[sane-devel] Canon P-208II calibration

m. allan noah kitno455 at gmail.com
Thu Sep 6 12:31:55 BST 2018

I did previously spend some time trying to determine the calibration
algorithm of these P-2xx scanners, but did not have much success. I
suppose what is needed is to take some scans with the windows driver,
and reverse engineer the formula the driver is using to derive the
calibration data it sends into the scanner. Once that is known, we can
try to do something similar in the canon_dr backend.

On Wed, Sep 5, 2018 at 7:51 PM <timokau at zoho.com> wrote:
> Hi!
> I have a canon P-208II (1083:165f) scanner. While sane makes it possible to scan
> documents with it, the color calibration is severely off. That has been known
> for a while[1]. Amongst other factors, the brightness depends on the DPI (higher
> DPI -> slower scan -> darker image).
> I have a windows VM set up with the windows driver and scanning software
> installed and I can sniff USB traffic. There is also an old 32 bit sane backend
> distributed by canon themselves which apparently doesn't work anymore and is
> part-binary.
> I looked into the backend (`canon_dr.c`), but the 7768 lines of C are pretty
> hard to understand . My C knowledge is "advanced beginner".
> Is there anything I can do to improve the support of my scanner?
> Timo
> [1] http://sane-devel.alioth.debian.narkive.com/GRzsHBKu/canon-scanner-p-208-ii
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