Canon ImageClass MF4770n not listed on Canon OpenPrinting list

Hello,

I have access to a Canon ImageClass MF4770n printer, and I wanted to 
print to it from Trisquel. Canon provides a Linux driver [1], but I 
don't want to use it because it's proprietary, and the license might 
preclude my use case anyway (use in a business). Maybe I am reading the 
license too strictly, but I would like to avoid it anyway.

I looked at a list on openprinting.org [2] and didn't see this model 
mentioned as working or non-working, so my understanding is that this is 
a printer that hasn't been investigated much yet.

The ppd files included with the Canon driver package are released under 
a free license, but they depend on a nonfree filter program called 
"rastertoufr2", presumably to convert raster input to UFR II output. I 
found a different repository with a filter to convert PostScript to UFR 
II [3], and a different program to convert raster to PostScript [4].

Would I be correct to think those programs could be combined to build a 
fully-free printer driver for this model, or am I missing something 
important?

I also made a similar post on the Trisquel forums [5].

  - Jacob K

[1] https://in.canon/en/support/0100924010?model=imageCLASS+MF4770n
[2] https://openprinting.org/printers/manufacturer/Canon
[3] https://github.com/vicamo/cndrvcups-lb
[4] https://github.com/pts/sam2p
[5] 
https://trisquel.info/en/forum/canon-imageclass-mf4770n-will-not-work-without-proprietary-software-it-seems