University of Illinois–Urbana-Champaign
The following is a not very accurate, but functional, gravitational lensing program I made in undergrad. It's intended to model gravitational lensing from supermassive black holes, and I think it's fun to play around with. Feel free to download the program and add a black hole to any picture you like:
Black Hole Gravitational Lensing Program
Some examples of pictures before and after lensing:
A boring grid pattern
A more fitting application of the program, the Cat's Eye Nebula
Me, in undergrad:
The lensed picture is split into quadrants due to the poor choice of cartesian parameterization underlying the lensing method. This can be fixed pretty easily, but I haven't gotten around to it...