[sane-devel] scan lines

[Henning Meier-Geinitz]

Hi,

On Tue, Sep 23, 2003 at 06:15:27PM +0100, kevin lyda wrote:
> i have a packard bell diamond 1200 plus scanner.  i'm scanning in a
> slew of old photos at 600dpi.  on parts of the picture that seem to get
> more complex as the scanner goes across there seem to be weird lines.

Can you put an example of such an image on the web, please?

> my theory is that since it's having to send too much data down the wire
> and this is causing it to have to go back and rescan.

That's true but it shouldn't cause the image to look weird.

> is the solution to scan at a lower dpi or are there other options?

If you use more that 8 bits/pixel, use 8 bits/pixel. Lower the
resolution. Decrease the scan width. Use a fast USB controller and
driver (e.g. try usb-uhci instead of uhci).

If you like to edit some source code, get the sane-backends code and
look at backend/gt68xx.c at the beginning:


#if 0
#ifdef HAVE_SYS_SHM_H

Change the 0 to 1 and conpile as usual. That may increase the speed a
bit.

> also, this is connected to a laptop - could it be a power issue since
> the scanner is powered off usb.

Maybe. You could try at a different computer or with a powered hub.
However, I haven't headr about such a problem yet.

Bye,
  Henning