Image processing calculations edge

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Minhal
Minhal 2013-12-22
评论： Minhal 2013-12-23
I have a script that performs calculations on a image. I want to have the pixels on the edge to have different weighing in this calculation.
I believe the eta20 being produced normally (without the *2) is correct. I'd like to be able to manipulate its value by changing the weight assigned to the boundary pixels
a = ['1.jpg'];
b = imread(a);
a = double(a);
[M, N] = size(a);
[x, y] = meshgrid(1:N, 1:M);
[p, q] = size(b); % Turning image into matrix or p by q dimensions
% Turn x, y, and a into column vectors.
x = x(:);
y = y(:);
a = a(:);
BW = edge(b,'sobel'); %inbuilt matlab function that gives '1' for boundary pixels
imshow(BW)
% Loop through the matrix which is assigning different moments if the pixel
% is on the boundary or not.
for r = 1:p
for c = 1:q
if BW(r,c)==1 %If value is 1 pixel is on the boundary
m.m00 = sum(a);
m.m10 = sum(x .* a);
m.m01 = sum(y .* a);
m.m20 = sum(x.^2 .* a)*2; % *2 has no on effect on eta20
else
m.m00 = sum(a);
m.m10 = sum(x .* a);
m.m01 = sum(y .* a);
m.m20 = sum(x.^2 .* a)*2; %*2 has effect on eta20
end
end
end
xbar = m.m10 / m.m00;
ybar = m.m01 / m.m00;
e.eta20 = (m.m20 - xbar*m.m10) / m.m00^2
If someone could explain what I did wrong? I know its probably more math than matlab.
Note: The final purpose is to calculate Hu's moments which consider the pixels at the edge of the image to be more important in the final calculations but that's exactly what isn't happening

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Image Analyst
Image Analyst 2013-12-22
BW equals 1 not just for the boundary but everywhere it's true. If you want to find pixels on the boundary, use bwperim:
boundaryPixels = bwperim(BW);
[boundaryRows, boundaryCols] = find(boundaryPixels);
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Image Analyst
Image Analyst 2013-12-23
It will not be the opposite. Edges will still be indicated by white lines.
There is nothing to change. If you do
if BW(r,c)==1
then it will do what follows ("the first calculation") if the pixel is on the boundary, just like you asked.
Minhal
Minhal 2013-12-23
Thanks a lot. So the the calculation now considers the boundary pixels. Perfect I really appreciate your help!

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