I wrote a short MATLAB function that runs the random walker image segmentation algorithm as an add-on to the above Graph Analysis Toolbox. The files contain a function to run the random walker algorithm and a script demonstrating its usage. The code may be found here. Another (3rd party) implementation of the random walker algorithm with 3D support is available here.
Code to run our combinatorial optimization of the Mumford-Shah functional is available. The code provides combinatorial optimization of the piecewise smooth Mumford-Shah functional, which may be used for both image denoising and segmentation. The code which includes a demo script an example image. The code may be found here.
Code to run the power watershed algorithm, including example usage, is available here.