[sane-devel] Backend for plustek Opticbook 3600

stef stef.dev at free.fr
Wed Mar 3 06:03:55 UTC 2010

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

	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.


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