1. An image processing apparatus comprising: read means for reading an original document; determination means for determining whether the original document read by the read means is characterized as a character image or a gradation image; and display means for making a thumbnail display based on the determination means, wherein: (a) a portion of the character image is used as the thumbnail display when the original document is characterized as a character image, with the display means selecting the portion of the character image that is used as the thumbnail display by dividing the original document into a plurality of divisions, sequentially scanning the original document, determining if each divided portion is a background portion or a character portion, and deciding which is a first division in which a character exists, and (b) the gradation image is used as the thumbnail display when the original document is characterized as a gradation image.