Extracting radially symmetric data from a matrix

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MatlabUser17
MatlabUser17 2018-5-15
评论： Rena Berman 2018-5-30
Hi. I have a 2D matrix which I can plot using imagesc with respect to distance: x and y (from -xs to +xs). Here's how I discretize my data on x and y:
xs=D./2;
dx=2.*xs./N;
dy=dx;
X=linspace(-xs,xs,N);
Y=linspace(-xs,xs,N);
[x y]=meshgrid(X,Y);
r1=(x.^2+y.^2).^(0.5);
TH1=atan2(y,x);
Now I need to extract radially symmetric sets of data for further analyzing. I mean from 0 to r1. How should I choose the width of r? If I have two matrices like this, how can I interpolate and compare the data on the same 'r' from one matrix with the other one? Thanks

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回答（1 个）

Image Analyst
Image Analyst 2018-5-16
Do you want something like this:
D = 10
N = 100
xs=D./2;
dx=2.*xs./N;
dy=dx;
X=linspace(-xs,xs,N);
Y=linspace(-xs,xs,N);
[x y]=meshgrid(X,Y);
r1=(x.^2+y.^2).^(0.5);
subplot(2, 2, 1);
imshow(r1, []);
axis on;
circleMask = r1 < 3;
subplot(2, 2, 2);
imshow(circleMask, []);
axis on;
r2 = r1 .* double(circleMask);
subplot(2, 2, 3);
imshow(r2, []);
axis on;
% Get mean of r1 image inside circle mask
mean_r1 = mean(r1(circleMask))
message = sprintf('The mean of r1 inside the circle mask = %f', mean_r1);
uiwait(helpdlg(message));
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MatlabUser17
MatlabUser17 2018-5-16
I do have the toolbox. How should I do it? So we get radial distribution of intensity line?
Image Analyst
Image Analyst 2018-5-17
No, pass the coordinates of the circle perimeter (your x and y) into improfile().

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