[sane-devel] Colour problem with Canon Maxify MB5150

[Dr Rainer Woitok]

Greetings,

since our good ol'  Canon Pixma MX885  has eventually reached its End Of
Life, we've bought a Canon Maxify MB5150.  And because

   http://www.sane-project.org/sane-mfgs.html

listed this scanner  as using the same  "pixma" backend  as the MX885, I
just had to update the IP address in "~/.config/sane/pixma.conf" to acc-
ess the new scanner via "scanimage".   However, scanning the same single
page from flatbed or via ADF produced significantly different results:

  - The PNG file from the flatbed clearly showed the original paper hav-
    ing been rather thin, since some colours from the reverse side shone
    slightly through, and the background colour having been faintly grey
    rather than white.   In other words, this PNG file was a fairly good
    copy of the original.

  - But the PNG file from the ADF did show almost no shine through and a
    more or less purely white background.  Dark colours appeared slight-
    ly darker and light colours slightly lighter than the original.  The
    effect was somewhat similar to using ImageMagick's "-normalize" opt-
    ion.

While this sort of normalization seems good to have,  if one needs it, I
would prefer controlling it  via options to "scanimage"  rather than via
the scanning source.

Is there some way  to prevent this normalization effect  for the  MB5150
when scanning via ADF?

Oh, almost forgot:  using "media-gfx/sane-backends" version 1.0.31-r2 on
Gentoo.

Sincerely,
  Rainer