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

netukar201409+sane at mailbox.org netukar201409+sane at mailbox.org
Sun Sep 20 18:43:15 BST 2020


thank you for your hints. I reconnected the book scanner and was now 
recognized as video2.

scanimage --list-devices
device `v4l:/dev/video2' is a Noname JY-VP216: JY-VP216 virtual device
device `v4l:/dev/video0' is a Noname USB2.0 HD UVC WebCam: USB2.0 HD 
virtual device

Then I tried

scanimage -d v4l:/dev/video2 --help --all-options

with result

Usage: scanimage [OPTION]...
Start image acquisition on a scanner device and write image data to
standard output.
Options specific to device `v4l:/dev/video2':
Scan Mode:
--mode Gray|Color [Gray]
Selects the scan mode (e.g., lineart, monochrome, or color).
--channel Camera 1 [inactive]
Selects the channel of the v4l device (e.g. television or video-in.
-l 0..-513pel (in steps of 1) [inactive]
Top-left x position of scan area.
-t 0..-209pel (in steps of 1) [inactive]
Top-left y position of scan area.
-x 1280..767pel (in steps of 1) [inactive]
Width of scan-area.
-y 720..511pel (in steps of 1) [inactive]
Height of scan-area.
--brightness 0..255 [102]
Controls the brightness of the acquired image.
--hue 0..255 [0]
Controls the "hue" (blue-level) of the acquired image.
--color 0..255 [119]
Sets the picture's color.
--contrast 0..255 [136]
Controls the contrast of the acquired image.
--white-level 0..255 [0]
Selects what radiance level should be considered "white".

All options specific to device `v4l:/dev/video2':
[same output ...]

Geometry settings seem not to be supported by V4L module.

I also tried successlessly

SANE_DEBUG_V4L=128 scanimage -v -d v4l*/dev/video2
Output format is not set, using pnm as a default.
scanimage: open of device v4l*/dev/video2 failed: Invalid argument



Michael Dittmer

FSFE fellower

Am 2020-09-06 um 08:18 schrieb Olaf Meeuwissen:
> Hi,
> Suggestions inlined below.
> netukar201409+sane at mailbox.org  writes:
>> ---------- Urspr√ľngliche 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
>> 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
>   GnuPG key: F84A2DD9/B3C0 2F47 EA19 64F4 9F13  F43E B8A4 A88A F84A 2DD9
>   Support Free Softwarehttps://my.fsf.org/donate
>   Join the Free Software Foundationhttps://my.fsf.org/join
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