Real-time radiation sensor calibration

A method of calculating an offset calibration parameter of a pixel of a camera, comprising acts of:

• determining a gain of the pixel during a period of operation of the camera between first and second times, after an initial calibration procedure;
• exposing the pixel to both scene and ambient radiation at a third time;
• measuring an ambient temperature of the pixel at the third time;
• and
• calculating the offset calibration parameter of the pixel using the gain of the pixel between the first and second times and the ambient temperature of the pixel at the third time.

An imaging apparatus, comprising:

• at least one pixel to detect radiation and to output image signals based on the detected radiation;
• a temperature sensor to detect an ambient temperature;
• and
• means for calculating an offset calibration parameter for the at least one pixel using a gain of the at least one pixel during a period of operation of a camera between first and second times after an initial calibration procedure, and an ambient temperature at a third time, wherein the pixel is exposed to both scene and ambient radiation at the third time.