[sane-devel] False colors with Canon LIDE 25

[Gerhard Jaeger]

On Saturday 10 February 2007 18:17, Todd Pytel wrote:
> Hello,
>
> I just received a Canon LIDE 25 and am hitting some problems with false
> colors. I've basically never used a scanner before, much less on Linux
> (though I'm pretty handy with Linux in general), so I'm not sure what
> component of the scanning system I should be looking at.
>
> I set up the scanner without any issues - it's using libusb and
> scanimage detects the make and model correctly, as well as identifying
> the plustek backend. I've got xsane running fine as a regular user and
> can preview and scan to an image. Full-color documents (like a map, for
> example) seem to scan OK. The problem document is primarily
> black-and-white text and line graphics (boxes and such), with a few red
> numbers and graphics that I'd like to keep in color. When I scan this, I
> get a lot of false color in parts that should be black - for example, a
> solid black line that's part of a box will show up with a kind of
> spectrum effect. I tried fiddling with a couple of the xsane settings,
> but didn't come across anything helpful.

It might help, that you play with scanresolution. I'm pretty sure that
you hit a common "scanning" problem, called "Moiré pattern" - see
http://en.wikipedia.org/wiki/Moire

As already set, you may play around with the resolution.
HTH
Gerhard