I am aware that there is already a similar question here, but unfortunately I find the discussion there to be beyond my grasp.
I am looking for an intuitive explanation of spectral graph theory, as well as some examples of its applications in practice. Specifically, I want to know how it might or might not be relevant to image processing and machine learning.
I am comfortable with freshman-level mathematics (such as linear algebra and partial differential equations), but I will be lost if you invoke more advanced concepts in your answer.
Thank you in advance for your help!