Image pickup apparatus and image pickup system

A system comprising:

• a detector including a plurality of pixels which converts radiation into analog electric signals;
• an A/D convertor configured to convert an analog electric signal into a digital signal;
• a generating device configured to generate radiation;
• and
• a controller configured to control the generating device,
• wherein the controller controls the generating device in accordance with information on an A/D conversion characteristic of the A/D convertor and information on an input analog electric signal to be input to the A/D convertor.

A method comprising:

• converting radiation or light into analog electric signals by a detector including a plurality of pixels;
• reading an analog electric signal by a reading circuit output from the detector and converting the read analog electric signal into a digital signal by an A/D converter of a signal processor;
• applying bias to the detector and the signal processor by a power-supply unit;
• and
• controlling at least one of the signal processor and the power-supply unit in accordance with information on an A/D conversion characteristic of the A/D convertor and information on an input analog electric signal.