Process for automatic focusing

Abstract

The automatic focusing technology is used for finding out optimized focus position in the cases of insufficient background brightness, over large distance between the taken body and the background and varying background during focusing. The automatic focusing process includes the following steps: adjusting the focal length of the lens in the focusing range to obtain one frame of digital image in each relative position; separating the digital image into several regions and finding out the evaluation value for each region; weighting each region; finding out relative position evaluation value to the digital image found for each relative position based on the region evaluation value and region weight; recording the relative position with maximum evaluation value and focusing the lens to the position as optimal focusing position.

Description

technical field [0001] The invention relates to an automatic focus technology, in particular to an intelligent multi-point focus technology used in a digital imaging system. Background technique [0002] In the process of image shooting, the distance between the camera or video camera and the object is often changed, so the image is often blurred due to exceeding the depth of field range. In order to keep the image clear, it is necessary to change the focus position of the lens during the viewfinder process to keep the image clear. This process of adjusting the focus position is called focusing or focusing. [0003] Autofocus technology has been widely used in imaging fields such as cameras, video cameras, and image scanning. It enables the imaging system to automatically adjust the position of the focusing lens group in the lens according to the distance of the object, so that the object is clearly imaged on the imaging plane. There are many kinds of autofocus methods in...

AI Technical Summary

Problems solved by technology

The TTL method has the advantages of correct long-distance focus and no parallax in focus. The disadvantage is that it cannot work normally when the light is too dark and the contrast of the object is low.

[0006] The accuracy of traditional autofocus technology depends on the AF evaluation value. However, since the AF evaluation value only contains contrast information, in specific shooting, if the ambient brightness is not enough, or the distance between the subject and the background is very different, or the When the background changes during the autofocus process, the contrast information cannot accurately reflect the focus situation, so there is no guarantee that the best focus position can be found every time

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