Lecture 10 Image sharpening

Comparison between the difference operators

Enhancement with second derivatives Laplacian: 1 -4 Laplacian mask

Enhancement using laplacian Original image Blurred image Laplacian output Scaled Laplacian image

How to enhance the profile?

Sharpening with Laplacian

Image sharpening with Laplacian Blurred image

Laplacian kernels 1 -4 -1 4 1 -8 -1 8

Unsharp masking

Gradient for enhancement Gradient of f(x,y): Gradient magnitude:

Gradient kernels Some of the gradient kernels are: -1 1 1 -1

Detecting discontinuities using gradient

Gradient magnitude of a profile + -

Gradient kernels 1 -1 2 -2 -1 -2 1 2 Sobel gradient masks -1 2 -2 -1 -2 1 2 Sobel gradient masks Gradients are used for edge detection rather then sharpening