1. A video image stabilisation system for correction of camera motion, that is arranged to receive one or more signals representative of a plurality of images from an image source wherein, for an image n following at least an image (n−1) and an image (n−2) the system is arranged to estimate a Global Motion Offset (GMO) value between image n and a previous image representative of the spatial separation between the scene imaged in image n and the previous image, and apply a corrective movement to the image n based upon this GMO, characterised in that: the system is arranged to estimate the GMO for the image n with reference to a mask that represents a region or regions of the image n not to be considered in the GMO estimation, the region(s) being region(s) estimated as likely to mislead the estimation of the GMO.