[sane-devel] Weirdness with Canon FS2720U

Gerald Murray gmurray at cloudnet.com
Thu Aug 3 09:54:24 UTC 2006

Quoting Tabor Kelly <tkelly-sane-devel at taborandtashell.net>:

> What I would love for someone to take a look at is URB 289-300 in this 
> file 
>   It looks like the windows driver writes 24kB of data to the scanner. 
> But look at the data, it isn't firmware, it is a pretty pattern. Any 
> idea? Was the developer who wrote this driver just having a little fun 
> at my expense?

I took a quick look at the urbs, and have seen similar transfers.  I do not
pretend to
be an expert in that area yet, as I have not reached coding phase for the
that I have been involved with.   This may not be a firmware upload.  For the
time I have been thinking that there are tables that are uploaded into a
for the purpose of gamma correction, and for shading tables at the point of
of the data.  Some scanners obtain 48bits of data, but send only a smaller
number of
bits/pixel, such as 42, or 36.  A table could then alter the colors sent back.
Uwe posted some code like those urbs about July 5, 2006. 


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