An Interactive Guide to the Fourier Transform

If anyone wants to learn about the 2D DFT, the best explanation I've ever read was the relevant chapter in Digital Image Processing by Nick Efford.

If anyone wants to see my favorite application of the 2D DFT, I made a video of how the DFT is used to remove rainbows in manga on Kaleido 3 color eink on Kobo Colour:

https://youtu.be/Dw2HTJCGMhw?si=J6dUYOj2IRX1nPRF

In the video you show a 2D mask to blur diagonal lines. How is that mask applied to the DFT? Is the mask also converted to a DFT and the two signals get combined?

Just remove anything under the mask basically, similar to a low pass filter.