1. Laboratory of Image Processing Pier Luigi Mazzeo pierluigi.mazzeo@cnr.it

2. Filtering

3. Neighbourhood processing

4. Mean

5. Filtering in MatLab

6. filter2

7. filter2 (cont.)

8. fspecial (low pass filters) Produce an Average filtering image using 9x9 filter and a 25x25 filter

9. >> hsize = 10; >> sigma = 5; >> h = fspecial(‘gaussian’ hsize, sigma); >> mesh(h); >> imagesc(h); >> outim = imfilter(c, h); >> imshow(outim); fspecial (low pass filters)

10. for sigma=1:3:10 h = fspecial('gaussian‘, fsize, sigma); out = imfilter(c, h); imshow(out); pause; end fspecial (low pass filters)

11. >> noise = randn(size(c)).*sigma; >> output = c+ noise; Noise Periodic noise

12. Cleaning salt and pepper noise

13. fspecial (high pass filters)

15. Unsharp masking Find the image ‘pelicans.tif’ from internet and use u filter >> My = fspecial(‘sobel’); >> outim = imfilter(double(c), My); >> imagesc(outim); >> colormap gray;

16. Canny edge detector MATLAB: edge(c, ‘canny’); >>help edge I = imread('circuit.tif'); BW1 = edge(I,'prewitt'); BW2 = edge(I,'canny'); figure, imshow(BW1) figure, imshow(BW2)