1. An image magnification device for generating a high-resolution image from a low-resolution image, comprising: an interpolation computation unit that treats, as positions of interest, positions where pixels in the high-resolution image occupy when the high-resolution image is superimposed on the low-resolution image, and for each position of interest, obtains a pixel value for a pixel of interest assumed to be present at that position by performing an interpolation computation using pixel values of a plurality of pixels within the low-resolution image and interpolation coefficients for the plurality of pixels; and an interpolation coefficient calculation unit that obtains the interpolation coefficients by giving the interpolation coefficients values that increase with increasing strength of correlation of the pixels in the plurality of pixels in the low-resolution image with the pixel of interest, and outputs the interpolation coefficients to the interpolation computation unit; wherein the interpolation coefficient calculation unit includes a first variation quantity calculation unit for obtaining a first variation quantity in a first direction centered on each pixel in the low-resolution image, a second variation quantity calculation unit for obtaining a second variation quantity in a second direction centered on each pixel in the low-resolution image, a direction calculation unit for using a first interpolated variation quantity obtained by interpolation from the first variation quantity and a second interpolated variation quantity obtained by interpolation from the second variation quantity to obtain direction indication data indicating a direction of strong correlation, and a coefficient calculation unit for obtaining the correlation coefficients from the direction indication data.