Images are upsampled using a knowledge base derived from a plurality of high-quality training images. The knowledge base is used to refine a high-frequency component including high-frequency aspects of a high-resolution, low-frequency image, interpolated from a low-resolution full-frequency image, into a high-frequency component. An enhancement step is performed without using a knowledge base to construct a high-compatibility component from the low-resolution, full-frequency image. The low-resolution, full-frequency image is combined with the coarse high-frequency component to yield an enhanced high-frequency component. A second knowledge base step is performed to construct an improved high-frequency component from the enhanced high-frequency component. The improved high-frequency component is blended with a high-resolution, low-frequency image to yield a high-resolution image.