An image forming apparatus includes an image reading device which extracts character images from an original document image read by an image reader. The reading device further extracts an area of predetermined size including a single character from the extracted character images, and detects punctuation marks among characters included in the respective extracted areas based on a distribution of image elements in the respective extracted area so as to discriminate the directional orientation of the character image based on a position of punctuation marks. Alternatively, the reading device detects the presence of white space in the extracted character images so as to discriminate the directional orientation of the character images based on a distribution of the detected white space.