Image processing apparatus, image processing method, and recording medium

1. An image processing apparatus comprising:

correction unit configured to generate, from first image data captured while the flash light is emitted, first developed image data by correcting the first image data with use of a first white balance correction value corresponding to flash light, and second developed image data by correcting the first image data with use of a second white balance correction value corresponding to external light;

division unit configured to divide the first image data into a plurality of blocks;

combining ratio calculation unit configured to calculate a flash component and an external light component of each of the blocks divided by the division unit from a luminance value of the first image data and a luminance value of second image data captured while flash light is not emitted, and calculate a combining ratio for each of the blocks based on the calculated flash component and external light component of each of the blocks; and

combining unit configured to combine the first developed image data and the second developed image data generated by the correction unit according to said combining ratio.

2. The image processing apparatus according to claim 1 , further comprising:

first calculation unit configured to calculate the first white balance correction value corresponding to flash light from the first image data captured while the flash light is emitted;

second calculation unit configured to calculate the second white balance correction value corresponding to external light from the second image data captured while the flash light is not emitted.

3. The image processing apparatus a according to claim 1 , wherein the combining ratio calculation unit calculates a combining ratio of each pixel by interpolation processing.

4. The image processing apparatus according to claim 1 , wherein the combining unit selectively combines the first developed image data and the second developed image data at a block based on a luminance value satisfying a predetermined condition.

5. The image processing apparatus according to claim 2 , wherein the second calculation unit calculates the second white balance correction value so as to maintain a tint of a light source.

6. The image processing apparatus according to claim 2 , wherein the second calculation unit corrects the second white balance correction value according to an imaging drive mode.

7. The image processing apparatus according to claim 2 , further comprising a third calculation unit configured to calculate a mixture ratio of the first and second white balance correction values from the ratio of flash light to external light projected onto an object contained in the first image data in a case where a difference between the first white balance correction value and the second white balance correction value is equal to or smaller than a predetermined value, and calculate a third white balance correction value from the first white balance correction value and the second white balance correction value based on the calculated mixture ratio,

wherein the correction unit generates third developed image data with use of the third white balance correction value calculated by the third calculation unit.

8. The image processing apparatus according to claim 2 , further comprising a third calculation unit configured to calculate a mixture ratio of the white balance correction values from the ratio of flash light to external light projected onto an object in a case where the object in the first image data is moving, and calculate a third white balance correction value from the first white balance correction value and the second white balance correction value based on the calculated mixture ratio,

wherein the correction unit generates third developed image data with use of the third white balance correction value calculated by the third calculation unit.

9. The image processing apparatus according to claim 2 , further comprising a third calculation unit configured to calculate a mixture ratio of the white balance correction values from the ratio of flash light to external light projected onto an object in a case where a distance to the object in the first image data is larger than a predetermined amount, and calculate a third white balance correction value from the first white balance correction value and the second white balance correction value based on the calculated mixture ratio,

wherein the correction unit generates third developed image data with use of the third white balance correction value calculated by the third calculation unit.

10. An image processing method comprising:

first calculation of calculating a white balance correction value corresponding to flash light from first image data captured while the flash light is emitted;

second calculation of calculating a white balance correction value corresponding to external light from second image data captured while the flash light is not emitted,

generating, from first image data captured while the flash light is emitted, first developed image data by correcting the first image data with use of a first white balance correction value corresponding to flash light, and second developed image data by correcting the first image data with use of a second white balance correction value corresponding to external light;

dividing the first image data into a plurality of blocks;

calculating a flash component and an external light component of each of the divided blocks from a luminance value of the first image data and a luminance value of second image data captured while flash light is not emitted, and calculating a combining ratio for each of the blocks based on the calculated flash component and external light component of each of the blocks; and

combining the first developed image data and the second developed image data generated by the correcting according to the calculated combining ratio.

11. The image processing method according to claim 10 , further comprising:

calculating the first white balance correction value corresponding to flash light from the first image data captured while the flash light is emitted; and

calculating the second white balance correction value corresponding to external light from the second image data captured while the flash light is not emitted.

12. A non-transitory computer-readable storage medium that stores a program comprising instruction which, when executed by a computer, cause the computer to perform the method of claim 10 .