Ricoh Company, Ltd.

Gen Sato

Hiroshi Nakayama

Keiji Kojima

Akira Sakurai

Kiyohiko Kobayashi

In a method of extracting feature quantities of a character, a pair of region dividing lines which intersect a character image are obtained by using generated projections of direction codes. Then, a reference position for extracting feature quantities of the character is decided by finding positions at which the region dividing lines intersect the character image. Thereafter, the feature quantities of the character having the reference position are extracted by subjecting the codes of the divided segments to a predetermined operation for obtaining information regarding a shape of each of the divided segments.

Method for extracting feature quantities of a character

A method of segmenting characters of a document image comprises the steps of dividing the document image into a plurality of divided regions and setting a check width with respect to each of the divided regions, where each check width is greater than or equal to a width of a corresponding one of the divided regions so that the check widths of two mutually adjacent divided regions partially overlap each other, reading image data amounting to one line of the document image, obtaining from the image data horizontal projections of each line data within each of the check widths, where each horizontal projection is a number of black picture elements in a corresponding data line within a check width and each data line is made up of a plurality of picture elements arranged horizontally, segmenting a line based on the horizontal projections, obtaining from the image data vertical projections, where each vertical projection is a number of black picture elements in a vertical direction, determining a character segmentation range based on the vertical projections, and segmenting each character of the line within the character segmentation range.

Method of segmenting characters in lines which may be skewed, for

A code sequence matching method adapted to pattern recognition of characters compares one code selected from an unknown code sequence which is extracted from an input pattern with one code selected from a reference code sequence. The reference code sequence comprises one or more special codes for controlling an order of comparison between the codes of the unknown and reference code sequences. Then, selecting of the codes from the unknown and reference code sequences is carried out in accordance with the special codes.

Code sequence matching method and apparatus

A pattern recognition method comprises a contour tracing step of a contour of a binary image in a predetermined direction along a predetermined type of pixels. At this time, four adjacent pixels on upper, lower, left-hand and right-hand sides of a point of interest are sequentially checked. Then, one pixel of a predetermined type out of the four adjacent pixels which is the first pixel of the predetermined type found by the check is designated as a next trace point subsequent to the point of interest. In this process, a feature of each of the traced pixels is extracted. The feature is represented by a directional code which indicates a direction of motion from the point of interest to the next trace point. The features are successively registered in a one-dimensional form. Histogram is produced for each sub-region storing a part of the one-dimensional feature sequence. A histogram for each sub-region is compared with a related reference histogram for a known character.

Pattern recognition method

A code sequence matching method adapted to pattern recognition of characters compares one code selected from an unknown code sequence which is extracted from an input pattern with one code selected from a reference code sequence. The reference code sequence comprises one or more special codes for controlling an order of comparison between the codes of the unknown and reference code sequence. Then, selecting of the codes from the unknown and reference code sequences is carried out in accordance with the special codes.

An input, unknown character is optionally read to form a binary character image, and a plurality of directionality codes are assigned to pixels defining the contour of the character image selectively to define a code-assigned character image, which is then subdivided into a plurality of sub-regions in the form of mesh such that each sub-region includes a substantially equal number of assigned codes. Then, a histogram of the codes is defined for each of the sub-regions to form a collection of histograms for the input character. The input character is compared with each of registered, known characters, each having a collection of similar histograms, and the one having a greatest similarity is selected to identify the input character. The similarity is determined by calculating a distance between the histograms of the input character and the histograms of the each of the registered characters. Preferably, the binary character image is subjected to line-broadening processing prior to the step of assigning the codes.

Character recognition with variable subdivisions of a character region

A character recognition system includes a scanner for scanning a character to be processed to produce a character data, which is processed in a predetermined manner to extract a character feature, preferably contour information of the character. Preferably, a plurality of predetermined directionality codes each associated with a unique pixel arrangement pattern are prepared and they are assigned to the contour depending on the local pixel arrangement condition. The contour information defined by such directionality codes is further processed to define a histogram or feature vector of the directionality codes which is compared with a first group of reference characters without inclination and a second group of reference characters with inclination. When a predetermined condition is met, then the mode of operation is switched such that an unknown character is compared with only one of the first and second groups of reference characters.

Growing community of inventors

Yokohama, Japan

Gen Sato