Abstract: An optical character recognition system comprising a reader head which includes the single line array of photo-sensitive elements, a clock pulse generator under control of which the elements of the array are sequentially sampled to produce video output pulses one from each element, the level of each pulse being dependent upon the light incident upon the element from which it originated, all elements being sampled in one scan and the elements being scanned repeatedly, data storage means into which the output pulses derived from the array are clocked under control of the clock pulse generator, a feature detector comprising gating circuits responsive to predetermined signals obtaining contemporaneously in two or more predetermined locations within the store for providing a signal indicating that a feature has been detected, a plurality of different features being detectable, each being regarded as havng a certain priority relative to the others, priority selection gating means operative for selecting the feature