Techniques are disclosed to enable generation of a high-resolution image from any generic low-resolution image. In one described implementation, a method includes extracting, at a training phase, a plurality of primal sketch priors from training data. At a synthesis phase, the plurality of primal sketch priors are utilized to improve a low-resolution image by replacing one or more low-frequency primitives extracted from the low-resolution image with corresponding ones of the plurality of primal sketch priors.