1. An apparatus for processing radiographic images, comprising: an inputting unit which inputs a plurality of radiographic images; a blending unit which blends the input radiographic images to form a blended composite radiographic image; and a pixel value adjusting unit which applies a pixel value adjustment to each pixel of the composite image that is located within a stitching boundary of the radiographic images, and which adjusts values of other pixels in the composite image that are located within an adjustment area that is adjacent to the stitching boundary; wherein the adjustment area is determined based on a rate of change of an adjustment amount of the other pixels, wherein the rate of change is dependent on boundary pixel values and on the pixel value adjustment made to the boundary pixels, and wherein the rate of change is a decreasing rate.