Techniques for sharpening an image using local spatial adaptation and/or patch-based image processing. An image can be sharpened by creating a high-frequency image and then combining that high frequency image with the image. This process can be applied iteratively by using the output of one iteration, i.e., the sharpened image, as the input to the next iteration. Using local spatial adaptation and/or patch-based techniques can provide various advantages. How to change the intensity at a given position in the image can be calculated from more than just information about that same position in the input image and the blurred image. By using information about neighboring positions an improved high frequency image can be determined that, when combined with the input image, reduces ringing and halo artifacts, suppresses noise boosting, and/or generates results with sharper and cleaner edges and details.