Quick automatic focusing method and image acquisition apparatus

An image acquisition apparatus comprising:

• a lens comprising focal length lens group and a focus lens group;
• a processor coupled to the lens;
• and
• memory coupled to the processor and configured to store a photographing parameter-image data-photographing distance correspondence and a preset image size,
• wherein the processor is configured to:
• obtain image data of a photographed subject and current photographing parameters, wherein the current photographing parameters comprise a photographing focal length and a focus, wherein the image data comprises a position of the photographed subject in a formed image and an image size, wherein the image acquisition apparatus is adjusted such that the position of the photographed subject in the formed image is a first position;
• determine a target value of the photographing focal length according to the current photographing focal length, the image data, and the preset image size, wherein the focal length lens group is adjusted such that the current photographing focal length of the image acquisition apparatus is the target value of the photographing focal length;
• and
• determine a target value of a focus position according to the target value of the photographing focal length, wherein the focus lens group is adjusted such that a focus of the image acquisition apparatus is the target value of the focus position.

A method, comprising:

• detecting, by an image acquisition apparatus, image data of a photographed subject following current photographing parameters, wherein the current photographing parameters comprise a photographing focal length, and wherein the image data comprises a position of the photographed subject in a formed image and an image size;
• determining whether the position of the photographed subject in the formed image is a first position;
• adjusting the image acquisition apparatus such that the position of the photographed subject in the formed image is the first position when the position of the photographed subject in the formed image is not the first position;
• determining a target value of the photographing focal length based on a photographing parameter-image data-photographing distance correspondence and according to a current photographing focal length, the image data, and a preset image size;
• adjusting the current photographing focal length of the image acquisition apparatus to the target value of the photographing focal length.