Digital information reproduction method

Abstract

An optical disc using super-resolution effects that achieves higher-density recording exceeding the optical resolution suffers from the signal-quality degradation caused by the normal resolution component included in the reproduction signal. To address this problem, a data reproduction method is provided. In the method, characteristic error patterns are identified and parity check codes in conformity with run-length limited coding are used to carry out efficient and reliable error correction. Error patterns caused by the normal resolution crosstalk are localized in the leading edges of a mark following a long space and in the trailing edges of a long mark. Whether an error exists in the data is determined by use of the parity check codes. When an error occurs, a pattern in which an error is most likely to occur is selected from the above-mentioned patterns by taking account of the edge shift direction, and then the error therein is corrected.