Image range expansion control methods and apparatus

• US 9,501,817 B2
• Filed: 05/26/2015
• Issued: 11/22/2016
• Est. Priority Date: 04/08/2011
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Atkins, Robin, Margerm, Steve
• Primary Examiner(s): Crawford, Jacinta M
• Assistant Examiner(s): PATEL, SHIVANG I
• Application Number:
  US14/721,345
• Publication Number:
  US 20150254823A1
• Time in Patent Office: 546 Days
• Field of Search: 345/581
• US Class Current: 1/1
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 2207/20008 Globally adaptive
• CPC Class Codes: G06T 2207/20208 High dynamic range [HDR] image processing
• CPC Class Codes: G06T 5/92 based on global image properties
• CPC Class Codes: G06V 40/162 using pixel segmentation or colour matching
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 2320/08 Arrangements within a display terminal for setting, manually or automatically, display parameters of the display terminal
• CPC Class Codes: G09G 2340/04 Changes in size, position or resolution of an image
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 2370/04 Exchange of auxiliary data, i.e. other than image data, between monitor and graphics controller
• CPC Class Codes: G09G 5/04 using circuits for interfacing with colour displays
• CPC Class Codes: G09G 5/10 Intensity circuits
• CPC Class Codes: H04N 21/4854 for modifying image parameters, e.g. image brightness, contrast
• CPC Class Codes: H04N 21/84 Generation or processing of descriptive data, e.g. content descriptors systems specially adapted for using meta-information in broadcast systems H04H60/73

Abstract

Image data is adjusted for display on a target display. Maximum safe expansions for one or more attributes of the image data are compared to maximum available expansions for the attributes. An amount of expansion is selected that does not exceed either of the maximum safe expansion and the maximum available expansion. Artifacts caused by over expansion may be reduced or avoided.

Claims

1. A method for image processing, the method comprising:

storing in a non-transitory memory a data stream received over a digital network;

obtaining, from the stored data stream, image data comprising a digital image to be displayed and metadata, wherein the metadata from the data stream includes both;

(i) a multiplicative factor value for safe luminance dynamic range expansion for a scene of the image data; and

(ii) metadata indicative of a luminance dynamic range of a source display, the metadata including parameters for each of color primaries, black level, and white level of the source display;

obtaining target display information to determine a luminance dynamic range of the target display;

computing, by one or more processors, a maximum available expansion of a luminance dynamic range for the image data as a ratio of the luminance dynamic range of the target display and the luminance dynamic range of the source display;

comparing the computed maximum available expansion and the factor value obtained from the data stream; and

by the one or more processors, expanding the luminance dynamic range of the image data by the lesser of the factor value obtained from the data stream and the computed maximum available expansion.

2. The method of claim 1 wherein obtaining target display information includes interrogating the target display.

3. The method of claim 2 further comprising displaying the image data with expanded luminance dynamic range by the target display.

4. The method of claim 1 further comprising displaying by the target display the image data with expanded luminance dynamic range.

7. A non-transitory computer-readable medium storing a sequence of instructions, which when executed by one or more computing processors, causes the one or more computing processors to perform the method of claim 1.

8. A non-transitory computer-readable medium storing a sequence of instructions, which when executed by one or more computing processors, causes the one or more computing processors to perform the method of claim 2.

9. A non-transitory computer-readable medium storing a sequence of instructions, which when executed by one or more computing processors, causes the one or more computing processors to perform the method of claim 3.

10. A non-transitory computer-readable medium storing a sequence of instructions, which when executed by one or more computing processors, causes the one or more computing processors to perform the method of claim 4.

13. An apparatus comprising one or more computing processors configured to perform the method of claim 1.

14. An apparatus comprising one or more computing processors configured to perform the method of claim 2.

15. An apparatus comprising one or more computing processors configured to perform the method of claim 3.

16. An apparatus comprising one or more computing processors configured to perform the method of claim 4.

5. A method for image processing, the method comprising:

storing in a non-transitory memory a data stream received over a digital network;

obtaining, from the stored data stream, image data comprising a digital image to be displayed and metadata, wherein the metadata from the data stream includes both;

(i) a multiplicative factor value for safe luminance dynamic range expansion for a scene of the image data and

(ii) metadata indicative of a luminance dynamic range of a source display, the metadata including parameters for each of color primaries, black level, and white level of the source display;

obtaining target display information to determine a luminance dynamic range of the target display;

computing, by one or more processors, a maximum available expansion of a luminance dynamic range for the image data as a ratio of the luminance dynamic range of the target display and the luminance dynamic range of the source display;

comparing the computed maximum available expansion and the factor value obtained from the data stream; and

by the one or more processors, expanding without override control the luminance dynamic range of the image data by the lesser of the factor value obtained from the data stream and the computed maximum available expansion using a sigmoidal expansion function, and

by the one or more processors, expanding with override control the luminance dynamic range of the image data by the computed maximum available expansion.

11. A non-transitory computer-readable medium storing a sequence of instructions, which when executed by one or more computing processors, causes the one or more computing processors to perform the method of claim 5.

17. An apparatus comprising one or more computing processors configured to perform the method of claim 5.

6. A method for image processing, the method comprising:

storing in a non-transitory memory a data stream received over a digital network;

obtaining, from the stored data stream, image data comprising a digital image to be displayed and metadata, wherein the metadata from the data stream includes both;

(i) a multiplicative factor value for safe luminance dynamic range compression for a scene of the image data and

(ii) metadata indicative of a luminance dynamic range of a source display, the metadata including parameter for each of color primaries, black level, and white level of the source display;

obtaining target display information to determine a luminance dynamic range of the target display;

computing, by one or more processors, a maximum available compression of a luminance dynamic range for the image data as a ratio of the luminance dynamic range of the target display and the luminance dynamic range of the source display;

comparing the computed maximum available compression and the factor value obtained from the data stream; and

by the one or more processors, compressing without override control the luminance dynamic range of the image data by the lesser of the factor value obtained from the data stream and the computed maximum available compression using a sigmoidal function, and

by the one or more processors, compressing with override control the luminance dynamic range of the image data by the computed maximum available compression.

12. A non-transitory computer-readable medium storing a sequence of instructions, which when executed by one or more computing processors, causes the one or more computing processors to perform the method of claim 6.

18. An apparatus comprising one or more computing processors configured to perform the method of claim 6.