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A camera autofocus method and system based on frequency domain histogram analysis

An automatic focus and frequency histogram technology, applied in the field of camera focusing, can solve the problems of high cost and low accuracy, and achieve the effects of fast running speed, improved accuracy and improved performance

Active Publication Date: 2021-08-10
SHANGHAI UNIV
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  • Application Information

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Problems solved by technology

The autofocus technology used in traditional cameras has problems such as low precision and high cost, and the widely used autofocus method based on image processing also requires a lot of calculations and many considerations

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  • A camera autofocus method and system based on frequency domain histogram analysis
  • A camera autofocus method and system based on frequency domain histogram analysis
  • A camera autofocus method and system based on frequency domain histogram analysis

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Embodiment Construction

[0026] The invention will be further described below in conjunction with the accompanying drawings, but it is not used to limit the scope of the invention.

[0027] Such as figure 1 As shown, a camera autofocus method based on frequency domain histogram analysis includes the following steps:

[0028] Step 1, the camera 1 provides the shooting data to the processor 2, and performs two-dimensional Fourier transform on the image through the image processing module 3 to obtain a spectrogram;

[0029] Step 2, statistical module 4 carry out histogram statistics on the frequency size and the probability of occurrence thereof obtained after the Fourier transform of the image;

[0030] Step 3, fitting module 5 analyzes the frequency histogram, and draws a normal (Gaussian) distribution density curve and a kernel density (KDE) estimation curve according to the nonparametric density estimation method;

[0031] Step 4. During the out-of-focus-focus-out-of-focus process of the camera 1, ...

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Abstract

The invention discloses a camera auto-focus method and system based on frequency domain histogram analysis. The method includes the following steps: Step 1. The camera provides shooting data to a processor, and two-dimensional Fourier transform is performed on each frame of image to obtain a frequency spectrum Figure; Step 2, carry out histogram statistics on the frequency in the frequency domain; Step 3, analyze the frequency histogram, and draw the normal distribution density curve and kernel density estimation curve according to the non-parametric density estimation method; Step 4, the camera is out of focus — During the process of focusing and defocusing, calculate each frame of image separately, and record the image parameters when the similarity of the two curves is the highest and the peak difference is the smallest; step 5, when the image parameters match the clearest image parameters during the focusing process , the focus is successful. The present invention performs statistical analysis based on frequency domain histograms, obtains focusing parameters by fitting curves, has no special requirements on the environment and calibration targets, and realizes high-precision, high-efficiency, low-cost, and low-complexity autofocus.

Description

technical field [0001] The invention relates to an image focusing method, in particular to a camera auto-focus method and system based on frequency-domain histogram analysis, and belongs to the technical field of camera focusing. Background technique [0002] With the development of information and network technology, the application of cameras has been involved in various fields of our lives. The autofocus technology used in traditional cameras has problems such as low precision and high cost, and the widely used autofocus method based on image processing also requires a lot of calculations and many considerations. In contrast, because different frequency information has different functions in the image structure, analyzing the image from the distribution density of the frequency size histogram in the frequency domain can solve the problems existing in the traditional camera and spatial domain analysis. Contents of the invention [0003] In view of the defects existing i...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06T5/40G06F17/14H04N5/232
CPCG06F17/14G06T5/40H04N23/67
Inventor 曾丹马嘉敏刘涵张之江
Owner SHANGHAI UNIV