Communications data such as traffic levels in a communications network is analysed using techniques adapted from the study of chaos. A method of detecting data in an image includes detecting an edge in the image, identifying a portion of the image having a known spatial relationship with the edge, and applying a transformation to the portion of the image source to provide a data space from which to detect the data. Leaves are yellow green with a green border having a distinctive fish-bone like pattern of yellow-green extending into the border. By providing a constrained domain of extensions and optimizations, the process can be automated to a high degree, thereby facilitating fast and reliable development. Each polarity detector monitors the bias of an OR-ing diode electrically connected to a corresponding DC input terminal.