Image pickup apparatus and image pickup system

An apparatus comprising:

• a detection unit including a plurality of pixels arranged in a matrix, each of the plurality of pixels being configured to convert radiation or light into an analog signal, the plurality of pixels being divided into at least a first pixel group and a second pixel group;
• a signal processing unit including a first readout circuit configured to read an analog signal output from the first pixel group, a second readout circuit configured to read an analog signal output from the second pixel group, a first analog-to-digital (A/D) converter configured to convert an analog signal from the first readout circuit into a digital signal, and a second A/D converter configured to convert an analog signal from the second readout circuit into a digital signal;
• a power supply unit configured to supply components included in the signal processing unit with respective biases;
• and
• a control unit configured to control at least one of the signal processing unit and the power supply unit,
• wherein the control unit is configured to perform processing of altering an analog signal capable of being input into at least one of the first and second A/D converters or altering an A/D conversion characteristic of at least one of the first and second A/D converters.