To make the color reproducibility of a test print consistent with that of a print obtained at a laboratory.

A user obtains a test print TP by printing original image data S0 obtained by a digital camera 11 by a printer 13. The test print TP is read by a read means 21 at the laboratory 21 to obtain read image data S2. The read image data S2 are converted by a 1st converting means 22 to a Lab color space to obtain converted read image data S2' and further a computing means 23 obtains the correspondence relation LUT2 between the converted read image data S2' and original image data S1. Then a 2nd converting means 24 converts the original image data S1 into converted original image data S1' according to the LUT2, a 3rd converting means 25 converts the data into image data S3 for a print, and a printing means 26 obtains the print image P1.