An image processing apparatus for processing and outputting image data includes a image processing content storage unit for storing contents of an image processing; a thumbnail magnification ratio determining unit for determining a magnification ratio of a thumbnail image according to the contents of the image processing thus stored; a thumbnail image creation unit for creating the thumbnail image from the image data according to the magnification ratio; and an image processing unit for applying the image processing to the thumbnail image thus created according to the contents of the image processing.