Cameras are used in many different applications, both indoors and outdoors, to monitor a variety of environments. In certain situations there may be a need to treat one part of a captured image different from another part, for example, for privacy reasons. In such instances, a privacy mask may be defined by an operator during set-up of the surveillance equipment. The privacy mask can be used to distort or completely block out certain portions of the image. This is useful, for example, in situations when a surveillance camera is needed, but some parts should be kept hidden from the surveillance system operator, for example, to protect the privacy of the monitored people.
Typically, privacy masks are created during setup of the system by an operator, by manually marking the area(s) of the image that are to be masked using a graphical user interface. The marked areas are typically in the shape of a polygon or a circle and can usually be easily distinguished from the rest of the image captured by the camera. In some cases, the area inside the polygon or circle is “pixelized” or “blurred,” while in other cases, the polygon or circle has a uniform color (e.g. black) to mask the area of the image. In either case, the mask is very uniform and this can have a significant impact on the image, drawing attention to the mask itself rather than to the information that is actually of interest in the image.