Source: https://patents.google.com/patent/US9646546B2/en
Timestamp: 2019-12-06 10:32:00
Document Index: 764772982

Matched Legal Cases: ['application No. 60', '§119', 'application No. 60', 'art.\n3', 'art.\n4', 'art.\n5', 'art.\n6', 'art.\n7', 'art.\n8', 'art.\n9']

US9646546B2 - Color display based on spatial clustering - Google Patents
Color display based on spatial clustering Download PDF
US9646546B2
US9646546B2 US14/979,425 US201514979425A US9646546B2 US 9646546 B2 US9646546 B2 US 9646546B2 US 201514979425 A US201514979425 A US 201514979425A US 9646546 B2 US9646546 B2 US 9646546B2
US14/979,425
US20160125818A1 (en
2007-06-22 Priority to US72270607A priority
2010-11-08 Priority to US12/941,961 priority patent/US8890795B2/en
2014-11-14 Priority to US14/542,324 priority patent/US9224341B2/en
2015-12-27 Priority to US14/979,425 priority patent/US9646546B2/en
2015-12-27 Application filed by Dolby Laboratories Licensing Corp filed Critical Dolby Laboratories Licensing Corp
2016-01-22 Assigned to BRIGHTSIDE TECHNOLOGIES INC., A COMPANY INCORPORATED IN THE PROVINCE OF NOVA SCOTIA, CANADA reassignment BRIGHTSIDE TECHNOLOGIES INC., A COMPANY INCORPORATED IN THE PROVINCE OF NOVA SCOTIA, CANADA CONTINUANCE Assignors: BRIGHTSIDE TECHNOLOGIES INC., A COMPANY INCORPORATED UNDER THE LAWS OF CANADA
2016-01-22 Assigned to DOLBY CANADA CORPORATION reassignment DOLBY CANADA CORPORATION MERGER (SEE DOCUMENT FOR DETAILS). Assignors: 3191283 NOVA SCOTIA COMPANY, BRIGHTSIDE TECHNOLOGIES INC.
2016-01-22 Assigned to DOLBY LABORATORIES LICENSING CORPORATION reassignment DOLBY LABORATORIES LICENSING CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: DOLBY CANADA CORPORATION
2016-01-22 Assigned to THE UNIVERSITY OF BRITISH COLUMBIA reassignment THE UNIVERSITY OF BRITISH COLUMBIA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SEETZEN, HELGE
2016-01-22 Assigned to BRIGHTSIDE TECHNOLOGIES INC. reassignment BRIGHTSIDE TECHNOLOGIES INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: THE UNIVERSITY OF BRITISH COLUMBIA
2016-05-05 Publication of US20160125818A1 publication Critical patent/US20160125818A1/en
2017-05-09 Publication of US9646546B2 publication Critical patent/US9646546B2/en
239000003086 colorant Substances 0 abstract claims description 105
This application is a continuation of U.S. patent application Ser. No. 14/542,324 filed 14 Nov. 2014, which is a continuation of U.S. patent application Ser. No. 12/941,961 filed 8 Nov. 2010 now U.S. Pat. No. 8,890,795, which is a continuation of U.S. patent application Ser. No. 11/722,706 filed 22 Jun. 2007 now U.S. Pat. No. 7,830,358, which is the US national stage of PCT international patent application No. PCT/CA2005/001975 filed 23 Dec. 2005, which claims priority from U.S. patent application No. 60/638,122 filed 23 Dec. 2004 all of which are hereby incorporated herein by reference. This application claims the benefit under 35 U.S.C. §119 of U.S. patent application No. 60/638,122 filed 23 Dec. 2004.
In some embodiments of the invention, the number of light sources 16 of each color in array 14 is at least approximately inversely proportional to the flux ratio of the light sources. For example, where an array has light sources of three colors having flux ratios of 3:5:1, then the numbers of light sources of each of the three colors in the array could be in the ratio 5:3:15. The light sources of each color are substantially uniformly distributed on the array. In some embodiments, the point spread functions of the light sources of each color have widths that increase with the spacing between adjacent light sources of that color. The point spread functions of the light sources of one color may have widths that are in direct proportion to the spacing between adjacent light sources of that color in array 14. In some embodiments, a ratio of an average spacing between adjacent ones of the light sources in any one of the groups of light sources to a width of a point spread function of the light sources in the group of light sources is the same within ±20% for all of the groups of light sources in the array.
It can be appreciated that method 40 sequentially changes the values for the pixels of modulator 12. Except in unusual cases (for example, monochrome images) array 14 provides light of all colors for each setting of modulator 12. For an embodiment in which there are three colors with correction provided for all colors, for each color, the accuracy with which that color component of the image is displayed varies across subsequent frames as: “perfect”→“average”→“average”→perfect” etc. In a pure field sequential display method, each color is displayed only during a sub-frame during which the color is properly displayed. However, the color is “off” in other sub-frames.
Block 52 may limit the amount of correction provided to avoid undesirable flicker. If for example, a single pixel of the second-ranked color is dimmer than it should be by 80%, increasing the brightness of that pixel by 80% in the next frame could cause undesirable perceptible flicker. Block 52 may simply cut off compensation at a certain point, for example, block 50 may clip the intensity of a pixel at 150% of its pixel value. In the alternative, block 52 may implement a non-linear correction scale such that small corrections are made completely whereas larger corrections are reduced. For example, an adjustment table such as Table I may be provided.
Software for implementing he invention may provide adjustable parameters which control things such as the amount of variation permitted for any pixel between sequential frames; the maximum amount of correction for a color provided in a frame; the method by which colors are ranked; the manner in which the active area of the modulator is divided into parts; and so on.
The parts of the active area of modulator 12 within which the most important colors are identified do not necessarily correspond with one cluster of light sources in array 14. For example, where array 14 comprises a plurality of clusters each having one red, one green and one blue light source, the parts over which block 42 of method 40 determine the most important color may correspond to one or several such clusters of light sources. In some embodiments of the invention acceptable performance may be achieved by treating the entire active area of modulator 12 as a single part so that the entire area of modulator 12 uses one color priority.
Instead of determining color priority for parts of modulator 12 which include groups of pixels, color priority may be computed for “parts” which each include only one pixel. In such cases, what is the most important color for the pixel may be determined with reference to what color is specified by image data 11 as being brightest in that pixel.
The “colors” discussed in each embodiment of the invention do not need to be “sharp” or “narrow bandwidth” primary colors. The colors could be blends of two or more primary colors. For example, method 30 (FIG. 1A) could work if a distinct combination of light sources of different colors were active in each block 32A, 32B, 32C to project the same luminance pattern onto the modulator. Having narrow bandwidth primaries tends to yield a wider color gamut. In some embodiments of the invention, ranking the colors may comprise identifying linear combinations of primary colors for each of the parts and treating the linear combinations as the most important, second most important, third most important, etc. colors. For example, for a specific part of a specific image, the most important color might be identified as an equal mixture of red and blue.
1. A method for controlling a display to display a color image specified by image data, the image data specifying color and brightness for each of a plurality of image pixels, the display comprising a modulator having an active area comprising a plurality of modulator pixels and a light source operable to selectively illuminate the active area of the modulator with light of any one or more of a plurality of colors, the method comprising:
separately, for each of a plurality of parts of the active area of the modulator:
determining from the image data a selected color of the plurality of colors that is most important to the part by one or any combination of:
which color has the highest average brightness per pixel in the part;
which color has the highest average pixel values in the part as specified in the signal;
which color has the maximum brightness for any pixel in the part;
which color has the maximum pixel value for any pixel in the part;
colors having higher maximum pixel values are ranked higher than colors having lower maximum pixel values;
which color has the maximum variation in brightness or pixel value or some combination of brightness and pixel value over the part; and
which color exhibits the greatest degree of spatial clustering in the part;
based on the image data for the selected color determining first light source driving signals which, when applied to the light source, will cause the light source to illuminate the part with a spatially-varying luminance pattern of the selected color;
determining first pixel driving values for those of the modulator pixels in the part based at least on both the image data for the selected color and the first light source driving signals;
determining additional light source control signals for at least one of the plurality of colors other than the selected color based on the first pixel driving values and the image data for the one or more colors other than the selected color wherein, when applied to the light source, the additional light source control signals will cause the light source to illuminate the part with spatially-varying luminance patterns of each of the one or more colors other than the selected color; and
applying the first pixel driving values to drive the pixels of the modulator to selectively allow light from the part of the active area to pass to a viewing area and, while applying the first pixel driving values to drive the modulator pixels:
applying the first light source driving signals to cause the light source to illuminate the part of the active area of the modulator with the spatially varying luminance pattern of the selected color and applying the additional light source driving signals to cause the spatially varying luminance patterns of each of the one or more colors other than the selected color.
2. A method according to claim 1 wherein the first pixel driving values set the modulator pixels to modulate the spatially-varying luminance pattern of the selected color to accurately represent the selected color in the part and to approximately represent the one or more colors other than the selected color in the part.
3. A method according to claim 1 wherein determining the selected color comprises identifying the one of the plurality of colors having the highest average brightness in the part.
4. A method according to claim 1 wherein determining the selected color comprises identifying the one of the plurality of colors having the maximum pixel value in the part.
5. A method according to claim 1 wherein determining the selected color comprises identifying the one of the plurality of colors having the maximum variation in brightness or pixel value in the part.
6. A method according to claim 1 wherein determining the selected color comprises identifying the one of the plurality of colors having the maximum pixel value in the part.
7. A method according to claim 1 wherein determining the selected color comprises identifying the one of the plurality of colors having the greatest degree of spatial clustering in the part.
8. A method according to claim 1 wherein determining the selected color comprises determining for each of the plurality of colors a weighted combination of two or more of:
a variation in brightness or pixel value in the part;
an average brightness in the part;
an average pixel value in the part;
a maximum pixel value in the part; and
a degree of spatial clustering in the part.
9. A method according to claim 1 wherein the image data comprises video data comprising a plurality of frames and the method is repeated for each of the frames of the video data.
10. A method according to claim 9 wherein the modulator is a monochrome modulator.
11. A method according to claim 9 comprising, for a frame of the video data, applying correction factors to pixel values in the image data for one or more of the colors other than the selected color of a previous frame, the correction values selected to compensate for the light emitted in the previous frame by the pixels of the modulator for the for one or more of the colors other than the selected color being higher or lower than desired.
12. A method according to claim 11 comprising generating the correction values according to a non-linear correction scale.
13. A method according to claim 12 wherein the non-linear correction scale makes small corrections completely and reduces larger corrections.
14. A method according to claim 11 comprising determining the correction values by a lookup table that relates an amount that one of the one or more of the colors other than the selected color in a pixel is too dim in the previous frame to an amount of increase to apply to the pixel value for the pixel in the current frame.
15. A method according to claim 11 comprising cutting off the correction values at a predetermined level.
16. A method according to claim 1 wherein one or more of the plurality of colors comprises a blend of two or more primary colors of the display.
17. A method according to claim 16 wherein the plurality of colors comprises identifying a plurality of linear combinations of primary colors for each of the parts and using the linear combinations as the plurality of colors.
18. A method according to claim 1 comprising determining a first effective luminance pattern for the selected color, the first effective luminance pattern indicating the amount of light of the selected color in the spatially-varying luminance pattern produced when the light source is driven by the first light source driving signals and using the first effective luminance pattern to determine the first pixel driving values.
19. A program product comprising a physical medium recording non-transitory computer software instructions which, when executed by a computer processor, causes the computer processor to execute a method according to claim 1.
20. A display for displaying images specified by image data for viewing, the display comprising:
a modulator having an active area comprising a plurality of modulator pixels;
a light source operable to selectively illuminate the active area of the modulator with light of any one or more of a plurality of colors; and
a controller configured to deliver modulator control signals to the modulator and light source control signals to the light source the processor connected to receive the image data, the image data specifying color and brightness for each of a plurality of image pixels, the processor configured to, separately, for each of a plurality of parts of the active area of the modulator:
determine from the image data a selected color of the plurality of colors that is most important to the part by one or any combination of:
based on the image data for the selected color determine first light source driving signals which, when applied to the light source, will cause the light source to illuminate the part with a spatially-varying luminance pattern of the selected color;
determine first pixel driving values for those of the modulator pixels in the part based at least on both the image data for the selected color and the first light source driving signals;
determine additional light source control signals for at least one of the plurality of colors other than the selected color based on the first pixel driving values and the image data for the one or more colors other than the selected color wherein, when applied to the light source, the additional light source control signals will cause the light source to illuminate the part with spatially-varying luminance patterns of each of the one or more colors other than the selected color; and
apply the first pixel driving values to drive the pixels of the modulator to selectively allow light from the part of the active area to pass to a viewing area and, while applying the first pixel driving values to drive the modulator pixels:
21. A display according to claim 20 wherein the controller comprises a computer processor and a program memory accessible to the computer processor, the program memory carrying a set of computer-readable instructions which configure the processor to perform the recited steps.
22. A display according to claim 20 wherein the light source comprises a backlight.
23. A display according to claim 22 wherein the backlight comprises a plurality of light emitters of each of the plurality of colors.
24. A display according to claim 23 wherein the light emitters comprise light-emitting diodes.
US14/979,425 2004-12-23 2015-12-27 Color display based on spatial clustering Active US9646546B2 (en)
US72270607A true 2007-06-22 2007-06-22
US12/941,961 US8890795B2 (en) 2004-12-23 2010-11-08 Field sequential display of color images with color selection
US14/542,324 US9224341B2 (en) 2004-12-23 2014-11-14 Color display based on spatial clustering
US14/979,425 US9646546B2 (en) 2004-12-23 2015-12-27 Color display based on spatial clustering
US15/493,596 US20170221427A1 (en) 2004-12-23 2017-04-21 Color display based on spatial clustering
US14/542,324 Continuation US9224341B2 (en) 2004-12-23 2014-11-14 Color display based on spatial clustering
US15/493,596 Continuation US20170221427A1 (en) 2004-12-23 2017-04-21 Color display based on spatial clustering
US20160125818A1 US20160125818A1 (en) 2016-05-05
US9646546B2 true US9646546B2 (en) 2017-05-09
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