Sign language recognition using competitive learning in the HAVNET neural network

An optical modeless Sign Language Recognition (SLR) system is presented. The system uses the HAusdorf-Voronoi NETwork (HAVNET), an artificial neural network designed for two-dimensional binary pattern recognition. It uses an adaptation of the Hausdorff distance to determine the similarity between an input pattern and a learned representation. A detailed review of the architecture, the learning equations, and the recognition equations for the HAVNET network are presented. Competitive learning has been implemented in training the network using a nearest-neighbor technique. The SLR system is applied to the optical recognition of 24 static symbols from the American Sign Language (ASL) convention. The SLR system represents the target images in a 80×80 pixel format. The implemented HAVNET network classifies the inputs into categories representing each of the symbols, using an output layer of 24 nodes. The network is trained with 5 different formats for each symbol and is tested with all 24 symbols in 15 new formats. Results from the SLR system without competitive training show shape identification problems, when distinguishing symbols with similar shapes. Implementation of competitive learning in the HAVNET neural network improved recognition accuracy on this task to 89%. The hand gestures are identified through a window search algorithm. Feature recognition is obtained from edge enhancement by applying a Laplacian filter and thresholding, which provides robustness to pose, color and background variations.