I wasted some time this weekend trying to get my scanner working on Ubuntu+VirtualBox again. 'Again' because it was working okay back on Hardy but when I tried it recently it was not working. This is probably because I upgraded to Lucid a few months back and haven't used the scanner since, well not on VirtualBox anyway. The reason for that is that there are scanner drivers that come with Lucid that work on my Canon scanner. So no need to use the Windows ones. Yay!
Not so fast.
I have a need to do OCR scans. Not many but I tried various tools available on Ubuntu and while I could make them work, the error rate was way too high. I've seen much better on the tools that come with my scanners. But they run on Windows. Sigh.
Anyway there are tricks to this. You have to make sure you get the right version of VirtualBox. There's the ose (Open Source Edition) which doesn't have USB support and my scanner is a USB one. That's fine, the non OSE (called something like PEUL) version supports OSE, and is free for personal use. But you have to download it from the site, not from the usual repositories. Okay.
A little more complexity comes in when you get the latest version (4.x) instead of 3.x because the rules changed. There is only one version now plus extensions you install on top of it and those handle USB. Actually I gave up on that and went back to 3.2.
Then you need to make sure you have a user group called vboxusers and that your username belongs to it.
With that in place it still did not work for me, although Windows could see the USB devices (well the devices showed up in VirtualBox and they had a tick beside them). But no joy. What fixed it was this post. It worked fine after I unchecked the USB 2.0 box in VirtualBox settings.
Now I can scan from Windows, more importantly I can OCR.