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Digital image-forming automatic focusing method based on Contourlet transform

A kind of automatic focus and digital technology, applied in the direction of focusing device, image communication, color TV parts, etc., can solve the problem of poor noise resistance

Inactive Publication Date: 2008-09-17
NINGBO UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The calculation amount required for the focus evaluation method based on space is relatively small, but its disadvantage is that it is greatly affected by noise, that is, the noise immunity is poor

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  • Digital image-forming automatic focusing method based on Contourlet transform
  • Digital image-forming automatic focusing method based on Contourlet transform
  • Digital image-forming automatic focusing method based on Contourlet transform

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Embodiment Construction

[0018] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0019] A digital imaging autofocus method based on Contourlet transform, which includes the following steps: ①For a digital microscopic imaging system, continuously adjust the focus to obtain input signals of images with different resolutions; ②Two-dimensional input for each image The signal f is subjected to multi-level Contourlet transformation to obtain a set of Contourlet transformation coefficients {C j，k}, where C j，k Represents the coefficient matrix of the kth subband of the jth layer of the Contourelet domain (j=1, ..., J, J is the layer with the highest resolution); ③Contourlet transform has sparsity, that is, only a small number of transform domain coefficients are used for inverse transformation It can effectively approximate the original image. As far as the high-frequency coefficients of Contourlet transform are concerned, most...

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Abstract

The invention discloses a digit imaging automatic focusing method based on Contourlet transforming, which uses the multiple resolution factor multidirection characteristic of the Contourlet transforming, selects important coefficient in the Contourlet domain capable of expressing the image profile sharpness detail enrichment degree, so as to determine the accurate focusing position of the digit image-forming system. According to images including a plurality of veins with rather consistent direction, the method using the veins peripheral dominant direction to determine the subband of the Contourlet domain domain dominant direction, can more effectively utilize direction information of the images, thereby improving focusing sensitivity,and reducing calculation complicated degree.

Description

[0001] This application is a divisional application of the invention patent application No. 200610053118.6. technical field [0002] The invention relates to a digital imaging automatic focusing method, in particular to a digital imaging automatic focusing method based on Contourlet transformation. Background technique [0003] In an imaging system, the lens has an optimal image plane position for imaging an object. Deviation from this position will result in blurred images and reduced imaging quality; therefore, it is very important for an imaging system to be able to focus accurately. The imaging system based on the digital image adopts the automatic focus method, and its key lies in the focus evaluation function. The ideal focus evaluation function curve shows a parabolic shape, its peak value corresponds to the best imaging position, and the function value decreases when leaving the best point. Therefore, the process of autofocus is essentially a process of finding the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G03B13/36H04N5/232
Inventor 蒋刚毅易文娟郁梅
Owner NINGBO UNIV