Sharpening is used to enhance the fine details of images that have been smoothed or blurred. This Demonstration shows how to sharpen images in the spatial domain by using two common methods: the Laplacian operator and unsharp masking.
The Laplacian operator obtains intensity transitions in the image and adds this filtered image to the original to enhance the smoothed details.
Unsharp masking first generates an image (mask) having only the fine details. This is created by subtracting from the original image a smoothed version of it. Then this mask is added to the original image to obtain an enhanced version with more visible fine details. Incidentally, we can boost the effect of the mask added to the image by increasing the weight of the mask in the addition operation.