1. A video surveillance method, comprising: under control of a video camera module, capturing a subject image of a zone being monitored; analyzing the subject image to detect an occurrence of a variation in the subject image compared to a previously captured image; and outputting the subject image if the occurrence of the variation has been detected in the subject image, wherein: analyzing the subject image includes dividing the subject image into image zones; and the occurrence of a variation in the subject image compared to the previously captured image is detected if a condition is confirmed in at least one image zone of the subject image, the condition being: 
 | MR ( t,i )− MRF ( t− 1 ,i )|≧ G ( i )· VRF ( t− 1 ,i ), in which MR(t,i) is the average value of pixels of the image zone i in the subject image t, MRF(t−1,i) is an average value of pixels of the image zone i calculated on several previous images from a previous image t−1, G(i) is a detection threshold value defined for the image zone i and VRF(t−1,i) is an average variance value calculated on several previous images from the previous image t−1.