1. An image processing apparatus for enlarge-processing an original image represented by large number of pixels to acquire an enlarged image, the image processing apparatus comprising: a domain block extracting unit for dividing the original image by a first block unit to extract a plurality of domain block images from the original image; a range block extracting unit for extracting a range block image by a second block unit from the original image, the second block unit being larger than the first block unit and being smaller than an enlarged block unit, which is obtained by enlarging the first block unit by a preset enlarging ratio; an enlarged range block forming unit for forming an enlarged range block image in such a manner that the range block image extracted by the range block extracting unit is enlarged to the enlarged block unit, and each of pixel values of the image enlarged to the enlarged block unit is converted based upon a relationship between the domain block image and the range block image; and an enlarged image acquiring unit for acquiring an enlarged image in such a manner that while employing each of the enlarged range block images formed by the enlarged range block forming unit, the original image is enlarged by the preset enlarging ratio.