Matlab Image Processing Toolbox

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MatlabImage Processing Toolbox

• SBIM 2243 Traitement Informatique des Images
  Médicales
• Prof. Benoît Macq

http//www.mathworks.com/access/helpdesk/help/tool
box/images/images.shtml
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Some Basic Topics

• Read and display an image
• Histogram equalization on the image
• Convolution and filtering
• FFT
• Write the image to a disk file

http//www.mathworks.com/access/helpdesk/help/tool
box/images/images.shtml
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Read and display an image

• I imread(cou.jpg')
• imshow(I)
• colormap(hot(256))
• image(I)
• Autres palettes de couleur
• hsv, gray, pink, cool, bone, copper, jet,
• Intensities Y rgb2gray(I) (default rgb)

http//www.mathworks.com/access/helpdesk/help/tool
box/images/images.shtml
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Histogram

• imhist(I)
• histeq(I)

http//www.mathworks.com/access/helpdesk/help/tool
box/images/images.shtml
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Convolution - filtering
The image A 17 24 1 8 15 23 5 7 14
16 4 6 13 20 22 10 12 19 21 3
11 18 25 2 9 the convolution kernel h
8 1 6 3 5 7 4 9 2
conv2(A,h) ou imfilter(A,h)
imfilter fournit des options de traitement des
frontières autres que le zero-padding
http//www.mathworks.com/access/helpdesk/help/tool
box/images/images.shtml
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FFT

• spectrum fft2(I)
• fftshift(spectrum)
• mesh(abs(spectrum))
• (process)
• fftshift(spectrum)
• ifft2(spectrum)

http//www.mathworks.com/access/helpdesk/help/tool
box/images/images.shtml
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Write an image on a disk file

• imwrite( I, filename, format)
• imwrite( I, cou.png, PNG)
• warning to process an image, do not forget to
  convert the uint8 default format into double.
• I imread(filename)
• I double(I)

http//www.mathworks.com/access/helpdesk/help/tool
box/images/images.shtml