A method, image processing apparatus, and computer readable medium for image enhancement are provided. In the method, a low-resolution image is received and upscaled to generate an upscaled image having first pixels. Edge detection is performed on the upscaled image to obtain edge information of the first pixels. Each piece of the edge information includes an edge direction and an edge intensity, and each of the edge directions includes a horizontal and vertical component having a constant summation. A non-edge region of the upscaled image is enhanced to generate a high-resolution detail image; based on unsharp masking sharpening methods, an edge region of the low-passed upscaled image is enhanced according to the horizontal and vertical components of the edge directions to generate a high-resolution edge image. Image fusion is performed on the high-resolution edge image and the high-resolution detail image according to the edge intensities to generate a super-resolution image.