Tone mapping adaptation for saturation control

Patent metadata

Field	Value
Publication number	US-2019164262-A1
Application number	US-201816205505-A
Country	US
Kind code	A1
Filing date	Nov 30, 2018
Priority date	Nov 30, 2017
Publication date	May 30, 2019
Grant date	—

Abstract

A system and methods is provided for performing, by a processor, an initial tone mapping function on a first image to produce a second image. The first and second images are of different dynamic ranges. The method also includes applying, by the processor, a second tone mapping function to the second image when it contains any saturated portions. The second tone mapping function lowers luminance by a first fraction. The overall luminance of the second image is also determined and a fine tuning filter is applied when at least portions of said second image contain areas darker than an amount.

First claim

1 . A method comprising:
applying an initial tone mapping function on a first image to produce a second image wherein said first and second images are of different dynamic ranges; applying a second tone mapping function to said second image when it contains any saturated portions; wherein said second tone mapping function lowers luminance by a first fraction; and determining overall luminance of said second image and applying a fine tuning filter
when at least portions of said second image contain areas darker than an amount, wherein said fine tuning filter increases the overall luminance of the second image by a second fraction.

2 . The method of claim 1 , wherein the first image has a high dynamic range and the second image has a standard dynamic range and fine tuning and luminance determination is provided so as to prevent any pixel in said second image to be clipped because of the maximum and minimum luminance levels in said first or second image in said saturation portions.

3 . The method of claim 1 , wherein said first and second image comprises at least a portion of pixel counts in red or green.

4 . The method of claim 3 , wherein said at least one processor is configured for applying a Red-Green-Blue (RGB) filter for color correction of said first and second images prior to displaying said second image on said output device.

5 . The method of claim 1 , wherein said second tone mapping function includes a calculated coefficient that lowers a plurality of luminance values.

6 . The method of claim 1 , wherein said second image has a reduced dynamic range in comparison to said first image.

7 . The method of claim 1 , wherein said fine tuning filter increases overall luminance of said second image by a second fraction, wherein said second fraction is lower than said first fraction.

8 . The method of claim 1 , wherein the input color gamut is defined as a finite set of points in an xy plane of a XYZ colorspace.

9 . The method of claim 1 , wherein a final image is to be displayed on an output device having a display.

10 . The method of claim 6 further comprising:
obtaining an input color gamut related to said first image;
obtaining an output color gamut related to said second image as it will be displayed on said output device;
modifying the output color gamut to match the input color gamut by calculating a minimized perceived color error between the input color gamut and the output color gamut.

11 . The method of claim 6 further comprising applying a Red-Green-Blue (RGB) filter for color correction of said first and second images prior to displaying said second image on said output device.

12 . A system comprising at least one processor configured to:
perform an initial tone mapping function on a first image to produce a second image wherein said first and second images are of different dynamic ranges; apply a second tone mapping function to said second image when it contains any saturated portions; wherein said second tone mapping function lowers luminance by a first fraction; and determine overall luminance of said second image and applying a fine tuning filter when at least portions of said second image contain areas darker than an amount, wherein said fine tuning filter increases the overall luminance of the second image by a second fraction.

13 . The system of claim 12 , wherein the first image has a high dynamic range and the second image has a standard dynamic range and fine tuning and luminance determination is provided so as to prevent any pixel in said second image to be clipped because of the maximum and minimum luminance levels in said first or second image in said saturation portions.

14 . The system of claim 12 , wherein said first and second image comprises at least a portion of pixel counts in red or green.

15 . The system of claim 14 , wherein said at least one processor is configured for applying a Red-Green-Blue (RGB) filter for color correction of said first and second images prior to displaying said second image on said output device.

16 . The system of claim 12 , wherein said second tone mapping function includes a calculated coefficient that lowers a plurality of luminance values.

17 . The system of claim 12 , wherein said second image has a reduced dynamic range in comparison to said first image.

18 . The system of claim 12 , wherein said fine tuning filter increases overall luminance of said second image by a second fraction, wherein said second fraction is lower than said first fraction.

19 . The system of claim 12 , wherein the input color gamut is defined as a finite set of points in an xy plane of a XYZ colorspace.

20 . The system of claim 12 , wherein a final image is to be displayed on an output device having a display.

21 . A non-transitory storage medium carrying instructions of program code for executing steps of the method according to claim 1 , when said program is executed on a computing device.

Assignees

• Interdigital Vc Holdings Inc

Inventors

• Cellier Francois
• Lopez Patrick
• Olivier Yannick
• Touze David

Classifications

• G06T5/20

  using local operators · CPC title

• G06T5/009 Primary

  Physics · mapped topic

• G06T2207/10024

  Color image · CPC title

• G06T2207/20208

  High dynamic range [HDR] image processing · CPC title

• G06T5/92 Primary

  based on global image properties · CPC title