1. A personal identity verification process for evaluating authenticity of an input facial image against a class of different training images representing the face of an individual, the process including processing image data representing the input facial image to generate a first error correcting output code (ECOC) classifier output vector, processing image data representing the different training images of the class to generate a set of second ECOC classifier output vectors, comparing the first ECOC classifier output vector with the set of second ECOC classifier output vectors, wherein the comparing includes measuring a distance d(y) between the first ECOC classifier output vector and the set of second ECOC classifier output vectors using a first order Minkowski metric, the distance d(y) being given by the expression d ⁡ ( y _ ) = 1 N ⁢ ∑ l = 1 N ⁢ ∑ j = 1 b ⁢  y j l - y j  , where y j is the jth element of the first ECOC classifier output vector, y j l is the jth element of the lth member of the set of second ECOC classifier output vectors. N is the number of members in the set, and b is the number of classifiers, and the input facial image is evaluated to be authentic if the distance d(y)≦t, where t is a predetermined threshold value, and evaluating authenticity of the input facial image with respect to the class of training images in dependence on the comparing.