Methods and devices arranged to provide functions for generating a security code are described. These functions include defining a set of locations in the one or more images on the basis of one or more user-selected locations, and generating a security code based on values determined and derived from display parameters associated with imaging elements having locations corresponding to the defined set of locations. This enables a security code to be generated that contains a high level of entropy, and is therefore capable of providing high levels of security, based on user input that is easy for the user to remember.