Exposure control methods and apparatus for capturing an image with a moving subject region

• US 9,041,856 B2
• Filed: 04/16/2012
• Issued: 05/26/2015
• Est. Priority Date: 05/02/2011
• Status: Active Grant

• Current Assignee: Sony Semiconductor Solutions Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kurita, Teppei, Mitsunaga, Tomoo, Jo, Kensei, Kaizu, Shun
• Primary Examiner(s): Velez, Roberto
• Assistant Examiner(s): Segura, Cynthia
• Application Number:
  US13/447,320
• Publication Number:
  US 20120281133A1
• Time in Patent Office: 1,135 Days
• Field of Search: 348/362
• US Class Current: 348/362
• CPC Class Codes: G06T 2207/10144 Varying exposure
• CPC Class Codes: G06T 2207/20208 High dynamic range [HDR] image processing
• CPC Class Codes: G06T 2207/20221 Image fusion; Image merging
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 5/90 Dynamic range modification of images or parts thereof
• CPC Class Codes: H04N 23/6811 based on the image signal
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/741 by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors
• CPC Class Codes: H04N 25/533 by using differing integration times for different sensor regions
• CPC Class Codes: H04N 9/8205 involving the multiplexing of an additional signal and the colour video signal

Abstract

A moving subject detection map is generated by performing moving subject region determination based on input image information from an image capture portion, and is used to set an exposure pattern for a moving subject detected pixel region. The exposure pattern is cyclically arranged with multiple different exposure times. The exposure time for a stationary subject region is set according to the brightness of the subject. Regarding an image captured based on the exposure time control, an output image is generated by computing pixel values for a moving subject region, using pixel value combination processing that utilizes the pixel values of pixels with a plurality of different exposure times being set, and by computing pixel values for the stationary subject region by multiplying a gain according to the exposure time. This achieves the acquisition of a dynamic range image while keeping deterioration of the resolution to a minimum.

Claims

1. An image capture device, comprising:

an image capture circuit comprising an image sensor configured to convert incident light into electrical signals; and

at least one computer processor programmed to;

generate a moving subject detection map that includes moving subject region identification information for a current image received from the image capture circuit;

generate an exposure control map based, at least in part, on the moving subject detection map and having an exposure pattern that cyclically applies a plurality of different exposure times to a moving subject region identified by the moving subject detection map;

output exposure control signals to the image capture circuit based, at least in part, on the exposure control map; and

determine output image pixel values by combining a plurality of pixel value information items for a plurality of pixels for which the plurality of the different exposure times have been set that are derived from the moving subject region.

2. The image capture device according to claim 1, wherein generating the exposure control map further comprises:

setting an exposure time for a stationary subject region of the exposure control map in accordance with a brightness of the subject in the stationary subject region of the current image.

3. The image capture device according to claim 1,

wherein generating the exposure control map comprises generating the exposure control map to define the exposure pattern for the moving subject region such that a same exposure time is not set for adjacent pixels in the moving subject region.

4. The image capture device according to claim 1,

wherein determining the output image pixel values comprises determining the output pixel values to have a wider dynamic range than pixel values of corresponding individual pixels of the current image received from the image capture circuit.

5. The image capture device according to claim 1,

wherein determining the output image pixel values comprises determining the output image pixel values for at least some pixels by multiplying a large gain for a pixel where the exposure time is short and multiplying a small gain for a pixel where the exposure time is long.

6. The image capture device according to claim 1, wherein the at least one computer processor is further programmed to reduce the current image received from the image capture circuit, and generate the moving subject detection map, the exposure control map, and the exposure control signals based, at least in part, on the reduced image.

7. The image capture device according to claim 1, further comprising:

a storage device configured to store the current image received from the image capture circuit, and

wherein generating the moving subject detection portion comprises generating the moving subject detection map based, at least in part, on the current image received from the image capture circuit and a past image stored by the storage device.

8. An image capture device control method that is implemented in an image capture device, comprising:

capturing, by an image capture circuit, a current image;

generating a moving subject detection map that includes moving subject region identification information for the current image;

generating an exposure control map based, at least in part, on the moving subject detection map, wherein the exposure control map includes an exposure pattern that cyclically applies a plurality of different exposure times to a moving subject region identified by the moving subject detection map;

outputting based, at least in part, on the exposure control map, exposure control signals to the image capture circuit; and

determining output image pixel values by combining a plurality of pixel value information items for a plurality of pixels for which the plurality of the different exposure times have been set that are derived from the moving subject region.

9. A non-transitory storage medium having stored thereon a program that causes image capture device control processing to be performed in an image capture device, the program comprising:

capturing, by an image capture circuit, a current image;

generating a moving subject detection map that includes moving subject region identification information for the current image;

generating an exposure control map based, at least in part, on the moving subject detection map, wherein the exposure control map includes an exposure pattern that cyclically applies a plurality of different exposure times to a moving subject region identified by the moving subject detection map;

outputting based, at least in part, on the exposure control map, exposure control signals to the image capture circuit; and

determining output image pixel values by combining a plurality of pixel value information items for a plurality of pixels for which the plurality of the different exposure times have been set that are derived from the moving subject region.