[sane-devel] HP 5590 ADF end of page

[Rainer Keller]

Hi,

good to know someone has the same scanner I am using. It seems only few/none 
people own and use it.

> First some background: I'm using 64-bit openSUSE 13.1 and SANE 1.0.23
> (provided by the packet manager) along with an HP ScanJet 5590 scanner
> and have been running into some problems lately with the ADF unit.
You wrote "lately". Does this mean the behavior has changed? I make similar 
experiences as you described but I have them from the beginning.

> After
> some 20+ pages have been scanned, the bottom of one page starts to show
> up in the next one.
My observation is that the scanner scans about 5 mm more than expected. This 
is not depending on the papersize. This means with every page you see 5 mm 
more of the next page at the bottom of the current page. But for me this start 
directly with the first scanned page.

> I've looked up online for answers and apparently
> setting the page size has fixed it for some people, but in my case it
> just doesn't seem to help.
I tried to change the scanner driver some month ago to drop 5 mm of extra 
data. But my first attempt wasn't successful.


> Anyway, I took a closer look at an image I'd scanned recently and
> noticed a 1px-wide bar of black pixels along the right-hand side. Now,
> things get interesting when one page ends and the other one begins: the
> end of the first one is marked by a single blue pixel in the bar
That is interesting. I did not notice this. Maybe the driver could recognize 
the pixel and drop addtionional data.

> Is there a reason this is not used by SANE to separate the pages? Or
> were you just unaware of this resource?
As far as I can see there is no "page change" notification in the API. At least 
I didn't find it when trying to change the driver. The driver is given the 
expected page size and has to deliver exactly that amount of scanned lines.
If the scanner provides more lines for whatever reason it does not handle 
that. Each page is separated by  the scanimage tool by counting the scanned 
lines.

Best Regards,
Rainer