In one embodiment, a method of examining contents of an object is disclosed comprising scanning an object at first and second radiation energies, detecting radiation at the first and second energies, and calculating a function of the radiation detected at the first and second energies. Each of the upper and lower springs includes an outer annular portion and an inner annular portion, and coupled by bridge portions. A video decoder for decoding video signal data for an image block includes a decoder for decoding all color components of the video signal data using a common predictor. Accordingly, a residual prediction mode is applied for a macro block of an enhanced layer even if a frame temporally simultaneous with a frame of the enhanced layer does not exist in a base layer, thereby improve coding efficiency.