1. An apparatus for extracting each character from a character string having a plurality of characters arranged in a first direction and included in an image, comprising: an integrating device integrating pixel values along a second direction orthogonal to the first direction for all coordinate positions in the first direction of the image; a first threshold setting device setting a first threshold; an extracting device extracting an area corresponding to a coordinate position along the first direction where the integrated pixel value exceeds the first threshold set by the first threshold setting device as a character candidate area; a second threshold setting device setting a second threshold that is larger than the first threshold set by the first threshold setting device; and a recognition device determining, with respect to the character candidate areas, whether an area in which the integrated pixel value exceeds the second threshold exists or not, and recognizing the area in which the integrated pixel value exceeds the second threshold as a character area.