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Find Vertical and Horizontal Edges in Image

Construct Haar-like wavelet filters to find vertical and horizontal edges in an image.

Read the input image and compute the integral image.

I = imread('pout.tif');
intImage = integralImage(I);

Construct Haar-like wavelet filters. Use the dot notation to find the vertical filter from the horizontal filter.

horiH = integralKernel([1 1 4 3; 1 4 4 3],[-1, 1]);
vertH = horiH.'
vertH = 
  integralKernel with properties:

    BoundingBoxes: [2x4 double]
          Weights: [-1 1]
     Coefficients: [4x6 double]
           Center: [2 3]
             Size: [4 6]
      Orientation: 'upright'

Display the horizontal filter.

imtool(horiH.Coefficients, 'InitialMagnification','fit');

Compute the filter responses.

horiResponse = integralFilter(intImage,horiH);
vertResponse = integralFilter(intImage,vertH);

Display the results.

figure; 
imshow(horiResponse,[]); 
title('Horizontal edge responses');

figure; 
imshow(vertResponse,[]); 
title('Vertical edge responses');