Automatic background scene defocusing for image compositing

A method for automatically defocusing a video background scene behind a subject, in real time, by defocusing said background scene in proportion to a percent of image frame area occupied by said subject, using a ratio of subject area to background scene area to select for each pixel in the background scene area, a number of adjacent pixels to form an average pixel level.

An apparatus for automatically defocusing a background scene including background pixels, each having a signal level as said background scene is being composited with a foreground subject during the photography of said subject and where said background scene becomes increasingly defocused as said subject appears to approach the camera comprising:

• a compositing device having a foreground input for receiving foreground image signals and a background input for receiving background image signals, said device capable of averaging a selected group of background pixels from a received background image signal and generating a matte signal, said device adapted to use said matte signal to determine the ratio of foreground subject area to image frame area, and the determined area ratio to select, for each pixel in said background image, a number of adjacent pixels to be averaged to form an average pixel level, said device further operating to replace said signal levels at each pixel in said background scene with said average pixel level to defocus said background scene in proportion to the apparent reduction in camera to subject distance.