System and method for measuring the color output of a computer monitor

• US 6,313,823 B1
• Filed: 01/20/1998
• Issued: 11/06/2001
• Est. Priority Date: 01/20/1998
• Status: Expired due to Term

• Current Assignee: Apple Computer Incorporated (Apple Inc.)
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Devine, Jesse, Cappels, Richard
• Primary Examiner(s): Brier, Jeffery
• Assistant Examiner(s): Blackman, Anthony J.
• Application Number:
  US09/009,042
• Time in Patent Office: 1,386 Days
• Field of Search: 345/150, 345/431
• US Class Current: 345/589
• CPC Class Codes: G09G 1/165 Details of a display terminal using a CRT, the details relating to the control arrangement of the display terminal and to the interfaces thereto details suitable for both CRT and flat panel G09G5/003; specific for a flat panel G09G3/2092
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607

Abstract

A system measures the color output of a computer monitor by using predetermined phosphor characteristics of the monitor that are stored in monitor memory. The relationship between beam current and pixel values is then determined and stored in computer memory. When a color output measurement is taken, the average pixel values are determined. The beam currents associated with the average pixel values are then accessed from the computer memory and multiplied by the phosphor characteristics to obtain an accurate color output measurement.

Claims

1. A method for measuring color output of a monitor, comprising the steps of:

determining monitor phosphor characteristics corresponding to said monitor;

generating a lookup table containing a beam current entry for every pixel value entry,

identifying a measurement area smaller than a display area on said monitor;

separately averaging said red, green, and blue pixel values in said measurement area;

determining beam currents associated with red, green, and blue pixel values displayed in said measurement area;

calculating color values for said measurement area by using said monitor phosphor characteristics; and

converting said color values into a user-specified format and displaying said user-specified format.

4. The method of claim 1, wherein said step of averaging further comprises the steps of:

converting each red, green and blue pixel value in said measurement area into a tristimulus format; and

averaging said converted red, green, and blue pixel values.

16. The computer readable memory of claim 1 wherein the loading step loads phosphor characteristics from monitor memory.

17. The method of claim 1 further comprising the step of retrieving phosphor characteristics stored on a computer readable memory during a prior calibration.

18. The method of claim 1 further comprising the step of retrieving phosphor characteristics stored on a read only computer readable memory.

19. The method of claim 1 further comprising the step of retrieving phosphor characteristics from monitor memory and storing the phosphor characteristics in computer memory.

2. A method for measuring color output of a monitor, comprising the steps of:

determining monitor phosphor characteristics corresponding to said monitor;

generating a lookup table containing at least one pixel value entry and a beam current entry for every pixel value entry, including at least the steps of

calibrating said monitor so that a pixel value of zero results in a beam current measurement of zero amperes,

measuring a beam current for said every pixel value entry, and

storing said every pixel value entry and said beam current entry in said lookup table;

identifying a measurement area on said monitor;

separately averaging red, green, and blue pixel values in said measurement area;

determining beam currents associated with red, green, and blue pixel values displayed in said measurement area;

calculating color values for said measurement area by using said monitor phosphor characteristics; and

converting said color values into a user-specified format and displaying said user-specified format.

3. A method for measuring color output of a monitor, comprising the steps of:

determining monitor phosphor characteristics corresponding to said monitor,

generating a lookup table containing a beam current entry for every pixel value entry, including at least the steps of

calibrating said monitor so that a pixel value of zero results in a beam current measurement of zero amperes,

generating a flat white field on said monitor,

measuring a first set of red, green and blue pixel values,

measuring a first set of beam currents associated with said first set of red, green, and blue pixel values,

generating a gray field on said monitor,

measuring a second set of red, green and blue pixel values,

measuring a second set of beam currents associated with said second set of red, green, and blue pixel values,

determining a relationship between pixel values and beam currents using said first and second sets of beam currents and said first and second sets of red, green, and blue pixel values, and

generating said lookup table for red, green, and blue pixel values based on said relationships;

identifying a measurement area on said monitor;

separately averaging red, green, and blue pixel values in said measurement area;

determining beam currents associated with red, green, and blue pixel values displayed in said measurement area;

calculating color values for said measurement area by using said monitor phosphor characteristics; and

converting said color values into a user-specified format and displaying said user-specified format.

5. A system for measuring color output of a monitor, comprising:

a memory device, coupled to said monitor, including pixel values and a digital colormeter module; and

a processor coupled to said memory device for measuring said color output of said monitor based on said pixel values by executing said digital colormeter module wherein said digital colormeter module determines an average pixel value of a measurement area that is a smaller than a display area on said monitor.

6. The system of claim 5, wherein said monitor further comprises an Electrically-Erasable Programmable Read-Only Memory, said Electrically-Erasable Programmable Read-Only Memory comprising an array of phosphor characteristics of said monitor.

7. The system of claim 6, wherein said memory device includes a color database and said digital colormeter module further includes instructions for matching said color output to said color database.

8. The system of claim 6, wherein said digital colormeter module further includes instructions for converting said color output into a user-specified format and displaying said user-specified format.

23. The system of claim 5 further comprising phosphor characteristics stored on a computer readable memory.

24. The system of claim 5 further comprising phosphor characteristics stored on a read only computer readable memory.

25. The system of claim 5 further comprising phosphor characteristics stored on monitor memory.

9. A computer-readable medium storing instructions for causing a computer to perform the steps of:

identifying a measurement area that is smaller than a display area of a monitor,

determining average red, green and blue pixel values of said measurement area of said monitor;

determining beam currents associated with said average red, green and blue pixel values;

loading phosphor characteristics of said monitor into computer memory; and

calculating color output of said measurement area by using said phosphor characteristics of said computer monitor and said beam currents associated with said average red, green, and blue pixel values.

11. The computer-readable medium of claim 9, further causing said computer to perform the step of generating a lookup table containing a beam current entity for every pixel value entry.

10. A computer-readable medium storing instructions for causing a computer to perform the steps of:

identifying a measurement area of a monitor;

determining average red, green and blue pixel values of said measurement area;

determining beam currents associated with said average red, green and blue pixel values;

loading phosphor characteristics of said monitor into computer memory; and

calculating color output of said measurement area by using said phosphor characteristics monitor and said beam currents; and

searching a color database to match said color output and displaying a set of three closest matches.

12. A computer-readable medium storing instructions for causing a computer to perform the steps of:

identifying a measurement area of a monitor;

determining average red, green and blue pixel values of said measurement area of said monitor;

determining beam currents associated with said average red, green and blue pixel values;

loading phosphor characteristics of said monitor into computer memory;

calculating color output of said measurement area by using said phosphor characteristics and said beam currents; and

generating a lookup table containing a beam current entry for every pixel value entry, by

calibrating said computer monitor so that a pixel value of zero results in a beam current measurement of zero amperes;

measuring red, green, and blue beam currents for each of said red, green, and blue pixel values; and

storing said red, green, and blue pixel values and beam current values in said lookup table.

13. A computer-readable medium storing instructions for causing a computer to perform the steps of:

identifying a measurement area of a monitor;

determining average red, green and blue pixel values of said measurement area of said monitor;

determining beam currents associated with said average red, green and blue pixel values;

loading phosphor characteristics of said monitor into computer memory;

calculating color output of said measurement area by using said phosphor characteristics and said beam currents; and

generating a lookup table containing a beam current entry for every pixel value entry by at least the steps of

calibrating said monitor so that a pixel value of zero results in a beam current measurement of zero amperes;

generating a flat white field on said monitor;

measuring a first set of red, green and blue pixel values;

measuring a first set of beam currents associated with said first set of red, green, and blue pixel values;

generating a gray field on said monitor;

measuring a second set of red, green and blue pixel values;

measuring a second set of beam currents associated with said second set of red, green, and blue pixel values;

determining a relationship between pixel values and beam currents using said first and second sets of beam currents and said first and second sets of red, green, and blue pixel values; and

generating said lookup table for red, green, and blue pixel values based on said relationship.

14. A computer-readable medium storing instructions for causing a computer to perform the steps of:

identifying a measurement area that is smaller than a display area of a monitor;

determining average red, green and blue pixel values of said measurement area of said monitor;

determining beam currants associated with red, green and blue pixel values in said measurement area;

loading an array of phospbor characteristics of said computer monitor into computer memory; and

calculating color output of said red, green, and blue pixel values in said measurement area by using said phosphor characteristics of said computer monitor and said beam currents associated with said red, green, and blue pixel values.

15. A method for measuring color output of a monitor, comprising the steps of:

determining monitor phosphor characteristics corresponding to said monitor;

generating a lookup table containing a beam current entry for every pixel value entry;

identifying a measurement area on said monitor;

separately averaging a red, green, and blue pixel values in said measurement area;

determining beam currents associated with red, green, and blue pixel values displayed in said measurement area;

calculating color values for said measurement area by using said monitor phosphor characteristics;

converting said color values into a user-specified format and displaying said user-specified format; and

searching a color database to match a color output and displaying a set of three closest matches.

20. A system for measuring color output of a monitor, comprising:

a memory device, coupled to said monitor, including pixel values and a digital colormeter module and a calibration routine for creating a lookup table containing pixel values and corresponding beam currents required to produce said pixel values; and

a processor coupled to said memory device for measuring said color output based on said pixel values by executing said calibration routine and said digital colormeter module;

wherein said memory includes instructions that direct the processor to search a database to match a color output and display a set of three matches that are closest.

21. A system for measuring color output of a monitor, comprising:

a memory device, coupled to said monitor, including pixel values and a digital colormeter module and a calibration routine for creating a lookup table containing pixel values and corresponding beam currents required to produce said pixel values; and

a processor coupled to said memory device for measuring said color output based on said pixel values by executing said calibration routine and said digital colormeter module;

wherein said memory includes instructions for directing the processor to determine a relationship between pixel values and beam currents using first and second sets of beam currents and first and second sets of red, green and blue pixel values.

22. A system for measuring color output of a monitor, comprising:

a memory device, coupled to said monitor, including pixel values and a digital colormeter module and a calibration routine for creating a lookup table containing pixel values and corresponding beam currents required to produce said pixel values; and

a processor coupled to said memory device for measuring said color output based on said pixel values by executing said calibration routine and said digital colormeter module;

wherein a monitor calibration related to a pixel value of zero results in a beam current of zero.

26. A computer-readable medium storing instructions for causing a computer to perform the steps of:

determining average red, green and blue pixel values of a measurement area identified by a user that is smaller than a display area of a monitor;

determining beam currents associated with said average red, green and blue pixel values;

loading phosphor characteristics of said monitor into memory; and

calculating color output of said measurement area by using said phosphor characteristics of said monitor and said beam currents associated with said average red, green, and blue pixel values.

27. A computer-readable medium for storing instructions for causing a computer to perform the steps of:

determining average red, green and blue pixel values of a measurement area of a monitor identified by a user;

determining beam currents associated with said average red, green and blue pixel values;

loading phosphor characteristics of said monitor into computer memory;

calculating color output of said measurement area by using said phosphor characteristics of said monitor and said beam currents associated with said average red, green, and blue pixel values; and

searching a color database to match said color output and displaying a set of three closest matches.

28. The computer-readable medium of claim 27, further storing instructions for causing said computer to perform the step of generating a lookup table containing a beam current entry for every pixel value entry.

29. A computer-readable medium for storing instructions for causing a computer to perform the steps of:

determining average red, green and blue pixel values of a measurement area of a monitor identified by a user;

determining beam currents associated with said average red, green and blue pixel values;

loading phosphor characteristics of said monitor into computer memory;

calculating color output of said measurement area by using said phosphor characteristics of said monitor and said beam currents associated with said average red, green, and blue pixel values; and

generating a lookup table containing at least one pixel value entry and a beam current entry for every pixel value entry, including at least the steps of

calibrating said monitor so that a pixel value of zero results in a beam current measurement of zero amperes,

measuring red, green, and blue beam currents for each of said red, green, and blue pixel values, and

storing said red, green, and blue pixel values and beam current values in said lookup table.

30. A computer-readable medium for storing instructions for causing a computer to perform the steps of:

determining average red, green and blue pixel values of a measurement area of a monitor identified by a user;

determining beam currents associated with said average red, green and blue pixel values;

loading phosphor characteristics of said monitor into computer memory;

calculating color output of said measurement area by using said phosphor characteristics of said monitor and said beam currents associated with said average red, green, and blue pixel values; and

generating a lookup table containing at least one pixel value entry and a beam current entry for every pixel value entry, including at least the steps of

calibrating said monitor so that a pixel value of zero results in a beam current measurement of zero amperes,

generating a flat white field on said monitor,

measuring a first set of red, green and blue pixel values,

measuring a first set of beam currents associated with said first set of red, green, and blue pixel values,

generating a gray field on said monitor,

measuring a second set of red, green and blue pixel values,

measuring a second set of beam currents associated with said second set of red, green, and blue pixel values,

determining a relationship between pixel values and beam currents using said first and second sets of beam currents and said first and second sets of red, green, and blue pixel values, and

generating said lookup table for red, green, and blue pixel values based on said relationship.

31. A computer-readable medium storing instructions for causing a computer to perform the steps of:

determining beam currents associated with red, green and blue pixel values in a measurement area that is smaller than a display area on a monitor identified by a user;

determining average red, green and blue pixel values of said measurement area of said monitor;

loading an array of phosphor characteristics of said monitor into computer memory; and

calculating color output of said red, green, and blue pixel values in said measurement area by using said phosphor characteristics of said monitor and said beam currents associated with said red, green, and blue pixel values.

35. The computer-readable memory of claim 31 wherein the loading step loads phosphor characteristics stored on a computer readable memory during a prior calibration.

36. The computer-readable memory of claim 31 wherein the loading step loads phosphor characteristics stored on a read only computer readable memory.

32. A computer-readable medium storing instructions for causing a computer to perform the steps of:

determining beam currents associated with red, green and blue pixel values in a measurement area on a monitor identified by a user;

loading an array of phosphor characteristics of said monitor into computer memory;

calculating color output of said red, green, and blue pixel values in said measurement area by using said phosphor characteristics; and

said beam currents; and

searching a database to match a color output and displaying a set of three matches that are closest.

33. A computer-readable medium storing instructions for causing a computer to perform the steps of:

determining beam currents associated with red, green and blue pixel values in a measurement area on a monitor identified by a user;

loading an array of phosphor characteristics of said monitor into computer memory;

calculating color output of said red, green, and blue pixel values in said measurement area by using said phosphor characteristics of said monitor and said beam currents associated with said red, green, and blue pixel values; and

determining a relationship between pixel values and beam currents using first and second sets of beam currants and first and second sets of red, green and blue pixel values.

34. A computer-readable medium storing instructions for causing a computer to perform the steps of:

determining beam currents associated with red, green and blue pixel values in a measurement area on a monitor identified by a user;

loading an array of phosphor characteristics of said monitor into computer memory; and

calculating color output of said red, green, and blue pixel values in said measurement area by using said phosphor characteristics of said monitor and said beam currents associated with said red, green, and blue pixel values;

wherein when implementing the instructions a monitor calibration related to a pixel value of zero results in a beam current of zero.