Intelligent adjustment method when video camera performs automatic exposure and apparatus therefor

Patent metadata

Field	Value
Publication number	US-10042233-B2
Application number	US-201415314028-A
Country	US
Kind code	B2
Filing date	Aug 20, 2014
Priority date	May 30, 2014
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

The present invention relates to the field of video camera image processing. Disclosed are an intelligent adjustment method when a video camera performs automatic exposure and an apparatus therefor. In the present invention, a first corresponding relationship between a rate and an aperture is pre-set. The first corresponding relationship records corresponding upper and lower aperture limits required by each rate for achieving the best depth of field of an image. The method comprises the following steps: acquiring the current rate of a video camera; searching for upper and lower aperture limits corresponding to the current rate in a first corresponding relationship; if the current aperture value exceeds the range of the searched upper and lower aperture limits corresponding to the current rate, adjusting the current aperture value to be within the range of the upper and lower aperture limits; and according to the adjusted aperture value, adjusting exposure time and gain to satisfy the need of image brightness. In the present invention, according to different field scenario rates, the aperture is adjusted to be within the aperture range corresponding to the best depth of field so as to acquire the best depth of field, and a shutter and gain are adjusted accordingly, so that the best brightness can be ensured and the best depth of field is achieved at the same time so as to improve image quality.

First claim

What is claimed is:

1. An intelligent adjustment method for automatic exposure performed by a video camera, wherein a first corresponding relationship between magnifications and apertures is preset in the video camera, and the first corresponding relationship records corresponding upper and lower aperture limits required for reaching an optimal depth of field of an image under each magnification, the intelligent adjustment method comprising:
acquiring a current magnification of a video camera;
searching for upper and lower aperture limits corresponding to the current magnification in the first corresponding relationship based on the current magnification;
adjusting a current aperture value to be within a range of the upper and lower aperture limits corresponding to the current magnification if the current aperture value exceeds the found range of the upper and lower aperture limits; and
adjusting exposure time and gain based on the adjusted aperture value to meet requirements of image brightness.

2. The intelligent adjustment method according to claim 1 , wherein a second corresponding relationship between magnifications and lower exposure time limits is pre-set in the video camera, and the step of adjusting exposure time and gain based on the adjusted aperture value to meet requirements of image brightness further comprising:
searching for a lower exposure time limit corresponding to the current magnification in the second corresponding relationship based on the current magnification;
judging whether a current exposure time is smaller than the lower exposure time limit;
adjusting the current exposure time to be not smaller than the lower exposure time limit if the current exposure time is smaller than the lower exposure time limit.

3. The intelligent adjustment method according to claim 1 , wherein a third corresponding relationship between speeds of a motion object and upper exposure time limits is pre-set in the video camera, and the step of adjusting exposure time and gain based on the adjusted aperture value to meet requirements of image brightness further comprising:
determining a speed of a motion object in current scene;
searching for an upper exposure time limit corresponding to the speed in the third corresponding relationship based on the speed of the motion object in current scene;
judging whether a current exposure time is larger than the upper exposure time limit;
adjusting the current exposure time to be not larger than the upper exposure time limit if the current exposure time is larger than the upper exposure time limit.

4. The intelligent adjustment method according to claim 3 , wherein in the step of determining a speed of a motion object in current scene, the speed of the motion object in current scene is determined via image signal processing to obtain a difference between adjacent frames.

5. The intelligent adjustment method according to claim 1 , wherein an upper aperture threshold under lower brightness is pre-set in the video camera, and before the step of adjusting exposure time and gain based on the adjusted aperture value to meet requirements of image brightness, it further comprising:
judging whether a current environment brightness is lower than a predetermined lower brightness threshold;
if yes, judging whether the current aperture value is larger than the upper aperture threshold under lower brightness;
if the current aperture value is larger than the upper aperture threshold under lower brightness, adjusting the current aperture value to be not larger than the upper aperture threshold.

6. The intelligent adjustment method according to claim 1 , wherein in the step of acquiring a current magnification of a video camera, the current magnification is determined by a lens magnification feedback.

7. An intelligent adjustment apparatus for automatic exposure performed by a video camera, wherein a first corresponding relationship between magnifications and apertures is pre-set in the video camera, and the first corresponding relationship records corresponding upper and lower aperture limits required for reaching the optimal depth of field of an image under each magnification, and the apparatus comprising:
a processor and a memory having computer-readable instructions that when executed by the processor performs a method, including: acquiring a current magnification of the video camera;
searching for upper and lower aperture limits corresponding to the current magnification in the first corresponding relationship based on the current magnification;
adjusting a current aperture value to be within a range of the upper and lower aperture limits corresponding to the current magnification if the current aperture value exceeds the found range of the upper and lower aperture limits; and
adjusting exposure time and gain based on the adjusted aperture value to meet requirements of image brightness.

8. The intelligent adjustment apparatus according to claim 7 , wherein a second corresponding relationship between magnifications and lower exposure time limits is pre-set in the video camera, and the processor further:
searches for a lower exposure time limit corresponding to the current magnification in the second corresponding relationship based on the current magnification,
judges whether a current exposure time is smaller than the lower exposure time limit and adjusts the current exposure time to be not smaller than the lower exposure time limit if the current exposure time is smaller than the lower exposure time limit.

9. The intelligent adjustment apparatus according to claim 7 , wherein a third corresponding relationship between speeds of a motion object and upper exposure time limits is pre-set in the video camera, and the processor further:
determines a speed of a motion object in current scene,
searches for an upper exposure time limit corresponding to the speed in the third corresponding relationship based on the speed of the motion object in current scene,
judges whether a current exposure time is larger than the upper exposure time limit and adjusts the current exposure time to be not larger than the upper exposure time limit if the current exposure time is larger than the upper exposure time limit.

10. The intelligent adjustment apparatus according to claim 7 , wherein an upper aperture threshold under lower brightness is pre-set in the video camera and the processor further
judges whether a current environment brightness is lower than a predetermined lower brightness threshold,
judges whether the current aperture value is larger than the upper aperture threshold under lower brightness if the current environment brightness is lower than the predetermined lower brightness threshold, and adjusts the current aperture value to be not larger than the upper aperture threshold if the current aperture value is larger than the upper aperture threshold under lower brightness.

Assignees

• Hangzhou Hikvision Digital Tec

Inventors

• Ma Weimin
• You can

Classifications

• H04N23/71

  Circuitry for evaluating the brightness variation · CPC title

• H04N23/684

  performed by controlling the image sensor readout, e.g. by controlling the integration time · CPC title

• H04N23/73

  by influencing the exposure time · CPC title

• H04N23/6811

  based on the image signal · CPC title

• H04N23/76

  by influencing the image signals · CPC title