Printer calibration using a scanner and interpolated equivalent aim curve

• US 8,564,834 B2
• Filed: 10/31/2011
• Issued: 10/22/2013
• Est. Priority Date: 10/31/2011
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Lin, Guo-Yau, Sanchez, James M., Purdum, Connie F., Stein, Adam E., Guesmia, Mustapha
• Primary Examiner(s): Rogers, Scott A
• Application Number:
  US13/285,029
• Publication Number:
  US 20130107290A1
• Time in Patent Office: 722 Days
• Field of Search: 358/1.9, 358/504, 358518-523
• US Class Current: 358/1.9
• CPC Class Codes: H04N 1/6033 using test pattern analysis H04N1/6055 takes precedence

Abstract

Methods of performing print engine calibration create a color space conversion equation for a scanner of a class of printing devices, print test patches on a sheet, and scan the test patches using a scanner of the printing device to produce a scanned RGB value for each test patch. Such methods convert each scanned RGB value to an XYZ pseudo space using the color space conversion equation to produce XYZ values. These methods compare the XYZ values to second XYZ values of white paper to generate DeltaE curves for each of the test patches relative to white paper. The DeltaE curves are interpolated to form an equivalent aim curve. After the equivalent aim curve is determined, the methods periodically calibrate the same or an additional printing device that is within the class of printing devices using the color space conversion equation to produce second XYZ values.

Claims

1. A method of performing print engine calibration comprising:

creating a color space conversion equation for a scanner of a class of printing devices;

printing first test patches on a first sheet using a previously established master tone reproduction curve (TRC) relating to a master aim curve for said class of printing devices using a printing engine of said a printing device within said class of printing devices;

scanning said first test patches using a scanner of said printing device to produce a first scanned RGB value for each first test patch;

converting each said first scanned RGB value to an XYZ pseudo space using said color space conversion equation to produce first XYZ values;

comparing said first XYZ values to second XYZ values of white paper to generate DeltaE curves for each of said first test patches relative to white paper;

interpolating said DeltaE curves to form an equivalent aim curve; and

after said equivalent aim curve is determined, periodically calibrating any printing device that is within said class of printing devices using said color space conversion equation to produce second XYZ values and producing a resulting TRC for said second XYZ values based on said equivalent aim curve.

2. The method according to claim 1, further comprising selecting a power of said color space conversion equation that resultants in said DeltaE curves all being approximately linear.

3. The method according to claim 1, further comprising:

scanning said first test patches by passing said first sheet by a spectrophotometer to produce a scanned XYZ value for each first test patch; and

producing said master TRC for said scanned XYZ values based on said master aim curve.

4. The method according to claim 3, said resulting TRC matching a quality of said master TRC using said scanner in place of said spectrophotometer.

5. The method according to claim 1, said scanner comprising a full width array scanner.

6. A method of performing print engine calibration comprising:

creating a color space conversion equation for a scanner of a class of printing devices;

printing first test patches on a first sheet using a previously established master tone reproduction curve (TRC) relating to a master aim curve for said class of printing devices using a printing engine of said a first printing device within said class of printing devices;

scanning said first test patches using a scanner of said first printing device to produce a first scanned RGB value for each first test patch;

converting each said first scanned RGB value to an XYZ pseudo space using said color space conversion equation to produce first XYZ values;

comparing said first XYZ values to second XYZ values of white paper to generate DeltaE curves for each of said first test patches relative to white paper;

interpolating said DeltaE curves to form an equivalent aim curve;

after said equivalent aim curve is determined, periodically calibrating a second printing device that is within said class of printing devices by;

printing second test patches on a second sheet using a printing engine of said second printing device;

scanning said second test patches by passing said second sheet by a scanner of said second printing device to produce a second scanned RGB value for each second test patch;

converting each said second scanned RGB value to said XYZ pseudo space using said color space conversion equation to produce second XYZ values; and

producing a resulting TRC for said second XYZ values based on said equivalent aim curve.

7. The method according to claim 6, further comprising selecting a power of said color space conversion equation that resultants in said DeltaE curves all being approximately linear.

8. The method according to claim 6, further comprising:

scanning said first test patches by passing said first sheet by a spectrophotometer to produce a scanned XYZ value for each first test patch; and

producing said master TRC for said scanned XYZ values based on said master aim curve.

9. The method according to claim 8, said resulting TRC matching a quality of said master TRC using said scanner in place of said spectrophotometer.

10. The method according to claim 6, said scanner comprising a full width array scanner.

11. A method of performing print engine calibration comprising:

creating a color space conversion equation based on manufacturing specifications for a scanner of a first printing device classified within a class of printing devices;

printing first test patches on a first sheet using a previously established master tone reproduction curve (TRC) relating to a master aim curve for said class of printing devices using a printing engine of said first printing device;

scanning said first test patches by passing said first sheet by said scanner to produce a first scanned RGB value for each first test patch;

converting each said first scanned RGB value to an XYZ pseudo space using said color space conversion equation to produce first XYZ values;

comparing said first XYZ values to second XYZ values of white paper to generate DeltaE curves for each of said first test patches relative to white paper;

interpolating said DeltaE curves to form an equivalent aim curve that is different than said master aim curve;

after said equivalent aim curve is determined, periodically calibrating a second printing device that is within said class of printing devices by;

printing second test patches on a second sheet using an identity TRC using a printing engine of said second printing device, said identity TRC making no alterations to printing input;

scanning said second test patches by passing said second sheet by a scanner of said second printing device to produce a second scanned RGB value for each second test patch;

converting each said second scanned RGB value to said XYZ pseudo space using said color space conversion equation to produce second XYZ values; and

producing a resulting TRC for said second XYZ values based on said equivalent aim curve.

12. The method according to claim 11, further comprising selecting a power of said color space conversion equation that resultants in said DeltaE curves all being approximately linear.

13. The method according to claim 11, further comprising:

scanning said first test patches by passing said first sheet by a spectrophotometer to produce a scanned XYZ value for each first test patch; and

producing said master TRC for said scanned XYZ values based on said master aim curve.

14. The method according to claim 13, said resulting TRC matching a quality of said master TRC using said scanner in place of said spectrophotometer.

15. The method according to claim 11, said scanner comprising a full width array scanner.

16. A non-transitory computer storage medium readable by a computerized device, said non-volatile computer storage medium storing instructions executable by said computerized device to perform a method of print engine calibration, said method comprising:

creating a color space conversion equation for a scanner of a class of printing devices;

printing first test patches on a first sheet using a previously established master tone reproduction curve (TRC) relating to a master aim curve for said class of printing devices using a printing engine of said a first printing device within said class of printing devices;

scanning said first test patches using a scanner of said first printing device to produce a first scanned RGB value for each first test patch;

converting each said first scanned RGB value to an XYZ pseudo space using said color space conversion equation to produce first XYZ values;

comparing said first XYZ values to second XYZ values of white paper to generate DeltaE curves for each of said first test patches relative to white paper;

interpolating said DeltaE curves to form an equivalent aim curve; and

after said equivalent aim curve is determined, periodically calibrating a second printing device that is within said class of printing devices using said color space conversion equation to produce second XYZ values and producing a resulting TRC for said second XYZ values based on said equivalent aim curve.

17. The non-transitory computer storage medium according to claim 16, said method further comprising selecting a power of said color space conversion equation that resultants in said DeltaE curves all being approximately linear.

18. The non-transitory computer storage medium according to claim 16, said method further comprising:

scanning said first test patches by passing said first sheet by a spectrophotometer to produce a scanned XYZ value for each first test patch; and

producing said master TRC for said scanned XYZ values based on said master aim curve.

19. The non-transitory computer storage medium according to claim 18, said resulting TRC matching a quality of said master TRC using said scanner in place of said spectrophotometer.

20. The non-transitory computer storage medium according to claim 16, said scanner comprising a full width array scanner.