[sane-devel] EpsoPerfection 640U: skewed scan in binary mode, 600dpi

Karl Heinz Kremer khk@khk.net
Fri, 31 Aug 2001 07:24:21 -0400

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This is fixed in 1.0.5. The 610/640 is different from other EPSON
scanners: It always expects an even number of bytes in monochrome
mode. This means that the scanner did round the number of requested
bytes down to the next even number.

Please download 1.0.5 and try again.

Karl Heinz

On Fri, Aug 31, 2001 at 09:12:24AM +0200, Christoph Ludwig wrote:
> I have an Epson Perfection 640U and use it frequently to scan documents
> in binary mode at 600dpi. The SANE backend is libsane-epson.so.1.0.4.
> Sometimes the resulting image is skewed. Each line seems to be shifted
> to the right, relative to the preceding line. If I set SANE_DEBUG_EPSON,
> I get messages similar to the following:
> [...]
> > [epson] sane_read: begin
> > [epson] sane_read: begin scan1
> > [epson] receive buf, expected =3D 6, got =3D 6
> > [epson] sane_read: buf len =3D 551
> > [epson] sane_read: buf len (adjusted) =3D 32509
> > [epson] receive buf, expected =3D 32509, got =3D 32508
> > [epson] send buf, size =3D 1
> > [epson] sane_read: begin scan2
> > [epson] sane_read: end
> [...]
> The problem seems to be that the backend receives one Byte(?) less than
> expected, since I do not observe such a discrepancy in the log when the
> scan succeeds. This phenomenon affects about half of all scans in binary
> mode at 600dpi, but it is not really reproducible. Some days most of the
> scans are successful, some days most fail. Neither powercycling the
> scanner nor restarting the software helps. There is no problem with gray
> or color scans or at a lower resolution.
> Has anyone an idea what to do about the problem?
> Thanks
> Christoph
> --=20
> http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/cludwig.html
> LiDIA-CA: http://www.informatik.tu-darmstadt.de/TI/Forschung/LiDIA-CA/
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Karl Heinz Kremer                                  khk@khk.net
PGP Key at http://www.freecolormanagement.com/download/khk.asc
EPSON Sane Backend:         http://www.freecolormanagement.com

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