Implement average filter without using built-in functions

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kaan köken
kaan köken 2019-10-21
评论： Image Analyst 2019-10-21
I am trying to blur the image, but I did not succeed. I am keep getting almost black image? What am I missing here?
clc;
clear all;
img = imread("Q3_Input", "tif");
imshow(img);
[M, N] = size(img);
filter = averageFilter(img, M, N);
%blurredImage = conv2(single(img), filter, 'full');
figure;
imshow(filter, []);
%{
since the filter 3x3
i == 1 & j == 1 or
i == 1 & (N - j) == 0 or
(M - i) & j == 1 or
(M - i) & (N - j) == 0
covers the corner areas
x = covered areas
__________
|_x_|__|_x_|
|__|__|__|
|_x_|__|_x_|
the other coverts the middle of the area
|__|_x_|__|
|_x_|_x_|_x_|
|__|_x_|__|
%}
function img = averageFilter(image, M, N)
newImg = zeros(M, N);
for i = 1: M
for j = 1: N
if i == 1
if j == 1
summation = 0;
for k = i: i + 1
for l = j: j + 1
summation = summation + image(k,l);
end
end
newImg(i, j) = ceil(summation / 4.0);
elseif (N - j) == 0
for k = i: i + 1
for l = j - 1: j
summation = summation + image(k,l);
end
end
newImg(i, j) = ceil(summation / 4.0);
else
for k = i: i + 1
for l = j - 1: j + 1
summation = summation + image(k,l);
end
end
newImg(i, j) = ceil(summation / 6.0);
end
elseif (M - i) == 0
if j == 1
for k = i - 1: i
for l = j: j + 1
summation = summation + image(k,l);
end
end
newImg(i, j) = ceil(summation / 4.0);
elseif (N - j) == 0
for k = i -1: i
for l = j -1: j
summation = summation + image(k,l);
end
end
newImg(i, j) = ceil(summation / 4.0);
else
for k = i - 1: i
for l = j - 1: j + 1
summation = summation + image(k,l);
end
end
newImg(i, j) = ceil(summation / 6.0);
end
else
if j == 1
for k = i - 1: i + 1
for l = j: j + 1
summation = summation + image(k,l);
end
end
newImg(i, j) = ceil(summation / 6.0);
elseif (N - j) == 0
for k = i - 1: i + 1
for l = j - 1: j
summation = summation + image(k,l);
end
end
newImg(i, j) = ceil(summation / 6.0);
else
for k = i - 1: i + 1
for l = j - 1: j + 1
summation = summation + image(k,l);
end
end
newImg(i, j) = ceil(summation / 9.0);
end
end
end
end
img = newImg;
end
untitled.jpguntitled1.jpg
original image

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采纳的回答

Matt J
Matt J 2019-10-21
编辑：Matt J 2019-10-21
In all likelihood, you have not converted your image to floating point
img = im2double( imread("Q3_Input", "tif") );
  2 个评论
kaan köken
kaan köken 2019-10-21
If I get rid of the floating points, and do not change the im read. Also, If I add this I am getting white image as result.
blurredImage = img .* filter;
figure;
imshow(blurredImage, []);
However, if I change the imread to your version I am getting this image. Can I do it without floating point solution?
untitled.jpg
Image Analyst
Image Analyst 2019-10-21
No. Computing the mean in a window inherently gives you a floating point number. However, if you want, you can cast the final floating point image into uint8 after the whole window scanning process has finished.

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