of your photos with it yet?
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  • Peter Smith

    I've taken a couple of images using pixel shift Brian. The resulting image does seem to be sharper. Pixel shift is supposed to render sharper images of static objects but one of my images was of one of my palm trees, taken on a breezy day. My shutter speed was 1/800th of a second and should have been fast enough to stop all motion.

    The image  has some parts of leaves showing and they are quite blurry,  whereas the trunk is perfectly still and sharp.

    As I understand it, if motion is detected between each of the 4 captured sharp frames, only information from one of the frames might be used for areas that would have a blurred result, and so reduce the blur in the final image.

    That seems to be the way RAWTherapee does it and has many controls to use to influence the outcome. I was just wondering how On1 dealt with Pixel Shift images.

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  • Brian Lawson Community moderator

    You should ask tech support about this. I doubt anyone here has the technical answer you're looking for.

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  • Raymond Griffiths

    I occasionally use pixel shift with a Sony A7Riii for which Sony has its own software app to combine the image. This I export as a tiff for editing in ON1. I only use static subjects, I don't think subjects that are prone to movement, however small, will make a good image. Any demosaic algorithm will surely have great difficulty dealing with the randomness of movement of this type, but I may be wrong. Be interested to know.

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