Neural network with back propagation controlled through an output confidence measure

Apparatus, and an accompanying method, for a neural network, particularly one suited for use in optical character recognition (OCR) systems, which through controlling back propagation and adjustment of neural weight and bias values through an output confidence measure, smoothly, rapidly and accurately adapts its response to actual changing input data (characters). Specifically, the results of appropriate actual unknown input characters, which have been recognized with an output confidence measure that lies within a pre-defined range, are used to adaptively re-train the network during pattern recognition. By limiting the maximum value of the output confidence measure at which this re-training will occur, the network re-trains itself only when the input characters have changed by a sufficient margin from initial training data such that this re-training is likely to produce a subsequent noticeable increase in the recognition accuracy provided by the network. Output confidence is measured as a ratio between the highest and next highest values produced by output neurons in the network. By broadening the entire base of training data to include actual dynamically changing input characters, the inventive neural network provides more robust performance than which heretofore occurs in neural networks known in the art.