To present a preview image to a user which faithfully reproduces the finishing of an image reproduced on recording paper without performing complicated work.

A plotter 9 forms a calibration image on recording paper, a scanner 1 reads the recording paper with the calibration image formed thereon to acquire image information for calibration, a CPU 4 performs calibration using the image information for calibration, changes target image characteristics into characteristics of an image forming means or target image characteristics reflecting an image formation condition, and generates a correction table that can be corrected to the changed target image characteristics. A memory 5 stores image data to be outputted; an output image processing part 7 performs image processing of the image data to be outputted with reference to the correction table, and converts the image data into image data for preview, reflecting the changed target image characteristic; and an operation display part 12 displays a preview image of converted image data for preview.