[sane-devel] HP ScanJet 6300C head moving back/forth during scan >200dpi

[Michael Ole Olsen]

I found that I can scan at maximum of 160dpi at Slow scan speed.

If there was a possible way to change scan speed to slower than slow,
i.e. set some integer value for scanspeed, im
sure it would make the scanner stop moving the head back and forth while
scanning.

if i set it to high scan speed it moves forth and back very often, and
not so often at slow speed - tested with 200dpi

is it possible to set scan speed with some argument to sane backend or
such with hp libusb driver?



On Mon, 14 Apr 2008, Michael Ole Olsen wrote:

> Hello, I am having problem using my HP ScanJet 6300C with libusb and
> xsane+sane backend from debian testing. I have also tried debian etch
> version on another computer with same issues, and I even tried
> downgrading my sane backend (then it went completely insane and almost
> broke the scanner). Right now im testing on a cometely fresh install of
> Debian/testing.
> 
> There are no scanner modules loaded/in kernel and the kernel is PREEMPT 2.6.23.9
> 
> When I do a scan, it waits about 6-8 seconds before scanning (just like
> it is calibrating), then it moves the scanner head back and forth while
> scanning (only when i get over approx. 200dpi)
> 
> I did read somewhere on this mailinglist, that it had to do with USB
> bandwidth, so the scanner must wait at above 200dpi for the transfer of
> data to complete over USB.
> 
> I'm using it with a high-speed USB 2.0 hub, so i dont see how there
> could be any kind of transfer-bottleneck.
> 
> I tried adding 'option enable-image-buffering' to top of
> /etc/sane.d/hp.conf just like man sane-hp says to make it global, with
> no results.
> 
> I tried enabling debugging a few times, the output didn't seem useable,
> but I can post it if needed.
> 
> I have had the same issues with a plustek scanner (Canon LIDE 30) and libusb: grinding
> noise and scanner head moving forth and back while scan > 200dpi.
> 
> 
> Can anybody help me sort this out?
> 
> 
> best regards
> Michael Ole Olsen
> gnu at gmx.net
> 
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