[sane-devel] Backend for plustek Opticbook 3600

stef stef.dev at free.fr
Fri Mar 5 19:26:26 UTC 2010

Le jeudi 4 mars 2010 17:13:12 Chris Berry, vous avez écrit :
> On 03/03/2010 06:03 AM, stef wrote:
> 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 :)
> Chris

	I think there are a couple of things to look. First compute_coefficient() 
can't handle case where averaging is enabled for CCD, either disable averaging 
it or improve the function. Then you'll have to find what the offset to feed 
as a parameter. To find it I usually give 0 offset, then I count the number of 
vertical lines between a dark line and a bright one. Because a dark line isn't 
corrected and another is applied the correction which turns it bright. Then I 
use this value as offset. With some trial and error you can have a good value. 
You may also look at the color matrix.


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