Autofocus method and system, shooting device

Abstract

The present invention relates to an autofocus method and system, and a photographing device. The method includes the following steps: obtaining a preview image generated by an imaging device; performing face recognition on the preview image, determining a feature frame of the face contour, and obtaining the The size information of the face contour feature frame; determine the current object distance according to the size information of the human face contour feature frame, the preset object distance, the reference size information of the human face contour feature frame and the preset correction coefficient, and determine the current object distance according to the current object distance auto focus. The present invention can quickly calculate the object distance and perform automatic focusing, and the focusing speed is fast without sacrificing masking pixels and increasing manufacturing costs, thereby meeting the use requirements of the front camera.

Description

technical field [0001] The invention relates to the field of imaging technology, in particular to an autofocus method and system, and a photographing device. Background technique [0002] Generally speaking, the auto-focus technology means that the shooting device will move the lens to change the distance between the lens and the object to be photographed, so as to obtain the subject image with maximum clarity. [0003] Existing mobile devices, such as smart phones, are equipped with a front camera and a rear camera. The front camera is often used for self-portraits, but the front cameras of mobile devices on the market use fixed focus due to various reasons. Autofocus cannot be achieved. Commonly used autofocus technologies for rear cameras include contrast detection focusing, PDAF phase focusing, and infrared focusing. Among them, contrast focusing is carried out in the main sensor CMOS in the shooting device, and the focus point can be set arbitrarily within a wide rang...

AI Technical Summary

Problems solved by technology

Among them, contrast focusing is carried out in the main sensor CMOS in the shooting device, and the focus point can be set arbitrarily within a wide range, but the focus speed is slow; PADF phase focus calculates the object distance based on the phase difference between the left and right pixels. Then convert the object distance into a current signal that drives the focus motor to move, but PADF phase focusing will sacrifice some pixels of the image sensor (these pixels are called masked pixels, or Masked Pixels, appearing in pairs); infrared focusing uses infrared ranging The device measures the distance between the object and the shooting device (that is, the object distance), and then converts the object distance into a current signal that drives the focus motor to move. However, due to the introduction of an infrared distance measuring device, it is bound to increase the manufacturing cost.

Therefore, none of the autofocus techniques in the traditional method is suitable for use on the front camera

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