IMAGE ANALYSER

摘要

In a method and apparatus for analysing an electronic image signal, the signal is treated as representing one or more cells each comprising a plurality of pixels. A set of pointers is generated and sequentially set according to characteristic values related to detailed image content. The pointers are used to address a memory array and for successive frames, the values of an address in each array row indicated by the pointer corresponding to that row is updated. In this way, for each frame the characteristic values can be accumulated so that in a single operational mode, both a time history of the image, stored in a memory, is updated and an indication is produced indicative of the occurrence or non-occurrence of an event not associated with image background. The characteristic values can be generated by randomly or pseudo-randomly selecting pairs of pixels and for each, generating a binary signal depending on whether or not the intensity of incident light on a predetermined one of the pair is greater than the intensity on the other. Over all the rows, the values in the addresses being updated can be summed, as well as the maximum value in each row. The ratio of the two sums can be time weighted averaged with respect to the ratios obtained from previous frames. The ratio is compared with the average andthe result used to determine the occurrence or non-occurrence of a significant event within the image.