An image processing apparatus includes an image processing device. The image processing device includes a receiving port and a processor connected together. The receiving port receives old image data corresponding to a document image of a document. The processor divides the old image data into first area image data corresponding to a first area image of the document, and second area image data corresponding to a second area image of the document, and further performs image enhancement processing on the first area image data to obtain enhanced first area image data. Thus, the first area image may be separated from the second area image, and the image enhancement processing is performed on the first area image. The enhanced first area image data and the second area image data are separately outputted or combined for output.