Method and device for improving automatic focusing accuracy and speed of camera

Abstract

The invention relates to the field of image processing and food monitoring, and particularly discloses a method and a device for improving the automatic focusing accuracy and speed of a camera. The method for improving the automatic focusing accuracy and speed of the camera is characterized by sequentially comprising the steps of video image collection, image format conversion, focusing template setting, night vision low-illumination scene definition evaluation value calculation, daytime scene definition evaluation value calculation, peak searching and motor-driven lens focus finding. The threshold value of the change of the definition evaluation value in the hill climbing algorithm is adaptively adjusted according to the brightness contrast, the gradient contrast and the ISO value, the change trend of the current evaluation value can be effectively judged, the peak value can be found more quickly, and the automatic focusing speed and accuracy of night vision and low-illumination scenes are improved.

Description

[0001] (1) Technical field [0002] The invention relates to the field of image processing and food monitoring, in particular to a method and device for improving the accuracy and speed of automatic focusing of a camera. [0003] (2) Background technology [0004] Focusing can be divided into two categories, one is automatic focus, and the other is manual focus. When the camera first appeared, the focus could only be achieved by manually adjusting the focus ring. With the continuous improvement and development of technology, autofocus technology has also emerged. Automatic focusing is also divided into two categories: (1) Active: The infrared generator and ultrasonic generator on the camera emit infrared light or ultrasonic waves to the subject, and the receiver on the camera receives the emitted infrared light or ultrasonic waves for active focusing. Type focus. This method is difficult to focus on oblique surfaces, smooth surfaces, light-absorbing or wave objects, and difficult ...

AI Technical Summary

Problems solved by technology

[0006] The existing disclosed technical solutions propose a method for calculating the image focus evaluation value using the spatial domain and frequency domain sharpness evaluation value algorithms. These image sharpness evaluation methods can obtain better focus curve monotonicity and peaks in scenes with better light , but in scenes with weak light, low contrast or complex lighting, it will be affected by noise and light. The specific performance is that the monotonicity is not obvious, the glitch phenomenon is serious, the peak is not good, and the evaluation value of the same scene at different times fluctuates. , Oscillation, the position with the highest evaluation value is not necessarily the clearest position

In addition, for the focusing curve obtained by the above method, the extremum search algorithm is relatively easy to fall into the local extremum, resulting in focusing failure

In summary, for scenes with a lot of noise, complex light, and low contrast, it is difficult for existing technologies to guarantee the speed and accuracy of autofocus

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