I am have some well-grounded knowledge in Bayesian Inference, Linear mixed models, and probabilistic graphical models. Image processing is a new learning topic for me.
If you wish to explore the mathematical foundations of image science, as opposed to image processing, take a look at the encyclopedic tome by HH Barrett and KJ Myers, Foundations of Image Science, 2004, Wiley, New York. This book does not contain IP algorithms or computer codes, but instead develops the underlying mathematics and ideas behind imaging.