1. A method for upscaling an image, comprising: upscaling an image at a first resolution by pixel interpolation to obtain a coarse upscaled image at a second resolution, the second resolution being higher than the first resolution; and for each pixel of the coarse upscaled image, determining a nonlinear regression function for a patch of at least 3×3 pixels around a current pixel of the coarse upscaled image; and enhancing a value of the current pixel of the coarse upscaled image by adding a result of the nonlinear regression function, wherein a pixel of an enhanced upscaled image at the second resolution is obtained and wherein pixels adjacent to the current pixel are not modified.