ADAPTING DISPLAY COLOR FOR LOW LUMINANCE CONDITIONS

• US 20110175925A1
• Filed: 01/20/2010
• Published: 07/21/2011
• Est. Priority Date: 01/20/2010
• Status: Active Grant

• Current Assignee: Monument Peak Ventures, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Intellectual Ventures Fund 83 LLC (Intellectual Ventures LLC)
• Inventors: Kurtz, Andrew F., Kane, Paul J.
• Granted Patent: US 8,847,972 B2
• Time in Patent Office: Days
• US Class Current: 345/589
• CPC Class Codes: G01J 1/32 adapted for automatic variation of the measured or reference value regulation of light intensity G05D25/00
• CPC Class Codes: G01J 1/42 using electric radiation detectors optical or mechanical part G01J1/04; by comparison with a reference light or electric value G01J1/10
• CPC Class Codes: G01J 1/4204 with determination of ambient light solar light G01J2001/4266
• 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 2340/06 Colour space transformation
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• 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: G09G 5/10 Intensity circuits
• CPC Class Codes: H04N 21/42202 environmental sensors, e.g. for detecting temperature, luminosity, pressure, earthquakes
• CPC Class Codes: H04N 21/4318 by altering the content in the rendering process, e.g. blanking, blurring or masking an image region image enhancement or restoration in general G06T5/00
• CPC Class Codes: H04N 5/58 in dependence upon ambient light
• 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

Abstract

A method for adapting color appearance of a display (200) for low luminance conditions includes operating a projection (100) to display images on a display surface (30); detecting ambient light conditions and displayed image brightness; determining low luminance conditions based on the detected ambient light conditions and the detected display brightness; determining changes in color appearance to be applied to the displayed images based on the low luminance conditions, a model of photopic vision of the human eye, and a model of mesopic vision of the human eye; and applying the determined changes in the color appearance to image data using an image processor (130) that alters the image data for the projected images.

Claims

1. A method for adapting color appearance of a display for low luminance conditions, comprising:

operating an electronic display to display images on a display surface using color appearance parameter values;

detecting ambient light conditions and displayed image brightness over time;

determining initial and subsequent luminance conditions in an adaptive field based on the detected ambient light conditions and the detected display brightness;

determining when luminance conditions change to or from low luminance conditions corresponding to human mesopic vision or lower;

determining changes in color appearance to be applied to the displayed images based upon both the determined initial luminance conditions, the low luminance conditions, the current color appearance parameter values, and a color appearance model of human vision that encompasses at least photopic and mesopic viewing conditions; and

applying the determined changes in the color appearance to image data using an image processor that alters the image data for the displayed images.

2. The method as in claim 1 wherein the step of determining changes in color appearance is comprised of the following steps:

computing color appearance parameter values at each pixel location for both photopic and mesopic conditions using a color appearance model; and

determining changes in the values of the mesopic color appearance parameters at each pixel location, by selectively modifying them to approach or match the values of the photopic color appearance parameters at each pixel location for conditions, provided that such changes are within the color gamut of the display.

3. The method as in claim 2 wherein the action of selectively modifying the mesopic color appearance parameters includes substituting mesopic values with photopic values, or with values clipped at the color gamut boundary.

4. The method as in claim 1 wherein the step of determining changes in color appearance is comprised of the following steps:

receiving an input image signal at each of a plurality of image pixel locations;

computing input red, green and blue image intensities at each pixel location;

computing input X, Y and Z tristimulus values at each pixel location;

receiving viewing environment data for initial luminance conditions and low luminance conditions;

computing the color appearance parameter values at each pixel location for both photopic and mesopic conditions using a color appearance model;

selectively modifying the mesopic color appearance parameter values at each pixel location to use photopic color appearance parameter values, or intermediate color appearance parameter values between mesopic and photopic conditions;

computing output X, Y and Z tristimulus values at each pixel location using an inverse color appearance model and the modified color appearance parameter values;

computing output red, green and blue image intensities at each pixel location;

further modifying the color appearance parameters at each pixel location for mesopic conditions to correct the output red, green and blue image intensities, as necessary; and

sending the output red, green and blue image intensities at each pixel location to the display.

5. The method as in claim 1 wherein changes in color appearance are determined relative to parameters including lightness, chroma, hue angle, brightness, saturation, or colorfulness.

6. The method as in claim 1 wherein the color appearance is corrected with respect to human brightness adaptation, human chromatic adaptation, or both.

7. The method as in claim 1 wherein changes in color appearance are determined for viewing under scotopic conditions, using a color appearance model of human vision extensible to scotopic conditions.

8. The method as in claim 7 wherein images are selectively modified for scotopic viewing by applying determined changes in color appearance that include modifying the initial color values to grey scale or saturated color values.

9. The method as in claim 1 wherein values including the luminance conditions, color appearance parameter values, changes in color appearance parameters are tracked over time.

10. The method as in claim 1 wherein changes in color appearance are determined on an ongoing basis in accordance with changes in luminance conditions or estimates of current viewer adaptation.

11. The method as in claim 1 wherein the color appearance model provides for the temporal response of human visual adaptation to sudden increases or decreases in brightness.

12. The method as in claim 11 wherein the temporal course of visual adaptation is analyzed using a time-dependent adaptation or luminance factor.

13. The method as in claim 1 wherein the application of the determined changes in the color appearance are applied to the image data over an extended time or an image sequence.

14. The method as in claim 1 wherein the application of the determined changes in the color appearance are applied to the image data at scene changes occurring in an image sequence.

15. The method as in claim 1 wherein changes in color appearance are applied to the image data using means including correction values, transformative matrices, or look up tables (LUTs).

16. The method as in claim 15 wherein the correction values, transformative matrices, or look up tables (LUTs) are computed in advance for a set of one or more enumerated viewing conditions, stored, and applied to the image data upon display as needed.

17. The method as in claim 1 wherein the electronic display is of a type including an image projector, a self emissive display, a reflective display, or a trans-reflective display.

18. The method as in claim 17, wherein the self emissive display is of a type including a CRT display, a liquid crystal display, a plasma display, an LED display, or an OLED display.

19. A method for adapting color appearance of a display for low luminance conditions, comprising:

operating an electronic display to display images on a display surface;

detecting ambient light conditions and displayed image brightness;

determining low luminance conditions based on the detected ambient light conditions and the detected display brightness;

determining changes in color appearance to be applied to the displayed images based upon both the determined low luminance conditions and a color appearance model of human vision that encompasses at least photopic and mesopic viewing conditions; and

applying the determined changes in the color appearance to image data using an image processor that alters the image data for the displayed images.

20. The method as in claim 19 wherein the step of determining changes in color appearance is comprised of the following steps:

computing values for color appearance parameters at each pixel location for both photopic and mesopic conditions using a color appearance model; and

determining changes in the values of the mesopic color appearance parameters at each pixel location, by selectively modifying them to approach or match the values of the photopic color appearance parameters at each pixel location for conditions, provided that such changes are within the color gamut of the display.

21. The method as in claim 20 wherein the action of selectively modifying the mesopic color appearance parameters includes substituting mesopic color appearance parameter values with photopic color appearance parameter values, or with values clipped at the color gamut boundary.

22. The method as in claim 19 wherein the step of determining changes in color appearance is comprised of the following steps:

receiving an input image signal at each of a plurality of image pixel locations;

computing input red, green and blue image intensities at each pixel location;

computing input X, Y and Z tristimulus values at each pixel location;

receiving viewing environment data;

computing the color appearance parameter values at each pixel location for both photopic and mesopic conditions in the viewing environment using viewing environment data and a color appearance model;

selectively modifying the mesopic color appearance parameter values at each pixel location to use photopic color appearance parameter values, or intermediate color appearance parameter values between mesopic and photopic conditions;

computing output X, Y and Z tristimulus values at each pixel location using an inverse color appearance model and the modified color appearance parameter values;

computing output red, green and blue image intensities at each pixel location;

further modifying the color appearance parameters at each pixel location for mesopic conditions to correct the output red, green and blue image intensities, as necessary; and

sending the output red, green and blue image intensities at each pixel location to the display.

23. The method as in claim 19 wherein changes in color appearance are determined relative to parameters including lightness, chroma, hue angle, brightness, saturation, or colorfulness.

24. The method as in claim 19 wherein the determined changes in color appearance are corrected relative to color appearance with respect to human brightness adaptation, human chromatic adaptation, or both.

25. A method for adapting color appearance of a display for low luminance conditions, comprising:

operating an electronic display device to display images on a display surface to viewers in a local environment;

detecting ambient light conditions and displayed image brightness over time;

determining initial luminance conditions in the adaptive field based on the detected ambient light conditions and the detected display brightness;

determining when luminance conditions become low luminance conditions corresponding to human mesopic vision or lower;

assessing viewer conditions relative to the display device or luminance exposure history;

determining changes in color appearance to be applied to the displayed images based upon both the determined initial luminance conditions, the low luminance conditions, the viewer conditions; and

a color appearance model of human vision that encompasses at least photopic and mesopic viewing conditions; and

applying the determined changes in the color appearance to image data using an image processor that alters the image data for the displayed images.

26. The method as in claim 25 wherein the step of determining changes in color appearance is comprised of the following steps:

computing values for the color appearance parameters at each pixel location for both photopic and mesopic conditions using a color appearance model; and

determining changes in the values of the mesopic color appearance parameters at each pixel location, by selectively modifying them to approach or match the values of the photopic color appearance parameters at each pixel location for conditions, provided that such changes are within the color gamut of the display.

27. The method as in claim 26 wherein the action of selectively modifying the mesopic color appearance parameters includes substituting mesopic values with photopic values, or with values clipped at the color gamut boundary.

28. The method as in claim 25 wherein changes in color appearance are determined relative to parameters including lightness, chroma, hue angle, brightness, saturation, or colorfulness.

29. The method as in claim 25 wherein the presence, location, or number of viewers in the local environment of the electronic display is monitored.

30. The method as in claim 29 wherein the viewers are sensed using one or more sensors, including a proximity sensor, a motion sensor, a electro-magnetic bio-field detecting sensor, or combinations thereof.

31. The method as in claim 25 wherein the luminance exposure history of viewers is determined by means including distributed sensing, sensors worn by the viewers, or by user input.

32. An electronic display, comprising:

a modulator, to display image data on a display surface;

one or more sensors for detecting environmental data including ambient light conditions and displayed image brightness;

a processor for altering image data for the displayed images;

a computer program, which is accessible from a memory and is operable within the processor, for determining luminance conditions in the environment, computing color appearance parameter values, and determining changes in color appearance parameter values; and

wherein the computer program determines luminance conditions based on the detected ambient light conditions and the detected display brightness, computes color appearance parameters based on a color appearance model of human vision that encompasses at least photopic and mesopic viewing conditions, determines changes in color appearance parameters based on the color appearance model and changes in luminance conditions.

33. The electronic display according to claim 32 wherein the sensors are operated to collect the environmental data over time, and the computer program utilizes this temporal environmental data and temporal models of human visual adaptation to modify color appearance parameters on an ongoing basis.