1. A method for restoring a resized depth frame into an original depth frame, comprising steps of: obtaining a first sub-pixel value from one pixel of the resized depth frame; storing the first sub-pixel value in all sub-pixels of a first pixel of the original depth frame; obtaining a second sub-pixel value of the pixel of the resized depth frame; and storing the second sub-pixel value to all sub-pixels of a second pixel of the original depth frame.