[sane-devel] Backend for plustek Opticbook 3600

stef stef.dev at free.fr
Wed Mar 17 04:35:51 UTC 2010

Le mardi 16 mars 2010 20:02:33 Chris Berry, vous avez écrit :
> On 03/09/2010 05:15 AM, stef wrote:
> > Le lundi 8 mars 2010 17:20:23 Chris Berry, vous avez écrit :
> >> Ok Stef I have a bit more time to concentrate on this at the minute. I
> >> have updated the white_shading.pnm and included it at
> >> http://sites.google.com/site/bez625/updates-1/update080310 there is also
> >> a copy of the latest scan there too. I only have 20 shading lines in the
> >> shading area because there is a lot of blue in that area. Should I widen
> >> it (more shading lines) or should those blue areas be included?
> >>
> >> Also how do I disable the averaging? Is it a software thing or is it on
> >> one of the registers? I'm also not too sure what you mean about the
> >> offset, is it the DAC offset?
> >>
> >> Thanks
> >>
> >> Chris
> >
> > 	Hello,
> >
> > 	the white shading picture must be all white. The picture you posted is
> > mostly OK, but there is still some blue on the right. This is not a
> > blocker, but it will certainly have to be fixed to reach best image
> > quality.
> > 	By averaging, I was thinking of the AVEENB bit of register 3 which tells
> > the ASIC to delete extra data points or average them to produce data from
> > higher dpi.
> >
> > Regards,
> > 	Stef
> Hey guys,
> I have experimented with disabling average and altering the offset as
> Stef suggested. Disabling averaging seems to make things worse (dark and
> light lines where solid colour appears with AVEENB) and changing the
> offset seems to make no real difference so i'm not sure what is
> happening. Also I am unsure about what target code I should use for the
> shading compute_coefficients (assumed 0xdc00 as it seems popular).
> At the project site (update ) there are a few images in a bzip file to
> show what I mean about toggling the AVEENB. It certainly seems better to
> have it on but this might just be misleading images.
> The main issue now seems to be the different coloured vertical lines
> down the document. In addition I performed higer dpi scans (300, 600)
> and the whole image seems darker and the vertical lines are more
> prominent, i cant say im entirely sure whats causing them but im
> guessing its the shading function.
> I have also attached my source on the project update if this will make
> it easier to advise on what im doing wrong. I will get around to tidying
> up my code soon so i can commit to git without it looking messy. Has
> there been anymore information about a next release date? I have been
> skimming the mailing list and not seen anything mentioned.
> Thanks
> Chris

	in order to properly review the result of your hard work, we need the changes 
you done as patches. Either against the version you started to modify, or as a 
git patchset against latest version, which is the best solution. On your site, 
I only found the full sources, may you have a look into it ?



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