Real time calibration of a marking engine in a print system

• US 7,027,187 B1
• Filed: 12/11/2001
• Issued: 04/11/2006
• Est. Priority Date: 08/07/1995
• Status: Expired due to Fees

• Current Assignee: Electronics For Imaging Incorporated
• Original Assignee: Electronics For Imaging Incorporated
• Inventors: Zuber, Peter A.
• Primary Examiner(s): Rogers, Scott A.
• Application Number:
  US10/013,949
• Time in Patent Office: 1,582 Days
• Field of Search: 358/1.9, 358/3.23, 358/518, 358/520, 358/521, 358/523, 358/406, 358/504
• US Class Current: 358/1.9
• CPC Class Codes: H04N 1/00002 Diagnosis, testing or measuring; Detecting, analysing or monitoring not otherwise provided for error detection, error correction or monitoring in digital computers or digital computer components G06F11/00
• CPC Class Codes: H04N 1/00015 Reproducing apparatus
• CPC Class Codes: H04N 1/00031 Testing, i.e. determining the result of a trial H04N1/00029 takes precedence; using test signals for transmission mode changing H04N2201/33371
• CPC Class Codes: H04N 1/00045 using a reference pattern designed for the purpose, e.g. a test chart
• CPC Class Codes: H04N 1/00053 out of service, i.e. outside of normal operation
• CPC Class Codes: H04N 1/00063 using at least a part of the apparatus itself, e.g. self-testing
• CPC Class Codes: H04N 1/00087 Setting or calibrating picture signal circuits H04N1/40
• CPC Class Codes: H04N 1/6033 using test pattern analysis H04N1/6055 takes precedence

Abstract

A method for modifying the rendered output of a marking engine for a print job in progress is disclosed, comprising the steps of comparing a sample rendered input image having included therewith a print target scale corresponding to a specified image parameter having a range of possible renderings set forth in a table, with a rendering included in the table and modifying, to match a desired rendering, numerical correction data in one or more look-up tables of a print adapter, which print adapter is coupled to a source of input image data for the print job in progress and having an output coupled to the marking engine. The modified input image data is transmitted to the marking engine for rendering the remainder of the print job.

Claims

1. A method for modifying the rendered output of a marking engine for a print job in progress, comprising the steps of:

comparing a sample rendering of an input image, which includes a print target scale corresponding to a specified image parameter having a range of possible renderings set forth in a printed table, with a rendering included in the printed table;

modifying, in real time and to match a desired rendering, numerical correction data in one or more look-up tables of a print adapter, the print adapter being coupled to a source of the input image data for the print job in progress and having an output coupled to the marking engine; and

transmitting the modified input image data to the marking engine for rendering the remainder of the print job.

2. The method of claim 1, wherein the step of comparing comprises the step of:

making the comparison visually.

3. The method of claim 1, wherein the step of comparing comprises the step of:

selecting an image parameter to be specified from the group including linearity, grey balance and image density.

4. The method of claim 1, wherein the step of comparing comprises the step of:

selecting an image parameter to be specified from the group including hue, saturation, lightness, contrast and brightness.

5. The method of claim 1, wherein the step of modifying comprises the steps of:

selecting the closest match to a desired rendering from the printed table associated with the print target scale; and

entering the numerical correction data corresponding to the selected rendering into the look-up table to provide the modification.

6. The method of claim 5, wherein the step of entering comprises the step of:

providing information to an operator about the amount of correction entered.

7. The method of claim 6, wherein the step of providing comprises the step of:

providing a printed output of the information.

8. The method of claim 6, wherein the step of providing comprises the step of:

providing an output display of the information.

9. The method of claim 1, wherein the step of modifying comprises the steps of:

receiving the input image data, a line at a time, into an exchange register;

substituting numerical correction data from the look-up table for the data in the exchange register to provide corrected data for the input image;

transferring the corrected data for the line of input image data to a print buffer; and

repeating the preceding steps until the print buffer is full.

10. The method of claim 9, wherein the step of substituting comprises the step of:

comparing each byte of the input image data with the corresponding byte of numerical correction data in the look-up table; and

substituting correction data that is not identical with the input image data.

11. The method of claim 1, further comprising the step of:

configuring the print adapter to process a plurality of pages of a print job.

12. The method of claim 1, further comprising the step of:

configuring the print adapter to process a plurality of print jobs.

13. The method of claim 1, further comprising the step of:

configuring the print adapter to process one or more print jobs for one or a plurality of marking engines.

14. The method of claim 1, further comprising the step of:

configuring a single look-up data adapted for use by all of a plurality of marking engines.

15. The method of claim 1, further comprising the step of:

configuring a unique look-up table adapted to each of a plurality of marking engines.

16. The method of claim 1, further comprising the step of:

adapting a secondary look-up table as an appendix to an existing look-up table in a system having a plurality of marking engines.

17. A method for modifying the rendered output of a marking engine for a print job in progress, comprising the steps of:

accessing a print manager having control of the print job in progress;

comparing a sample rendering of an input image, which includes a print target scale corresponding to a specified image parameter, the print target scale having a range of possible renderings set forth in a printed table, with a rendering included in the printed table;

modifying, in real time and to match a desired rendering, numerical correction data in one or more look-up tables of a print adapter, the print adapter being coupled to a source of the input image data for the print job in progress and having an output coupled to the marking engine; and

resuming printing of the print job in progress by the marking engine with input image data modified by the look-up table data.

18. The method of claim 17, wherein the step of comparing comprises the step of:

making the comparison visually.

19. The method of claim 17, wherein the step of comparing comprises the step of:

selecting an image parameter to be specified from the group including linearity, grey balance and image density.

20. The method of claim 17, wherein the step of comparing comprises the step of:

selecting an image parameter to be specified from the group including hue, saturation, lightness, contrast and brightness.

21. The method of claim 17, wherein the step of modifying comprises the steps of:

selecting the closest match to a desired rendering from the printed table associated with the print target scale; and

entering the numerical correction data corresponding to the selected rendering into the look-up table to provide the modification.

22. The method of claim 21, wherein the step of entering comprises the step of:

providing information to an operator about the amount of correction entered.

23. The method of claim 22, wherein the step of providing comprises the step of:

providing a printed output of the information.

24. The method of claim 22, wherein the step of providing comprises the step of:

providing an output display of the information.

25. The method of claim 17, wherein the step of modifying comprises the steps of:

receiving the input image data, a line at a time, into an exchange register;

substituting numerical correction data from the look-up table for the data in the exchange register to provide corrected data for the input image;

transferring the corrected data for the line of input image data to a print buffer; and

repeating the preceding steps until the print buffer is full.

26. The method of claim 25, wherein the step of substituting comprises the step of:

comparing each byte of the input image data with the corresponding byte of numerical correction data in the look-up table; and

substituting correction data that is not identical with the input image data.

27. The method of claim 17, further comprising the step of:

configuring the print adapter to process a plurality of pages of a print job.

28. The method of claim 17, further comprising the step of:

configuring the print adapter to process a plurality of print jobs.

29. The method of claim 17, further comprising the step of configuring

the print adapter to process one or more print jobs for one or a plurality of marking engines.

30. The method of claim 17, further comprising the step of:

configuring a single look-up table adapted for use by all of a plurality of marking engines.

31. The method of claim 17, further comprising the step of:

configuring a unique look-up table adapted to each of a plurality of marking engines.

32. The method of claim 18, further comprising the step of:

adapting a secondary look-up table as an appendix to an existing look-up table in a system having a plurality of marking engines.

33. A method for modifying the rendered output of at least one marking engine in a system for a print job in progress, comprising the steps of:

monitoring, in a monitor device responsive to a feedback input from a metering agent coupled to the output of the marking engine being monitored, at least one parameter affecting the color balance of the rendered output;

adjusting, in real time, color mapping data for rendering the print job in progress, in proportion to the difference between the at least one parameter associated with the rendered output and a reference value;

downloading adjusted values of the color mapping data to at least one look-up-table of a print adapter, the print adapter being coupled to a source of the input data for the print job in progress and to the marking engine being monitored; and

continuing the print job in progress by the marking engine using input image data modified by the adjusted color mapping data in the look up table of the print adapter associated with the marking engine.

34. The method of claim 33, wherein the step of monitoring comprises the steps of:

observing the print job in progress for an indication that color has shifted in the rendered output;

selecting the metering agent to measure a selected color parameter as the rendered output appears at a marking engine output; and

coupling a measured value of the selected color parameter to the feedback input of the monitor device.

35. The method of claim 34, wherein the step of selecting comprises the step of:

suspending printing of the next page to be rendered after the metering agent has measured the selected color parameter.

36. The method of claim 34, wherein the step of selecting comprises the steps of:

selecting a measuring agent corresponding to the selected color parameter of the rendered output to be evaluated; and

suspending printing of the next page to rendered after the selected metering agent has measured the selected color parameter.

37. The method of claim 36, wherein the step of selecting a measuring agent comprises the step of:

selecting an instrument from among the group including densitometer, colorimeter and spectrophotometer.

38. The method of claim 34, wherein the step of observing comprises the step of visually comparing the rendered output with a target.

39. The method of claim 38, wherein the step of visually comparing comprises the step of comparing the rendered output with a color target.

40. The method of claim 38, wherein the step of visually comparing comprises the step of comparing the rendered output with a contone target.

41. The method of claim 38, wherein the step of visually comparing comprises the step of comparing the rendered output with a job page target.

42. The method of claim 33, wherein the step of adjusting comprises the steps of:

comparing the selected color parameter with the color mapping data value in the look-up table; and

outputting a correction to the color mapping data proportional to the difference between the selected color parameter and the color mapping data value.

43. The method of claim 33, wherein the step of downloading comprises the steps of:

accessing the at least one look-up table of the print adapter;

replacing the contents of the look-up table with the adjusted values.

44. The method of claim 33, wherein the step of continuing comprises the step of:

resuming printing using the adjusted values of the color mapping data in the look-up table.

45. The method of claim 33, wherein the step of monitoring comprises the step of monitoring by a human agent.

46. The method of claim 33, wherein the step of monitoring comprises the step of monitoring by a machine agent.

47. A method for correcting the output of a marking engine, comprising the steps of:

measuring the parameters of at least one page of a print job during the running of the print job;

comparing the measured parameters to a reference; and

if there is a predetermined difference between the measured parameters and the reference, modifying the parameters of the marking engine during the print job and before completion thereof, such that all portions of the print job after the step of modifying are rendered with the modified parameters.

48. The method of claim 47, wherein the marking engine is comprised of a plurality of marking engines, each of the plurality of marking engines operating on only a portion of the print job and the step of measuring the parameters of each of the marking engines and the step of modifying operable to modify only the parameters of the ones of the marking engines wherein the step of comparing determined that there was a predetermined difference between the reference and the measured parameters.

49. The method of claim 48, wherein the step of measuring the parameters of at least one page of the print job on each of the marking engines comprises the steps of:

interrupting the print job;

printing a target sheet; and

in the step of comparing, comparing the parameters of the target sheet output by each of the marking engines with the predetermined reference.

50. The method of claim 49, wherein the step of interrupting the print job is automatic and occurs at a predetermined position within the print job.