[sane-devel] Scanner Recommendation for long receipts?

[Simon Matter]

Hi,

> I do think I have observed behavior indicative of the scanner internally
> buffering pages. If the network crashes during a scan over my software
> shuts down. I have sometimes reopened it and hit the scan button after
> carefully putting the pages back on the right order in the tray, but the
> tray never feeds and I get 9 or 10 pages in rapid succession far faster
> than the scanner has ever operated.
>
> I think the scanner has internal memory that it saves each page objects
> too
> and perhaps that memory is segmented in some way maybe partitioned just
> big
> enough to hold one legal size sheet of paper each.  As opposed to holding
> 10, 000 one-dimensional lines of pixels.
>
> That doesn't explain why it has to be that way but on my Epson
> multifunction printer scanner it seems to be working that way.
>
> For scanning a delicate artifact like a roll of piano paper I might
> imagine
> sliding it between two sheets of glass that don't quite squeeze the paper
> but keep it flat and then you can keep it moving at a constant speed like
> it was intended, and use a moving camera that snaps a photo while moving
> at
> the speed of the paper and then jumps back the other direction just enough
> to overlap an inch.  You have to work really hard and getting the lighting
> right.
>
> Or maybe act together two separate sheet feed scanners and put their
> sensors at different positions along the glass.  Then you have them take
> 17-in scans and succession so that when one is starting the other one is
> halfway done. Each of them I think it's only scanning one page at a time
> but because of their positioning it would be creating overlapping pages of
> one continuous document.  Hacking existing scanners might be easier than
> building your own and if their scanner element illuminates the page while
> scanning it like mine does then you wouldn't have to mess with lighting so
> much.
>
> I could also imagine wanting to shield both sides of the piano roll with a
> clear backer ribbon  Then you could feed the two backer layers between
> rollers the same way you would feed the paper between a roller but with
> less chance of damaging the paper.
>
> Interesting thought experiment.
>
> In the 90s I had something called a handheld scanner.  Back when it was
> quite a novelty to have images on a computer screen let alone photographs.
> Looked like a really fat and mouse and you could drag it across the page
> of
> a bound book to scan a 6-in wide column.  It had an optical sensor bar and
> a black wheel that measured distance.
>
> I wonder how that worked.  What would it have done if you dragged it
> across
> the gymnasium floor with a laptop?
> Then again I remember you had to install an ISA card just for the scanner,
> so, no laptops.  I wonder where this thing went so many years ago.
> Perhaps
> the manufacturer just never planned on it scanning longer than two times
> its cord length.

Now I remember something. I bought this scanner from Logitech decades ago:

https://upload.wikimedia.org/wikipedia/commons/2/28/Logitech_ScanMan_32-P4191186-white.jpg

Because I wanted it for my Commodore computer, it was either a Plus/4 or
C128, I've analyzed the wire protocol on its connector, I think it was
mini-DIN. I've then designed an interface card for the commodore and
implemented some scan software in 6502 assembler, which has worked very
well.

Now, IIRC the scanner produced a quite simple data stream and you could
scann almost endlessly with this device. At least it didn't seem to have a
limit as it didn't have much memory to buffer more than a few lines.

These were very interesting times :)

Regards,
Simon