Imaging device and imaging method

1. An imaging device comprising:

an optical system which captures an image of a subject;

an image sensor which converts the image captured by the optical system into an electric signal;

a classifying unit which classifies the captured image into a plurality of areas, including at least a first area and a second area, according to brightness information and color information;

a white balance correcting unit which calculates white balance correction coefficients for the first and second areas, the white balance correction coefficient for the first area being different from the white balance correction coefficient for the second area; and

a white balance correction coefficient adjusting unit which receives the white balance correction coefficients for the first and second areas and then calculates an adjusted white balance correction coefficient for at least one of the first and second areas, such that the adjusted white balance correction coefficient for the at least one of the first and second areas is within a predetermined range of a white balance correction coefficient for another one of the first and second areas;

wherein the first and second areas are a sunny area and a shadow area, respectively,

wherein the imaging device further comprises a face detecting unit which detects a facial area in a captured image,

wherein when the face detecting unit detects the facial area and the facial area includes the plurality of areas classified by the classifying unit, the white balance correction coefficient adjusting unit adjusts a difference in the white balance correction coefficients set for the plurality of areas to be within a second predetermined range,

wherein when the facial area does not include the plurality of areas classified by the classifying unit, the white balance correction coefficient adjusting unit adjusts the difference in the white balance correction coefficients set for the plurality of areas to be within a first predetermined range, and

wherein the second predetermined range is less than the first predetermined range.

2. An imaging device according to claim 1 , further comprising a cloudiness determining unit which determines whether or not a captured image is a cloudy scene, wherein when the cloudiness determining unit determines that the captured image is a cloudy scene, the white balance correcting unit adjusts a white balance correction coefficient set for the sunny area to be closer to a white balance correction coefficient set for the shadow area.

3. An imaging device according to claim 1 , wherein: the plurality of areas are each formed of n divided blocks having a predetermined size, the n being an arbitrary integer of 1 or more; and the white balance correcting unit adjusts a white balance correction coefficient for a divided block in the shadow area among divided blocks near a boundary between the sunny area and shadow area to be closer to a white balance correction coefficient for the sunny area.

4. An imaging device according to claim 1 , wherein: the plurality of areas are each formed of n divided blocks having a predetermined size, the n being an arbitrary integer of 1 or more; the white balance correcting unit sets a white balance correction coefficient for each of the divided blocks; and the white balance correction coefficient adjusting unit adjusts a difference in the white balance correction coefficients set for adjacent divided blocks in at least one of the plurality of areas to be within a third predetermined range.

5. An imaging method comprising the steps of:

classifying a captured image into a plurality of areas according to brightness information and color information;

setting different white balance correction coefficients for the plurality of areas;

subsequently, adjusting a difference in the white balance correction coefficients for the plurality of areas to be within a first predetermined range;

classifying an image into a strobe light area and an ambient light area as the plurality of areas when the image is captured with use of an auxiliary strobe light; and

detecting a facial area in a captured image; and

when the facial area is detected in the detecting step and the facial area includes the plurality of areas classified by the classifying unit, adjusting a difference in the white balance correction coefficients set for the plurality of areas to be within a second predetermined range;

when the facial area does not include the plurality of areas classified by the classifying unit, adjusting the difference in the white balance correction coefficients set for the plurality of areas to be within a first predetermined range; and

wherein the second predetermined range is less than the first predetermined range.

6. An imaging method according to claim 5 , further comprising the steps of: determining whether or not a captured image is a cloudy scene; and upon determining that the captured image is a cloudy scene in the determining step, adjusting a white balance correction coefficient set for the sunny area to be closer to a white balance correction coefficient set for the shadow area.

7. An imaging method according to claim 5 , wherein the plurality of areas are each formed of n divided blocks having a predetermined size, the n being an arbitrary integer of 1 or more, the method further comprising the step of adjusting a white balance correction coefficient for a divided block in the shadow area among divided blocks near a boundary between the sunny area and the shadow area to be closer to a white balance correction coefficient set for the sunny area.

8. An imaging method according to claim 5 , wherein the plurality of areas are each formed of n divided blocks having a predetermined size, the n being an arbitrary integer of 1 or more, the method further comprising the steps of: setting a white balance correction coefficient for each of the divided blocks; and adjusting a difference in the white balance correction coefficients set for adjacent divided blocks in at least one of the plurality of areas to be within a third predetermined range.

9. A non-transitory computer readable storage medium in which a program is stored, the program allowing a computer having an image processing function to execute:

classifying of a captured image into a plurality of areas according to brightness information and color information;

setting of different white balance correction coefficients for the plurality of areas; and

subsequently, adjusting a difference in the white balance correction coefficients for the plurality of areas to be within a first predetermined range;

classifying an image into a strobe light area and an ambient light area as the plurality of areas when the image is captured with use of an auxiliary strobe light;

detecting a facial area in a captured image; and

when the facial area is detected in the detecting step and the facial area includes the plurality of areas classified by the classifying unit, adjusting a difference in the white balance correction coefficients set for the plurality of areas to be within a second predetermined range;

when the facial area does not include the plurality of areas classified by the classifying unit, adjusting the difference in the white balance correction coefficients set for the plurality of areas to be within a first predetermined range; and

wherein the second predetermined range is less than the first predetermined range.