Horizontal average on Image

2017 10 6
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更新时间：2017 10 6
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Given that the mask is hor = 0 0 0, 1 1 1, 0 0 0
I have to apply to my image. Afterwards, find the sum and divide by 3.
My code is:
clear; % Clear the workspace
A = imread('Nature.jpg');
I = imrotate(A,90,'bilinear','loose');
grey = 0.21*I(:,:,1)+0.72*I(:,:,2)+0.07*I(:,:,3);
Grey = double(grey);
HorMask = [0 0 0;1 1 1;0 0 0];
[r,c] = size(Grey);
OUT = zeros(r-3,c-3);
for i = 1:(r-3)
for j = 1:(c-3)
GreySquare = Grey(i:(i+2),j:(j+2));
res = HorMask.*GreySquare;
Divide = res./3;
OUT(i,j) = sum(Divide);
end
end
figure()
imshow(OUT);
However, I am not able to divide by 3. with error message:
Subscripted assignment dimension mismatch.
Error in HorizontalAverage (line 16)
OUT(i,j) = sum(Divide);

1 个评论
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Jan
Jan 2017-10-6
"I am not able" does not explain, what the problem is. Do you get an error message? If so, please post it completely. It is much easier to solve a problem than to guess, what the problem is.

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 采纳的回答

Andrei Bobrov
Andrei Bobrov 2017-10-6
编辑：Andrei Bobrov 2017-10-6

1 个投票

A = imread('Nature.jpg');
I = imrotate(A,90,'bilinear','loose');
grey = 0.21*I(:,:,1)+0.72*I(:,:,2)+0.07*I(:,:,3);
Grey = double(grey);
OUT = conv2(Grey,[1,1,1]/3,'same'); % or OUT = filter2([1,1,1]/3,Grey);

7 个评论
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Edina Lee
Edina Lee 2017-10-6
I do not want to use the in-build function. Is there a way?
Andrei Bobrov
Andrei Bobrov 2017-10-6
编辑：Andrei Bobrov 2017-10-6
Hm! Homework?
[m,n] = size(Grey);
g = [zeros(m,1),Grey,zeros(m,1)];
ii = reshape(1:numel(g),[m, n + 2]);
OUT = mean(g(bsxfun(@plus,ii(:,1:end-2),reshape(m*(0:2),1,1,[]))),3);
Edina Lee
Edina Lee 2017-10-6
编辑：Edina Lee 2017-10-6
There is a error, the dimension do not match. do I need to change to double for the mean and reshape?
Image Analyst
Image Analyst 2017-10-6
If Andrei's new answer of not using built-in functions satisfies your definition of not using built-in functions, then please mark it as accepted to give him reputation points. Otherwise see this link.
http://www.mathworks.com/matlabcentral/answers/38787-what-can-be-programmed-without-any-built-in-functions
Andrei Bobrov
Andrei Bobrov 2017-10-6
编辑：Andrei Bobrov 2017-10-6
Thank you Image Analyst!
Hi Edina! I'm fixed my first comment.
Edina Lee
Edina Lee 2017-10-6
there is still an error and it shows:
Error using sum
Trailing string input must be 'double','native', or 'default'.
Error in mean (line 82)
y = sum(x,dim,flag)/size(x,dim);
Error in Untitled2 (line 10)
OUT = mean(g(bsxfun(@plus,ii(:,1:end-2),reshape(m*(0:2),1,1,[]))),3,'omitnan');

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