Contrast detection autofocus using adaptive step
AssigneeSz Dji Technology Co., Ltd.
InventorLifu Yu
Life of this patent
Estimating the term…
Abstract
A method for moving an optical device relative to an image sensor to focus an image includes receiving a current image acquired by the image sensor when the optical device is at a current position relative to the image sensor, obtaining a current contrast value of the current image and a current contrast variation rate at the current position, determining whether the current contrast variation rate meets a first threshold criterion, moving the optical device from the current position to a next position in accordance with the determination result, and repeating the aforementioned operations until a next contrast variation rate for a next image meets a second threshold criterion. The next image is acquired when the optical device is at the next position.
Claims20
A method for moving an optical device relative to an image sensor to focus an image, comprising:
- a. receiving a current image acquired by the image sensor when the optical device is at a current position relative to the image sensor;
- b. obtaining a current contrast value of the current image and a current contrast variation rate at the current position;
- c. determining whether the current contrast variation rate exceeds a first threshold gradient value;
- d. moving the optical device from the current position to a next position in accordance with the determination result;
- and
- repeating steps a to d until a next contrast variation rate for a next image exceeds a second threshold gradient value, the second threshold gradient value being less than the first threshold gradient value, the next image being acquired when the optical device is at the next position.
An unmanned aerial vehicle (UAV), comprising:
- a propulsion system;
- an imaging device comprising an image sensor and an optical device;
- and
- one or more processors individually or collectively configured to:
- a. receive a current image acquired by the image sensor when the optical device is at a current position relative to the image sensor;
- b. obtain a current contrast value of the current image and a current contrast variation rate at the current position;
- c. determine whether the current contrast variation rate exceeds a first threshold gradient value;
- d. move the optical device from the current position to a next position in accordance with the determination result;
- and
- repeat steps a-d until a next contrast variation rate for a next image exceeds a second threshold gradient value, the second threshold gradient value being less than the first threshold gradient value, the next image being acquired when the optical device is at the next position.
A system for focusing an image, comprising:
- one or more processors;
- and
- an optical device and an image sensor;
- the one or more processors configured for:
- a. receiving a current image acquired by the image sensor when the optical device is at a current position relative to the image sensor;
- b. obtaining a current contrast value of the current image and a current contrast variation rate at the current position;
- c. determining whether the current contrast variation rate exceeds a first threshold gradient value;
- d. moving the optical device from the current position to a next position in accordance with the determination result;
- and
- repeating steps a to d until a next contrast variation rate for a next image exceeds a second threshold gradient value, the second threshold gradient value being less than the first threshold gradient value, the next image being acquired when the optical device is at the next position.
Dependencies are inferred from the claim text.