When the edge magnitude of an image-block of interest is larger than both that of the image-block of interest after movement and that of an image-block which neighbors the image-block of interest in the moving direction, the edge magnitude and direction of the image-block of interest are updated to those of the image-block of interest after movement. The tray system includes one or more feet which are of a depth at least equal to deepest recessed retaining portion of the tray. The reference voltage from the reference voltage generation circuit is outputted to a power supply voltage generation circuit. The push button also initiates playback of a pre-loaded digital audio file, which may be a spoken message, a sound, a song, music or other such audio recording. It is possible to produce a high-quality radiation cassette having a simple structure which prevents the resin frames integrally molded on the flat plate from being deformed, according to a simple process. The method initiates a demodulation stage of the receiver prior to receiving an initial bit of the payload field.