Method and apparatus for controlling flash

1. A method for controlling a flash, the method comprising:

obtaining a statistical gray value of a preview image; and

when the statistical gray value of the preview image is less than a preset threshold,

searching for a corresponding fill light parameter in a preset dynamic fill light table according to the statistical gray value of the preview image;

setting a fill light drive current according to the fill light parameter;

driving a flash lamp to fire a pre-flash by using the fill light drive current;

searching for a corresponding exposure drive current in an exposure parameter table by using the fill light parameter; and

driving the flash lamp to flash by using the exposure drive current.

2. The method for controlling the flash according to claim 1 , further comprising not driving the flash lamp to flash when the statistical gray value of the preview image is greater than or equal to the preset threshold.

3. The method for controlling the flash according to claim 1 , wherein the statistical gray value of the preview image uniquely corresponds to the fill light parameter and the fill light parameter uniquely corresponds to the exposure drive current.

4. The method for controlling the flash according to claim 1 , wherein, after driving the flash lamp to flash, the method further comprises storing a picture taken by using the flash.

5. The method for controlling the flash according to claim 4 , wherein, after storing the picture taken by using the flash, the method further comprises obtaining the statistical gray value of the picture.

6. The method for controlling the flash according to claim 4 , further comprising:

modifying the exposure parameter table to increase the fill light drive current or the exposure drive current if the statistical gray value of the picture is less than a first preset threshold; and

modifying the exposure parameter table to decrease the fill light drive current or the exposure drive current, if the statistical gray value of the picture is greater than a second preset threshold.

7. The method for controlling the flash according to claim 4 , wherein the statistical gray value of the picture is less than a first preset threshold, the method further comprising modifying the exposure parameter table to increase the fill light drive current or the exposure drive current.

8. The method for controlling the flash according to claim 4 , wherein the statistical gray value of the picture is greater than a second preset threshold, the method further comprising modifying the exposure parameter table to decrease the fill light drive current or the exposure drive current.

9. An apparatus for controlling a flash, comprising:

a physical sensor, configured to obtain a statistical gray value of a preview image; and

a processor, configured, when the statistical gray value of the preview image is less than a preset threshold, to search for a corresponding fill light parameter in a preset dynamic fill light table according to the statistical gray value of the preview image, to use a fill light drive current to drive a flash lamp to fire a pre-flash after setting the fill light drive current according to the fill light parameter, to search for a corresponding exposure drive current in an exposure parameter table according to the fill light parameter, and to use the exposure drive current to drive the flash lamp to flash.

10. The apparatus for controlling the flash according to claim 9 , wherein the processor is configured not to drive the flash lamp to flash when the statistical gray value of the preview image is greater than or equal to the preset threshold.

11. The apparatus for controlling the flash according to claim 9 , further comprising a memory, configured to store a picture that is taken after the flash.

12. The apparatus for controlling the flash according to claim 11 , wherein the processor is further configured to obtain the statistical gray value of the picture and, when the statistical gray value of the picture is less than a first preset threshold, to modify the exposure table to increase the exposure drive current and, when the statistical gray value of the picture is greater than a second preset threshold, to modify the exposure table to decrease the exposure drive current.

13. A user terminal, comprising:

a camera;

a flash lamp, configured to operate with the camera;

a physical sensor, configured to obtain a statistical gray value of a preview image; and

a processor, configured, when the statistical gray value of the preview image is less than a preset threshold, to search for a corresponding fill light parameter in a preset dynamic fill light table according to the statistical gray value of the preview image, to use a fill light drive current to drive the flash lamp to fire a pre-flash after setting the fill light drive current according to the fill light parameter, to search for a corresponding exposure drive current in an exposure parameter table according to the fill light parameter, and to use the exposure drive current to drive the flash lamp to flash.

14. The user terminal according to claim 13 , wherein the processor is configured not to drive the flash lamp to flash when the statistical gray value of the preview image is not less than the preset threshold.

15. The user terminal according to claim 13 , further comprising a memory, configured to store a picture that is taken after the flash.

16. The user terminal according to claim 15 , wherein the processor is further configured to obtain the statistical gray value of the picture and, when the statistical gray value of the picture is less than a first preset threshold, to modify the exposure table to increase the exposure drive current, and, when the statistical gray value of the picture is greater than a second preset threshold, to modify the exposure table to decrease the exposure drive current.