image display apparatus wherein in the process of receiving and successively displaying a plurality of image data representing a plurality of pictures a previously displayed image can be distinguished from a next image easily and the outline of the previously displayed image can be grasped the image display apparatus includes a data receiving unit for receiving a plurality of image data an image data generating unit for generating overwritten image data at predetermined intervals a look up table altering unit for altering gradation processing condition of the first image data and setting that of the overwritten image data an image processing unit for executing gradation processing of the first image data in accordance with the altered condition and executing gradation processing of the overwritten image data in accordance with the set condition and a display unit for displaying the first picture and displaying an overwritten picture application_number US 98827901 A description embodiments of the present invention will now be described in detail with reference to the drawings the same constituent elements are designated by the same reference numerals and explanation thereof will be omitted 0020 fig1 shows a configuration of a medical image processing system including an image display apparatus according to one embodiment of the present invention in this embodiment a record sheet photostimulable phosphor sheet for radiophotography is coated with photostimulable phosphor substance and records information of an object when it is irradiated by radiation in fig1 an image display apparatus 1 and an image.