Abstract: A method and image processing system is for reconstruction of an input image. The method for reconstruction of an input image includes a step of inputting image data (for example, densities) of at least two pixels nearest to a position of an additional pixel to be added to the input image and those of neighbor pixels located on extension lines of segments drawn between the position of the additional pixel and that of each of the nearest pixels of which the image data were inputted, and a step of estimating the value of the image data of the additional pixel on the basis of the inputted image data of at least two pair of the nearest and corresponding neighbor pixels by using an improved and simple algorithm which is newly proposed herein and called "linear extrapolation and average method".