I didn't know anything about image processing at all until I read her paper. It took my quite a while to get to grips with all the terminology and ideas. I actually went through that paper line by line as I built my code and looked up every term I didn't understand on Wikipedia and then used links from there to understand what it was all about.

One thing that she needs to be commended on is the clarity of that paper. I was able to follow it and implement her algorithm starting from zero knowledge. She then provided me with the actual images that she had used so that I could verify that my implementation worked.

As with anything I'd suggest finding a project that inspires you and the inspiration will be enough motivation to make you learn anything.