A class code of a subject pixel of an HD signal is obtained from pixel data of a class tap extracted from an SD signal. In a memory bank, coefficient data for a generating equation, including parameters for adjusting image quality, for generating elements of a summation matrix for obtaining coefficient data for an estimate equation are stored on a class basis. A summation matrix is generated in accordance with the coefficient data stored in the memory bank and the values of the parameters as specified by a user operation, generating coefficient data for the estimate equation for each class in accordance with the values of the parameters, which is stored in a memory. A calculation circuit calculates pixel data of the subject pixel of the HD signal by the estimate equation from pixel data of the prediction tap extracted from the SD signal and from coefficient data associated with the class code, supplied from the memory.