Multi-scale variable-step autofocusing searching algorithm data transmission device and method

A technology of automatic focus search and variable step size, which is applied to color TV parts, TV system parts, TVs, etc., and can solve problems such as focus failure

Inactive Publication Date: 2016-05-11
MINNAN NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Especially in complex and changeable industrial image measurement sites, due to the interference of local peaks, the focusing process may fall into repeated back and forth oscillations for a long time, resulting in focusing failure

Method used

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  • Multi-scale variable-step autofocusing searching algorithm data transmission device and method
  • Multi-scale variable-step autofocusing searching algorithm data transmission device and method
  • Multi-scale variable-step autofocusing searching algorithm data transmission device and method

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Experimental program
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Embodiment 1

[0043] see Figure 1 to Figure 6(b) As shown, a multi-scale variable step size automatic focus search algorithm data transmission device of the present invention includes: driving the lens to perform multiple searches on the entire search area, gradually reducing the search range and search step size, and determining by curve fitting The highest point of the curve, so that the searched focus position is as close as possible to the real focus point; the threshold setting is used to compare the two search positions before and after to determine whether the search step is completed; in the multi-scale search process, each search The search position where the maximum evaluation value is located is used as the center point of the next search interval to search for a symmetrical interval to ensure that the real focal point is included in this interval.

[0044] Furthermore, the described multi-scale variable step-size automatic focus search algorithm includes the following steps:

...

Embodiment 2

[0067] During the focusing process, each time the lens advances by one step, an image is collected. In this embodiment, the “brake pad boss” is used as the focus object, and the area to be searched for the first time is a focus window cut at the center of the image with a size of 320×320. Figure 2(a) and Figure 2(b) show two images with different focusing conditions, which are blurred and clear images collected from the brake pad boss respectively. The sharpness evaluation algorithm used in this embodiment adopts Brenner operator.

[0068] The optimal magnification of the test platform used in this embodiment is 3, the optimal light intensity under this condition is 35, and the real focus position is at -74.6990 of the lens. image 3 The sharpness evaluation value curve under ideal test conditions is given, which has the characteristics of single peak and sharpness.

[0069] Figure 4(a) shows the fitting process of the last step of this search method. In the figure, the blac...

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Abstract

The invention discloses a multi-scale variable-step autofocusing searching method. Searching range and searching step length are gradually reduced through multiple times of searching, and the peak of a curve is determined through curve fitting rather than the maximum value of a sharpness evaluation value so that the searched focusing position is enabled to be close to the real focusing point as far as possible; two successive times of searching positions are compared by adopting threshold setting, and completion of searching steps is determined; and the searching position of the maximum value of the evaluation value of each time of searching acts as the center point of the next searching interval to take symmetric intervals for searching in the process of multi-scale searching so that real focusing point is ensured to be included in the interval. According to the method, interference of the local peak value can be effectively eliminated, and optimal searching can be realized, focusing efficiency is high and focusing is accurate.

Description

technical field [0001] The invention relates to the technical fields of image processing and automatic focus, in particular to a multi-scale variable step size automatic focus search method. Background technique [0002] With the continuous development of computer technology and image information processing technology, non-contact measurement based on image technology is widely used in various fields because of its fast, convenient and intelligent characteristics. The basis of non-contact image measurement is to obtain a clear image, and autofocus is an important process for the image system to obtain a clear image, and it is the key technology of the machine vision system. [0003] Auto focus is to evaluate the collected image by selecting the appropriate focus evaluation function, and according to the evaluation result, apply the search algorithm to search the focus point of the image, and then drive the focusing mechanism to make the CCD reach the focus position quickly a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N5/232
Inventor 刘书炘
Owner MINNAN NORMAL UNIV
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