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.
