1. A method of masking part of an image of a scene captured by a camera monitoring the scene, comprising: mounting a light source and marking a part of the scene with light having a predefined spectral content and a spatial verification pattern, capturing an analysis image of the scene by a sensor sensitive to the predefined spectral content, segmenting the analysis image, based on the predefined spectral content, to find a candidate image region, detecting a spatial pattern in the candidate image region, comparing a characteristic of the detected spatial pattern to a corresponding characteristic of the spatial verification pattern, and, if the characteristic of the detected spatial pattern and the corresponding characteristic of the spatial verification pattern match, identifying the candidate image region as a verified image region corresponding to the part of the scene which is illuminated by the light source, obtaining image data representing the scene, and hiding image data, corresponding to the verified image region, from being displayed, by blurring or substituting, and displaying remaining image data, thereby providing a privacy mask for the part of the scene which is illuminated by the light source, or displaying image data corresponding to the verified image region, and hiding remaining image data from being displayed, by blurring or substituting, thereby providing a privacy mask for a non-illuminated part of the scene, modulating the spatial verification pattern between at least a first and a second spatial verification pattern according to a temporal modulation sequence, and with a respective one of the first and the second spatial verification pattern, in accordance with the temporal modulation sequence, repeating said marking, said capturing, said segmenting, said detecting and said comparing.