Automatic focusing method and device for camera based on defocus estimation improved hill climbing method

A technology of automatic focusing and hill-climbing method, which is applied in the field of camera focusing, can solve the problems of difficulty in both focusing speed and accuracy, and achieve the effect of solving the difficulty of taking into account speed and accuracy and ensuring focusing accuracy.

Active Publication Date: 2018-07-06
LUOYANG INST OF ELECTRO OPTICAL EQUIP OF AVIC
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  • 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 imp...

Method used

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  • Automatic focusing method and device for camera based on defocus estimation improved hill climbing method
  • Automatic focusing method and device for camera based on defocus estimation improved hill climbing method
  • Automatic focusing method and device for camera 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 an automatic focusing method and device for a camera based on a defocus estimation improved hill climbing method. Thedefocus state of the camera can be regarded as a Gaussian blur state of an image. When the camera is in a quasi-focal state, the original image of a current frame image deviates greatly from a definition evaluation value of the Gaussian blurred image; when the camera is in the defocus state, the original image of the current frame image deviates little from the definition evaluation value of the Gaussian blurred image, and if the defocus depth is larger, the deviation of the definition evaluation value is smaller. Thus, the defocus depth of the current frame image can be expressed by calculating the deviation between the original image of the current frame image and the Gaussian blurred image of the current frame image, and the focusing step of the camera is adaptively adjusted according to the defocus depth, so that the quasi-focus position can be quickly arrived at on the premise that the focusing precision is ensured, and the problem that the speed and the precision of the camera are difficult to balance during focusing is solved.

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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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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