Projector and camera arrangements are provided for use in electronic whiteboard systems. The method includes sampling for four vertexes of each pixel in a plurality of pixels, sampling for a pivot of the each pixel, and determining a color of the each pixel using the sampling result on the four vertexes and the pivot. The navigational buttons thus affect the player device selection of video tracks through format information added to image frames of the disc. The protruding portions are arranged in a regular array of offset rows.