Method and System for Backlight Control Using Statistical Attributes of Image Data Blocks

• US 20120281028A1
• Filed: 12/09/2010
• Published: 11/08/2012
• Est. Priority Date: 12/16/2009
• Status: Abandoned Application

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Orlick, Christopher J., Miller, J. Scott, Shields, Jerome D.
• Application Number:
  US13/511,534
• Publication Number:
  US 20120281028A1
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

A method and system for generating backlight control values for a dual modulation display including a front panel having a first resolution and a backlight subsystem having lower resolution than the front panel, in response to input image data. Some embodiments determine statistical data indicative of at least one statistical measure of each of a number of spatially compact subsets of pixels of image data having the first resolution, where the pixels of image data are pixels of the input image data, color components of pixels of the input image data, or data values derived from pixels of the input image data. Some embodiments determine backlight drive values for each color channel of the backlight subsystem, including by determining statistical data for each color channel, determining backlight drive values for each color channel from the statistical data, and performing cross-channel correction on these backlight drive values.

Claims

1-89. -89. (canceled)

90. A method for determining backlight drive values for backlight elements of a backlight panel of a dual modulation display in response to input image data indicative of an image to be displayed, the method comprising the steps of:

(a) determining statistical data indicative of at least one statistical measure of each of a number of spatially compact subsets of pixels of image data, including by performing at least one nonlinear operation on each of the spatially compact subsets, where the dual modulation display comprises a front panel having a first resolution, the image data being mapped to the first resolution, the statistical data have resolution lower than the first resolution, and the pixels of image data comprise elements of the group consisting of pixels of the input image data, color components of pixels of the input image data, and data values derived from pixels of the input image data, and

band-limiting the statistical data; and

(b) determining the backlight drive values from the band-limited statistical data, wherein the statistical data are indicative of the mean and standard deviation of each of the spatially compact subsets, and step (a) comprises a step of determining standard deviation values including by filtering mean values of the spatially compact subsets to determine filtered mean values, and squaring each of the filtered mean values.

91. The method as recited in claim 90, wherein the pixels of image data comprise luminance values, including a luminance value for each pixel of the input image data.

92. The method as recited in claim 90, wherein the pixels of image data comprise maximal color components, including a maximal color component of the color components of each pixel of the input image data.

93. The method as recited in claim 90, wherein the statistical measure comprises the standard deviation of each of the spatially compact subsets of pixels of image data.

94. The method as recited in claim 90, wherein step (a) comprises a step of determining the mean and the standard deviation of each of the spatially compact subsets of pixels and step (b) comprises a step of determining each of the backlight drive values from a linear combination of the standard deviation and the mean of a different one of the spatially compact subsets of pixels.

95. The method as recited in claim 90, wherein the nonlinear operation is performed on data derived from each of the spatially compact subsets.

96. The method as recited in claim 90, wherein the nonlinear operation comprises an operation of squaring pixels of each of the spatially compact subsets.

97. The method as recited in claim 96, wherein the statistical measure comprises the standard deviation of each of the spatially compact subsets.

98. The method as recited in claim 90, wherein the nonlinear operation comprises an operation of squaring pixels of a downsampled image determined from the spatially compact subsets.

99. The method as recited in claim 98, wherein the nonlinear operation comprises an operation of squaring the mean value of each of the spatially compact subsets, where each pixel of the downsampled image comprises the mean value of a different one of the spatially compact subsets.

100. The method as recited in claim 98, wherein the nonlinear operation comprises an operation of squaring low-pass filtered mean values of the spatially compact subsets.

101. The method as recited in claim 90, wherein steps (a) and (b) are performed such that, in response to the backlight drive values determined in step (b), the backlight panel produces stable backlight.

102. The method as recited in claim 90, wherein steps (a) and (b) are performed by single pass data processing without feedback.

103. A processor for generating backlight drive values for backlight elements of a backlight panel of a dual modulation display in response to input image data indicative of an image to be displayed, wherein the dual modulation display also comprises a front panel having a first resolution and the processor is configured to:

determine and band-limit statistical data indicative of at least one statistical measure of each of a number of spatially compact subsets of pixels of image data, including by performing at least one nonlinear operation on each of the spatially compact subsets, wherein the image data are mapped to the first resolution, the statistical data have a resolution lower than the first resolution, and the pixels of image data comprise elements of the group consisting of pixels of the input image data, color components of pixels of the input image data, and data values derived from pixels of the input image data;

and generate the backlight drive values in response to the band-limited statistical data,

wherein the statistical data are indicative of the mean and standard deviation of each of the spatially compact subsets, and the processor is configured to generate standard deviation values including by filtering mean values of the spatially compact subsets to determine filtered mean values, and squaring each of the filtered mean values.

104. An apparatus, comprising:

a dual modulation display including a front panel having a first resolution and a backlight panel having a second resolution, where the second resolution is less than the first resolution and the backlight panel is positioned to backlight the front panel; and

a processor, coupled to the dual modulation display and configured to downsample a set of image pixels to generate downsample image pixels, to band-limit the downsample image pixels to generate a first signal, and to determine backlight drive values from the first signal such that backlight drive values are capable of driving the backlight panel to cause the backlight panel to emit stable backlight for display by the front panel of an image determined by the image pixels,

wherein the image pixels have the first resolution, the downsample image pixels have the second resolution, and the processor is configured to perform low-pass filtering on the downsample image pixels,

wherein the first signal is indicative of a statistical measure of each of a number of spatially compact subsets of the image pixels,

wherein the processor is configured to pre-process the image pixels to generate processed image pixels, to downsample and band limit the processed image pixels to generate a second signal, to generate, in response to the first signal and the second signal, a third signal indicative of a second statistical measure of each of the spatially compact subsets of the image pixels, and to determine each of the backlight drive values by generating a linear combination of a value determined by the first signal and a value determined by the third signal, and

wherein the processor is configured to pre-process the image pixels including by squaring each of the image pixels.

105. A system, comprising:

means for determining statistical data indicative of at least one statistical measure of each of a number of spatially compact subsets of pixels of image data, including by performing at least one nonlinear operation on each of the spatially compact subsets, where the dual modulation display comprises a front panel having a first resolution, the image data being mapped to the first resolution, the statistical data have resolution lower than the first resolution, and the pixels of image data comprise elements of the group consisting of pixels of the input image data, color components of pixels of the input image data, and data values derived from pixels of the input image data, and

means for band-limiting the statistical data; and

means for determining the backlight drive values from the band-limited statistical data, wherein the statistical data are indicative of the mean and standard deviation of each of the spatially compact subsets, and wherein the statistical data determination means comprises means for determining standard deviation values and wherein the standard deviation determination means comprises;

means for filtering mean values of the spatially compact subsets to determine filtered mean values; and

means for squaring each of the filtered mean values;

wherein the system functions to determine backlight drive values for backlight elements of a backlight panel of a dual modulation display in response to input image data, which is indicative of an image to be displayed therewith.