In a digital ticketing system, tickets are created in groups. A path of connected pixels in first image data is calculated based on pixel gradient energy. However, not all the service requirements negotiated through the signalling layer can be supported at the bearer layer by any user’s equipment. A translation mechanism is coupled to the first and second electronic devices. Then the control unit performs a fine feedback control on the variable gain amplifier based on the detected level. Since the positioning frame secures the flexible substrate and the copper plate against movement, a thin optical device can be attained without employing a resin-molded construction.