# US 8,570,592 B2 · Method of creating lookup table, printing apparatus, lookup table, and printing method

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- Number: US 8,570,592 B2
- Document ID: US8570592B2
- Status: Granted
- Kind: B2
- Application number: 12/685,634
- Filed: 2010-01-11
- Published: 2010-07-15
- Granted: 2013-10-29
- Earliest claimed: 2009-01-13
- Assignees: Seiko Epson Corporation
- Applicants: Seishin Yoshida
- Inventors: Seishin Yoshida
- Web page: https://patentgrep.com/patent/US8570592B2

## CPC

- H04N 1/54: Conversion of colour picture signals to a plurality of signals some of which represent particular mixed colours, e.g. for textile printing
- H04N 1/6019: {using look-up tables (H04N1/6025 takes precedence)}
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A method of creating a lookup table which describes a correspondence relationship between an input value to a printing apparatus for performing printing by ejecting ink onto a printing medium, and output values of a special gloss ink and a color ink of the printing apparatus, includes: a first process of determining the output value of the special gloss ink to be relatively low at a lattice point where an index value relating to color intensity is dark to be equal to or lower than a predetermined value, with regard to each lattice point of the lookup table; and a second process of determining the output value of the color ink at each lattice point by increasing an ink duty limit value which is the upper limit of the sum of the color ink that can be ejected onto a unit area of the printing medium, according to the determined output value of the special gloss ink.

## Claims

### Claim 1

A method of creating a lookup table which describes a correspondence relationship between an input value to a printing apparatus for performing printing by ejecting ink onto a printing medium, and output values of a special gloss ink and a color ink of the printing apparatus, the printing apparatus comprising a processor and a non-transitory computer readable medium storing the lookup table and code executable by the processor to implement the method, the method comprising:
in a first process, determining the output value of the special gloss ink to be low at a lattice point where an index value relating to color intensity is dark to be equal to or lower than a predetermined value, with regard to each lattice point of the lookup table; and
in a second process, determining the output value of the color ink at each lattice point by increasing an ink duty limit value which is an upper limit of the sum of the color ink that can be ejected onto a unit area of the printing medium, according to the determined output value of the special gloss ink.

### Claim 2 (depends on 1)

The method according to claim 1,
wherein in the first process, the output value of the special gloss ink is reduced at a lattice point where the index value is dark to be equal to or lower than the predetermined value, as the index value is darker, and
in the second process, the ink duty limit value is increased as the index value is darker.

### Claim 3 (depends on 1)

The method according to claim 1, further comprising;
in a first color measurement process, performing color measurement on the index value for each predetermined color gradation in a printing region printed by using only the color ink;
in a second color measurement process, performing color measurement on the index value for each predetermined color gradation in a printing region printed by using the color ink and the special gloss ink; and
obtaining an intersection index value which is the index value at an intersection between a line representing a relationship between the color gradation and the index value obtained in the first color measurement process and a line representing a relationship between the color gradation and the index value obtained in the second color measurement process,
wherein the predetermined value is a dark value to be equal to or less than the intersection index value.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the index value is brightness.

### Claim 5 (depends on 4)

The method according to claim 4, wherein the brightness is a value measured at a light-receiving angle of 0 degrees and an illumination angle of -45 degrees.

### Claim 6 (depends on 1)

A printing apparatus comprising:
a storage unit that stores the lookup table created by the method of creating a lookup table according to claim 1;
a color conversion unit that performs a color conversion process of converting the input value into the output value by using the stored lookup table; and
a print unit that performs printing by using a result of the color conversion process.

### Claim 7

A non-transitory computer-readable medium storing a lookup table which describes a correspondence relationship between an input value to a printing apparatus for performing printing by ejecting ink onto a printing medium and output values of a special gloss ink and a color ink of the printing apparatus, wherein the output value of the special gloss ink is relatively reduced, and the sum of the output value of the color ink is increased at a lattice point where an index value relating to color intensity is dark to be equal to or lower than a predetermined value.

### Claim 8

A printing method of performing printing using a special gloss ink and a color ink in a printing apparatus, the printing apparatus comprising a processor and a non-transitory computer readable medium, the non-transitory computer readable medium storing code executable by the processor to perform the printing method comprising;
in a printing region where an index value relating to color intensity is dark to be equal to or lower than a predetermined value,
reducing an amount of the special gloss ink to be used; and
increasing the sum of an amount of the color ink to be used.