Patent ID: 8184514

Claim:
A signal quality evaluating apparatus comprising: a judging means for judging a first reproduced signal corresponding to a first logical value and a second reproduced signal corresponding to a second logical value from a reproduced signal containing information corresponding to said first logical value and said second logical value; a calculating means for calculating a standard deviation σ 1 of distribution of luminance values of said first reproduced signals and a standard deviation θ 2 of distribution of luminance values of said second reproduced signals; a calculating means for calculating an average value μ 1 of the distribution of luminance values of said first reproduced signals and calculating an average value μ 2 of the distribution of luminance values of said second reproduced signals; and a calculating means for calculating a signal quality σ′ of said reproduced signal by: σ ′ = σ 1 2 + σ 2 2 μ 1 - μ 2 .