This overview talk introduces the concept of canonical images, why they are useful and how we could approach computing them. A new method for the calculation of canonical images uses backtrack methods involving graphs, so there is also a brief discussion of backtrack search and of our recent new approach using stacks of directed graphs. This is on joint work with Chris Jefferson, Markus Pfeiffer and Wilf Wilson, another collaborator was Eliza Jonauskyte, and future work will include Ruth Hoffmann as well.