When I think of digital signal processing I think of things like audio and Fourier transforms. In my experience there’s quite a bit to graphics programming that’s different from that. A lot of shader code is linear algebra / matrix math, and physics equations for light. There’s also a lot of thinking about memory layouts and how to reuse calculations as much as possible.

I say this as someone who does a lot of graphics programming in my job but failed “Feedback Control Systems” the first time through.

Try explaining the physics behind any graphics or sound application without using the name Nyquist