Adaptive focusing method

An adaptive, normal-phase technology, applied in the field of image processing, can solve the problems of long time consumption, low precision, low focusing efficiency, etc., to reduce the number of searches, ensure accuracy, and improve focusing efficiency.

Inactive Publication Date: 2016-11-16
UNIV OF SHANGHAI FOR SCI & TECH
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Problems solved by technology

[0002] The adaptive focusing method based on the focus depth method is easy to implement, but the focus depth method has high requirements on the evaluation function and a focus evaluation function cannot be applied to all different target objects. The focus depth method needs to collect a large number of pictures for processing, which costs The time is long and the focusing efficiency is very low
The focusing method based on the depth of defocus only needs to collect two or a few images for corresponding calculations to obtain the defocus amount of the target object. The efficiency is very high, but the accuracy is relatively low.

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specific Embodiment

[0014] Such as figure 1 The flow chart of the method for adaptive focusing shown, the specific embodiment is as follows: comprise the following steps:

[0015] 1) At a certain position, three images are collected continuously, and the interval between two adjacent images is 2DOF (2 times the depth of field), and the value of the focus evaluation function corresponding to the three images is calculated by using the gray variance function, which is recorded as FV 1 、FV 2 、FV 3 , take the minimum value as min(FV) and the maximum value max(FV);

[0016] 2) If min(FV)>70%max(FV), it means that the current position of the target object is near the focus position, and there is no need to perform a rough focus process, skip to step 6), and directly perform fine focus; if min(FV)≤ 70% max(FV), indicating that the current position of the target object is far away from the focus position, enter step 3), and perform rough focus first;

[0017] 3) At the position of the third image col...

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Abstract

The present invention relates to an adaptive focusing method. A focusing depth method and a de-focusing depth method are combined for adaptive focusing. An adaptive focusing process is divided into two phases: rough focusing and fine focusing. In the rough focusing process, a current de-focusing amount of a target object is calculated firstly by means of the de-focusing depth method, the de-focusing amount serves as a reference basis to design a search step size, the search process lasts until an estimated de-focusing amount is smaller than a preset threshold, and the rough focusing process is ended. Then, the focusing depth method is adopted to enter the fine focusing process. Large-step-size search is adopted in an algorithm firstly, thereby greatly reducing the search count and improving the focusing efficiency. Moreover, a large-step-size search policy can also avoid influence of a local peak value of an evaluation function. In addition, an area close to a focusing position is focused by means of a high-precision focusing depth method, thereby ensuring the precision of the algorithm.

Description

technical field [0001] The invention relates to an image processing technology, in particular to a method for adaptive focusing by combining a focus depth method and a defocus depth method. Background technique [0002] The adaptive focusing method based on the focus depth method is easy to implement, but the focus depth method has high requirements on the evaluation function and a focus evaluation function cannot be applied to all different target objects. The focus depth method needs to collect a large number of pictures for processing, which costs If the time is long, the focusing efficiency is very low. However, the focusing method based on the depth of defocus only needs to collect two or a few images for corresponding calculation to obtain the defocus amount of the target object. The efficiency is very high, but the accuracy is relatively low. Contents of the invention [0003] The present invention aims at the problem of image processing by the focus depth method, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N5/232G03B13/36
CPCG03B13/36H04N23/67
Inventor 江旻珊刘召庆张楠楠张学典
Owner UNIV OF SHANGHAI FOR SCI & TECH
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