Image sensor and image capturing apparatus

An image sensor, comprising:

• a pixel region in which a plurality of unit pixels are arranged in a matrix, each unit pixel having a plurality of photoelectric conversion portions;
• a readout unit that performs a first readout operation and a second readout operation, the first readout operation reading out a first signal from at least one of the plurality of photoelectric conversion portions in each unit pixel, and the second readout operation reading out second signals from all of the plurality of photoelectric conversion portions in each unit pixel;
• a generation unit that generates, based on the first signals and the second signals, a third signal equivalent to signals of photoelectric conversion portions that have not been read out in the first readout operation;
• and
• an output unit that outputs the first signals, the second signals, and the third signal.

An image capturing apparatus, comprising:

• an image sensor including
• a pixel region in which a plurality of unit pixels are arranged in a matrix, each unit pixel having a plurality of photoelectric conversion portions,
• a readout unit that performs a first readout operation and a second readout operation, the first readout operation reading out a first signal from at least one of the plurality of photoelectric conversion portions in each unit pixel, and the second readout operation reading out second signals from all of the plurality of photoelectric conversion portions in each unit pixel, and
• a generation unit that generates a first luminance signal based on the first signals corresponding to different colors;
• a signal processing unit that generates a second luminance signal based on the second signals corresponding to different colors, and generates, based on the first luminance signal and the second luminance signal, a third luminance signal equivalent to signals of photoelectric conversion portions that have not been read out in the first readout operation;
• and
• a focus detection unit that performs focus detection based on the first luminance signal and the third luminance signal.

An image capturing apparatus, comprising:

• an image sensor including
• a pixel region in which a plurality of unit pixels are arranged in a matrix, each unit pixel having a plurality of photoelectric conversion portions,
• a readout unit that performs a first readout operation and a second readout operation, the first readout operation reading out a first signal from at least one of the plurality of photoelectric conversion portions in each unit pixel, and the second readout operation reading out second signals from all of the plurality of photoelectric conversion portions in each unit pixel,
• a generation unit that generates, based on the first signals and the second signals, a third signal equivalent to signals of photoelectric conversion portions that have not been read out in the first readout operation, and
• an output unit that outputs the first signals, the second signals, and the third signal;
• a focus detection unit that performs focus detection based on the first signals and the third signal output from the image sensor;
• and
• a signal processing unit that generates image data based on the second signals output from the image sensor.