[sane-devel] maximum image size for a scan for Canon pixma backend

Gernot Hassenpflug aikishugyo at gmail.com
Thu Dec 30 17:41:10 UTC 2010

On Fri, Dec 31, 2010 at 2:19 AM, Gerard Klaver <gerard.klaver at xs4all.nl> wrote:
> On Fri, 2010-12-31 at 01:29 +0900, Gernot Hassenpflug wrote:
>> Dear all,
>> I have been involved in trying to support the Canoscan 9000F, and the
>> testing community has grown to about 15 individuals. A few of them
>> have programming knowledge and tonight one individual send in
>> corrected code to handle the final hurdle: correctly aligning the
>> sub-images in the 9600dpi TPU mode. So the scanner is now supported
>> for all modes.
>> However, for large images at both 4800dpi and 9600dpi modes, it seems
>> the max size of the image is limited in some way, so that only a
>> section of the desired image is delivered. Is this something that can
>> be set in the individual driver files (like pixma_mp150.c) or in some
>> of the generic pixma driver .c or .h files (which I do not want to
>> touch if possible)? I don't see a problem in the linesize or
>> dimensions, only in the image_size value seen by [pixma] debugging
>> output.
>> Best regards,
>> Gernot Hassenpflug
>> --
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> One possible solution (if not yet done), is to check the declaration of
> the  image_size parameter, for a 9600 dpi A4 scan (color) size is about
> 550 000 000 000 bytes. (long long is needed)

Hi, thank you for that. I see that image_size is currently declared as
"unsigned". I imagine that changing the declaration will need to be
checked in all places where the calculations using image_size are
done, or not?

Currently, from the report I obtain from a test user, a 4800x4800dpi image with

dimensions: 32824 px (width) * 47248 px (height)

should have a image_size of 4652605056 bytes (W*H*3 for channel number)

whereas the actual image_size used is 357637760 bytes (approximately
341.1 MiB). I am still trying to ascertain whether for some reason the
wrong calculation for image_size might have been made, but certainly
the width and height are correctly there.


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