A data processing apparatus for converting discrete original image data into interpolated image data having a different number of sampling data from the original image data, including generating means for generating a plurality of the interpolated image data from the original image data, first virtualizing means for generating first virtual data including a virtual succession of the original image data, second virtualizing means for generating second virtual data including a virtual succession of each of the plural interpolated image data, error calculating means for calculating error between each of the second virtual data with respect to the plural interpolated image data and the first virtual data, and selecting means for selecting either one of the plural interpolated image data based on the error.