Up to now, the cloud cover is obtained for METAR messages by human observers and by special treatment of ceilometers data following algorithm like the ASOS one. In the few past years, several instruments that we can qualify of sky dome imagers and analysers appeared. In this communication we will present the different potential uses of these instruments, and emphasize on the fact that they could be an interesting help for human observers considering repeatability of provided measurements. Finally, we will suggest a list of extra features for these instruments.