Four color digital cinema system with extended color gamut and copy protection

• US 20060152524A1
• Filed: 01/12/2005
• Published: 07/13/2006
• Est. Priority Date: 01/12/2005
• Status: Active Grant

• Current Assignee: IMAX Theatres International Limited (IMAX Corporation)
• Original Assignee: Eastman Kodak Company
• Inventors: Miller, Michael E., Murdoch, Michael J., Madden, Thomas E.
• Granted Patent: US 7,362,336 B2
• Time in Patent Office: Days
• US Class Current: 345/589
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 2201/0064 for copy protection or copy management, e.g. CGMS, copy only once, one-time copy
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00826 wherein a spoiler signal is added to degrade the signal quality
• CPC Class Codes: G11B 20/00884 involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm
• CPC Class Codes: H04N 2005/91392 using means for preventing making copies of projected video images
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• CPC Class Codes: H04N 9/3173 wherein the projection device is specially adapted for enhanced portability
• CPC Class Codes: H04N 9/3182 Colour adjustment, e.g. white balance, shading or gamut white balance per se H04N9/73; control of amplitude of colour signals H04N9/68; colour control circuits for displays in general G09G5/02, G09G3/2003, G09G3/3607
• CPC Class Codes: H04N 9/3194 including sensor feedback
• CPC Class Codes: H04N 9/67 for matrixing camera processing pipelines for matrixing of colour signals H04N23/85

Abstract

A color display system including a display device for four or more visible color primaries and a processor for controlling the four or more color primaries to selectively render portions of an image or image sequence such that visually equivalent colors displayed in two or more image portions differ in their spectral composition.

Claims

1. A color display system, comprising:

(a) a display device having four or more visible color primaries capable of producing metamerically matched color stimuli; and

(b) a processor for controlling the four or more color primaries to selectively render portions of an image or image sequence such that visually equivalent colors displayed in two or more image portions differ in their spectral composition.

2. The color display system claimed in claim 1, wherein the four or more color primaries are arranged in a spatial pattern and wherein the different portions of the image or image sequence are rendered such that there is no perceived difference in the spatial pattern of the input image color when displayed in the two or more portions.

3. The color display system claimed in claim 1, wherein the portions contain watermark information and/or color degradation when captured with an image-capture device and subsequently redisplayed.

4. The color display system claimed in claim 1, wherein the processor converts three or more channel color-image signals to four or more channel color-image signals for use by the display device.

5. The color display system claimed in claim 1, wherein an input image color displayed in a first portion is rendered using one combination of the four or more color primaries and a given input image color displayed in a second portion is rendered using a second combination of the four or more visible color primaries.

6. The color display system claimed in claim 1, wherein an input image is rendered for display using the four or more color primaries in real time.

7. The color display system claimed in claim 1, wherein an input image is pre-rendered for display using the four or more color primaries for subsequent display.

8. The color display system claimed in claim 3, wherein the processor receives a three or more color input image signal, and an instruction for spatial, temporal and/or color patterning for different portions of an image when embedding the watermark information and/or causing the significant color degradation when captured with an image capture device and subsequently redisplayed.

9. The color display system claimed in claim 8, wherein at least one of the image portions has a shape of a text character.

10. The color display system claimed in claim 9, wherein one or more regions provides textual information, wherein the textual information is selected from the group consisting of:

(a) a name of the copyright owner;

(b) a date of the copyright;

(c) an owner of the color display system;

(d) an address of the owner of the color display system;

(e) a location of the color display system; and

(f) a reminder of copyright penalties.

11. The color display system claimed in claim 8, wherein the instruction of the spatial and/or temporal pattern includes a random variable to decrease predictability of the embedded watermark information and/or the significant color degradation when captured with the image capture device and is subsequently redisplayed.

12. The color display system claimed in claim 8, wherein the instruction of the color pattern includes colors that are particularly salient in human memory.

13. The color display system claimed in claim 12, wherein the instruction of the color pattern includes colors often associated with skin, sky, and/or foliage.

14. The color display system as claimed in claim 1, wherein the color display system is distributed with a dedicated viewing apparatus.

15. The color display system as claimed in claim 14, wherein the dedicated viewing apparatus contains a color filter.

16. The color display system as claimed in claim 1, wherein a color primary is rendered to image pixels in a particular color cluster different from color primary rendering applied to remaining pixels in a scene.

17. The color display system as claimed in claim 1, wherein the display device is a projection display device.

18. The color display system as claimed in claim 1, wherein the display device is a direct view display.

19. The color display system as claimed in claim 1, further comprising:

c) a display sensor for measuring a value that correlates with light output of one or more of the four or more visible color primaries.

20. The color display system as claimed in claim 19, wherein the display sensor measures characteristics of the display device selected from the group consisting of tristimulus values, chromaticity coordinates, luminance, radiance, and reflectance.

21. The color display system as claimed in claim 19, wherein the display sensor measures current and/or voltage of a light source within the display device.

22. The color display system as claimed in claim 21, wherein a measurement of current and/or voltage is used to compute and/or derive an output luminance value.

23. The color display system as claimed in claim 19, wherein the processor uses the value measured by the display sensor to dynamically alter the spectral composition of one or more of the portions of the image or image sequence.

24. The color display system as claimed in claim 19, wherein the processor provides real time characterization of the four or more visible color primaries.

43. The color display system as claimed in claim 1, wherein three of the four or more visible color primaries emit red, green, and blue light.

44. The color display system as claimed in claim 1, wherein light emitted by at least one of the four or more visible color primaries is either white, cyan, yellow, or magenta.

45. The color display system as claimed in claim 1, further comprising:

(a) a first visible color primary having a first chromaticity coordinate;

(b) a second visible color primary having a second chromaticity coordinate; and

(c) wherein the first and second chromaticity coordinates are substantially the same and spectra corresponding to the first and second visible color primaries are substantially different.

25. A method for rendering different portions of an image or image sequence such that a given input image color displayed in two or more portions has different spectral composition and is perceived as visually equivalent, comprising the steps of:

(a) selecting two or more subgamuts that enclose the color coordinates associated with the input image color;

wherein each subgamut is defined by the color coordinates of three color primaries;

(b) calculating intensities of each of the three color primaries within each subgamut;

(c) calculating two or more weighted averages of the calculated intensities; and

(d) converting the calculated intensities to code values for displaying an image.

26. A method for using visible light to deter unwanted copying of image content, comprising the steps of;

(a) combining four or more visible color primaries to render different portions of an image or image sequence such that a given input image color displayed in two or more portions has a different spectral composition and is perceived as visually equivalent; and

(b) displaying the image portions as part of the image content.

27. The method claimed in claim 26, wherein the two or more portions form watermark information and/or undergoes significant color degradation when captured with an image capture device and is subsequently redisplayed.

28. The method claimed in claim 26, wherein at least one of the portions has the shape of a text character.

29. The method claimed in claim 28, wherein one or more regions are shaped to provide textual information, wherein the textual information is selected from the group consisting of:

(a) a name of the copyright owner;

(b) a date of the copyright;

(c) an owner of the color display system;

(d) an address of the owner of the color display system;

(e) a location of the color display system; and

(f) a reminder of copyright penalties.

30. The method claimed in claim 26, further comprising the steps of:

(c) receiving three or more color input image signals, and an instruction for spatial, temporal and/or color patterning for the two or more portions of an image; and

d) partitioning the three or more color input image signal into different portions according to the instruction.

31. The method claimed in claim 30, wherein the instruction of the spatial and/or the location of the temporal pattern include a random variable to decrease predictability of a position and/or rendering of at least one of the two or more portions.

32. The method claimed in claim 30, wherein the instruction of the color pattern includes colors that are particularly salient in human memory.

33. The method claimed in claim 26, wherein a timing or location of at least one of the two or more portions is determined as a function of a random variable.

41. The method claimed in claim 26 wherein a color primary is rendered to image pixels in a particular color cluster different from color primary rendering applied to remaining pixels in a scene.

34. A display device, comprising:

(a) four or more color primaries that emit visible light; and

(b) a means for combining the four or more visible color primaries to produce two or more regions of color that are visually equivalent and have different spectral composition.

35. The display device claimed in claim 36, wherein the display device uses sequential color presentation to form an image.

36. The display device claimed in claim 34, wherein the display device displays a spatial pattern of color primaries to form an image.

37. A method for hiding and revealing text or image data using a display device, comprising the steps of:

(a) combining four or more visible color primaries to render portions of an image or image sequence such that visually equivalent colors displayed in two or more image portions differ in their spectral composition; and

(b) providing a means for visually differentiating the portions.

38. The method claimed in claim 37, wherein the means for visually differentiating the portions is a dedicated viewing apparatus.

39. The method claimed in claim 38, wherein the dedicated viewing apparatus uses color filters.

40. The method claimed in claim 38, wherein the dedicated viewing apparatus is a camera.

42. The method claim in claim 37, wherein a color primary is rendered to image pixels in a particular color cluster different from color primary rendering applied to remaining pixels in a scene.