# US 9,521,311 B2 · Quick automatic focusing method and image acquisition apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,521,311 B2 - Document ID: US9521311B2 - Status: Granted - Kind: B2 - Application number: 14/595,655 - Filed: 2015-01-13 - Published: 2015-05-07 - Granted: 2016-12-13 - Earliest claimed: 2013-03-28 - Assignees: Huawei Technologies Co., Ltd. - Applicants: Huawei Technologies Co., Ltd. - Inventors: Kai Li - Web page: https://patentgrep.com/patent/US9521311B2 ## CPC - H04N 23/67: Focus control based on electronic image sensor signals - G03B 13/36: Autofocus systems - H04N 23/61: based on recognised objects - H04N 23/611: where the recognised objects include parts of the human body - H04N 23/69: Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D) ## Abstract A method that includes: detecting, by the image acquisition apparatus, image data of a photographed subject in the case of current photographing parameters, where the photographing parameters include a photographing focal length and a focus, and the image data includes a position of the photographed subject in a formed image and an image size; adjusting the image acquisition apparatus based on the position of the photographed subject in the formed image, so that the position of the photographed subject in the formed image is a 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; and adjusting a photographing focal length of the image acquisition apparatus to the target value of the photographing focal length. ## Claims ### Claim 1 A quick automatic focusing 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; adjusting the image acquisition apparatus such that the position of the photographed subject in the formed image is a first position based on the position of the photographed subject in the formed image; determining a target value of the photographing focal length based on a photographing parameter-image data-photogaphing 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, wherein a focus automatically varies continuously with a continuous variation in the photographing focal length. ### Claim 2 (depends on 1) The method according to claim 1 further comprising: determining a target value of a focus position according to the target value of the photographing focal length; and adjusting a focus of the image acquisition apparatus to the target value of the focus position. ### Claim 3 (depends on 1) The method according to claim 1, further comprising determining the photographing parameter-image data-photographing distance correspondence, wherein determining the photographing parameter-image data-photographing distance correspondence comprises: fixing a photographing distance as a first object distance; adjusting the current photographing focal length; adjusting the focus such that an image of the photographed subject is displayed clearly; and detecting and recording the image data and the adjusted photographing focal length. ### Claim 4 (depends on 1) The method according to claim 1, further comprising determining the photographing parameter-image data-photographing distance correspondence, wherein determining the photographing parameter-image data-photographing distance correspondence comprises: fixing the photographing focal length as a first photographing focal length; adjusting a photographing distance; adjusting the focus such that an image of the photographed subject is displayed clearly; and detecting and recording the photographing distance, the image data, the first photographing focal length, and the adjusted focus. ### Claim 5 (depends on 1) The method according to claim 1, further comprising determining the photographing parameter-image data-photographing distance correspondence, wherein determining the photographing parameter-image data-photographing distance correspondence comprises: setting an initial photographing focal length; setting an initial photographing distance; adjusting the focus such that an image of the photographed subject is displayed clearly; detecting and recording the current photographing focal length, the focus, a photographing distance, and the image data; and updating the photographing distance when the photographing distance is greater than a minimum photographing distance. ### Claim 6 (depends on 5) The method according to claim 5, wherein the photographing focal length is updated when the photographing distance is not greater than the minimum photographing distance. ### Claim 7 (depends on 1) The method according to claim 1, further comprising determining the photographing parameter-image data-photographing distance, wherein determining the photographing parameter-image data-photographing distance correspondence comprises: setting an initial photographing distance; setting an initial photographing focal length; adjusting the focus such that an image of the photographed subject is displayed clearly; recording the focus; and updating the photographing focal length when the current photographing focal length is less than a maximum focal length. ### Claim 8 (depends on 7) The method according to claim 7, wherein the photographing distance is updated when the current photographing focal length is not less than the maximum focal length. ### Claim 9 (depends on 1) The method according to claim 1, wherein determining the target value of the photographing focal length according to the current photographing focal length, the image data, and the preset image size comprises: determining a photographing distance between the photographed subject and the image acquisition apparatus according to the current photographing focal length, the image size, and the photographing parameter-image data-photographing distance correspondence; and determining the target value of the photographing focal length according to the preset image size, the photographing distance, and the photographing parameter-image data-photographing distance correspondence. ### Claim 10 (depends on 1) The method according to claim 1, wherein before adjusting the image acquisition apparatus such that the position of the photographed subject in the formed image is a first position, the method further comprises: determining whether the position of the photographed subject in the formed image is the first position; and skipping adjusting the image acquisition apparatus when the position in the image is the first position such that the position of the photographed subject in the formed image is the first position. ### Claim 11 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. ### Claim 12 (depends on 11) The apparatus according to claim 11, wherein the processor is further configured to enable the focus to automatically vary continuously with a continuous variation in a focal length. ### Claim 13 (depends on 11) The apparatus according to claim 11, wherein the processor is further configured to determine whether the position of the photographed subject in the formed image is the first position. ### Claim 14 (depends on 11) The apparatus according to claim 11, wherein the processor is further configured to: determine a photographing distance between the photographed subject and the image acquisition apparatus according to the current photographing focal length, the image size, and the photographing parameter-image data-photographing distance correspondence; and determine the target value of the photographing focal length according to the preset image size, the photographing distance, and the photographing parameter-image data-photographing distance correspondence. ### Claim 15 (depends on 11) The apparatus according to claim 11, wherein the processor is further configured to adjust the current photographic focal length when a photographic distance is fixed to be a first object distance. ### Claim 16 (depends on 11) The apparatus according to claim 11, wherein the processor is further configured to adjust a photographic distance when the photographing focal length is fixed to be a first photographing focal length. ### Claim 17 (depends on 11) The apparatus according to claim 11, wherein the processor is further configured to determine the photographing parameter-image data-photographing distance correspondence. ### Claim 18 (depends on 11) The apparatus according to claim 11, wherein the processor is further configured to: set an initial photographing focal length; set an initial photographing distance; and adjust the focus such that an image of the photographed subject is displayed clearly. ### Claim 19 (depends on 11) The apparatus according to claim 11, wherein the photographing focal length is updated when the photographing distance is not greater than the minimum photographing distance. ### Claim 20 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.