High quality imaging is a key parameter in many scientific applications. CCD and ICCD cameras have proven to be powerful tools and are consequently used in a wide range of fields such as engineering research and physical or biological sciences. The very new Electron Multiplying CCD technology seems now to provide the most sensitive detection capabilities. Here we compare analytically the signal-to-noise performance of the three systems and identify the most influencing parameters. The SNR provided by CCDs is strongly influenced by the readout noise and is also a significant function of the pixel rate. ICCD cameras are practically not at all affected by the CCD chip temperature and are shown to be mostly shot-noise-limited because readout and dark current noises are negligible. Therefore no cooling is needed for ICCDs. Although EMCCDs unite the quantum efficiency of CCDs and the gain of ICCDs, their performance is constricted by charge transfer and dark current noises which will be multiplied up along with the signal by the gain register. Therefore, EMCCDs must be strongly cooled (down to -70°C) and slowly read out in order to get rid of any unwanted "pseudo signal". In addition, their properties limit exposure times to milliseconds time scales and longer. We conclude that ICCD cameras remain the most efficient systems in all gated experiments and perform very well in extreme low light situations. They still keep great advantages over standard CCDs and the new incoming generation of EMCCDs.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.