An image processing apparatus includes an achromatization determination portion, an achromatization processing portion, and a line designation portion. If a black pixel is present within a predetermined peripheral range from a target pixel in a sub-scanning direction, the achromatization determination portion determines whether to achromatize the target pixel, on the basis of an attribute of a background determination pixel present in an opposite direction from the target pixel with respect to the black pixel and within a range of a predetermined number of pixels from the black pixel. If no black pixel is present within the predetermined peripheral range from the target pixel in the sub-scanning direction, the achromatization determination portion determines not to achromatize the target pixel. The achromatization processing portion achromatizes the target pixel determined to achromatize by the achromatization determination portion, and does not achromatize the target pixel determined not to achromatize by the achromatization determination portion.