simple image processing practical

1. DIGITAL IMAGE PROCESSING
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Dr.S.SHAJUN NISHA, MCA.,M.Phil.,M.Tech.,MBA.,Ph.D
Assistant Professor & Head
PG and Research Dept. of Computer Science
Sadakathullah Appa College
shajunnisha78@gmail.com
+91 99420 96220

2. MATLAB Environment
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3. Procedure to create a new script
NewScript
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4. Saving a new script
SaveSave As
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5. Running a program
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6. IMAGE I/O OPERATIONS
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7. Reading and displaying an Image
Syntax
A = imread(filename)
imshow(A)
Example
rgb=imread(‘peppers.png’)
imshow(rgb)
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8. Displaying output with caption
Syntax
A = imread(filename)
imshow(A)
title(‘caption of the output image')
Example
rgb=imread(‘cameraman.tif’)
imshow(rgb)
title(‘cameraman')
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9. Displaying pair of images
Syntax
imshowpair(I,J,'montage’)
Example
I = imread('cameraman.tif’);
J = imread(‘peppers.png’)
imshowpair(I,J,'montage')
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10. Displaying multiple images using subplot
Syntax
subplot(x,y,z)
Example
I = imread('cameraman.tif');
figure,subplot(3,3,1),imshow(I),title('Cameraman');
J = imread('peppers.png');
subplot(3,3,2),imshow(J),title('Peppers');
k = imread('eight.tif');
subplot(3,3,3),imshow(k),title('eight');
L = imread('rice.png');
subplot(3,3,4),imshow(L),title('rice');
M = imread('onion.png');
subplot(3,3,5),imshow(M),title('onion');
N = imread('pears.png');
subplot(3,3,6),imshow(N),title('pears');
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11. Reading and saving a file
Syntax
f=imread(filename)
imshow(f)
imwrite(f,’filename’)
Example
rgb=imread(‘peppers.png’)
imshow(rgb)
imwrite(rgb,’newrgbfile.jpg’)
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12. Arithmetic operations on image
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13. Adding two images
Syntax
Z = imadd(X,Y)
Example
I = imread('rice.png’);
J = imread('cameraman.tif’);
K = imadd(I,J,'uint16’);
imshow(K,[])
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14. Subtracting images
Syntax
Z = imsubtract(X,Y)
Example
I = imread('rice.png');
J=imread('cameraman.tif');
K = imsubtract(I,J);
imshow(K)
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15. Multiply an image
Syntax
Z = immultiply(X,Y)
Example
a=imread('cameraman.tif’)
imshow(a);
J = immultiply(a,0.5);
figure,imshow(J);
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16. Dividing an image
Syntax
Z = imdivide(X,Y)
Example
I = imread('rice.png');
J = imdivide(I,2);
imshow(J)
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17. Complementing images
Syntax
J = imcomplement(I);
Example
I = imread('cameraman.tif');
J = imcomplement(I);
imshow(J)
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18. Absolute difference of image
Syntax
K = imabsdiff(I,J);
Example
I = imread('cameraman.tif');
J=imread('rice.png');
K = imabsdiff(I,J);
imshow(K)
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19. Mathematical operations
I = imread('rice.png’);
J = imread('cameraman.tif’);
K = imadd(I,J,'uint16’);
figure,subplot(3,3,1),imshow(K),title(‘Addition’);
L = imsubtract(I,J);
subplot(3,3,2),imshow(L),title('Subtraction’);
M = immultiply(J,0.5);
subplot(3,3,3),imshow(M),title('Multiplication');
O = imdivide(J,2);
subplot(3,3,4),imshow(O),title('Division');
P= imcomplement(J);
subplot(3,3,5),imshow(P),title('Complement');
Q = imabsdiff(I,J);
subplot(3,3,6),imshow(Q),title('Absolute difference');
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20. Intensity transformations
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21. Adjusting intensity of an image
Syntax
I=imadjust(filename)
Example
I = imread('cameraman.tif');
J=imadjust(I,[0.5 0.75],[0,1]);
imshowpair(I,J,'montage');
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22. Histogram equalization of an image
Syntax
J=histeq(I)
Example
I = imread('cameraman.tif’);
J=histeq(I,50)
imshowpair(I,J,'montage');
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23. Adaptive histogram equalization
Syntax
J = adapthisteq(I)
Example
I = imread('cameraman.tif’);
J = adapthisteq(I);
imshowpair(I,J,'montage');
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24. Histogram of an image
Syntax
J=histeq(I)
Example
I = imread('cameraman.tif’);
figure,imshow(I);
figure,imhist(I);
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25. Spatial filtering
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26. Applying filter
Syntax
B = imfilter(A,h)
Example
originalRGB = imread('peppers.png’);
imshow(originalRGB)
h = fspecial('motion', 50, 45);
filteredRGB = imfilter(originalRGB, h);
figure, imshow(filteredRGB)
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27. Columnwise neighborhood operations
Syntax
B = colfilt(A,[m n],block_type,fun)
Example
I= imread('tire.tif');
I2 = uint8(colfilt(I,[5 5],'sliding',@mean));
imshow(I) title('Original Image’)
figure imshow(I2)
title('Filtered Image')
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28. Pre defined 2D filter
Syntax
h = fspecial(type)
Example
I= imread('cameraman.tif’);
imshow(I);
H = fspecial('disk',10);
blurred = imfilter(I,H,'replicate’);
imshow(blurred);
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29. 2-D order-statistic filtering
Syntax
B = ordfilt2(A,order,domain)
Example
A = imread('snowflakes.png’);
figure imshow(A)
B = ordfilt2(A,25,true(5));
figure imshow(B)
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30. 2-D median filtering
Syntax
J = medfilt2(I)
Example
I = imread('eight.tif’);
figure, imshow(I)
J = imnoise(I,'salt & pepper',0.02);
K = medfilt2(J);
imshowpair(J,K,'montage')
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31. Image restoration
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32. Add noise to image
Syntax
J = imnoise(I,'gaussian’)
Example
I= imread('eight.tif');
imshow(I)
J = imnoise(I,'salt & pepper',0.02);
imshow(J)
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33. Deblur image using regularized filter
Syntax
J = deconvreg(I,psf)
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34. Deblur image using Wiener filter
Syntax
J = deconvwnr(I,psf,nsr)
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35. Taper discontinuities along image edges
Syntax
J = edgetaper(I,PSF)
Example
original = imread('cameraman.tif’);
PSF = fspecial('gaussian',60,10);
edgesTapered = edgetaper(original,PSF);
figure, imshow(original,[]);
figure, imshow(edgesTapered,[]);
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36. Working with different types of
images
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37. Color image to gray scale image
Syntax
I = rgb2gray(RGB)
Example
RGB = imread('peppers.png’);
imshow(RGB)
I = rgb2gray(RGB);
figure imshow(I)
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38. Convert grayscale or binary image to indexed
image
Syntax
[X,cmap] = gray2ind(I,c)
Example
I = imread('cameraman.tif');
[X, map] = gray2ind(I, 16);
imshow(X, map);
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39. Convert indexed image to grayscale image
Syntax
I = ind2gray(X,cmap)
Example
[X, map] = imread('trees.tif');
I = ind2gray(X,map);
imshow(X,map) ;
title('Indexed Image’)
figure imshow(I);
title('Converted Grayscale Image')
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40. Convert RGB image to indexed image
Syntax
[X,cmap] = rgb2ind(RGB,Q)
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41. Convert grayscale image to indexed image
using multilevel thresholding
Syntax
X = grayslice(I,N)
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42. Morphological operations
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43. Dilate image
Syntax
J = imdilate(I,SE)
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44. Erode image
Syntax
J = imerode(I,SE)
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45. Morphologically open image
Syntax
J = imopen(I,SE)
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46. Morphologically close image
Syntax
J = imclose(I,SE)
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47. Morphological operations on binary images
Syntax
BW2 = bwmorph(BW,operation)
remove skeleton
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48. Morpological reconstruction
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49. Fill image regions and holes
Syntax
BW2 = imfill(BW,locations)
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50. Morphological reconstruction
Syntax
J = imreconstruct(marker,mask)
original image eroded image
reconstructed image
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51. Segmentation
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52. Find edges in intensity image
Syntax
BW = edge(I)
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53. Canny operator
Syntax
BW = edge(I,’canny’)
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54. Prewitt Operator
Syntax
BW = edge(I,’prewitt’)
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55. Roberts operator
Syntax
BW = edge(I,’roberts’)
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56. Sobel operator
Syntax
BW = edge(I,’sobel’)
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57. Laplacian of Gaussian(LoG)
Syntax
BW = edge(I,’log’)
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58. Global Thresholding
Syntax
g=im2bw(I,T); T=0.2 T=0.5
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59. Global image threshold using Otsu's method
Syntax
T = graythresh(I)
Example
I = imread('coins.png');
level = graythresh(I)
BW = imbinarize(I,level);
imshowpair(I,BW,'montage')
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