Method and apparatus for calibrating spot color

Patent metadata

Field	Value
Publication number	US-9056511-B2
Application number	US-201214129799-A
Country	US
Kind code	B2
Filing date	May 18, 2012
Priority date	Nov 30, 2011
Publication date	Jun 16, 2015
Grant date	Jun 16, 2015

Abstract

The present invention provides a method for calibrating a spot color comprising: determining a target value for the spot color; and calibrating a printing device in an enumeration cycling manner, so that a spot color measurement value of a color block output by the printing device approximates the target value. The present invention further provides an apparatus for calibrating a spot color, comprising: a target module used for determining a target value for the spot color; a calibrating module used for calibrating a printing device in an enumeration cycling manner, so that a spot color measurement value of a color block output by the printing device approximates the target value. The present invention precisely calibrates the spot color of the printing device.

First claim

What is claimed is:

1. A method for calibrating a spot color, comprising:
determining a target value for the spot color; and
calibrating a printing device in an enumeration cycling manner, so that a spot color measurement value of a color block output by the printing device approximates the target value, wherein the calibrating further comprises:
1) setting the target value as a spot color standard value;
2) setting a plurality of spot color values centered at the spot color standard value, the spot color standard value and the plurality of spot color values constituting a set of spot color enumeration values;
3) printing, by the printing device, a color target chart by using the spot color enumeration values;
4) measuring each color block on the color target chart to obtain a spot color measurement value of the each color block;
5) determining a chromatic aberration between the spot color standard value and each obtained spot color measurement value;
6) determining the spot color enumeration value of the color block corresponding to the spot color measurement value having a minimum chromatic aberration;
7) setting the determined spot color enumeration value which is corrected by a set amplitude as a new spot color standard value;
8) repeating steps 2 to 7 until a minimal value of the chromatic aberrations begins to rebound, then stopping the repeating and determining the spot color enumeration value of the color block corresponding to the spot color measurement value having a minimum chromatic aberration as a final print value.

2. The method of claim 1 , wherein the determining a target value for the spot color further comprises:
measuring a spot color block on a color card to obtain a color value as the target value for the spot color.

3. The method of claim 1 , wherein the printing device has a color space of Lab, and the step of setting a plurality of spot color values centered at the spot color standard value further comprises:
setting step sizes of Lab as:
L step i =( L step 0 , . . . ,L step m-1 )
a step i =( a step 0 , . . . ,a step z-1 )
b step i =( b step 0 , . . . ,b step k-1 )

where m, z, k are numbers of step sizes of Lab respectively;
wherein m*z*k spot color values are obtained by using spot color standard values L std , a std , b std as center and using L step i , a step i , b step i as step size.

4. The method of claim 3 , further comprising:
determining values of m, a, k based on chromatic aberrations ΔL, Δa, Δb between Lstd, a std , b std and spot color target values L target , a target , b target ,
wherein m, z, k are ranked according to their values so as to correspond to a rank of ΔL, Δa, and Δb.

5. The method of claim 3 , wherein the step of determining a chromatic aberration between the spot color standard value and each obtained spot color measurement value is carried out by rule of:

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Assignees

• Li Haifeng
• Yan Xueyan
• Bai Yuying
• Univ Peking Founder Group Co
• Univ Beijing
• Beijing Founder Electronics Co
• Univ Peking Founder R & D Ct

Inventors

• Li Haifeng
• Yan Xueyan
• Bai Yuying

Classifications

• H04N1/603 Primary

  controlled by characteristics of the picture signal generator or the picture reproducer · CPC title

• B41J29/393 Primary

  Devices for controlling or analysing the entire machine {; Controlling or analysing mechanical parameters involving printing of test patterns} · CPC title