a method of improving image resolution by interpolation combines the concept of convolution with a parameter - controlled mask , with the concept of adjustment of the mask based on edge information . in the method , first the edge information is extracted from the original image data , and then interpolated to the size to which the original image data will be interpolated . with the guidance of the interpolated edge information , the interpolation process will produce an image with high contrast but minimal artifacts . a spline - under - tension function is applied to generate interpolated values , the function being modified for image data points located close to edges .