Patent ID: 8209172

Claim:
A pattern identification method of identifying a pattern of input data by hierarchically extracting features of the input data, comprising: using a processor to perform the steps of: a first feature extraction step of extracting a feature of a first layer from the input data; an analysis step of analyzing a distribution of a feature extraction result in the first feature extraction step; a calculation step of calculating a respective likelihood of extracting from the input data a feature of one of a plurality of categories for features of a second layer, each feature of the second layer corresponding to a combination of features of the first layer, on the basis of the distribution analyzed in the analysis step, wherein the likelihood is calculated by filtering using a mask unique to the feature to be extracted, and integrating results of the filtering; a selection step of selecting at least one extraction module, among a plurality of extraction modules which extract features of respective categories, whose calculated likelihood of the category for the feature of the second layer to be extracted from the input data is not less than a predetermined value; a second feature extraction step of causing the selected extraction module to extract a feature of the second layer from the input data; and a storing step of storing the extracted feature of the second layer in a memory.