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A camera automatic focusing method and device based on defocus estimation improved hill climbing method

A technology of automatic focus and hill-climbing method, which is applied in the field of camera focus, can solve the problem of difficulty in balancing the focus speed and accuracy, and achieve the effect of solving the difficulty in balancing speed and accuracy and ensuring focus accuracy

Active Publication Date: 2020-08-07
LUOYANG INST OF ELECTRO OPTICAL EQUIP OF AVIC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a camera auto-focus method and device based on defocus estimation and improved hill climbing method, to solve the problem that it is difficult to balance the focus speed and accuracy in the camera focus process

Method used

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  • A camera automatic focusing method and device based on defocus estimation improved hill climbing method
  • A camera automatic focusing method and device based on defocus estimation improved hill climbing method
  • A camera automatic focusing method and device based on defocus estimation improved hill climbing method

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Embodiment 1

[0048] Embodiment 1 provides a camera auto-focusing device based on defocus estimation to improve the hill climbing method, including a memory, a processor, and a program stored in the memory and operable on the processor. When the processor executes the program, a camera based on Defocus estimation improves camera autofocus methods for hill climbing methods, such asfigure 1 As shown, the specific process is as follows:

[0049] 1. Obtain the current frame image and calculate the focus step of the current frame image.

[0050] The out-of-focus state of the lens can be regarded as the state of the Gaussian blur of the image. It has been proved by experiments that the Sobel operator is used to evaluate the image quality. The difference between the blurred image and the blurred image after Gaussian blur is small, and the greater the depth of defocus, the smaller the deviation of the sharpness evaluation value. Therefore, the step size of the focus can be adaptively adjusted accor...

Embodiment 2

[0069] Embodiment 2 provides a camera auto-focusing method based on improved hill-climbing method based on defocus estimation, such as Figure 4 As shown, on the basis of Embodiment 1, after calculating the focus step of the current frame image, it is also judged whether the focus step L of the current frame image is the minimum focus step L 0 .

[0070] When L>L 0 , then control the motor to adjust along the set focus direction with the focus step L of the current frame image, and perform step 1 of embodiment 1 again, and cycle until L=L 0 .

[0071] When L=L 0 , the image has reached the close-to-focus position, and the motor is controlled with the minimum focus step size L 0 Adjust along the set focus direction, and perform step 2 of Example 1. Only when the image quality evaluation is the best, that is, when the sharpness evaluation value is the largest and the focus step length is the smallest, can the quasi-focus state be achieved, avoiding local peaks and the impac...

Embodiment 3

[0076] On the basis of Embodiment 1 and Embodiment 2, Embodiment 3 provides a camera auto-focus method based on improved hill-climbing method based on defocus estimation. Less background pixels have an influence on the image definition evaluation value, and the accuracy of the definition evaluation value on the definition evaluation is improved.

[0077] It can be inferred from the usage habits when taking pictures that the uppermost background of the observed target is mostly, and the lower part is mostly the background and target mixed. The auto focus window is selected as the lower center position, for example, if Figure 5 As mentioned above, selecting the position lower than the center as the focus window can avoid the influence of too much background on the calculation of the image definition evaluation value.

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Abstract

The invention relates to the technical field of camera focusing, in particular to a camera automatic focusing method and device based on an improved hill climbing method based on defocus estimation. The out-of-focus state of the camera can be regarded as the Gaussian blur state of the image. When the camera is in the in-focus state, the sharpness evaluation value deviation between the original image of the current frame image and the Gaussian blur image is large; when the camera is in the out-of-focus state, the current The sharpness evaluation value deviation between the original image of the frame image and the Gaussian blur image is small, and the greater the defocus depth is, the smaller the deviation of the sharpness evaluation value is, so the Gaussian blur between the original image of the current frame image and the current frame image can be calculated The deviation of the sharpness evaluation value between images, the defocus depth of the current frame image is represented by the deviation, and the camera’s focusing step can be adaptively adjusted according to the defocus depth, which can quickly and quickly under the premise of ensuring the focusing accuracy It can reach the quasi-focus position, which solves the problem that it is difficult to balance the speed and precision in the process of camera focusing.

Description

technical field [0001] The invention relates to the technical field of camera focusing, in particular to a camera automatic focusing method and device based on an improved hill climbing method based on defocus estimation. Background technique [0002] The camera's autofocus technology is designed to achieve sharper images. Commonly used image autofocus techniques can be divided into focus depth method and defocus depth method. The defocus depth method obtains the focus depth information from the defocus image to complete autofocus. Therefore, the defocus depth method needs to establish a mathematical model to describe The camera imaging system adjusts the focal length of the lens to the quasi-focus position, and the focusing speed is fast, but due to the difficulty in establishing a mathematical model of the imaging system, it is rarely used. The focus depth method is a focus method based on the search process. Through image analysis and calculation, combined with historica...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04N5/232
CPCH04N23/67
Inventor 陈水忠姜良伟
Owner LUOYANG INST OF ELECTRO OPTICAL EQUIP OF AVIC
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