[sane-devel] Epson 3490

[Bjorn Solberg]

Oliver Schwartz writes:

> Hi,
>> > If it is always the same ratio of real distance to scanned
>> > distance (also for -l and -t) it is most likely that the
>> > calculation of the scan area is not handled correctly. That could
>> > be corrected by changing the value of pos_factor in function
>> > set_window() in snapscan-scsi.c.
>> 
>> That would seem to be the case here.

> Yes, so maybe it's enough to just change that value for the 3490. It's 
> set in line snapscan-scsi.c, line 810. The value is currently set to 
> 1600 for resolutions below 1600, 3200 for resolutions above. If your 
> distances are off by 25%, try setting it to 1600/0.75 = 2130.

The CVS snapshot I downloaded for 20050815 didn't contain that patch.
And the CVS version doesn't work for me now (whether I make that
modification or not), I alternately get messages like

scanimage: open of device snapscan:libusb:001:003 failed: Error during device I/O

and

scanimage: no SANE devices found

But even so, scanimage -L reports

device `snapscan:libusb:001:003' is a EPSON EPSON Scanner1 flatbed scanner


Reinstalling the version from 20050815 (rev. 1.32 of snapscan-scsi.c)
makes the scanner work again though, but with the same scaling (and
brightness) problem as before of course.


[...]

>> > I don't think that this is an unsolvable problem. It may be
>> > necessary to do some deeper analysis and maybe get some USB
>> > traces from the windows driver, though.
>> 
>> How do I go about getting such traces for you (or whoever it is
>> who'll likely be working on this)?

> You can use usbsnoop:  http://benoit.papillault.free.fr/usbsnoop/
> The files tend to get very large, so chose a very small scan area and 
> a low resolution. You can send them to me in private mail.

I'll get you that shortly.

[...]

>> (On a side note: Is brightness supposed to work for lineart mode? 
>> As it is, it tends to make Lineart mode scans too dark - things
>> that are clearly (but somewhat faded) white paper gets smothered in
>> black.  My UMAX Astra 1200 didn't have that problem at all.)

> Yes. The parameter is called "Threshold" in lineart mode. It's 
> available in the Standard Options window in xsane or as option 
> --threshold in scanimage.

I get (with the 20050815 version)

scanimage: attempted to set inactive option threshold


Bjorn.