PURPOSE: To shorten processing time and to accurately obtain character information even when a diagram or the like is mixed in a document image or there is inclination by calculating the character information while considering the inclining angle of a character image.

CONSTITUTION: An area segmentation part 12a segments one part of the document image stored in an image storage part 11a. A character candidate rectangle extraction part 12b discovers the set of black picture elements from this area, calculates a circumscribed rectangle surrounding this and selects the circumscribed rectangle considered as a character from them. It is judged in the middle of a processing whether the segmented area is an area to easily obtain the character information or not. A character rectangle selection part 12c decides the size of the character from the character candidate rectangle and calculates a character pitch from the selected character rectangle. It is judged from the calculated character size whether the segmented area is an area to obtain the correct character information or not. A line space detection part 12d calculates the inclining angle of the document image, detects a line space from the information of this inclining angle and the character rectangle and corrects the character information according to the inclining angle.