Auto-focusing method and device of thermal imager

Abstract

The invention discloses an auto-focusing method and a device of a thermal imager, belonging to the technical field of infrared image processing. In the invention, a compound video signal output by aninfrared detector outputs digital image data to a microprocessor by a video decoder, or an infrared detector outputs a high-precision digital signal to a microprocessor by a deserializer, the microprocessor calculates definition evaluation functional values, and a motor is driven to drive an infrared lens to move to an optimal focusing position according to the variation trend of the obtained definition evaluation functional values. The method and the device have the advantages that the microprocessor can exactly and rapidly find out the optimal focusing position, reduce the repeated manual operation and manual intervention and improve the imaging quality and the convenience.

Description

technical field [0001] The invention relates to an automatic focusing device of a thermal imager, belonging to the technical field of infrared image processing. Background technique [0002] Obtaining a clear image is the most basic requirement of various digital imaging equipment. There is a set of focusing lenses in the multi-group lenses of the camera lens. The focusing purpose can be achieved by changing the position of the focusing group lenses. Automatic focusing can replace manual completion of this process. This saves a lot of time and improves image quality. Autofocus can be divided into active and passive types. Active autofocus is to measure the distance of the subject by emitting infrared rays or ultrasonic waves, and use a certain mathematical model to calculate the best focus position. This method requires additional distance measuring equipment and has a relatively small scope of application. The passive method refers to the use of the acquired image’s own i...

AI Technical Summary

Problems solved by technology

[0003] Because the infrared lens used in the thermal imager is made of different materials from the ordinary visible light lens, it is usually used to manually rotate the lens or manually control the DC motor to drive the lens to obtain a clearly focused image. This method takes a long adjustment process and the focus accuracy is subject to the subjective influence of the operator. Large; infrared thermal imaging reflects the temperature distribution on the surface of the object. The thermal image of the target is different from the visible light image that the human eye can see. The visible light lens is usually driven by a stepping motor, and the search algorithm is usually controlled by the stepping motor. Therefore, the existing The passive autofocus technology applied to CCD visible light images is not suitable for thermal imagers

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