[sane-devel] HP Scanjet 3670 bad colors

[Stef]

On 31/03/2014 15:51, Octavio Alvarez wrote:
> Hi.
>
> I'm trying to get my HP Scanjet 3670 under Linux. The scanner works (it
> scans and all) but the scan has some color distortion.
>
> I confirmed the scanner works: here is a comparison of a section of a
> scanned image in both, Windows and Linux:
>
> http://blog.alvarezp.org/files/scan-hp3670/scan-hp3670-win7.jpg
> http://blog.alvarezp.org/files/scan-hp3670/scan-hp3670-linux.png
>
> The scan is a black and white section of a creased document.
>
> Even the problem itself is very unstable. Sometimes the whole page is
> distorted, sometimes only gray shades are. *Once* in my 40-like attempts
> the output was acceptable but I could not reproduce this success case. I
> noticed, though that solid strong colors are usually not distorted.
>
> I wanted to find out if this was an introduced bug, but I could only
> compile as back as 1.0.22 + 2 commits and it failed too. Before that,
> there is a V4L compilation blocker that prevented me from going further
> back.
>
> I tried looking at the code but I realized I understand very little
> (near to nothing) about how a scanner works.
>
> Is this a SANE bug? What can be done to make it properly work?
>
> Thanks.
>
     Hello,

     the problem is coming from incorrect calibration by the backend.  
Gain is too high. Could you please run SANE 1.0.24 backend version with 
traces enabled, and send me log file and *.pnm files created during 
calibration ?
In a command shell type:
export SANE_DEBUG_GENESYS=255
export SANE_DEBUG_GENESYS_LOW=255
export SANE_DEBUG_GENESYS_GL646=255
export SANE_DEBUG_GENESYS_GL841=255
scanimage -d genesys --resolution 75 --preview --mode Color 
2>preview.log >preview.pnm


Regards,
     Stef