Gamma correction for HP

From: Michael Zapf (zapf@vsb.informatik.uni-frankfurt.de)
Date: Fri Apr 14 2000 - 00:57:45 PDT

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    I am using a HP ScanJet 4p with sane. The images from the scanner have a slight
    blue-green tint. By using a calibration image I found out that the gamma curves
    need to be adjusted; especially the red one must be raised in the mid-tones.

    xscanimage offers a device dialog with the "custom gamma table" selection.
    However, I can only adjust "image intensity", not the separate color channels;
    there are no selections for them. Although the adjustment greatly enhanced the
    quality, the image is still tinted green-blue.

    Are those selections dependend on the scanner backend? (I'm using sane-hp). Does
    the HP backend not allow separate color gamma adjustments?

    Michael 

    --
* Michael Zapf  -----------  http://www.vsb.cs.uni-frankfurt.de/~zapf/
* Fachbereich Informatik, Verteilte Systeme und Betriebssysteme
* (Dept. of Comp.Science, Distributed Systems and Operating Systems)
* Johann Wolfgang Goethe-Universitaet Frankfurt/Main

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