1. An image inspection system comprising: an image reading unit that reads a formed image which is formed on a recording medium based on original image data to generate read image data; an acquisition unit that acquires the original image data; a determination unit that compares the read image data generated by the image reading unit and the original image data acquired by the acquisition unit to determine whether or not the formed image includes a defective region; an extraction unit that extracts an image of characters which are present around the defective region from the read image data according to a predetermined rule when the determination unit determines that the formed image includes the defective region; and an image display device that displays the image of the characters, extracted by the extraction unit and an image of the defective region such that both the images overlap with each other.