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Thread: Creating Scanner LCC/Gain/Custom White File

  1. #1

    Join Date
    Jun 2006

    Creating Scanner LCC/Gain/Custom White File

    My scanner (4990) is old and somewhat uneven across the frame (red here, cyan there...)
    Usually it's not a big problem but for 8x10 scans it can be a headache (yes I clean inside my scanner often, it helps a bit)

    Would it work to scan a large 18% grey card or sheet of white paper and create a file that can be applied in PS to correct this similar to what digital back manufacturers do with LCC/Gain files?

    If so what would be the best way to do this and how should the file be applied in PS?

    Sorry if this has been asked before, I've searched but found nothing (or used the wrong terms)

    Perhaps the scanner is just too old and needs replacing - any owners of newer models (750/850) care to scan a full area grey or white card and report how even your scanners are?

  2. #2

    Join Date
    Nov 2017

    Re: Creating Scanner LCC/Gain/Custom White File

    What you’re asking to do reminds me very much of dark frame subtraction in digital photography. It’s most commonly used for noise correction in long exposure photographs. Baiscally as the pixels get hot they create false signals aka noise, and they do this in a repeatable way every time. So the idea is the photographer can take a long exposer with the lens cap on and capture just the noise pattern on a black frame, and then subtract this from the final images. Here’s an article on it
    I would first determine if your scanner is producing these aberrations in a predictable manner, if so this technique could maybe be adapted to work.
    It would likely be easisiest if these abberations are visible on a completely black image, but if not an 18% gray card might be a good starting point, but you might need to fiddle around in photoshop to find a way to clear away the clean gray parts of the image to black, leaving only the affected areas (I’d start with the layer styles).

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