I'm already into the CNN (Convolutional Neural Networks) course. CNN, of course, is used to break photos down into components through a computationally expensive process. For example, it can be trained to identify various objects in an image, such as kitchen sinks. It does this by using, among other things, "ReLUs" - Rectified Linear Units. And guess what? These use piecewise linear functions based on the hinge function max(0, x), which is similar to one of MARS' hinge functions max(0,x-c) or max(0,x-0). In a sense, analyzing a large photo, extracting its components, recognizing what they are, and reassembling them into some description is a special case of what MARS does in analyzing, for example, a neighborhood of houses. CNN like MARS models non-linear data. CNN is better at handling the higher dimentions of image transformations but simpler in the math. MARS has more complex math - but can't (and doesn't need to) deal with the extraordinarily large dimentisons needed for image processing. They both have their similarities and dissimilarities.
Also studying the Toeplitz matrix transformations which are used to both blur and sharpen images. ...