Method for matching colors of an object to printing colors

• US 5,973,801 A
• Filed: 07/10/1996
• Issued: 10/26/1999
• Est. Priority Date: 08/21/1995
• Status: Expired due to Term

• Current Assignee: Kodak Limited (Eastman Kodak Company)
• Original Assignee: Scitex Corporation Ltd. (Suny Cellular Communication Ltd.)
• Inventors: Bresler, Yoav
• Primary Examiner(s): Coles, Edward L.
• Assistant Examiner(s): Nguyen, Madeleine Av
• Application Number:
  US08/676,642
• Time in Patent Office: 1,203 Days
• Field of Search: 358/520, 358/518, 358/523, 358/504, 358/501, 358/517, 358/524, 358/527, 382/167, 382/164, 382/163, 348/431, 348/650, 348/651, 348/652, 348/672
• US Class Current: 358/520
• CPC Class Codes: H04N 1/62 Retouching, i.e. modification of isolated colours only or in isolated picture areas only

Abstract

A method for automatically matching the color of a printed representation of an object or swatch to that of the object or swatch itself is provided. The method includes the steps of measuring the colors of the object with a calorimeter. An object image, showing mainly the object, is produced and a representative image color is determined. From the colors of the object (as measured by a colorimeter or some other color measuring device), a representative object color is determined. Finally, the colors of the object image in the vicinity, in color space, of the representative image color are corrected to colors in the vicinity, also in color space, of the representative object color.

Claims

1. A method for determining the colors with which to print an image of an object such that printed output colors approximately match colors of the object, the method comprising the steps of:

measuring colors of said object;

determining a representative image color of an object image showing mainly said object having colors, some of said colors being in vicinity, in color space, of a representative object color;

measuring a representative sample of a color gamut of a printing press on which said image is to be printed, thereby to provide a color conversion book converting from ink values to colorimeter values;

determining a representative object color of said colors of said object, the stop of determining comprising the steps of;

providing the colors of said object in luminance, hue and saturation color space;

generating representative luminance, hue and saturation values over said colors of said object;

the step of generating comprising the steps of;

generating a histogram of saturation weighted hue from hue and saturation values of said colors of said object;

selecting a hue value having the highest saturation level as a representative hue;

generating a saturation level close to the saturation level at which said representative hue was found; and

generating a luminance level associated with said representative hue;

utilizing said color book to convert said representative luminance, hue and saturation values to representative inking values forming said representative object color; and

correcting the colors of said object image which are in the vicinity, in color space, of said representative image color, to colors in the vicinity, in color space, of said representative object color.

2. A method for determining the colors with which to print an image of an object such that printed output colors approximately match colors of the object, the method comprising the steps of:

measuring colors of said object;

measuring a representative sample of a color gamut of a printing press on which said image is to be printed, thereby to provide a color conversion book converting from ink values to colorimeter values;

determining a representative image color of an object image showing mainly said object having colors, some of said colors being in vicinity, in color space, of a representative object color;

the step of determining comprising the steps of;

utilizing said color book to convert the colors of said object image from inking values to their luminance, hue and saturation values;

generating representative luminance, hue and saturation values over said colors of said object image;

utilizing said color book to convert said representative luminance, hue and saturation values to representative inking values forming said representative image color;

determining a representative object color of said colors of said object;

correcting the colors of said object image which are in the vicinity, in color space, of said representative image color, to colors in the vicinity, in color space, of said representative object color.

3. A method according to claim 2 and wherein said step of generating representative luminance, hue and saturation values over said colors of said object image comprises the steps of:

generating a histogram of saturation weighted hue from the hue and saturation values of said colors of said object image;

selecting a hue value having a highest saturation level, as the representative hue value;

generating the saturation level close to the saturation level at which said representative hue value was found; and

generating a luminance level associated with said representative hue value.