[sane-devel] Scan Correction Program! :)

[Ekkehard Morgenstern]

Thanks! :)



On Mon, 2008-05-12 at 10:01 -0400, m. allan noah wrote:
> sniffer: http://www.pcausa.com/Utilities/UsbSnoop/default.htm
> 
> see also http://www.sane-project.org/contrib.html and
> pirsoft-dsl-dropzone.de/scanner-technical.pdf for more info
> 
> allan
> 
> On Mon, May 12, 2008 at 8:14 AM, Ekkehard Morgenstern
> <ekkehard at ekkehardmorgenstern.de> wrote:
> >
> >  Thank you! :)
> >
> >  How do I log USB communication in Windows?
> >
> >  I might try to implement what you said sometime. I love controlling
> >  devices! :)
> >
> >  I also have to analyze the source code of the backend. Its implementor
> >  already used reverse engineering data, perhaps code that I'd need is
> >  already there.
> >
> >  I've never done driver development on Windows, Linux or BSDs, but I'm
> >  certainly interested in it! :)
> >
> >  And since SANE operates on top of normal OS services, this would be like
> >  an initiation rite for me! ;)
> >
> >
> >
> >  On Mon, 2008-05-12 at 07:51 -0400, m. allan noah wrote:
> >  > The results might be caused by poor (or no) CIS calibration being done
> >  > by the backend. You could try getting a trace of the device in action
> >  > with the windows driver, and investigate adding the calibration steps
> >  > to the backend.
> >  >
> >  > generally this involves doing several small scans of a white area
> >  > under the shell of the scanner, with and without the lamp on. this is
> >  > usually pretty easy to identify in the logs. interpreting it is a
> >  > different matter... :)
> >  >
> >  > allan
> >  >
> >  > On 5/12/08, Ekkehard Morgenstern <ekkehard at ekkehardmorgenstern.de> wrote:
> >  > >
> >  > >  It's the ma1509 backend.
> >  > >
> >  > >  I've already seen that there's a possibility to provide gamma correction
> >  > >  tables and such to SANE from within a backend. How does it work?
> >  > >
> >  > >  I'm not sure whether the poor results of my scanner are the result of
> >  > >  hardware aging, or if it's just because the backend seems to pass on the
> >  > >  data from the scanner chipset unchanged.
> >  > >
> >  > >  It's an LED scanner, so there must be a set of photo diodes or photo
> >  > >  transistors somewhere. It appears as if the scanner sends the data in
> >  > >  raw form, unadapted to the characteristics of the semiconductors.
> >  > >
> >  > >  Distribution of RGB values across their channels suggest that the data
> >  > >  should be scaled or transformed somehow. I spent a whole night this
> >  > >  weekend trying to figure out some formula that would solve the problem,
> >  > >  but I didn't find a solution.
> >  > >
> >  > >  Instead, I wrote this program to simply compute the difference between a
> >  > >  blank page and the color white. The program generates one line of
> >  > >  averaged out scaling data, which is stored in the file "white.shape".
> >  > >  I'm not sure whether the data can be made constant. If it were to be
> >  > >  included in the backend driver, it has to be fairly constant over all
> >  > >  scanners of that type.
> >  > >
> >  > >  After all, the Windows driver must do the same thing somehow! ;)
> >  > >
> >  > >
> >  > >
> >  > >  On Sun, 2008-05-11 at 15:42 -0400, m. allan noah wrote:
> >  > >
> >  > >  > Ekkehard- another choice might be to do this sort of calibration
> >  > >  > inside the driver in sane, but that would require becoming familiar
> >  > >  > with the code of the sane backend which drives the scanner....
> >  > >  >
> >  > >
> >  > >
> >  > >
> >  >
> >  >
> >
> >
> 
> 
>