Electronic device and method for controlling autofocus of camera

1. An electronic device comprising:

a display;

a camera module configured to move an image sensor, wherein the camera module includes a lens unit comprising at least one lens disposed on the image sensor and a lens driving unit configured to move the at least one lens; and

a processor configured to:

in response to triggering of depth from defocus (DFD) auto-focus function, display a first image comprising an external object obtained with a first view angle by using the camera module through the display,

move a location of the at least one lens by using the lens driving unit so that the view angle of the external object changes from the first view angle to a second view angle,

obtain, using the camera module, a second image comprising the external object with the second view angle by moving a location of the at least one lens with a predetermined movement distance through the lens driving unit,

select a part of the second image by cropping the second image, wherein a view angle of the selected part of the second image corresponds to the first view angle,

display the selected part of the second image by using the display, and

determine a focus location of an image for the external object based on a difference between the first image and the second image, and the predetermined movement distance.

2. The electronic device of claim 1 , wherein the processor is further configured to select the part of the second image by cropping the second image based on the predetermined movement distance.

3. The electronic device of claim 1 , wherein the processor is further configured to identify defocus amounts of the first image and the second image based on the first image, the second image, and the predetermined movement distance by using a point spread function, and determine the focus location based on the defocus amounts of the first image and the second image.

4. The electronic device of claim 1 , wherein the processor is further configured to obtain a third image according to the determined focus location and display the third image through the display.

5. The electronic device of claim 1 , wherein the processor is further configured to control the camera module to move the at least one lens in order to obtain the second image at least based on a change of the external object.

6. The electronic device of claim 1 , wherein the processor, as at least one operation of selecting a part of the second image, is further configured to determine a resolution of at least one part of the selected second image based on a resolution of the display.

7. An electronic device comprising:

a display;

a camera module comprising a lens unit and a lens driving unit configured to move the lens unit in order to change a camera focus;

a memory; and

a processor configured to:

in response to triggering of depth from defocus (DFD) auto-focus function, obtain a first image corresponding to a first location of the lens unit by using the camera module,

display the first image by using the display,

move the lens unit according to a predetermined movement distance by using the lens driving unit,

obtain a second image corresponding to a second location of the lens unit by using the camera module,

select a part of the second image by cropping the second image, wherein a view angle of the selected part of the second image corresponds to a view angle of the first image,

display the selected part of the second image by using the display,

determine a focus location of the lens unit at least based on a difference between the first image and the second image, and the predetermined movement distance, and

move the lens unit to the focus location by using the lens driving unit.

8. The electronic device of claim 7 , wherein the view angle of the first image is smaller than a view angle of the second image.

9. The electronic device of claim 8 , wherein the processor is further configured to:

detect a change of an external object,

obtain a third image corresponding to a third location that is identical to the focus location of the lens unit by using the camera module,

obtain a fourth image corresponding to a fourth location of the lens unit by using the camera module, and

determine a focus location corresponding to the change of the external object in the lens unit at least based on a difference between the third image and the fourth image.

10. The electronic device of claim 9 , wherein the processor is further configured to move the lens unit from the third location to the fourth location by the predetermined movement distance or less by using the lens driving unit.

11. A method for controlling an autofocus function in an electronic device, the method comprising:

in response to triggering of depth from defocus (DFD) auto-focus function, obtaining and displaying a first image comprising an external object obtained with a first view angle;

moving a location of at least one lens with a predetermined movement distance, so that a view angle of the external object changes from the first view angle to a second view angle;

obtaining a second image comprising the external object obtained with the second view angle in a state that the location of at least one lens is moved;

selecting a part of the second image by cropping the second image, wherein the view angle of the selected part of the second image corresponds to the first view angle;

displaying the selected part of the second image, and

determining a focus location of an image for the external object based on a difference between the first image and the second image, and the predetermined movement distance.

12. The method of claim 11 , wherein selecting a part of the second image further comprises selecting the part of the second image by cropping the second image based on the predetermined movement distance.

13. The method of claim 11 , wherein determining the focus location further comprises:

identifying defocus amounts of the first image and the second image based on the difference between the first image or the second image and the predetermined movement distance by using a point diffusion function; and

determining the focus location based on the defocus amounts of the first image and the second image.