[sane-devel] gt68xx: Manual red hue compensation for Mustek BearPaw 1200CU Plus II

[Jiri Bajer]

Hello,

my scanner Mustek BearPaw 1200CU Plus II has a problem with default
settings of gt68xx driver in SANE: the scanned image has a red hue
(contains light red instead of white).

I've managed to compensate it manually by specifying manual afe settings
in gt68xx.conf - could anyone confirm whether this issue is specific to
my piece of HW or not? If not, could this adjustment be incorporated
into the default settings?

I would also suggest to add a simple HOWTO for tuning the hue to the web
page describing the drivers (in this case
http://www.meier-geinitz.de/sane/gt68xx-backend/#FIRMWARE ). It gets
indexed by search engines and could help others with troubleshooting.
Basically a slightly more commented excerpt of sane-gt68xx manpage could
be enough (increase debug level note down the afe, put it into config
and tweak) - currently it's quite hard to find a solution just by
googling, one has to roll up the sleeves and dive into manpages/config
files.

My tweaked afe settings:
afe 0x06 0x02 0x16 0x02 0x16 0x02

Default afe settings:
afe 0x16 0x02 0x16 0x02 0x16 0x02

HW is detected by lsusb as:
055f:021b Mustek Systems, Inc. BearPaw 1200 CU Plus

HW is detected by SANE as:
USB scanner (vendor=0x055f, product=0x021b [USB Scanner], chip=GT-6816?)

Output of simple-scan GUI with debug level set to 3:
[gt68xx] SANE GT68xx backend version 1.0 build 84 from sane-backends
1.0.22
[gt68xx] attach: found Mustek flatbed scanner Bearpaw 1200 CU Plus at
libusb:003:004
[gt68xx] get_id: vendor id=0x021B, product id=0x055F, DID=0x00010004,
FID=0x0000
[gt68xx] gt68xx_afe_cis_auto: setting exposure reached limit
[gt68xx] afe 0x16 0x02 0x16 0x02 0x16 0x02
[gt68xx] exposure 0x54 0xa2 0x6d
[gt68xx] sane_get_parameters: pixels 2563x3531x256

Tested on Ubuntu 11.04 (sane-utils 1.0.22-2ubuntu1).

Cheers,
Jirka