Patent ID: 8295600

Claim:
An image document processing device, comprising: a font-feature dictionary for storing features of images of individual characters; a character-sequence clipping section for clipping an image of a character sequence including a plurality of characters in an input image document; an image-feature extracting section for dividing the image of the character sequence into images of individual characters and extracting features of the images of individual characters; a feature matching section for selecting N (N is an integer of more than 1) images of characters as candidate characters from the font-feature dictionary so as to generate an M×N index matrix where M (M is an integer of more than 1) is the number of characters in the character sequence, the candidate characters being selected in an order of high degree of feature-matching with the features of the images of individual characters that have been extracted by the image-feature extracting section; an index-information storage section for storing the index matrix so that the index matrix is related to the input image document; and a search section for searching the index-information storage section with respect to each search character included in a search keyword in an input search expression, and extracting one or more image documents each including an index matrix that includes the search character, wherein each element of the index matrix is given a similarity value corresponding to a position of the element, and the search section includes: an index-matrix searching process section for searching index matrices with respect to each search character included in the search keyword so as to detect an index matrix including the search character, and for storing, in a storage section, information indicative of a matching position of the search character in the index matrix, the information being stored in combination with information indicative of an image document including the index matrix; a similarity-degree calculating section for calculating a degree of similarity between the search keyword and the index matrix by accumulating a similarity value of each search character based on the information indicative of a matching position; and an order-determining section for determining an order of extracting image documents based on a result of calculation performed by the similarity-degree calculating section.