12. The title extracting apparatus as set forth in claim 11, wherein said character string region generating means is adapted for storing at least one of a first pointer that moves from the first circumscribed rectangle to the second circumscribed rectangle and a second pointer that moves from the second circumscribed rectangle to the first circumscribed rectangle in the connection relation table.
11. A title extracting apparatus for recognizing and extracting a required partial region from a document image of a document that has been converted into image data, comprising: character region generating means for generating character regions, including black pixel connected regions composed of connected black pixels of the document image; character string region generating means for unifying one or more character regions generated by said character region generating means, and for generating character string regions including one or more character regions; and title extracting means for extracting a particular character string region of the character string regions, according to attributes of a plurality of character string regions generated by said character string region generating means, as a title region, wherein said character region generating means is adapted for obtaining circumscribed rectangles of the black pixel connected regions as the character regions, and wherein said character string region generating means is adapted for obtaining a second circumscribed rectangle adjacent to a reference first circumscribed rectangle, generating a connection relation table that represents a connection relation of the first circumscribed rectangle and the second circumscribed rectangle, assigning same identification information to the first circumscribed rectangle and the second circumscribed rectangle using the connection relation table, and unifying the first circumscribed rectangle and the second circumscribed rectangle into one character string region.