[sane-devel] Out of Memory error when scanning at high DPI

[Olaf Meeuwissen]

Mark Richards <mark.richards at gmail.com> writes:

> Hi guys,
> 	Thanks for the quick reply.  Attached is the output of attempting to scan a 
> 4x6 photo a few times at different settings (SANE_DEBUG_EPSON=25).  Note that 
> the out of memory error happens the instant I press the scan button, not 
> part-way through a scan or anything.  The scanner doesn't even twitch.  It 
> previews fine and scans at lower dpi/colour-depth though.

# OK, I see.
# Somebody sure contributed an ugly hack just to get 4800dpi on the
# 4990 to work ;-{  The epson backend only uses ESC based commands,
# which implies that that you can't even set 4800dpi and even less
# so the scan area you are using and have the device behave.  The
# hack that went in probably shouldn't have ...

Anyway, you can not scan wider than about 3.4 inches without avoiding
this behaviour in sane-backends-1.0.18 on Linux.

If you don't mind experimenting, you could try with a larger value for
MAX_DATA in sanei/sanei_scsi.c but I have absolutely no idea what will
happen.  In the best case things will "work", in the worst your
scanner breaks.

Hope this helps,

> Thanks for the help,
>
> Mark
>
> On Thursday 16 November 2006 18:48, Olaf Meeuwissen wrote:
>> Gerard Klaver <gerard at gkall.hobby.nl> writes:
>> > On Thu, 2006-11-16 at 09:13 -0500, Mark Richards wrote:
>> >> Hi,
>> >> I have an Epson Perfection Photo 4990 (GT-X800) scanner connected by
>> >> USB to my PC (Athlon 64 3200 1GB ram 5GB swap, FC5).
>> >>
>> >> scanimage --version : scanimage (sane-backends) 1.0.18 ; backend
>> >> version 1.0.18
>> >>
>> >> Scanimage -L : device `epson:libusb:002:009' is a Epson GT-X800
>> >> flatbed scanner
>> >>
>> >> I can scan fine at 1200dpi (16-bit colour) or 2400 (8-bit colour) but
>> >> when I try to scan at anything higher I get an Out of Memory error.
>> >> It is my understanding that scanning at 4800dpi should be possible
>> >> with this scanner.  Any suggestions?
>> >>
>> >> Thanks,
>> >>
>> >> Mark
>> >
>> > With export SANE_DEBUG_EPSON=255
>>
>> You don't really want to do that at 4800dpi ;-).  It outputs a single
>> line for every sample.  Use 25 instead of 255 for more useful output
>> and mail me a (compressed) debug log.
>>
>> > and then start scanimage, check the logs for some info,
>> >
>> > For a A4 300dpi (24 bits, 8 bits per color) scan you get about 25Mbyte
>> > of data, for 600dpi about 100Mbyte, for 1200dpi about 400 Mbyte, for
>> > 2400dpi about 1600Mbyte.
>>
>> Mark mentions 1GB RAM ... if the frontend attempts to keep the whole
>> scanned image in memory than at 4800dpi, 24bits he may be hitting the
>> limit.
>>
>> Whereabouts does the out of memory occur?  Somewhere right at or near
>> you start the scan or after you are more than halfway through the
>> scan?
>>
>> Hope this helps,
>

-- 
Olaf Meeuwissen                          EPSON AVASYS Corporation, SE1
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Penguin's lib!       -- I hack, therefore I am --               LPIC-2