[sane-devel] HP Scanjet 4850 Development

Daniël Sonck dsonck92 at gmail.com
Wed Feb 8 23:03:21 UTC 2012

On 07-02-12 21:38, Stef wrote:
> Le dimanche 5 février 2012 22:27:53 Daniël Sonck a écrit :
>> On 05-02-12 09:01, Stef wrote:
>> I compiled from the latest git source code. The release that came with
>> openSUSE did not want to work or recognize my printer.
>> Daniel
> 	Hello,
> 	could test that adding your scanner to this test (line 710 of
> genesys_gl843.c) improves the scan ?
>    /* G4050 values */
>    if ((strcmp (dev->model->name, "hewlett-packard-scanjet-g4050") == 0)
>     || (strcmp (dev->model->name, "hewlett-packard-scanjet-g4010") == 0))
>      {
> Regards,
> 	Stef
Alright, I have made a simple script that calls scanimage with all 
possible combinations of scan settings (mode, resolution, bitdepth). I 
have clearly an error in my script as it calls lineart and depth 
together but somehow there is a (serious) bug in the driver. Whenever I 
call lineart together with depth, the driver actually sets the scan head 
to the beginposition but gives an error about the unused parameter. It 
doesn't return the scan head to the beginning. So as every new scan 
assumes that it is in the starting position (and it isn't far enough to 
let the scanner return the scan head self) it over-scans, and thus 
resulting in an awful bump.

But even if it is in the starting position, almost every scan resolution 
I use moves the scan head to the wrong starting position, always too far 
resulting in a dangerous overscan (it doesn't bump however).

The colors are strange too. In the folder (dss.nl.eu.org/pictures) you 
can see the results of Gray and Color mode. The second batch of scans 
are pictures of my printer-test-page as it shows all colors/Grays and 
text. Somehow my paper shows violet. That can be the paper, it does show 
a bit violet when it is being scanned. The background is clearly white 
(first couple of scans). Because I opened the lid (to see why it made 
strange noises like it was constantly bumping) the rest of the images 
have black backgrounds.

Mode Color 400dpi 16bit is pretty wrong. It moves the head forward for a 
couple of cm and then moves it back a bit and continues forward and 
reverses again (until it reaches the end).
Mode Color 600dpi 16bit is very wrong. It moves the head forward and 
back (more back than forward). The scanned image is correctly read, the 
head isn't correctly moved.

If you could tell me how to solve (or try to solve) this?



Daniël Sonck
WWW: http://dss.nl.eu.org/
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