Zooming method and electronic device using the same

1. A zooming method for an electronic device having a plurality of camera units, the zooming method comprising:

acquiring a first image by a first camera unit;

acquiring a current frame image by scaling the first image according to a zoom instruction;

acquiring a second image by a second camera unit; and

switching the first camera unit to the second camera unit for outputting the second image;

wherein switching the first camera unit to the second camera unit comprising: comparing a size of fields of view of the first camera unit against a size of fields of view of the second camera unit; setting a first threshold value; obtaining a comparison result by comparing a zoom magnification of the current frame image against the first threshold value; and switching the first camera unit to the second camera unit according to the comparison result;

wherein when the field of view of the first camera unit is larger than the field of view of the second camera unit, the first threshold value is set to be not less than a zoom magnification of the second camera unit; the zoom magnification of the current frame image is compared against the first threshold value, and the first camera unit is switched to the second camera unit when the comparison result indicates the zoom magnification of the current frame image is not less than the first threshold value.

2. The zooming method as claimed in claim 1 , wherein the current frame image is acquired at a moment when a zoom instruction input is completed.

3. An electronic device, comprising:

a processor; and

a memory for storing executable instructions of the processor;

wherein the processor is configured to perform the zooming method as claimed in claim 2 by executing the executable instructions.

4. The zooming method as claimed in claim 1 , wherein the first camera unit and the second camera unit have different fields of view.

5. The zooming method as claimed in claim 1 , wherein, when the electronic device has two camera units with different fields of view, the first threshold value is set to be not less than a zoom magnification of the camera unit which has a smaller field of view in both the first camera unit and the second camera unit.

6. The zooming method as claimed in claim 1 , when the field of view of the first camera unit is smaller than the field of view of the second camera unit, the first threshold value is set to be not less than a zoom magnification of the first camera unit; the zoom magnification of the current frame image is compared against the first threshold value, and the first camera unit is switched to the second camera unit when the comparison result indicates the zoom magnification of the current frame image is not less than the zoom magnification of the first camera unit and is less than the first threshold value.

7. The zooming method as claimed in claim 1 , wherein, when the field of view of the first camera unit is larger than the field of view of the second camera unit and there exists at least one camera unit having a field of view that is less than the second camera unit, a third camera unit is determined through the following method: a field of view of a camera unit is less than the field of view of the second camera unit and the difference between the fields of view of the camera unit and the second camera unit is smallest, the first threshold value is set to be not less than a zoom magnification of the second camera and not greater than a zoom magnification of the third camera unit; and the first camera unit is switched to the second camera unit when the zoom magnification of the current frame image is not less than the first threshold value and is less than the zoom magnification of the third camera unit.

8. The zooming method as claimed in claim 1 , wherein, when the field of view of the first camera unit is smaller than the field of view of the second camera unit and there exists at least one camera unit having a field of view that is less than the first camera unit, a third camera unit is determined through the following method: wherein a field of view of a camera unit is less than the field of view of the first camera unit and the difference between the fields of view of the camera unit and the first camera unit is smallest, the first threshold value is set to be not less than a zoom magnification of the first camera unit and not greater than a zoom magnification of the third camera unit; and the first camera unit is switched to the second camera unit when the zoom magnification of the current frame image is not less than zoom magnification of the first camera unit and is less than a zoom magnification of the first threshold value.

9. The zooming method as claimed in claim 1 , wherein, when the field of view of the first camera unit is smaller than the field of view of the second camera unit and there exists at least one camera unit having a field of view between the fields of view of the first camera unit and the second camera unit, a third camera unit is determined through the following method: wherein the field of view of the camera unit is less than the field of view of the second camera unit and the difference between the fields of view of the camera unit and the second camera unit is smallest, the first threshold value is set to be not less than a zoom magnification of the third camera and not greater than a zoom magnification of the first camera unit; and the first camera unit is switched to the second camera unit when the zoom magnification of the current frame image is not less than zoom magnification of the third camera unit and is less than the first threshold value.

10. The zooming method as claimed in claim 1 , wherein, when there exist a plurality of camera units having fields of view between the fields of view of the first camera unit and the second camera unit, a third camera unit is determined, wherein a field of view of the third camera unit is less than the field of view of the second camera unit and the difference between the fields of view of the camera unit and the second camera unit is smallest, and a fourth camera unit is determined, a field of view of the fourth camera unit is less than the second camera unit and the difference between the fields of view of the camera unit and the second camera unit is only greater than the difference between the fields of view of the third camera unit and the second camera unit, the first threshold value is set to be not less than a zoom magnification of the third camera and not greater than a zoom magnification of the fourth camera unit; and the first camera unit is switched to the second camera unit when the zoom magnification of the current frame image is not less than magnification of the third camera unit and is less than the first threshold value.

11. The zooming method as claimed in claim 1 , wherein, at least two of the plurality of camera units have different fields of view, and the zooming method is configured to realize a switch between any two of the plurality of camera units having different fields of view.

12. The zooming method as claimed in claim 1 , wherein, the zooming method further comprises: setting an adjustment coefficient to deform the current frame image or the second image.

13. The method as claimed in claim 12 , wherein setting the adjustment coefficient to deform the current frame image or the second image comprising:

acquiring a deformation parameter of the current frame image and the second image by matching the current frame image and the second image;

calculating a difference between a zoom magnification of the current frame image and a zoom magnification the first threshold value;

setting the adjustment coefficient to the deformation parameter and the difference; and

performing deformation on the current frame image or the second image according to the adjustment coefficient.

14. The method as claimed in claim 13 , wherein, acquiring the deformation parameter of the current frame image and the second image by matching the current frame image and the second image comprising:

marking pixel points, feature points or feature blocks on the current frame image and the second image respectively; and

matching the current frame image and the second image through an image registration method.

15. The method as claimed in claim 13 , wherein, the setting of the adjustment coefficient is related to the deformation coefficient;

when the difference between the zoom magnification of the current frame image and the zoom magnification of the first threshold value is larger, the adjustment coefficient is smaller; and

when the difference between the zoom magnification of the current frame image and the first threshold value is smaller, the adjustment coefficient is larger.

16. A storage medium, wherein the storage medium comprises a stored program, wherein a device in which the storage medium is stored is controlled to execute the zooming method as claimed in claim 1 when the program is running.

17. An electronic device, comprising:

a processor; and

a memory for storing executable instructions of the processor;

wherein the processor is configured to perform the zooming method as claimed in claim 1 by executing the executable instructions.

18. An electronic device having a plurality of camera units, wherein, the electronic device comprises:

at least two camera units having different fields of view, configured to acquire the first image and the second image;

an input unit, configured to acquire a zoom instruction;

a processing unit, configured to acquire a current frame image by scaling the first image according to the zoom instruction;

a control unit, configured to switch one camera unit to another camera unit of the at least two camera units having different fields of view according to the zoom instruction; and

a display unit, configured to output the second image;

the control unit further configured to compare a size of fields of view of the first camera unit against a size of fields of view of the second camera unit; set a first threshold value; obtain a comparison result by comparing a zoom magnification of the current frame image against the first threshold value; and switch the first camera unit to the second camera unit according to the comparison result;

wherein, when the field of view of the first camera unit is larger than the field of view of the second camera unit, the first threshold value is set to be not less than a zoom magnification of the second camera unit; the zoom magnification of the current frame image is compared against the first threshold value, and the first camera unit is switched to the second camera unit when the comparison result indicates the zoom magnification of the current frame image is not less than the first threshold value.

19. The electronic device as claimed in claim 18 , wherein the processing unit is further configured to set an adjustment coefficient for performing the deformation on the current frame image or the second image.