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

A document image filing system having means for generating digital image data by optically scanning a document, a CPU, an image memory and a filing unit connected to one another through a bus, the system comprising:

• means for extracting data of one character from the digital image data;
• means for extracting a feature from the data of one character which is extracted by said extraction means;
• character recognition dictionary means for storing the feature as a standard pattern;
• means for rotating the standard pattern stored in said character recognition dictionary means to produce a plurality of differently angled standard patterns different in direction from one another;
• means for calculating a plurality of similarity measures between the extracted feature and the plurality of standard patterns different in direction from one another;
• means for detecting a direction of the digital image data on the basis of the plurality of similarity measures wherein the similarity of measures in the comparing of angles of rotation between the extracted feature and the standard patterns;
• and
• correcting the direction of the digital image data by rotating the angle of the input image data so as to correct the input image data to a proper direction based on the detected direction thereof.

A method of detecting a direction of digital document image data inputted by scanning a document by an optical scanner, used in a document image filing system including at least a central processing unit (CPU), a character recognition dictionary and said scanner, said method comprising the steps of:

• extracting data of one character from the input digital document image data;
• extracting feature data from the extracted one character;
• reading out a standard pattern, which comprises feature data corresponding to the extracted feature data of the extracted character from the input digital document image data, from said character recognition dictionary which stores a plurality of feature data corresponding to a plurality of characters;
• generating four direction standard patterns which are obtained by rotating the read out standard pattern at intervals of substantially 90 degrees;
• calculating degrees of similarity between the feature data of the one character of the input digital document image data and the respective four standard patterns;
• executing from said step of extracting data to said step of calculating for respective characters of input data for a predetermined number of times;
• detecting a direction of the input digital document image data on the basis of the degree of similarity which is calculated by accumulating each one of the different directions;
• and
• correcting the direction of image data by rotating the input digital document image data so as to correct the input image data to a proper direction based on the detected direction thereof.

A document image filing system comprising:

• a document inputting unit to which is inputted digital document image data obtained in unrestricted directions by optically scanning a document having a directional nature;
• a processing unit which (i) extracts data of one character from the input digital document image data which is transferred from said document inputting unit, (ii) extracts a feature data from the extracted one character, (iii) reads out a standard pattern which comprises feature data corresponding to the extracted feature data of the extracted character, from a character recognition dictionary which stores a plurality of feature data corresponding to respective characters, (iv) generates four direction standard patterns at an interval of substantially 90 degrees, (v) calculates degrees of similarity between the feature data of one character of the input digital document image data and the respective four standard patterns, (vi) executes said steps from said extracting data processing to said calculating processing for respective characters of the input digital document image data for a predetermined number of times, (vii) detects a direction of the input digital document image data on the basis of the degrees of similarity which are calculated by accumulating the degrees of similarity for each one of the directions of the standard patterns, and (viii) corrects the direction of digital document image data by rotating the input image data so as to correct the input digital document image data to a proper direction based on the detected direction
• an image memory which stores said digital document image data being transferred from said document inputting unit and said digital document image data being corrected in the state of proper direction by said processing unit;
• and
• a display unit which displays said digital document image data being corrected in the state of proper direction read out from said image memory.