This was one of my first coding projects, all the way back in 2011. The objective of it was to enlarge pixel-art images in a "better" way than the simple nearest neighbor algorithm.
The main function in the repository is pixelartsuperres.m. It takes as input an image and a super-resolution factor (it has to be a power of 2), and outputs an enlarged version of the input image, such that size(output) = factor * size(input). Warning: this code can take a lot of time to run, especially if you use large images.
You can compare the result of the enlargement process with the regular nearest neighbor algorithm by running test_pixelartsuperres.m. Although our algorithm takes longer to run, we can see that our enlarged version is "smoother" than the one output by the standard nearest neighbor algorithm.