1. An image reading device comprising: image reading means for reading an original document image and for outputting document image data; extracting means for extracting character areas from the document image data outputted by said image reading means, each character area containing a single character; detecting means for detecting which of the characters contained in the extracted character areas are punctuation marks; and determining means for determining a directional orientation of the original document image based on a location of each respective detected punctuation mark within its respective extracted character area, wherein said detecting means detects the punctuation marks by identifying each character, which is formed by image elements distributed in lust one quadrant of the respective extracted character area, as a punctuation mark.