Standard Definition signals are divided into blocks at a tap extracting unit, and pixel data contained in each block is extracted as a class tap. A class classification unit obtains class code based on the pixel data contained in the class tap. An auxiliary data generating unit generates auxiliary data regarding conversion into High Definition signals, based on the class tap extracted by the tap extracting unit. A data generation processing unit performs processing based on the class code and the auxiliary data, thereby yielding excellent High Definition signals.