A feature extractor samples points on an input pattern drawn in real time. In
addition
to X and Y coordinates, each sample has an up/down or Z coordinate value representing
whether or not the sample point is a perceptible part of the pattern. The groups
of coordinate values are transformed into respective sets of coefficients of Chebyshev
polynomials by least-squares fit. A recognition unit can use the coefficients as
features to identify the character. Additional features, such as aspect ratio and
center of gravity, are also derived to aid in recognizing the pattern or reconstructing
its image.
