An image-generating system for generating data of an image on the basis of data of a photographic image obtained by capturing an image of an object. The image-generating system includes a color sample to be arranged in the proximity of an object, an illumination unit, an image pick-up unit, a color sample specifying unit and an image processing unit. The illumination unit can illuminate the object and the color sample with light lower in light quantity than ordinary light. The image pick-up unit obtains a photographic image by capturing an image of the object together with the color sample illuminated by the illumination unit. The color sample specifying unit specifies the color sample in the photographic image. The image processing unit converts colors of the object in the photographic image, taking the color sample specified by the color sample specifying unit as a reference.