Image pickup apparatus capable of controlling flash exposure and control method therefor

1. An image pickup apparatus comprising:

an image sensor that outputs an image signal;

a memory device that stores instructions; and

at least one processor that executes the instructions to:

calculate a main emission amount using a luminance of a pre-emission image corresponding to the image signal;

divide a picked-up image frame corresponding to the image signal into a plurality of blocks;

obtain distance information for each of the plurality of blocks;

adjust a luminance of the image signal for each of the plurality of blocks;

determine whether a distance continuously varies in a same direction between adjacent blocks within a region corresponding to a same object based on the distance information, which is obtained using the image signal of which the luminance has been adjusted;

generate a reflection luminance weight by employing one of a difference and a ratio between an image under external light luminance and an image under luminance at a time of pre-emission photographing; and

calculate an object weight for flash-exposure control using information about a distance weight that is obtained by the determination and information about the reflection luminance weight.

2. The image pickup apparatus according to claim 1 , wherein the at least one processor executes instructions in the memory device to obtain the distance information using an adjusted pre-emission image.

3. The image pickup apparatus according to claim 1 , wherein the at least one processor executes instructions in the memory device to adjust a pre-emission amount for flash-exposure control.

4. The image pickup apparatus according to claim 3 , wherein the at least one processor executes instructions in the memory device to adjust the pre-emission amount so that the luminance of the object at a time of pre-emission photographing will become high within a flash-exposure controllable range.

5. The image pickup apparatus according to claim 1 , wherein the at least one processor executes instructions in the memory device to adjust the external light luminance in exposure setting for flash-exposure control.

6. The image pickup apparatus according to claim 5 , wherein the memory device stores a predetermined pre-emission amount beforehand.

7. The image pickup apparatus according to claim 1 , wherein the at least one processor executes instructions in the memory device to determine that the distance between the adjacent blocks continuously varies in a case where a variation amount of the distance between the adjacent blocks falls within a predetermined range.

8. The image pickup apparatus according to claim 1 , wherein the at least one processor executes instructions in the memory device to determine that the adjacent blocks show a same object in a case where a variation amount of the distance between the adjacent blocks is less than a predetermined amount.

9. The image pickup apparatus according to claim 1 , wherein the at least one processor executes instructions in the memory device to:

divide the plurality of blocks into a first region where the distance is constant and a second region where the distance varies; and

decrease a weight in the second region in contrast with a weight in the first region.

10. The image pickup apparatus according to claim 1 , wherein the at least one processor executes instructions in the memory device to irradiate an object with AF assist light.

11. The image pickup apparatus according to claim 1 , wherein the at least one processor executes instructions in the memory device to presume distance of an object according to a face size of a person as the object in a case where the distance of the object cannot be obtained.

12. The image pickup apparatus according to claim 1 , wherein the at least one processor executes instructions in the memory device to determine whether the distance continuously varies in the same direction between adjacent blocks within the region corresponding to the same object based on the distance information, which is obtained using the image signal of which the luminance has not been adjusted in a case where the external light luminance is determined to be not less than a predetermined luminance.

13. A control method for an image pickup apparatus comprising an image sensor that outputs an image signal, a memory device that stores instructions, and at least one processor that executes the instructions to implement the control method, the control method comprising:

calculating a main emission amount using a luminance of a pre-emission image corresponding to the image signal;

dividing a picked-up image frame corresponding to the image signal into a plurality of blocks;

obtaining distance information for each of the plurality of blocks;

adjusting a luminance of the image signal for each of the plurality of blocks;

determining whether a distance continuously varies in a same direction between adjacent blocks within a region corresponding to a same object based on the distance information, which is obtained using the image signal of which the luminance has been adjusted;

generating a reflection luminance weight by employing one of a difference and a ratio between an image under external light luminance and an image under luminance at a time of pre-emission photographing; and

calculating an object weight for flash-exposure control using information about a distance weight that is obtained by the determination and information about the reflection luminance weight.