An image management system, image management method and program are provided that can favorably manage images for displaying images that underwent optimization processing or images for creating and displaying difference images in which the generation of artifacts is suppressed. An image from image generator 100 is input to server 109 and stored in storage device 105. The system then determines whether an image including attendant information that is the same as that of the input image is already registered in the system. When such an image is not already registered, attendant information included in the input image is read out and newly registered in association with the input image. In contrast, when an image including attendant information that is the same as that of the input image is registered in the system and the attendant information is registered, information indicating the fact that the image was input is registered.