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Bilateral Filter - MATLAB
clc, close all, clear all;
img = imread('puppy.jpg');
A = rgb2gray(img);
[m,n] = size(A);
%Filter Parameters setup
windowSize = input('Enter window size (3/5/7):\n ');
stDevSpace = input('Enter space standard deviation (1-20):\n ');
stDevColor = input('Enter color standard deviation (1-20):\n ');
switch windowSize
case 3
disp('Window size 3x3 is set')
wNum = 1;
centerPixelX = 1 + wNum;
centerPixelY = 1 + wNum;
xStartBoundary = 1 + wNum;
xEndBoundary = m - wNum;
yStartBoundary = 1 + wNum;
yEndBoundary = n - wNum;
case 5
disp('Window size 5x5 is set')
wNum = 2;
centerPixelX = 1 + wNum;
centerPixelY = 1 + wNum;
xStartBoundary = 1 + wNum;
xEndBoundary = m - wNum;
yStartBoundary = 1 + wNum;
yEndBoundary = n - wNum;
case 7
disp('Window size 7x7 is set')
wNum = 3;
centerPixelX = 1 + wNum;
centerPixelY = 1 + wNum;
xStartBoundary = 1 + wNum;
xEndBoundary = m - wNum;
yStartBoundary = 1 + wNum;
yEndBoundary = n - wNum;
otherwise
disp('Please choose something')
end
for i = xStartBoundary:xEndBoundary
for j = yStartBoundary:yEndBoundary
windowM = A([i-wNum:i+wNum],[j-wNum:j+wNum]);
sumTogether = 0.0;
sumOutput = 0;
%% Before Normalization
for runX = 1:windowSize
for runY = 1:windowSize
meanDifX = runX-centerPixelX;
meanDifY = runY-centerPixelY;
difSpace = double(sqrt(meanDifX^2 + meanDifY^2));
difColor = double(abs(windowM(runX,runY) - A(i,j)));
beforeNormSpace(runX,runY) = (0.399/stDevSpace) * exp(-difSpace/(2*stDevSpace^2)); %0.399 = 1/sqrt(2pi)
beforeNormColor(runX,runY) = (0.399/stDevColor) * exp(-difColor/(2*stDevColor^2)); %0.399 = 1/sqrt(2pi)
sumTogether = sumTogether + beforeNormSpace(runX,runY)*beforeNormColor(runX,runY);
end
end
%% After Normalization
for runXX = 1:windowSize
for runYY = 1:windowSize
afterNormMatrix(runXX,runYY) = (beforeNormSpace(runXX,runYY)*beforeNormColor(runXX,runYY))/sumTogether;
end
end
%% Convolution with input
for runXXX = 1:windowSize
for runYYY = 1:windowSize
sumOutput = sumOutput + afterNormMatrix(runXXX,runYYY) * windowM(runXXX,runYYY);
end
end
%%
outputImage(i,j) = sumOutput;
end
end
%Ignoring last rows and columns
for i = 1:m
for j = 1:n
if (i == 1 || j == 1 || i == m || j == n)
outputImage(i,j) = A(i,j);
end
end
end
%Result
figure(1)
subplot(1,2,1), imshow(A);
title('Input:');
subplot(1,2,2), imshow(outputImage);
str = sprintf('wndw = %d, stdspc = %d, stdclr = %d', windowSize, stDevSpace, stDevColor);
title(str)
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