Patent ID: 8121008

Claim:
An evaluation apparatus for obtaining an evaluation value of a signal read from an optical recording medium, the evaluation apparatus comprising: reading means for reading a signal recorded on the optical recording medium; edge position detection means for detecting edge positions of the read signal acquired by the reading means; frequency distribution table generation means for generating a frequency distribution table comprising a plurality of classes of the edge positions on the basis of accumulation result of information of the edge positions detected by the edge position detection means; and first calculation means for calculating a T degree value represented as [{Σ fi× ( xi−A ) (2m+1) }/F] {1/(2m+1)} Formula 1 (wherein m is a natural number excluding zero) wherein, in the frequency distribution table generated by the frequency distribution table generation means, xi, fi, F, and A represent the value of each of the classes, the frequency of each of the classes, the sum of the frequencies, and the weighted average value, respectively.