[sane-devel] Epson Perfection V10 missing resolutions

[Olaf Meeuwissen]

Hi Istvan,

I used to maintain the epkowa and utsushi third-party backends
@the-office.  I think I oughta know ;-)

Istvan Gabor writes:

> Istvan Gabor írta:
>>Hello:
>>
>>I have an Epson Perfection V10 scanner. I installed iscan drivers from
>>the downloaded file iscan-gt-s600-bundle-1.0.0.x64.rpm.tar.gz on
>>openSUSE 13.1 64 bit. It went smoothly and the scanner works with sane
>>and xsane. In xsane I can only choose resolutions 133 200 400 600 800
>>1200 etc. I would expect 100 and 300 on the list too. scanimage --help
>>-d epkowa doesn't list there resolutions either:
>>
>>  --resolution 200|400|600|800|1200|1600|3200dpi [200]
>>        Sets the resolution of the scanned image.
>>    --x-resolution 133|200|400|600|800|1200|1600|3200dpi [200]
>>        Sets the horizontal resolution of the scanned image.
>>    --y-resolution 133|200|400|600|800|1200|1600|2400|3200|4800|6400|9600dpi [200]
>>        Sets the vertical resolution of the scanned image.
>>
>>The scanner should be able to scan at those resolutions as well. How
>>could I set scan resolution to 100 or 300 dpi?
>
> I have tried Epson's iscan utility. It offers the following
> resolutions for the scanner: 50 72 96 150 200 240 300 360 400 600 720
> 800 1200 1600 2400 3200 4800 6400 9600
>
> Sane/xsane offers only these resolutions:
> 133 200 400 600 800 1200 1600 3200.
>
> Not only that sane offers less resolution options but it also offers
> some which is not on the iscan list: 133.
>
> Where does sane get the resolutions for the scanner?  I guess the
> resolutions are specified by sane and not by the proprietary Epson
> drivers or else iscan wouldn't show them either.

The SANE backends for all EPSON scanners supported by the epson, epson2,
epkowa, utsushi backends get their resolution lists or ranges from the
device's firmware.  There may be an occasional patch to the firmware
reply in the backend but this is what the device reports it can handle.
These are the supported *hardware* resolutions.

Whatever you see as supported when using a SANE frontend (or a Windows
or Mac driver) is under control of the frontend (or driver).  If the
frontend can scale (resample, really) it is free to show you another
list or range of *software* resolutions.

Hardware vendors want to make their devices as attractive as possible so
they normally put the resolutions supported by their drivers, i.e. the
*software* resolutions, in the device specs :-(

# I have seen specs claim 9600dpi for devices that only support 600dpi
# optical max ...  The drivers simply magnify by a factor 16!

> I wouldn't mind building sane from sources if I knew what to edit or change.

Doing so will of course not change what the hardware can do, so there is
no point in doing so.

> Any help would be appreciated.

Hope this helps,
-- 
Olaf Meeuwissen, LPIC-2            FSF Associate Member since 2004-01-27
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