# Re: problems with 1.0.3 and color scanning

From: Lawrence Glaister (lg@jfm.bc.ca)
Date: Thu Sep 21 2000 - 08:16:24 PDT

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  Hi Steve
  I have a couple of other ideas on the RGBRouter problem.... as I understand
  it, the router was designed to perform the data unpacking from scanner
  buffer format to the internal RGB sane buffer format while at the same time
  accommodating any color offset shifts needed (spatially aligning RGB). The
  new code uses offsets reported by the scanner... It could be possible that
  the snapscan 1212u is reporting bogus offsets that are getting the router
  totally confused... I will try and figure out how to ignore the offsets from
  the scanner and see if that makes things better. If you could describe how
  the elements of the rgbrouter structure are supposed to be used, it would
  help me decipher what is going on.
  An update on my earlier comment... the scanning of small color image at
  50dpi
  doesn't really work.... it doesn't hang xscanimage but the generated file is
  missing about 10-20% of its bytes and fails to open in gimp with an
  premature EOF message.
  I feel this is directly related to the rgbrouter problems. I'm getting quite
  an education in the sane code... its not one of the easier pieces of code to
  get ones mind wrapped around with all the nested virtual functions.

  Thankyou for your comments... I'll post some dumps of the router related
  stuff later today.

  =======================================================
  Lawrence Glaister VE7IT email: lg@jfm.bc.ca
  1462 Madrona Drive http://jfm.bc.ca
  Nanoose Bay BC Canada
  V9P 9C9
  =======================================================
  ----- Original Message -----
  From: Steve Underwood <steveu@coppice.org>
  To: <sane-devel@mostang.com>
  Sent: Thursday, September 21, 2000 7:48 AM
  Subject: Re: problems with 1.0.3 and color scanning

  > Lawrence Glaister wrote:
  >
  > > I am trying to get sane 1.0.3 working with my snapscan 1212u usb
  scanner.
  > > The scanner works properly under 1.0.1 but fails in various ways under
  1.0.2
  > > and 1.0.3 and the cvs code as of sept 19. I have narrowed the problem
  down
  > > to the snapscan-sources.c RGBRouter_remaining() function.
  > > - grayscale scanning works fine
  > > - color scanning a small image at 50dpi works
  > > - color scanning same image at 75dpi breaks xscanimage
  > > by broken, I mean that xscanimage enters into an infinite loop using
  100%
  > > cpu time.
  > > the cause for this appears to be a negative result returned by
  > > RGBRouter_remaining(). There are two possible return values calulated in
  > > RGBRouter_remaining() and one of them always looks like the correct
  > > answer... the problem comes in that the conditional used doesn't seem to
  > > work in all cases (sometimes the wrong value is returned and when this
  > > is -ve, all hell breaks loose.). I have been getting a headache trying
  to
  > > decipher how the new RGBRouter code is supposed to work... could the
  author
  > > (pere) or someone have a look at the function and see if they see any
  > > obvious errors. I have not seen a lot of postings about 1.0.3, so the
  > > problem may be related only to the snapscan backend with a usb patch
  applied
  > > to it.
  > > I can supply some rather detailed dumps of the good scans and bad scans
  as I
  > > have added a lot of dbg calls into the snapscan code.
  > >
  > > Are there any snapscan scanners usb or scsi out there working with sane
  > > 1.0.3???
  >
  > Excellent. This look likes a really solid lead for what goes wrong. I will
  try
  > to look at the RGBRouter code in the next couple of days, and see if I can
  spot
  > what goes amiss. Actually, I thought the current RGBRouter code was fairly
  > straightforward, but maybe that's only to my own twisted mind! The
  existing
  > code certainly does work for some scanners. It works just fine for my Acer
  > 610+, and a few other people have reported success with some scanners.
  >
  > Lets hope this is the root cause of several not quite identical problems
  people
  > have reported.
  >
  > If you have any debug logs, or other useful info please mail it to me. my
  code
  > hasn't given me any trouble so far, so a log of an actual failure would be
  > helpful.
  >
  > Steve
  >
  >
  >
  > --
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  >

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