To achieve optimum imaging performance, any camera system has to be thoroughly checked before
being used, particular care being given in evaluating the different contributions due to noise. Our work presents a
method for characterising the different sources of noise affecting CCD or CMOS cameras, emphasising the too
often overlooked pattern noise. This method is an extended and theoretical approach of the well-known photon
transfer technique [1]. Experimentation on our high speed CCD imager illustrates this approach.