US Patent 7474787 Apparatus and method of detecting specified pattern

In an apparatus which detects a specified pattern, a binarizing unit converts input image data to bi-level image data, and a storage device stores the converted bi-level image data. A pattern detection unit comprises a plurality of detectors which detect a specified pattern (for example, a circular pattern) independently of each other and in parallel to each other. Each of the detectors detects the specified pattern on a block different from those for the other detectors in the bi-level image data stored in the storage device. Then, one most probable block is selected among the blocks including the specified pattern, and careful image recognition is performed on the selected block.