[sane-devel] Backend for plustek Opticbook 3600

Chris Berry s0457957 at sms.ed.ac.uk
Thu Mar 4 16:13:12 UTC 2010

On 03/03/2010 06:03 AM, stef wrote:
> Le mardi 2 mars 2010 16:40:21 Chris Berry, vous avez écrit :
>> Hey guys, I resolved the issue I was having with the dark_shading
>> calibration. The lamp was turning off fine but the | REG03_LAMPPWR in
>> gl842_begin_scan was turning the light back on for the scan :/ . Having
>> resolved this there is still a black line down the center of the page.
>> The black_shading.pnm file is now completely black and the
>> white_shading.pnm file is mostly white with some dark edges.
>> Any thoughts on how I sort this out now? Is it related to the number of
>> sensor pixels or the shading area or something?
>> Chris
> 	Hello,
> 	the black patterns are often used to detect the exact geometry of the
> scanner. What is reliable is these black/white areas, while the casing may
> vary. For instance the HP2400/HP2300 and HP3670 have a black corner which is
> aligned on the exact vertical margin of the visible scan area.	So the dark
> edges may be harmless if they are outside the effective scan area used for
> final scan.
> 	For the big black vertical line (which is a third of the width of the
> picture), it seems that shading coefficients sent aren't send in the correct
> format. It's hard to tell without the code, but the results looks like
> 'planar' format (for CIS) was used when 'chunky' format (for CCD) was needed.
> Surely an issue in the genesys_send_shading_coefficient() where
> compute_coefficient() is for chunky, compute_planar_coefficient() is for
> planar and the CCD_CANONLIDE35 case looks for the planar case to me. Pierre
> may confirm this last point.
> Regards,
> 	Stef
Ok thanks guys, this seems to have done the trick! There is now a black 
line down one side of the page (not sure if that is supposed to be there 
or not) and the colours seem to be a bit grainy. I have attached photos 
to the site page 
(http://sites.google.com/site/bez625/updates-1/update040310), these show 
the shading calibration and the latest current scan.

If possible could you take a look and advise on how to sort out the 
grainy parts of colour, im completely unsure myself :)


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