Method of and apparatus for correcting color of print medium, and proofer used therein

A method of correcting the color of a print medium, comprising the steps of:

• converting device-dependent image data, which have been converted in gradation with respect to each color in order to match desired printing conditions by gradation converting means, to first colorimetric data with color converting means corresponding to standard printing conditions given to a standard print medium;
• thereafter, converting said first colorimetric data to second colorimetric data with color correcting means to correct the difference between the color of a desired print medium and the color of said standard print medium;
• and
• producing a proof on which the difference between the color of said desired print medium and the color of said standard print medium has been corrected, on a proof medium with an image output device based on said second colorimetric data,
• wherein the converting of the first colorimetric data to second colorimetric data includes a direct conversion between the first and second colorimetric data, and
• wherein each of the first and second colorimetric data each comprise device-independent color spaces.

An apparatus for correcting the color of a print medium, comprising:

• color converting means given to a standard print medium, for converting device-dependent image data to first colorimetric data;
• color correcting means for converting said first colorimetric data to second colorimetric data to correct the difference between the color of a desired print medium and the color of said standard print medium;
• and
• an image output device for producing a proof on which the difference between the color of said desired print medium and the color of said standard print medium has been corrected, on a proof medium based on said second colorimetric data;
• wherein said color correcting means comprises one-dimensional lookup tables for converting said first colorimetric data to said second colorimetric data,
• wherein the converting of the first colorimetric data to second colorimetric data includes a direct conversion between the first and second colorimetric data, and
• wherein each of the first and second colorimetric data each comprise device-independent color spaces.

An apparatus for correcting the color of a print medium, comprising:

• gradation converting means for converting the gradation of device-dependent image data with respect to each color in order to match desired printing conditions;
• color converting means corresponding to standard printing conditions given to a standard print medium, for converting the gradation-converted device-dependent image data to first colorimetric data;
• color correcting means for converting said first colorimetric data to second colorimetric data to correct the difference between the color of a desired print medium and the color of said standard print medium;
• and
• an image output device for producing a proof on which the difference between the color of said desired print medium and the color of said standard print medium has been corrected, on a proof medium based on said second colorimetric data,
• wherein the converting of the first colorimetric data to second colorimetric data includes a direct conversion between the first and second colorimetric data, and
• wherein each of the first and second colorimetric data each comprise device-independent color spaces.

A method of correcting the color of a print medium, comprising the steps of:

• converting device-dependent image data to first colorimetric data with color converting means given to a standard print medium;
• thereafter, converting said first colorimetric data to second colorimetric data with color correcting means to correct the difference between the color of a desired print medium and the color of said standard print medium;
• and
• producing a proof on which the difference between the color of said desired print medium and the color of said standard print medium has been corrected, on a proof medium with an image output device based on said second colorimetric data;
• wherein the color correcting means corrects the data based on ratios of Xα/X0, Yα/Y0 and Zα/Z0, where Xα, Yα and Zα are second colorimetric data values and X0, Y0 and Z0 are first colorimetric data values for which the difference between the color of a desired print medium and the color of said standard print medium has been corrected,
• wherein each of the first and second colorimetric data each comprise device-independent color spaces and the correcting means operates on said device independent color spaces.

An apparatus for correcting the color of a print medium, comprising:

• color converting means given to a standard print medium, for converting device-dependent image data to first colorimetric data;
• color correcting means for converting said first colorimetric data to second colorimetric data to correct the difference between the color of a desired print medium and the color of said standard print medium;
• and
• an image output device for producing a proof on which the difference between the color of said desired print medium and the color of said standard print medium has been corrected, on a proof medium based on said second colorimetric data;
• wherein the color correcting means corrects the data based on ratios of Xα/X0, Yα/Y0 and Zα/Z0, where Xα, Yα and Zα are second colorimetric data values and X0, Y0 and Z0 are first colorimetric data values for which the difference between the color of a desired print medium and the color of said standard print medium has been corrected, wherein each of the first and second colorimetric data each comprise device-independent color spaces and the correcting means operates on said device independent color spaces.