Abstract: It is an object to provide a reconstructing process method, for a secondary differential value image, being capable of correcting blurring at the contour portion of an original image to form an image having a sharp contour, an image contour emphasizing process method based on the reconstructing process method, and a thermal transfer printer for performing recording based on the contour emphasizing process method. For this purpose, the primary differential value and the second differential value of each pixel of an original image are calculated, the original image is scanned in horizontal and vertical directions to detect a contour line on the basis of the signs of the primary differential value and the secondary differential value, a secondary differential value at a position shifted from the interest pixel by an arbitrary width is substituted as a secondary differential value located at the interest pixel to reconstruct the secondary differential value image.