To make it possible to surely discriminate a character area even when the character area results from white/black inversion processing.

This device is provided with a 1st detection means 27 that detects a character object area from input image data, a 2nd detection means 28 that detects an area where a white background is in existence in the vicinity of noted picture element, a 3rd detection means 29 that detects an area where a black background is in existence in the vicinity of noted picture element, and a discrimination means 30 that discriminates an area satisfying an output of the 2nd detection means 28 or the 3rd detection means 29 and an output of the 1st detection means 27 simultaneously as a character area, then a character object area on the white black ground is discriminated to be a character area based on outputs of the 1st and 2nd detection means 27, 28 and a character object area on a black blackground is discriminated to be a character area based on the outputs of the 1st and 3rd detection means 27, 29.