1. A method comprising: representing an image as a graph of nodes connected together by edges, wherein the image includes first and second layered features; identifying nodes corresponding to first and second layered features; determining intensities of pixels of the image; and determining positions of nodes of the graph corresponding to other layered features based on the determined intensities of the pixels and the determined positions of nodes corresponding to the first and second layered features, and wherein determining positions of nodes of the graph corresponding to other layered features comprises graph cutting the graph of nodes, wherein a search associated with the graph cutting is limited to a region of the graph that excludes the nodes corresponding to first and second layered features.