A data processing apparatus for processing image data includes a variance information calculator configured to calculate variance information indicating the degree of variance of pixel values for each of a plurality of pixels constituting the image data; a smoothing section configured to smooth the variance information and to output a smoothed value; a determination section configured to determine an area to which the pixel belongs on the basis of the smoothed value and to output area information indicating the area; a parameter determination section configured to determine a parameter for a noise removal process for each of the pixels constituting the image data on the basis of the area information and the smoothed value; and a noise removal section configured to perform the noise removal process on the image data on the basis of the parameter determined for each of the pixels.