[sane-devel] HP3670c calibration problem?

[Carlos Maziero]

Hi all,

I have a problem with my HP3670c scanner: when I scan some documents in 
sequence, the first page is good (clear and bright), but the following 
are much darker. If I leave the scanner idle for some time (20 min or 
more), the pattern repeats.

I've packed three consecutive scans of the same document (white paper, 
black printing) as an example:

     scan 01: http://filebin.ca/1hi6F5IRZ0nq/scan01.tgz
     scan 02: http://filebin.ca/1hi6c0tiBGDJ/scan02.tgz
     scan 03: http://filebin.ca/1hi6tBYqo94r/scan03.tgz

Each .tgz file has scanned image (jpg file), a lot of debugging .pnm 
files, and the debugging output of the Genesys backend.

The scans were performed using scanimage:

    /usr/bin/scanimage --device genesys:libusb:001:004 \
                       --buffer-size=512                \
                       --resolution 300dpi --mode Color \
                       --brightness 25 --contrast 0

I also tried including the option "--clear-calibration", but apparently 
nothing changes.

I'm using the last SANE backends (1.0.25 stable, built today from Git) 
on Raspbian:

   # scanimage -V
   scanimage (sane-backends) 1.0.25git; backend version 1.0.25

   # scanimage -L
   device `genesys:libusb:001:004' is a Hewlett Packard ScanJet 3670c 
flatbed scanner

Do you have any suggestions on how to solve this issue?

Carlos

-- 
Prof. Carlos Maziero, PhD <http://dainf.ct.utfpr.edu.br/%7Emaziero>
/DAInf/UTFPR - Curitiba PR, Brazil/
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