Patent ID: 8194127

Claim:
A method for masking a surveillance image taken with a camera, comprising: (a) setting a masking zone corresponding to a protection area on a video frame being taken with the camera and obtaining initial video data from the set masking zone; (b) after a predetermined time, determining whether the masking zone is deviated from the protection area by calculating a correlation between the initial video data and video data obtained from the masking zone, wherein the correlation is calculated using high-frequency components of luminance signals of the initial video data and the video data obtained from the masking zone; and (c) adjusting a position of the masking zone on the video frame, if it is determined that the masking zone is deviated, by repeatedly searching a new masking zone on the video frame until the correlation between the initial video data and video data obtained from the new masking zone is less than a predetermined limit, wherein the new masking zone is obtained by moving the previous masking zone by a predetermined distance, wherein steps (b) and (c) are performed periodically, and wherein the correlation is a value determined based on: a sum of products of corresponding pixel values of two video data groups obtained from the masking zone at different times, an average of pixel values of the two video data groups, or a standard deviation of pixel values of the two video data groups.