[sane-devel] question about SANE backend fill_buffer function

Nicolas Martin nicolas0martin at gmail.com
Tue Sep 7 19:37:26 UTC 2010

Le mardi 07 septembre 2010 à 19:47 +0900, Gernot Hassenpflug a écrit :
> Dear all,
> I am working on the pixma backend for Canon devices (variation:
> pixma_mp150.c), and have a question about registration of pixels in
> the y dimension.
> Each backend I believe has variations on a <filename>_fill_buffer
> function called between <file>_scan and <>_finish_scan.
> The function reads sections of data from the scanner, and processes it
> line by line. Thus, pixels can be reorganized in the x-dimension.
> I am not sure if the amount of data read at once is controllable.
> I now have a problem where the pixels also need to be rearranged
> vertically. In particular, the first half of a line corresponds to the
> second half of a line much further along in the data.
> Is there any backend that has support for such processing, that I can
> look at for help? Or have I misunderstood what can be done with the
> current mp150_fill_buffer function in pixma_mp150.c?
Yes, as I answered you, the pixma_mp150 implements a vertical shift
reassembling that is needed by the CCD devices, as they produce scans
with vertically shifted color planes. Maybe you can just use this, or
use some modified version.


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