Damir's Corner.

Installing CanoScan LiDE 50 Scanner on 64-bit Windows 8.1

Canon CanoScan LiDE 50 is a small reliable flatbed scanner which has been serving my needs for years. Unfortunately Canon has dropped support for it long ago and has never released a 64-bit driver for it. Thanks to the unofficial driver it's still possible to use it in the latest version of Windows, but it requires a bit of tinkering to circumvent the security measures.

Since I'm rediscovering the steps to make it work every time I connect it to a newly installed machine, I decided to document it here for future reference. Follow the instructions at you own risk. If it doesn't work for you or worse, don't blame me or ask for help.

1. Download the unofficial driver and unpack it in a folder on your machine.
2. If you just follow the instructions inside the archive and run Setupsg.exe, it will quietly fail and do nothing because Windows will block the installation of unsigned drivers. To avoid that, you'll need to reboot Windows in advanced startup mode and disable driver signature enforcement in startup settings. You can find detailed instructions for that elsewhere, so I'm not going to repeat them here. When Windows reboots, Setupsg.exe will successfully install the driver. Once you disconnect and reconnect the scanner, Windows will detect it and complete the installation. Reboot Windows once again to re-enable driver verification.
3. Although the device will seem to be already properly installed when you look in the device manager, all attempts to open the TWAIN interface from another application (e.g. IrfanView) will result in the following error: "The program can't start because rmslantc.dll is missing from your computer. Try reinstalling the program to fix this problem." If you check the driver details in device properties window, you'll see where the file is on your computer, although the application obviously can't find it. To fix the problem, you'll need to add the folder with the file to your %PATH% environment variable and restart the application. Check Aaron Kelley's blogpost for details.

I suppose the above steps should also be helpful with other unsupported devices, as long as you manage to find a suitable driver. It feels nice when you don't have to replace your working hardware, just because the vendor decided not to support it any more.