Self-adaptive automatic focusing method used in digital camera

A digital camera and auto-focusing technology, applied in the field of auto-focusing technology, can solve problems such as less research

Inactive Publication Date: 2006-12-13
NANJING UNIV OF POSTS & TELECOMM
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Problems solved by technology

However, the current autofocus methods have less research on this problem.

Method used

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  • Self-adaptive automatic focusing method used in digital camera
  • Self-adaptive automatic focusing method used in digital camera
  • Self-adaptive automatic focusing method used in digital camera

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Experimental program
Comparison scheme
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Embodiment Construction

[0039] The steps of the self-adaptive autofocus method in a digital camera are as follows:

[0040] a. Collect original color images with a digital camera;

[0041] b. According to the resolution of the original image, the color middle area of ​​the original image is cut out as a sub-image by the method of adaptive window;

[0042] c. Convert the colored sub-image to a grayscale image;

[0043] d. Perform two-dimensional DCT transformation on the gray-scale sub-image to obtain two-dimensional DCT coefficients;

[0044] e. Carry out adaptive weighting to the two-dimensional DCT coefficient according to the size of its frequency, and calculate the image definition evaluation function;

[0045] f. According to the image definition evaluation function, a whole search strategy is used to control the movement of the stepping motor, and a clear focused image is searched.

[0046] The specific steps of the adaptive window method are as follows: first calculate the resolution of the...

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Abstract

Disclosed is a self-adapting self-focusing method in digital camera. The method comprises steps of: a. collecting original colorful image with digital camera; b. taking the central area in the original colorful image as sub image and cutting out with self-adapting window according to the resolution of the original image; c. converting the colorful sub image into gray-scale image; d. performing two dimensional DCT transformation on the gray-scale sub image and obtaining two dimensional DCT coefficients; e. performing self-adapting weight on the two dimensional DCT coefficients according to its frequency and calculating image clearness evaluation function; f. employing a global searching strategy to control the movement of the stepper motor according to the image clearness evaluation function and searching out clear focused-image.

Description

technical field [0001] The invention relates to an automatic focusing technology in a digital camera, which belongs to the technical field of image processing of the digital camera. Background technique [0002] In terms of basic principles, automatic focusing methods can be divided into two categories: one is the active method; the other is the passive method. The active method is a distance measurement method based on the distance measurement between the lens and the object to be photographed. The optical system is adjusted according to the situation of the object to be photographed. The characteristic of the active method is to measure the distance and Orientation, and calculate the best focus position according to the principle of optical imaging, and then control the motor through the information processor to achieve automatic focus, so this method is called the active method. Due to the need for additional distance measuring equipment, the instruments using this metho...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G03B13/36H04N5/232
Inventor 韩柯朱秀昌刘峰胡栋冯荃朱轶凡干宗良
Owner NANJING UNIV OF POSTS & TELECOMM
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