Oliver Schwartz wrote:
> > > I have an Acer ScanPrisa 620 UT. It works, but the RGB offsets are noticeable.
> >
> > Maybe the overhead (transparency unit) lamp *needs* special
> > calibration? The manual for the Prisa 620ST states that when
> > scanning slides or negs you must use the supplied mask and you
> > must leave the calibration window in this mask unobstructed.
>
> Yes, that's correct. And of course I'm using the mask in transparency mode. I
> have the impression that the calibration is done by the firmware - at least the
> trays move to the calibration area before each scan.
>
> The offsets appear in flatbed and transparency mode, though.
>
> However, the RGB offsets as I understand them are not an offset in value but a
> spatial offset. E. g. if you scan a black square on white background in
> color mode it doesn't have sharp edges but maybe a blue edge on one side and an
> orange edge on the other. Just try it.
>
> Oliver
May the source be with you.......
If you look in the source for the snapscan module in Sane 1.0.2, and the code on the
snapscan home page, you will see the code was undergoing heavy rework in the data
buffering area at the time the author "abandoned" it. He seems to have finished
everything but the colour offset handling. Dated comments state that this bit will be
completed in the next few days, so that should give a pretty accurate indication of
when he stopped work!
Older versions of the snapscan driver appear to have worked OK, using an older data
buffering scheme with correct colour offset handling.
It seems to be possible to actually ask the scanner about the physical offsets
between its three rows of CCD sesors, so handlign different models and revisions
should be automatic. I'm currently working to implement proper offset handling using
this. Watch this space....
Steve
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This archive was generated by hypermail 2b29 : Fri May 05 2000 - 08:20:45 PDT