A CPU 200 extracts ornamental image data and layout control information from an ornamental image file FF. When the layout control information does not include characteristic values, the CPU 200 analyzes the ornamental image data to acquire characteristic values representing a tendency of image quality of the ornamental image data. The CPU 200 may additionally compute correction rates for correcting values of image quality-relating parameters of objective image data from the acquired characteristic values of the ornamental image data. The CPU 200 writes either the acquired characteristic values or the computed correction rates into the layout control information. The layout control information including the acquired characteristic values or the computed correction rates is output together with the ornamental image data in the form of the ornamental image file FF.