[sane-devel] Fwd: book scanner recognized as v4l device

[Olaf Meeuwissen]

Hi,

Suggestions inlined below.

netukar201409+sane at mailbox.org writes:

> ---------- Ursprüngliche Nachricht ----------
> Von: Michael Dittmer
> An: "sane-devel at alioth-lists.debian.net"
> <sane-devel at alioth-lists.debian.net>
> Datum: 23.08.2020 12:00
> Betreff: book scanner recognized as v4l device
>
> I bought a book scanner
>
> JOURIST BT16
>
> from a german dealer
>
> looks like:
> http://www.scanner.expert/de/images/products/buchscanner/description/5_JOURIST_Buchscanner_BS16_Standalone.jpg
>
>
> It takes photos from the pages with a camera like a CZUR book
> scanner. My bookscanner camera also can be opened by
>
> guvcview
>
> It has maximum resolution of
>
> 4608x3456
>
> pixels for A3 scan (resolution can be selected by gucview and is shown
> later when starting xsane).
>
> When I plug it onto a usb port, several devices are recognized (dmesg
> output)
>
> [...]
>
> All book scanner manufacturers seem to deliver only twain drivers. So
> I tried to handle the scanner as an generic v4l device
>
> My linux mint 19.3 (based on Ubuntu 18.04) distribution has a sane
> backend package (1.0.27) without compiled v4l backend.
> After compiling current 1.0.30 sources with v4l-dev libraries I
> obtained the v4l backend
>
> scanimage --list-devices
> device `v4l:/dev/video3' is a Noname JY-VP216: JY-VP216 virtual device
>
> but xsane and scanimage are not able to perform scan ("illegal argument")

Check the supported settings and allowed values with

  scanimage -d v4l:/dev/video3 --help --all-options

> SANE_DEBUG_SANEI_USB=4 scanimage -v -d v4l:/dev/video3 --format tiff > output.tif
> scanimage: ignored request to set inactive option br-x
> scanimage: ignored request to set inactive option br-y
> scanimage: sane_start: Invalid argument

Try

  SANE_DEBUG_V4L=128 scanimage -v -d v4l*/dev/video3

and see if that sheds any light upon your issue.

> Another program
>
> simple scan
>
> from Ubuntu distribution is able to scan into pdf with 1600x1200 pixel
> but not with maximum resolution.
>
> It seems for me that the v4l backend has to support higher
> resolutions, like 4608x3456 e.g.

Hope this helps,
--
Olaf Meeuwissen, LPIC-2            FSF Associate Member since 2004-01-27
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