plustek@linuxhacker.org

Hi Josef,

thanks for that info - life is really funny, because last friday I found
the cause for this problem and so the explanation for your workaround...
All of the supported scanner in the backend, except the CIS devices
(CanoScan..) use the green-channel for grayscale scanning and so the
calibration setup is done for this green-channel. The Canoscans I found, use
the blue-channel and so if the scanner has been reset completely and you 
will scan in grayscale mode, there are no calibration data for the blue
channel, as the green one has been setup. So if you do now a color scan,
all the channels are setup and calibrated - you get the idea!
This is now fixed, but the fix came too late for sane-1.0.12. Within the next
days, I plan to release a bug-fix version, where this patch is applied...

cheers
   Gerhard

On Sonntag, 25. Mai 2003 00:20, Josef wrote:
> <Long story>
> Hey, I just plugged in the old Canon N650U the other day and tried to
> scan some stuff.  In grey mode I came up with a bunch of vertical
> stripes down the scan.  More stripes the higher the dpi scanned.
>
> Found several people her complaining of the same thing, and found
> Gerhard mention that some calibration stuff was broken and will get
> fixed someday.  Ok, I figure I'll just scan in color even though the
> quality is icky.  Well, then I get the urge to try Grayscale for
> whatever reason and it WORKED!
>
> <Short story>
> So do a BIG color scan (size of the scan matters, so I think if you do a
> 1inx1in scan then the grayscale will only work right in that area.  So
> grab a preview, set the dimensions, Scan at the DPI you want in color.
> Throw that away. The scan again in Grayscale.  No vertical lines.
> Crazy.  Maybe scanning in color calibrates it somehow, and when you scan
> in grayscale in doesn't bother to screw it up again :)
> </Short story>
> </Long story
>
> Anyway, hopefully this will help some people out.
>
> Josef Wells
>
> Debian Unstable (sid)
> Sane 1.0.11