DOCUMENT IMAGE TILT DETECTION METHOD, DOCUMENT IMAGE TILT CORRECTION METHOD, DOCUMENT IMAGE TILT DETECTION DEVICE AND DOCUMENT IMAGE TILT CORRECTION DEVICE

摘要

PPROBLEM TO BE SOLVED: To reduce a load in processing and improve accuracy while covering a wide range of document images in an image tilt detection method using run length coded images. PSOLUTION: An image processing part 4 reduces and converts an original document image by means of an image reduction function 100. By this, a character string is converted to an apparently approximately linear display object. The reduced document image is rotated little by little, for example, in a range of -5°to 5°, by means of a rotation operation function 16, and linearity based on an average value of runs constituting the reduced document image is computed to an image at each rotation angle by means of a linearity computation function 18. The average computation is carried out to the runs which are larger in size than a character. The image processing part 4 finds a rotation angle at which the linearity becomes maximum by means of a tilt angle determination function 20, and determines the tilt of the original document image from the rotation angle. PCOPYRIGHT: (C)2005,JPO&NCIPI