im2graph, Maximum variable size allowed by the program is exceeded?

I m trying to run the dijkstra algorithm for shortest path for an image. Many of the dijkstra examples available use graphs. And so I found an example with a maze image that converts the image into a graph. http://uk.mathworks.com/matlabcentral/fileexchange/46088-dijkstra-lowest-cost-for-images

However I get an error with the im2graph file. Maximum variable size allowed by the program is exceeded? I noticed that when I used a smaller image of 200*200 pixels that im2graph worked. But this maze example specifies StartPoint = [1, 497]; EndPoint = [533, 517];.

I don't really know why I cant run this.