Missing greys

Hi!

I've got a Canoscan Lide 50. I have discovered that when I
scan at 150 dpi  
or more the greys are missing in depth (in the black end).
But when I scan  
at only 75 dpi the result looks much better since darker and
lighter  
pixels are mixed to show the right grey nuance. Is it
possible to have  
this behaviour at higher resolutions as well and in that way
"creating"  
those missing greys?

http://got
o.glocalnet.net/huggla/75dpi.jpg
http://go
to.glocalnet.net/huggla/150dpi.jpg

This issue has been mentioned before here:
http://lists.alioth.debian.org/piperma
il/sane-devel/2006-April/016583.html

/Henrik Uggla

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Hi Henrik

Henrik Uggla schrieb:
> I've got a Canoscan Lide 50. I have discovered that
when I scan at 150
> dpi or more the greys are missing in depth (in the
black end). But when
> I scan at only 75 dpi the result looks much better
since darker and
> lighter pixels are mixed to show the right grey nuance.
Is it possible
> to have this behaviour at higher resolutions as well
and in that way
> "creating" those missing greys?

I can't explain why there is a difference between
calibration for 75dpi
compared to 150dpi(You didn't scan them at different bit
depth, i
guess). But anyways, dark shades were incorrect since the
beginning of
Canon LiDE 50 support.

I had some improvements to the calibration process sitting
in my local
copy since about 3 months, so i just committed them. You can
get them
from the cvs repository. Test results for the current method
are welcome.

Regards,
  Pierre


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