1. A video monitoring apparatus comprising: a video camera for observing a scene and providing an analog signal thereof; an analog-digital convertor for converting an analog signal from said camera consisting of n scanning lines to a digital signal, abridge and memory means for memorizing an abridged part of said digital signal abridged from said digital signal corresponding to said n scanning lines, picture range conversion means for converting a picture range by reading out memorized data from said memory means, to reconstitute a picture signal consisting of n scanning lines, and display means for displaying video pictures produced by said picture range conversion means.