1. A pattern recognition apparatus comprising a binary conversion means for converting signals generated from a pattern such as a character or figure recorded on a given medium into binary values, a threshold level feature extracting means for segmenting the binary pattern values and extracting features of the segments, memory means for storing extracted pieces of information and arithmetic means including means for defining a circumsquare of a given size on an unknown pattern, means for dividing said circumsquare into a plurality of meshes, means for computing a bit matrix of the unknown pattern dependent on whether a segment is present in each of the meshes, means for computing a cluster of characters of the unknown pattern by effecting a prescribed operation on the bit matrix, means for computing deviations serving as indices indicative of similarity between the cluster of characters of the unknown pattern and clusters of characters of respective registered patterns, means for registering the cluster of characters of the unknown pattern as a new cluster of characters when each one of the deviations exceeds a respective preset value, and means for preventing registration of the cluster of characters of the unknown pattern as a new cluster of characters when each one of the deviations does not exceed the respective preset value, wherein the elements of the clusters of characters of the unknown pattern and of the registered patterns are classified into pattern, blank, mask or deformation elements and the deviation between the cluster of characters of the unknown pattern and that of one of the registered patterns is computed by summing the deviations between individual elements of the cluster of characters of the unknown pattern and corresponding elements of the cluster of characters of the one of the registered patterns, where: (a) the deviation between a pattern element and another pattern element, a mask element or a deformation element is equal to 0; (b) the deviation between a pattern element and a blank element is equal to 1; (c) the deviation between a blank element and another blank element or a mask element is equal to 0; d the deviation between a blank element and a deformation element is equal to 1, if all elements corresponding to the elements of the deformation string to which the deformation element belongs are also blank elements, and is otherwise equal to 0; (e) the deviation between a mask element and a pattern element, a blank element, another mask element or a deformation element is equal to 0; and (f) the deviation between a deformation element and a pattern element, a mask element or another deformation element is equal to 0.