[sane-devel] Scan Correction Program! :)
ekkehard at ekkehardmorgenstern.de
Mon May 12 12:14:26 UTC 2008
Thank you! :)
How do I log USB communication in Windows?
I might try to implement what you said sometime. I love controlling
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
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... :)
> 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....
> > >
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