Printer Gradation Correction Method and Color Patch Image

• US 20100165367A1
• Filed: 12/15/2009
• Published: 07/01/2010
• Est. Priority Date: 12/26/2008
• Status: Active Grant

• Current Assignee: Konica Minolta Business Technologies Incorporated (Konica Minolta Inc.)
• Original Assignee: Konica Minolta Business Technologies Incorporated (Konica Minolta Inc.)
• Inventors: Nomura, Shoichi
• Granted Patent: US 8,488,188 B2
• Time in Patent Office: Days
• US Class Current: 358/1.900
• CPC Class Codes: G03G 15/0131 for transferring a pattern to a second base
• CPC Class Codes: G03G 15/5058 using a test patch
• CPC Class Codes: G03G 15/5062 by measuring the characteristics of an image on the copy material
• CPC Class Codes: G03G 2215/00059 on intermediate image carrying member, e.g. transfer belt
• CPC Class Codes: G03G 2215/00063 Colour
• CPC Class Codes: H04N 1/4078 using gradational references, e.g. grey-scale test pattern analysis
• CPC Class Codes: H04N 1/6033 using test pattern analysis H04N1/6055 takes precedence

Abstract

A printer gradation correcting method, comprises the steps of: outputting a color patch image by a printer based on image data of a color patch image; measuring a gradation of the outputted color patch image by a color measuring device so as to obtain a gradation measurement value; and correcting a gradation characteristic of the printer based on the gradation measurement value. The color patch image includes a patch-shaped image having a uniform gradation of a predetermined gradation representative value and gradation fluctuation of a predetermined color component added in the patch-shaped image, and the added gradation fluctuation is structured such that a total of gradation fluctuation measured in a measurement region by the color measuring device becomes a predetermined value. The gradation characteristic of the printer is corrected based on the gradation representative value, the predetermined value of the total of gradation fluctuation, and the gradation measurement value.

Claims

1. A printer gradation correcting method, comprising the steps of:

outputting a color patch image by a printer based on image data of a color patch image;

measuring a gradation of the outputted color patch image by a color measuring device so as to obtain a gradation measurement value; and

correcting a gradation characteristic of the printer based on the gradation measurement value;

wherein the color patch image includes a patch-shaped image having a uniform gradation of a predetermined gradation representative value and gradation fluctuation of a predetermined color component added in the patch-shaped image, and the added gradation fluctuation is structured such that a total of gradation fluctuation measured in a measurement region by the color measuring device becomes a predetermined value, and

wherein the gradation characteristic of the printer is corrected based on the gradation representative value, the predetermined value of the total of gradation fluctuation, and the gradation measurement value.

2. The printer gradation correcting method described in claim 1, wherein the gradation fluctuation is a stripe pattern in which a cycle of the stripe pattern is determined in accordance with a shape of the measurement region.

3. The printer gradation correcting method described in claim 1, wherein the color patch image is structured so as to be printed together with plural color patch images on a color chart on which a guide mark to determine a position of a measuring region is provided, and the color measuring device is adapted to measure a measurement region determined based on the guide mark and obtains a gradation measurement value on the color patch image.

4. The printer gradation correcting method described in claim 1, wherein the color patch image is structured so as to be printed together with plural color patch images on a color chart, and the amplitude of gradation fluctuation to be added into the color patch image is one third or more of a gradation difference between the color patch image and a neighboring color patch image of the color patch image.

5. The printer gradation correcting method described in claim 1, wherein the gradation fluctuation is a stripe or a lattice pattern and an orientation of gradation fluctuation is set in accordance with characteristics of the printer.

6. The printer gradation correcting method described in claim 1, wherein a gradation pattern image is outputted by the printer based on gradation pattern image data added with gradation fluctuation of a predetermined color component, the outputted gradation pattern image is measured by the color measuring device so as to obtain an amplitude of gradation fluctuation for each gradation value, and a gradation value to cause a tone jump of the predetermined color component is determined based on the size of the amplitude of each gradation value.

7. The printer gradation correcting method described in claim 6, wherein the amplitude of gradation fluctuation is made larger relatively in the vicinity of a gradation value predicted to cause a tone jump in the gradation characteristic of the printer.

8. The printer gradation correcting method described in claim 6, wherein when there is a region including discontinuous points in a different portion image between a standard image of a gradation chart image and the outputted gradation chart image or in a differential image of the outputted gradation chart image, the region is not made as the measurement region by the measuring device.

9. The printer gradation correcting method described in claim 1, wherein two kinds of color patch images having the same gradation representative value and different respective amplitudes of gradation fluctuations are outputted by the printer, and whether or not the number of kinds of color patch images is to be increased is determined in accordance with a difference in measurement values between the outputted two kinds of color patch images.

10. The printer gradation correcting method described in claim 6, wherein a gradation region in which a tone jump appears is recognized based on the measurement results, and image data in the gradation region is applied with additional processing after the correction of gradation.

11. The printer gradation correcting method described in claim 10, wherein the additional processing includes at least one of a change of a pseudo multi gradation processing method and random number addition processing.

12. The printer gradation correcting method described in claim 1, wherein amplitude of gradation fluctuation is set in accordance with a visual characteristic for a gradation region where the gradation fluctuation exists.

13. The printer gradation correcting method described in claim 1, wherein when there is a region including discontinuous points in a different portion image between a standard image of a color patch image and the outputted color patch image or in a differential image of the outputted color patch image, the region is not made as the measurement region by the measuring device.

14. A color patch image, including:

a patch-shaped image having a uniform gradation of a predetermined gradation representative value; and

gradation fluctuation of a predetermined color component added in the patch-shaped image,

wherein the added gradation fluctuation is structured such that a total of gradation fluctuation measured in a measurement region by the color measuring device becomes a predetermined value.