Method and device for improved display standard conformance

• US 9,368,057 B2
• Filed: 07/28/2006
• Issued: 06/14/2016
• Est. Priority Date: 08/01/2005
• Status: Active Grant

• Current Assignee: Barco NV
• Original Assignee: Barco NV
• Inventors: Kimpe, Tom, Dorval, Etienne
• Primary Examiner(s): Yodichkas, Aneeta
• Assistant Examiner(s): ELNAFIA, SAIFELDIN E
• Application Number:
  US11/494,570
• Publication Number:
  US 20070067124A1
• Time in Patent Office: 3,609 Days
• Field of Search: 345/204, 345/207, 345690-699
• US Class Current: 1/1
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• 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 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/2092 Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto suitable for both CRT and flat panel G09G5/003; specific for a CRT G09G1/165

Abstract

The invention provides a new method to calibrate a display system such that the display system is conforming to an enforced standard for a wider range of parameters, e.g. viewing angles, than compared to traditional calibration methods. This is obtained by calculating an optimised set of calibration parameters for the display to be conform to the enforced standard for the selected range of parameters.

Claims

1. A method for calibrating a matrix display with respect to at least one enforced greyscale or color display standard, the method comprising:

selecting one or more standards to which the display needs to be compliant,

choosing a viewing angle and selecting angles for which compliance is desired,

obtaining a characterization, based on said at least one enforced greyscale or color standard, of a non-conformance in greyscale or color values of the matrix display with respect to a plurality of relevant values of the viewing angle,

calculating a set of calibration parameters in function of the viewing angle, based n the at least one enforced greyscale or color display standard, and the characterized non-conformance in greyscale or color values of the matrix display,

defining a degree of conformance of the matrix display with respect to the at least one enforced greyscale or color display standard, wherein the degree of conformance is a comparison of a relative deviation of an absolute value of a calculated value to an absolute target value of the enforced greyscale or color display standard,

obtaining a same set of optimal calibration parameters valid for all values of the viewing angle and selected angles within a relevant viewing angle range by optimizing the set of calibration parameters with respect to said degree of conformance to the at least one enforced greyscale or color display standard for all values of the viewing angle within the relevant viewing angle range, wherein the relevant viewing angle range corresponds to a relevant range of different viewing positions,

wherein optimizing the same set of calibration parameters comprises assigning for all values of the viewing angle range within the relevant viewing angle range a weight value to the degree of conformance corresponding to that viewing angle and based on at least two calibration parameters and at least two viewing angles, calculating said set of optimal calibration parameters,

finishing the optimizing of the calibration parameters when its result falls within a predetermined deviation around the enforced at least one greyscale or color display standard, and

using the obtained optimal calibration parameters with the matrix display, wherein within said relevant viewing angle range, the set of optimal calibration parameters replaces the set of calibration parameters.

2. The method according to claim 1, wherein characterizing the non-conformance in greyscale or color values of the matrix display with respect to the viewing angle comprises creating native transfer curves for the matrix display, and this for every value of the viewing angle within the relevant viewing angle range.

3. The method according to claim 2, wherein creating native transfer curves for every value of the viewing angle within the relevant viewing angle range comprises measuring native transfer curves for some values of the viewing angle within the relevant viewing angle range, and generating native transfer curves for other values of the first viewing angle by interpolation.

4. The method according to claim 1, wherein the relevant viewing angle range is a viewing cone of 20°

.

5. The method according to claim 1, furthermore comprising configuring the matrix display with the set of optimal calibration parameters.

6. The method according to claim 5, wherein configuring the matrix display with the set of optimal calibration parameters comprises loading the set of optimal calibration parameters into the display, into a graphical board, into a host operating system or into an application running on the host operating system.

7. The method according to claim 1, wherein the set of optimal calibration parameters are in the form of a look-up table.

8. The method according to claim 1, wherein obtaining a characterization of the non-conformance in greyscale or color values of the matrix display with respect to relevant values of the viewing angle comprises characterizing the non-conformance in greyscale or color values of the matrix display with respect to relevant values of viewing angle.

9. The method according to claim 1, wherein obtaining a characterization of the non-conformance in greyscale or color values of the matrix display with respect to relevant values of the viewing angle comprises loading a previously determined characterization of the non-conformance in greyscale or color our values of the matrix display with respect to relevant values of the viewing angle.

10. The method according to claim 1, furthermore comprising determining an actual value of the viewing angle, and automatically selecting an optimal pre-set so that the display system has optimal conformance to the at least one enforced greyscale or color display standard with respect to the actual value of the viewing angle.

11. The method according to claim 1, there being a plurality of zones of emissive elements in the matrix display, at least two of the zones having a different value for the viewing angle at a particular moment in time, wherein the method comprises taking into account different relevant ranges of the viewing angle for at least two of the zones, and separately optimizing the set of calibration parameters of these at least two zones with respect to a degree of conformance to the at least one enforced greyscale or color display standard for all values of the viewing angle within the viewing angle range relevant for that zone, thus obtaining a set of optimal calibration parameters for use with the matrix display.

12. The method according to claim 1, wherein the characterization of the non-conformance in greyscale or color values of the matrix display is a function of drive signals with respect to the plurality of relevant values of the viewing angle of at least a first parameter.

13. A calibration device for calibrating a matrix display with respect to at least one enforced greyscale or color display standard, the calibration device comprising:

means for selecting one or more standards to which the display needs to be compliant,

means for choosing a viewing angle and selecting angles for which compliance is desired,

first storage means for storing a characterization, based on said at least one enforced greyscale or color standard, of a non-conformance in greyscale or color values of the matrix display with respect to a plurality of relevant values of the viewing angle,

second storage means for storing a set of calibration parameters in function of the viewing angle, based on the at least one enforced greyscale or color display standard, and the characterized non-conformance in greyscale or color values of the matrix display,

calculation means for obtaining a same set of optimal calibration parameters valid for all values of the viewing angle and selected angles within a relevant viewing angle range by optimizing the set of calibration parameters with respect to a degree of conformance to the at least one enforced greyscale or color display standard for all values within the relevant viewing angle range,

wherein the degree of conformance is a comparison of a relative deviation of an absolute value of a calculated value to an absolute target value of the enforced greyscale or color display standard,

wherein the set of calibration parameters is optimized by assigning for all values of the viewing angle within the relevant viewing angle range a weight value to the degree of conformance corresponding to that viewing angle and calculating said set of optimal calibration parameters based on at least two calibration parameters and at least two viewing angles, wherein the relevant viewing angle range corresponds to a relevant range of different viewing positions,

means for finishing the optimizing of the calibration parameters when its result falls within a predetermined deviation around the enforced at least one greyscale or color display standard, and

wherein the set of optimal calibration parameters for use with the matrix display is obtained, wherein within said relevant viewing angle range, the set of optimal calibration parameters replaces the set of calibration parameters.

14. The device according to claim 13, furthermore comprising means for creating native transfer curves for the matrix display, and this for every value of the viewing angle within the relevant viewing angle range.

15. The device according to claim 14, wherein the means for creating native transfer curves for every value of the viewing angle within the relevant viewing angle range comprises measurement means for measuring native transfer curves for some values of the viewing angle within the relevant viewing angle range, and calculation means for generating native transfer curves for other values of the viewing angle by interpolation.

16. The device according to claim 13, wherein the relevant viewing angle range is a viewing cone of 20°

.

17. The device according to claim 13, furthermore comprising configuration means for configuring the matrix display with the set of optimal calibration parameters.

18. The device according to claim 17, wherein the configuration means comprises means for loading the set of optimal calibration parameters into the display, into a graphical board, into a host operating system or into an application running on the host operating system.

19. The device according to claim 13, furthermore comprising a third storage means for storing pre-sets of optimal calibration parameters for pre-determined viewing angle values.

20. The device according to claim 19, furthermore comprising means for determining an actual value of the viewing angle, and selection means for automatically selecting an optimal pre-set from the third storage means so that the display system has optimal conformance to the at least one enforced greyscale or color display standard with respect to the actual value of the viewing angle.

21. A method for correcting non-conformance in greyscale or color values of at least one zone of emissive elements in a matrix display, the correcting being with respect to at least one enforced greyscale or color display standard, the method comprising:

choosing a viewing angle and selecting angles for which compliance is desired,

storing characterization data characterizing, based on said at least one enforced grevscale or color standard, a non-conformance in greyscale or color values of the at least one zone of emissive elements for a plurality of relevant values of the viewing angle of the characterization data,

pre-determining a deviation range of non-conformance of the matrix display with respect to at least one enforced greyscale or color display standard,

correcting, in accordance with the characterization data, said at least one zone of emissive elements so as to obtain a greyscale or color level conforming to said enforced greyscale or color display standard within said pre-determined deviation range from each of the at least one enforced greyscale or color display standards,

wherein said correcting is performed based on an input value of the greyscale or color value to be displayed and a selection of a range of the viewing angle of the characterization data for which non-conformance with respect to the at least one enforced greyscale or color display standard is to be corrected within the pre-determined deviation range, and

wherein said correcting is performed by obtaining a same set of optimal calibration parameters valid for all values of the viewing angle within a relevant viewing angle range for the at least one zone of emissive elements by optimizing the set of optimal calibration parameters to be valid for all values of the viewing angle and selected angles within the relevant range of viewing angles with respect to a degree of conformance to the at least one enforced greyscale or color display standard, the calibration parameters being optimized by assigning for all values of the viewing angles within the relevant viewing angle range a weight value to the degree of conformance corresponding to that viewing angle and calculating said set of optimal calibration parameters based on at least two calibration parameters and at least two viewing angles, wherein the degree of conformance is a comparison of a relative deviation of an absolute value of a calculated value to an absolute target value of the enforced greyscale or color display standard,

finishing the optimizing of the calibration parameters when its result falls within a predetermined deviation around the enforced at least one greyscale or color display standard, and

using said set of optimal calibration parameters, with the matrix display,

wherein within said relevant viewing angle range, the set of optimal calibration parameters replaces the set of calibration parameters, wherein the relevant viewing angle range corresponds to a relevant range of different viewing positions.

22. The method according to claim 21, wherein the range of the viewing angle includes at least one of a range of viewing angles under which the at least one zone of emissive elements is or is to be viewed at, a range of at least one display related parameter, or a range of at least one environmental parameter.

23. The method according to claim 22, wherein the display related parameter includes one or more of matrix display temperatures, backlight luminance, backlight color temperature, display settings, calibration tables, graphical board settings, settings of a host operating system, settings of an application running on a host operating system.

24. The method according to claim 22, wherein the environmental parameter includes any of intensity of ambient light, color temperature of ambient light, ambient temperature the matrix display is or is to be used at, ambient light values the matrix display is or is to be used at.

25. The method according to claim 21, wherein the pre-determined deviation range comprises a deviation up to 2%, preferably up to 5%, more preferably up to 10%, from the at least one enforced greyscale or color display standard.

26. The method according to claim 21, there being a plurality of zones of emissive elements, wherein each zone of emissive elements is corrected by a different calibration function.

27. The method according to claim 21, wherein a zone of emissive elements consists of one emissive element.

28. The method according to claim 21, wherein a zone of emissive elements comprises a plurality of emissive elements, each emissive element of a zone being assigned a same characterization data.

29. The method according to claim 21, wherein said correcting is performed based on using a look-up table.

30. The method according to claim 21, wherein said correcting is performed at least partially based on using a mathematical function.

31. The method according to claim 21, wherein the correcting is carried out in real-time.

32. The method according to claim 21, wherein the correcting is carried out off-line.

33. A system for correcting non-conformance in greyscale or color values of at least one zone of emissive elements in a matrix display, the correcting being with respect to at least one enforced greyscale or color display standard, the system comprising:

means for selecting one or more standards to which the display needs to be compliant,

means for choosing a viewing angle and for selecting angles for which compliance is desired,

a memory means for storing characterization data characterizing, based on said at least one enforced greyscale or color standard, a non-conformance in greyscale or color values of the at least one zone of emissive elements as a function of its drive signals for a plurality of relevant values of the viewing angle of the characterization data,

a correction device for correcting, based on an input value of the greyscale or color value to be displayed and a selection of a range of the viewing angle of the characterization data for which non-conformance with respect to the at least one enforced greyscale or color display standard is to be corrected within a pre-determined deviation range, and in accordance with the characterization data, the drive signals of said at least one zone of emissive elements so as to obtain a greyscale or color level conform said enforced greyscale or color display standard within a pre-determined deviation range from each of the at least one enforced greyscale or color display standards,

wherein the correction device performs correction by obtaining a same set of optimal calibration parameters valid for all values of the viewing angle within a relevant viewing angle range for the at least one zone of emissive elements by optimizing the set of optimal calibration parameters to be valid for all values of the viewing angles within the relevant range of viewing angles with respect to a degree of conformance to the at least one enforced greyscale or color display standard, the calibration parameters being optimized by assigning for all values of the viewing angles within the relevant viewing angle range a weight value to the degree of conformance corresponding to that viewing angle and calculating said set of optimal calibration parameters based on at least two calibration parameters and at least two viewing angles, wherein the degree of conformance is a comparison of a relative deviation of an absolute value of a calculated value to an absolute target value of the enforced greyscale or color display standard,

means for finishing the optimizing of the calibration parameters when its result falls within a predetermined deviation around the enforced at least one greyscale or color display standard,

wherein, when used with the matrix display within said relevant viewing angle range, the set of optimal calibration parameters replaces the set of calibration parameters, and wherein the relevant viewing angle range corresponds to a relevant range of different viewing positions.

34. The system according to claim 33, furthermore comprising a characterizing device for generating characterization data for the at least one zone of emissive elements by establishing a relationship between the greyscale or color levels of each of said at least one zone of emissive elements and the corresponding drive signal for a plurality of relevant parameter values in the range for the viewing angle.

35. The system according to claim 34, wherein said characterizing device comprises an image capturing device for generating an image of the emissive elements of the matrix display.

36. A method for calibrating a matrix display with respect to at least one enforced greyscale or color display standard, the method comprising:

choosing a viewing angle and selecting angles for which compliance is desired,

obtaining a characterization, based on said at least one enforced greyscale or color standard, of a non-conformance in greyscale or color values of the matrix display with respect to a plurality of relevant values of the viewing angle,

calculating a set of calibration parameters in function of the viewing angle, based on the at least one enforced greyscale or color display standard, and the characterized non-conformance in greyscale or color values of the matrix display,

defining a degree of conformance of the matrix display with respect to at least one enforced greyscale or color display standard, wherein the degree of conformance is a comparison of a relative deviation of an absolute value of a calculated value to an absolute target value of the enforced greyscale or color display standard,

obtaining a single set of optimal calibration parameters valid for a relevant range of viewing positions by optimizing the set of calibration parameters with respect to said degree of conformance to the at least one enforced greyscale or color display standard,

finishing the optimizing of the calibration parameters when its result falls within a predetermined deviation around the enforced at least one greyscale or color display standard and using said set of optimal calibration parameters with the matrix display, and

using the obtained optimal calibration parameters with the matrix display, wherein within said relevant range of viewing positions, the single set of optimal calibration parameters replaces the set of calibration parameters.