Tone mapping techniques for increased dynamic range

Patent metadata

Field	Value
Publication number	US-11030728-B2
Application number	US-201816127569-A
Country	US
Kind code	B2
Filing date	Sep 11, 2018
Priority date	May 29, 2018
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

An electronic device may be provided with a display. A content generator such as a camera may capture images in high dynamic range mode or standard dynamic range mode. The images may have associated image metadata such as face detection information, camera settings, color and luminance histograms, and image classification information. Control circuitry in the electronic device may determine tone mapping parameters for the captured images based on the image metadata. The tone mapping parameters for a given image may be stored with the image in the metadata file. When it is desired to display the image, the control circuitry may apply a tone mapping process to the image according to the stored tone mapping parameters. The algorithm that is used to determine tone mapping parameters based on image metadata may be based on user preference data gathered from a population of users.

First claim

What is claimed is:

1. An electronic device, comprising:
a camera that captures an image having associated image metadata;
a display; and
control circuitry configured to:
apply a first tone mapping to the image;
generate tone mapping parameters for the image using the image metadata, wherein the tone mapping parameters are based on at least one of: whether a face is present in the image and camera settings in the image metadata file;
apply a second tone mapping to the image using the tone mapping parameters;
display the image on the display after applying the second tone mapping.

2. The electronic device defined in claim 1 wherein the camera captures the image in high dynamic range mode.

3. The electronic device defined in claim 1 wherein the first tone mapping reduces a dynamic range of the image before the control circuitry generates the tone mapping parameters.

4. The electronic device defined in claim 3 wherein the second tone mapping increases the dynamic range of the image using the tone mapping parameters.

5. The electronic device defined in claim 1 wherein the control circuitry stores the tone mapping parameters with the image metadata.

6. The electronic device defined in claim 1 wherein the control circuitry uses a mapping algorithm to determine the tone mapping parameters using the image metadata.

7. The electronic device defined in claim 6 wherein the mapping algorithm is based on training data collected from a population of users.

8. The electronic device defined in claim 1 wherein the tone mapping parameters define a tone mapping curve that maps content luminance values associated with the image to display luminance values.

9. An electronic device, comprising:
a camera that captures an image in high dynamic range mode, wherein the image has an associated metadata file; and
control circuitry that:
applies a first tone mapping to the image;
determines tone mapping parameters for the image using the metadata file, wherein the tone mapping parameters are based on at least one of: face detection information and camera settings in the metadata file, and wherein the tone mapping parameters define a tone mapping curve that maps content luminance values to display luminance values; and
applies a second tone mapping to the image using the tone mapping parameters.

10. The electronic device defined in claim 9 wherein the first tone mapping reduces a dynamic range of the image and the second tone mapping increases the dynamic range of the image.

11. The electronic device defined in claim 10 further comprising a display that displays the image after the control circuitry applies the second tone mapping to the image.

12. The electronic device defined in claim 9 wherein the control circuitry determines the tone mapping parameters using a mapping algorithm, wherein the mapping algorithm is based on user preference data gathered from a population of users.

13. A method for operating an electronic device having a camera and control circuitry, comprising:
with the camera, capturing an image in high dynamic range mode, wherein the image has an associated data file with image metadata; and
with the control circuitry:
applying a first tone mapping to the image;
determining tone mapping parameters based on the image metadata, wherein determining the tone mapping parameters based on the image metadata comprises determining the tone mapping parameters based on at least one of: face detection information and camera settings in the image metadata;
storing the tone mapping parameters in the data file; and
applying a second tone mapping to the image using the tone mapping parameters.

14. The method defined in claim 13 wherein the tone mapping parameters define a tone mapping curve and wherein applying the second tone mapping to the image comprises applying the tone mapping curve to the image to increase a dynamic range of the image.

15. The method defined in claim 14 wherein the electronic device comprises a display, the method further comprising:
after applying the tone mapping curve to the image, displaying the image on the display.

16. The method defined in claim 14 wherein the first tone mapping reduces the dynamic range of the image.

17. The method defined in claim 13 wherein determining the tone mapping parameters based on the image metadata comprises applying a mapping algorithm that is based on user preference data gathered from a population of users.

Assignees

• Apple Inc

Inventors

• Samadani Ramin
• Abbas Gregory B
• Baar Teun R
• Bonnier Nicolas P
• De Araujo Oliveira Victor M
• Xia Zuo

Classifications

• H04N23/741

  by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors · CPC title

• H04N23/667

  Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes · CPC title

• G06T2207/20208

  High dynamic range [HDR] image processing · CPC title

• G06T2207/20081

  Training; Learning · CPC title

• H04N1/32128

  attached to the image data, e.g. file header, transmitted message header, information on the same page or in the same computer file as the image (for information embedded in the image H04N1/32144) · CPC title