Light falling on a pixel is converted into an electrical charge signal.
CIDs are highly resistant to space radiation. They can easily withstand more than 100 times the lethal dose of CCDs. The random x-y addressibility of CID pixels allow real time detection and cancellation of noise induced by the high rate of cosmic ray hits in space during long integrations. CIDs do not bloom. As a pixel saturates the charge is spilled into the silicon substrate, not into adjacent pixels.