Mapping for display emulation based on image characteristics

• US 9,514,508 B2
• Filed: 12/06/2012
• Issued: 12/06/2016
• Est. Priority Date: 12/08/2011
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Ballestad, Anders, Atkins, Robin, Johnson, Lewis
• Primary Examiner(s): Hoang, Phi
• Application Number:
  US14/358,117
• Publication Number:
  US 20140333660A1
• Time in Patent Office: 1,461 Days
• US Class Current: 1/1
• CPC Class Codes: G06T 1/20 Processor architectures; Processor configuration, e.g. pipelining
• CPC Class Codes: G06T 11/001 Texturing; Colouring; Generation of texture or colour inpainting G06T5/77
• CPC Class Codes: G09G 5/00 Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators image data processing or generation, in general G06T
• 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

Abstract

An emulator yields modified image data that predicts the appearance of image content on a target display. The emulator generates modified image data based in part on the image content. The emulator may perform a transformation in which one or more parameters representative of features such as black level and/or white level of the target display are functions of image statistics for the image content.

Claims

1. An image processing method to emulate image content as it will appear when viewed on a target display, the method comprising:

receiving an input image prepared on a source display, wherein the source display has different display characteristics than the display characteristics of the target display;

obtaining one or more image statistics data of the input image;

accessing a display function that characterizes how the behavior of the target display changes in response to characteristics of an image being viewed on the target display;

computing based on the obtained image statistics data of the input image one or more parameters of the display function;

obtaining one or more color image statistics relating to relative proportions of primary colors in the input image by processing the input image;

accessing a second display function that characterizes how the behavior of the target display changes in response to characteristics of an image being viewed on the target display;

computing based on the obtained color image statistics data of the input image one or more parameters of the second display function; and

generating an output image based at least on the input image, the display function, the computed parameters of the display function, the second display function, and the computed parameters of the second display function,

wherein the input image comprises pixel values corresponding to each of red, green and blue primary colors, wherein computing the color image statistics comprise computing;

2. The method of claim 1, wherein the image statistics comprise an average luminance of the input image.

3. The method of claim 1, wherein the image statistics are received together with the input image as metadata.

4. The method of claim 1, wherein the display function is related to the contrast, the black level, or the white level of the target display.

5. The method of claim 1, wherein the display function is characterized by an input output relationship

L=α

V^γ

+β

,

wherein L is an output pixel value, V is an input pixel value, α

is a parameter related to an estimated white level value of the target display, β

is a parameter related to an estimated black level value of the target display, and γ

is a parameter related to a gamma value of the target display.

6. The method of claim 5, comprising determining an average luminance for the input image and calculating β

as a function of the average luminance.

7. The method of claim 5 wherein determining the average luminance for the input image is performed for a local area in the input image around a pixel with luminance V.

8. The method of claim 7 wherein the local area is made up of pixels in the input image within a predetermined radius of the pixel with luminance V.

9. The method of claim 5, further comprising:

determining an average luminance for the input image;

computing a value for α

as a function of the average luminance for the input image;

determining a local average luminance for pixels of the input image in a local area of a pixel with luminance V; and

computing a value for β

as a function of the local average luminance.

10. The method of claim 1, wherein the second display function comprises an input-output relationship of

11. The method of claim 1, wherein the display function and its parameters are determined from measurements made on the target display using one or more test patterns.

12. The method of claim 11, wherein a test pattern comprises one or more black areas and one or more white areas, and determining the display function further comprises:

measuring white and black levels for the target display for each of a number of test patterns, each with a different average luminance;

fitting a suitable curve to the measuring results to obtain a first function relating black level output to average input luminance and a second function relating white level output to average input luminance.

13. The method of claim 1, wherein the second display function and its parameters are determined from measurements made on the target display using one or more test patterns.

14. The method of claim 13, wherein a test pattern comprises a first area in the center of a test image in a saturated first primary color surrounded by a second area in a mixture of a first primary color and a second primary color.

15. The method of claim 14, wherein the center area comprises a saturated red color and the surrounding area comprises a mixture of red and blue colors.

16. A non-transitory computer-readable storage medium having stored thereon computer-executable instructions for executing a method with a processor according to the method of claim 1.

17. An apparatus comprising a processor and configured to perform the method of claim 1.