Imaging device and imaging method

An imaging device comprising:

• a pixel that includes a photoelectric converter that converts light into a signal charge and a charge accumulator that accumulates the signal charge and outputs a pixel signal according to an amount of the signal charge accumulated in the charge accumulator;
• an AD conversion circuit that performs Analog-to-Digital (AD) conversion of the pixel signal output from the pixel;
• and
• a control circuit that sets a number of gradations of digital output of the AD conversion of the pixel signal performed by the AD conversion circuit,
• wherein
• the photoelectric converter includes a counter electrode, a pixel electrode connected to the charge accumulator, and a photoelectric conversion layer located between the counter electrode and the pixel electrode,
• the photoelectric converter has photoelectric conversion characteristics such that photoelectric conversion efficiency changes according to a potential difference between the counter electrode and the pixel electrode,
• linearity of a magnitude of the pixel signal with respect to an amount of light incident on the photoelectric converter changes depending on a first voltage supplied from a voltage supply circuit to the pixel, and
• the control circuit changes the number of gradations in accordance with the first voltage.