In general, a surveillance camera system can prevent or avert crimes and accidents but is likely to violate personal privacy. This is because even privacy-related parts can be captured by a surveillance camera.
Accordingly, a technology for hiding a privacy area or a subject in an image captured by a surveillance camera is being employed.
This conventional technology is called privacy masking technology (i.e., hiding an area or subject that needs to be concealed to protect personal privacy). The privacy masking technology makes a monitor unable to view a privacy area or a subject that needs to be protected from invasion of privacy by processing an image.
Here, a part of the image which is processed to be hidden from view by the monitor is referred to as a ‘mask area.’
In addition, a general fixed surveillance camera displays the screen that does not change. Therefore, according to the conventional technology, after a privacy mask is fixed once, the mask area continuously matches the privacy area or the subject to be hidden without a problem.
In the case of a pan, tilt and zoom (PTZ) camera, however, when the PTZ camera makes one or more of pan, tilt and zoom movements, the privacy area or the subject to be hidden is also moved. Accordingly, in the conventional technology, the mask area may also move but cannot accurately match the privacy area or the subject to be hidden. In some cases, there is a very high rate of mismatch between the mask area and the privacy area or the subject to be hidden.