1. A computer system for determining regions of interest in a static digital image for display on a display device, the system comprising a processor configured to compare parts of an image with characteristics of at least one region of interest specified by a user and to determine at least one region of interest in the image based at least in part on the degree of similarity between regions of the image and the at least one user-specified region of interest in which the at least one user-specified region of interest is specified from the same image as the image in relation to which the determination is made.