1. A data processing system comprising: a binary data detector having a hard decision output and operable to detect values in input data samples; a reliability calculator operable to calculate an error pattern reliability metric for each of a plurality of dominant error patterns associated with the hard decision output, wherein the reliability calculator is operable to calculate the plurality of error pattern reliability metrics based on the hard decision output, on the input data samples, on a priori values of the input data samples, and on a noise variance for the data processing system; and a converter operable to convert the plurality of error pattern reliability metrics to multi-level soft information.