Abstract: With the use of syntax analysis and waveform analysis, the length estimation algorithm of unconstrained handwritten connected numeral strings was proposed. Length estimation algorithm was the necessary preprocessing method to the segmentation and recognition of connected numeral strings. The correct rate of the algorithm reached above 87.5% at the free written style, and the algorithm has been incorporated into a practical bank check recognition system.

Key words: contour feature, syntax analysis, connected numeral strings, length estimation