I have now tested sane-1.08 with plustek-sane-0_44_2 on my Canoscan N670U. Compilation was routine and fast. I did have to edit the configutation file in /etc/sane.d to point at /dev/usb/scanner0, because I am using devfs and there is no such device here as /dev/usbscanner. But after this it does find the scanner.
I can report that basically this package works for me, but: 1. There is a typo in the file Plustek-USB.txt, where the N670U is given Product ID 0x220B (wrong) and it should be 0x220D This error is only in that readme file, but it could deceive the ignorant. 2. The light in the scanner does not turn itself off when the scan is finished. 3. The zoom features work; I can scan any small rectangular area of the image which I choose, but the brightness and contrast need to be adjusted drastically afterwards, in order to get an image which looks like the original. Scanning a small rectangular image gives a very dark image. Scanning the entire original image, however, does not have this problem. I used as a test for this the glossy paper which came with the scanner and says on one side, "Choosing Canon was a smart move" and has a picture of a girl wearing an earphone, at the bottom left. Try zooming in on the girl and scanning an image which avoids all of the text. The colors are also a little bit off; the background comes out somewhat blue instead of white. 4. I get the impression from reading the mailing list that there is a confusion about what is required for supporting a USB scanner vs. what is required for supporting a parallel port scanner. In my opinion, the instruction files and documentation for both USB and parport scanners should have big fat warning signs near the very beginning of the respective files. This would include at least the files Plustek-USB.txt and /backends/plustek_driver/INSTALL. 5. I didn't try the buttons. Do they work, too? Theodore Kilgore