2. Digital Image Processing Week V Thurdsak LEAUHATONG

3. Sharpening Spatial Filter First and Second Derivative Intensity profile 1 st derivative 2 nd derivative Edge

4. Sharpening Spatial Filter Laplacian Sharpening Laplacian sharpening results in larger intensity discontinuity near the edge.

5. Sharpening Spatial Filter Laplacian Sharpening Before sharpening After sharpening

6. Sharpening Spatial Filter Laplacian of an Image

7. Sharpening Spatial Filter Laplacian Mask 8 0 0 4 0 0 11 1 -8 1 1 1 1 1 10 0 -4 1 1 0 1 0 Application: Enhance edge, line, point Disadvantage: Enhance noise Used for estimating image Laplacian or The center of the mask is positive The center of the mask is negative

8. Sharpening Spatial Filter Laplacian Mask

9. 11 1 -8 1 1 1 1 1 10 0 -4 1 1 0 1 0

10. First Order Partial Derivative: Sobel operators 01 1 0 0 2 -2 -2 1 0 2 0 0 1

11. First Order Partial Derivative: Image Gradient Gradient magnitude A gradient image emphasizes edges

12. First Order Partial Derivative: Image Gradient

13. Spatial Domain Filtering : Spatial Domain Filtering : Mix things up ! + - A Sharpening smooth B EC D