Re: 3091 backend: Brightness, Contrast etc.

From: Ulrich Deiters (ukd@xenon.pc.Uni-Koeln.DE)
Date: Thu Mar 08 2001 - 03:07:34 PST

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    I must admit that I am not familiar with the internals of the light-receiving
    part of a modern scanner. In principle there has to be an analogue/digital
    converter somewhere, and in principle such a device can or should have
    adjustable zero setting and sensitivity. Hence it makes sense to transmit
    a brightness and a contrast setting to a scanner.

    But it does not seem practical to equip an ADC with 256 controls!
    If your scanner does not respond to the standard brightness and
    contrast controls, then the ADC is probably using fixed settings,
    and all picture manipulations are done after digitizing. Then, of
    course, you can do the manipulations just as well in the computer.

    Regards,

    Ulrich Deiters

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