A conversion table is generated for converting image data D to be processed by a first device into image data D' to be processed by a second device for thereby generating a proof. The conversion table saves an area percentage of an image of black produced from only the image data K by the first device, at the image data K=0% or 100%. Using the conversion table, the image data D is converted into the image data D' to generate a proof with the area percentage of black being saved.
First, a user who will try a service of a print system registers trial from a user system in the print system. When the trial of the print system from the user system is permitted and registered, the print system provides an RIP processing or a printing processing to a user in response to a processing request from the registered user system within a range set for the trial without charge or with a discount accounting.
During the device link processing, an original lookup table LUT0 is modified into a modified lookup table LUT1 so that achromatic color value sets B2a will be associated with all the achromatic color value sets B1a. Accordingly, during a color conversion processing, by using the modified lookup table LUT1, any input achromatic color value set B1 in (0, 0, 0, K1 in ) will be converted into an output achromatic color value set B2 out (0, 0, 0, K2 out). In this way, the black-print image part in the input image that is reproduced by black ink only by printer A1 will be maintained as a black-print image part and printed by a printer A2 by black ink only. Thus, the black-print information of the input image can be maintained through the color conversion processing.
