Image pickup apparatus capable of reducing influence of flicker, method of controlling the same, and storage medium
An image pickup apparatus capable of reducing influence of flicker while suppressing delay of start of photographing. An image pickup device and a photometric sensor pick up images of an object. A CPU obtains images by controlling driving of one of the device and the sensor to perform charge accumulation and charge readout. Further, the CPU detects a flicker frequency and a flicker phase of a flicker light source, and stores them in a memory as first information. When photographing, if the CPU determines that the first information is not valid, an ICPU obtains images by controlling driving of the other of them to perform charge accumulation and charge readout. Further, the ICPU detects the flicker frequency and the flicker phase and stores them in a memory as second information. The CPU controls exposure timing according to the second information to perform photographing.
1. An image pickup apparatus comprising:
an image pickup unit; and
at least one processor configured to perform:
first calculating light amount change characteristics of light from an object, based on a plurality of photometric values obtained at a period shorter than a first period;
second calculating the light amount change characteristics, based on luminance change information with a reference image, the reference image being an image obtained through charge accumulation using said image pickup unit while differentiating start timing on a region-by-region basis by taking more time than required to obtain the plurality of photometric values by said image pickup unit;
storing characteristics information concerning the light amount change characteristics calculated in a memory based on the plurality of photometric values by said first calculating;
suppression processing for suppressing influence of change in an amount of light from an object, on an image acquired by said image pickup unit; and
in a case where the characteristics information has been stored in said memory, first controlling for not causing said image pickup unit to obtain the reference image, but causing said suppression processing based on the characteristics information stored in said memory.
2. The image pickup apparatus according to claim 1 , wherein said at least one processor performs, in a case where the characteristics information has not been stored in said memory, second controlling for causing said image pickup unit to obtain the reference image, causing said second calculating the light amount change characteristics based on the obtained reference image, and causing said suppression processing based on the calculated light amount characteristics.
3. The image pickup apparatus according to claim 1 , wherein said at least one processor performs, in a case where the characteristics information has been stored in said memory, and a time period elapsed after the characteristics information was stored in said memory is not more than a threshold value, the first controlling, and performs, in a case where the characteristics information has been stored in said memory, and the time period elapsed after the characteristics information was stored in said memory is more than the threshold value, second controlling for causing said image pickup unit to obtain the reference image, causing said second calculating the light amount change characteristics based on the obtained reference image, and causing said suppression processing based on the calculated light amount characteristics.
4. The image pickup apparatus according to claim 1 , wherein in a case where the characteristics information stored in said memory indicates that the change in the amount of light does not occur, said at least one processor performs first controlling for not causing said suppression processing.
5. The image pickup apparatus according to claim 1 , wherein said suppression processing controls charge accumulation time of said image pickup unit for obtaining a moving image.
6. The image pickup apparatus according to claim 1 , wherein said suppression processing is also capable of performing, based on the light amount change characteristics calculated by said first calculating, suppressing influence of change in the amount of light from the object, on a still image obtained using said image pickup unit.
7. The image pickup apparatus according to claim 6 , wherein said suppression processing controls timing for charge accumulation of said image pickup unit for obtaining a still image, based on the light amount change characteristics calculated by said first calculating.
8. The image pickup apparatus according to claim 1 , wherein the first period is 1/120 seconds.
9. A method of controlling an image pickup apparatus, comprising:
first calculating light amount change characteristics of light from an object, based on a plurality of photometric values obtained at a period shorter than a first period;
second calculating the light amount change characteristics, based on luminance change information with a reference image, the reference image being an image obtained through charge accumulation using an image pickup unit while differentiating start timing on a region-by-region basis by taking more time than required to obtain the plurality of photometric values by said image pickup unit;
storing characteristics information concerning the light amount change characteristics calculated in a memory based on the plurality of photometric values by said first calculating;
suppressing influence of change in an amount of light from an object, on an image acquired by the image pickup unit; and
causing, in a case where the characteristics information has been stored in the memory, controlling for not causing said image pickup unit to obtain the reference image, but causing said suppression processing based on the characteristics information stored in the memory.
10. A non-transitory computer-readable storage medium storing a computer-executable program for executing a method of controlling an image pickup apparatus,
wherein the method comprises:
first calculating light amount change characteristics of light from an object, based on a plurality of photometric values obtained at a period shorter than a first period;
second calculating the light amount change characteristics, based on luminance change information with a reference image, the reference image being an image obtained through charge accumulation using an image pickup unit while differentiating start timing on a region-by-region basis by taking more time than required to obtain the plurality of photometric values by said image pickup unit;
storing characteristics information concerning the light amount change characteristics calculated in a memory based on the plurality of photometric values by said first calculating;
suppressing influence of change in an amount of light from an object, on an image acquired by the image pickup unit; and
causing, in a case where the characteristics information has been stored in the memory, controlling for not causing said image pickup unit to obtain the reference image, but causing said suppression processing based on the characteristics information stored in the memory.