Self-adaptive automatic focusing method used in digital camera

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...

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