How does an unsharp mask work?

Question

I\'ve been playing around with image processing lately, and I\'d like to know how the unsharp mask algorithm works. I\'m looking at the source code for Gimp and it\'s implement

Answer 1

Unsharp Mask works by generating a blurred version of the image using a Gaussian blur filter, and then subtracting this from the original image (with some weighting value applied), i.e.

blurred_image = blur(input_image)
output_image = input_image - blurred_image * weight