Method of detecting and correcting a direction of image data and document image filing system employing the same

摘要

A document is scanned by an optical scanner to be converted into digital image data to be transmitted to an image memory. Characters are extracted from the digital image data one by one and features are extracted from each of the extracted characters. The features as standard patterns stored in a character recognition dictionary are read out to be subjected to 90 degree rotation, 180 degree rotation and 270 degree rotation by a feature rotator, thereby to produce standard patterns of the four directions. Similarity measures are individually calculated between the standard patterns of the four directions and the features of each extracted character, with respect to the four directions. This processing is repeated for a plurality of characters recorded in the document to select a direction having the maximum add value of the similarity measures, thereby to detect an input direction of the document. When the detected direction is not a proper direction, the counterclockwise rotation is given to the digital image data to correct the digital image data to the proper direction.