Methods, Systems and Apparatus for Jointly Calibrating Multiple Displays in a Display Ensemble

• US 20130120589A1
• Filed: 11/11/2011
• Published: 05/16/2013
• Est. Priority Date: 11/11/2011
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Chang, James Zhixin, Dalrymple, John C., Watanabe, Chizu
• Granted Patent: US 8,531,474 B2
• Time in Patent Office: Days
• US Class Current: 348/189
• CPC Class Codes: G06F 3/1446 display composed of modules, e.g. video walls
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• 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
• CPC Class Codes: H04N 9/69 for modifying the colour signals by gamma correction controlling camera response for colour signals H04N23/83

Abstract

Aspects of the present invention are related to systems, methods and apparatus for calibration of multiple display apparatus in a display ensemble.

Claims

1. A system for calibrating a display apparatus in a display ensemble, said system comprising:

a display ensemble comprising a plurality of display apparatus;

a calibration computer communicatively coupled to said display ensemble;

a digital color camera, wherein;

said digital color camera is positioned at a location whereat said digital color camera may acquire a full-view image of said display ensemble; and

said digital color camera is communicatively coupled to said calibration computer;

a color-measurement device communicatively coupled to said calibration computer;

a display-driver computer communicatively coupled to said display ensemble; and

a non-transitory computer-readable medium encoded with a computer program code for a method for calibrating a first display apparatus, in said plurality of display apparatus, said method comprising;

determining a first camera model associated with said first display apparatus using said color-measurement device and said digital color camera;

determining a first display model associated with said first display apparatus using said digital color camera;

determining a first Gamma one-dimensional look-up table associated with said first display apparatus using said first display model and said first camera model; and

loading said first Gamma one-dimensional look-up table into said first display apparatus.

2. A system as described in claim 1, wherein said full-view image comprises a single image.

3. A system as described in claim 1, wherein said full-view image comprises multiple images.

4. A system as described in claim 1, wherein said determining a first camera model comprises:

acquiring, with said digital color camera, a dark-camera image of said display ensemble, wherein each display apparatus, in said plurality of display apparatus, is in a powered-down state under a normal lighting condition during said acquiring said dark-camera image;

determining, from said dark-camera image, a dark-camera summary RGB value associated with said first display apparatus;

acquiring, with said digital color camera, a plurality of color-patch images of said display ensemble, wherein each color-patch image is associated with a color in a plurality of camera-calibration colors;

from each color-patch image, determining a color-patch summary RGB value associated with said first display apparatus, thereby determining a plurality of color-patch summary RGB values;

acquiring, with said color-measurement device, a color-measurement value, at said first display apparatus, associated with each color in said plurality of camera-calibration colors, thereby acquiring a plurality of color-measurement values;

correcting each color-patch summary RGB value, in said plurality of color-patch summary RGB values, with said dark-camera summary RGB value associated with said first display apparatus, thereby producing a plurality of corrected, color-patch summary RGB values; and

calculating said first camera model for said first display apparatus using said plurality of corrected, color-patch summary RGB values and said plurality of color-measurement values.

5. A system as described in claim 4, wherein said plurality of camera-calibration colors comprises the eight colors associated with the corners of the Red-Green-Blue color cube.

6. A system as described in claim 4, wherein said plurality of camera-calibration colors comprises a second plurality of colors associated with a sampling of the gray line.

7. A system as described in claim 4, wherein said first camera model for said first display apparatus comprises a 3-by-3 matrix.

8. A system as described in claim 7, wherein said 3-by-3 matrix is calculated using a regression method.

9. A system as described in claim 4, wherein said determining, from each color-patch image, a color-patch summary RGB value associated with said first display comprises computing an average of all RGB values, in said color-patch image, within a measurement site associated with said first display apparatus.

10. A system as described in claim 4, wherein said dark-camera summary RGB value is an average of all RGB values, in said dark-camera image, within a measurement site associated with said first display apparatus.

11. A system as described in claim 1, wherein each display in said plurality of display apparatus comprises a measurement site.

12. A system as described in claim 1, wherein said computer program code further comprises:

determining a plurality of camera models, wherein each camera model in said plurality of camera models is associated with a display apparatus in said plurality of display apparatus;

determining a plurality of display models, wherein each display model in said plurality of display models is associated with a display apparatus in said plurality of display apparatus;

determining a plurality of Gamma one-dimensional look-up tables, wherein each Gamma one-dimensional look-up table in said plurality of Gamma one-dimensional look-up tables is associated with a display apparatus in said plurality of display apparatus; and

loading each of said Gamma one-dimensional look-up tables in said plurality of Gamma one-dimensional look-up tables into said associated display apparatus.

13. A system as described in claim 1, wherein said display-driver computer and said calibration computer are the same computing device.

14. A system as described in claim 1, wherein said calibration computer comprises a display-ensemble service solution within a cloud computing environment.

15. A system as described in claim 1, wherein said display-driver computer comprises a display-driver system within a cloud computing environment.

16. A system as described in claim 1, wherein said color-measurement device is a device selected from the group consisting of a colorimeter and a spectroradiometer.

17. A system as described in claim 1, wherein said digital color camera is attached to a permanent structure in a fixed position relative to said display ensemble.

18. A system as described in claim 17, wherein said determining a first display model may be scheduled to occur at a first time whereat said display ensemble is not in use.

19. A system as described in claim 17, wherein said determining a first display model may be scheduled to occur at a plurality of times whereat said display ensemble is not in use.

20. A system as described in claim 19, wherein said plurality of times occur with a periodic frequency.

21. A system as described in claim 17, wherein said determining a first camera model and said determining a first display model do not occur at substantially the same time.

22. A system as described in claim 1, wherein said method further comprises:

detecting specular highlights; and

compensating for said detected specular highlights.

23. A system as described in claim 1, wherein said first Gamma one-dimensional look-up table is a Gamma one-dimensional look-up table associated with a color component selected from the group consisting of red, green and blue.

24. A system as described in claim 1, wherein said determining a first display model comprises:

determining a first initial model of a display response function associated with said first display apparatus; and

refining said first initial model.

25. A system as described in claim 24, wherein said determining a first initial model comprises using said color-measurement device.

26. A system as described in claim 25, wherein said determining a first initial model comprises:

acquiring, with said color-measurement device, a color-measurement value, at said first display apparatus, associated with each color in a first plurality of display-calibration colors, thereby producing a plurality of color-measurement values;

computing a linear RGB value for each color value in said plurality of display-calibration colors, thereby producing a plurality of linear RGB values; and

calculating said first initial model for said first display apparatus using said plurality of linear RGB values and said plurality of color-measurement values.

27. A system as described in claim 26, wherein said first initial model for said first display apparatus comprises a 3-by-3 matrix.

28. A system as described in claim 27, wherein said 3-by-3 matrix is calculated using a regression method.

29. A system as described in claim 24, wherein said determining a first initial model comprises:

acquiring, with said digital color camera, a dark-camera image of said display ensemble, wherein each display apparatus, in said plurality of display apparatus, is in a powered-down state under a normal lighting condition during said acquiring said dark-camera image;

determining, from said dark-camera image, a dark-camera summary RGB value associated with said first display apparatus;

acquiring, with said digital color camera, a first plurality of color-patch images of said display ensemble, wherein each color-patch image, in said first plurality of color-patch images, is associated with a color in a plurality of display-calibration colors;

from each color-patch image, in said first plurality of color-patch images, determining a color-patch summary RGB value associated with said first display apparatus, thereby producing a plurality of color-patch summary RGB values;

correcting each color-patch summary RGB value, in said plurality of color-patch summary RGB values, with said dark-camera summary RGB value associated with said first display, thereby producing a plurality of dark-corrected, color-patch summary RGB values;

applying said first camera model to each corrected, color-patch summary RGB value in said plurality of corrected, color-patch summary RGB values, thereby producing a plurality of camera-model generated XYZ values;

computing a linear RGB value for each color value in said plurality of display-calibration colors, thereby producing a plurality of linear RGB values; and

calculating said first initial model for said first display apparatus using said plurality of linear RGB values and said plurality of camera-model generated XYZ values.

30. A system as described in claim 29, wherein said first initial model for said first display apparatus comprises a 3-by-3 matrix.

31. A system as described in claim 30, wherein said 3-by-3 matrix is calculated using a regression method.

32. A system as described in claim 29, wherein said determining, from each color-patch image, a color-patch summary RGB value associated with said first display apparatus comprises computing an average of all RGB values, in said color-patch image, within a measurement site associated with said first display apparatus.

33. A system as described in claim 29, wherein said dark-camera summary RGB value is an average of all RGB values, in said dark-camera image, within a measurement site associated with said first display apparatus.

34. A system as described in claim 24, wherein said refining said initial model comprises:

acquiring, with said digital color camera, a second plurality of color-patch images of said display ensemble, wherein each color-patch image is associated with a color in a plurality of refinement colors, wherein said refinement colors are around a neutral gray scale.

35. A system as described in claim 24, wherein said refining said first initial model comprises:

constructing, in a first color space, a plurality of refinement colors, wherein said refinement colors surround a desired neutral gray scale;

converting said plurality of refinement colors from said first color space to an XYZ color space;

obtaining a plurality of linear RGB values from said plurality of converted refinement colors using said first initial model associated with said first display apparatus;

performing a clipping operation on said plurality of linear RGB values, thereby producing a plurality of realizable, linear RGB values;

converting said plurality of realizable, linear RGB values to a plurality of display RGB values by applying an inverse display tone response function obtained in said determining a first initial model;

obtaining a plurality of camera-model generated XYZ values using said plurality of display RGB values;

tessellating, in a second color space, a plurality of values associated with said camera-model generated XYZ values into a plurality of tetrahedra associated with said first display apparatus; and

constructing said first Gamma one-dimensional look-up table using said plurality of tetrahedra.

36. A system as described in claim 35, wherein said first color space is an Lab color space and said second color space is a color space selected from the group consisting of an Lab color space and an XYZ color space.

37. A system as described in claim 35, wherein said tessellating comprises applying a Delaunay tessellation algorithm.

38. A system as described in claim 35, wherein said constructing comprises:

determining a maximum display-ensemble luminance value associated with said plurality of display apparatus;

sampling a luminance scale from a zero value to said maximum display-ensemble luminance value, thereby producing a plurality of luminance values;

combining said plurality of luminance values with a desired white point chromaticity;

performing a tetrahedral interpolation using said plurality of tetrahedra associated with said first display, thereby producing a plurality of linear RGB values associated with said plurality of luminance values; and

applying an inverse display tone response function obtained in said determining a first initial model to said plurality of linear RGB values to obtain a plurality of display RGB values; and

forming said first Gamma one-dimensional look-up-table using said plurality of display RGB values.

39. A system for calibrating a display in a display ensemble, said system comprising:

a display ensemble comprising a plurality of display apparatus;

a calibration computer communicatively coupled to said display ensemble;

a digital color camera, wherein;

said digital color camera is positioned at a location whereat said digital color camera may acquire a full-view image of said display ensemble; and

said digital color camera is communicatively coupled to said calibration computer;

a color-measurement device communicatively coupled to said calibration computer;

a display-driver computer communicatively coupled to said display ensemble; and

a non-transitory computer-readable medium encoded with a computer program code for a method for calibrating a display apparatus, in said plurality of display apparatus, said method comprising;

determining a camera model associated with said display apparatus using said color-measurement device and said digital color camera;

determining an initial display model associated with said display apparatus using said color-measurement device;

refining said initial display model associated with said display apparatus using said digital color camera, thereby producing a display apparatus model;

determining a Gamma one-dimensional look-up table associated with said display apparatus using said display model and said camera model; and

loading said Gamma one-dimensional look-up table into said display apparatus.