Even if the color of a print sheet to be actually used for printing is lighter than the color of a sheet according to a given standard printing profile, a printer outputs a proof on a dedicated sheet where the difference between the sheet colors has been corrected. Specifically, after input image data are converted to colorimetric data by a printing profile, the difference between the sheet colors is corrected by one-dimensional LUTs. Input/output gradients (straight lines) incorporated in the one-dimensional LUTs are represented by X.alpha./X0, Y.alpha./Y0, Z.alpha./Z0 where X.alpha., Y.alpha., Z.alpha. indicate colorimetric values of the color of the print sheet to be actually used for printing and X0, Y0, Z0 indicate colorimetric values of the color of a standard print sheet used to generate the print profile. The difference between the sheet color according to the standard printing profile and the sheet color to be actually used for printing thus becomes corrected.
This is a continuation-in-part of application Ser. No. 09/210,392 filed Dec. 14, 1998 (abandoned), the disclosure of which is incorporated herein by reference.
