Diffraction pattern manipulation.

Question

Regis Robles 2016-3-22

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https://ww2.mathworks.cn/matlabcentral/answers/274939-diffraction-pattern-manipulation

评论： Ali Dordaee 2019-10-31

I want to know how to take only the right part of a diffraction pattern matrix. Here is the diffraction pattern in a 1000x1000 matrix :

Here is the code I am using to take only the part from the center to the first 0 of the 'sinc like' pattern

 Mask_radius = 0.431*dx;
 Mask = sqrt(X.^2 + Y.^2) < Mask_radius;
 S1 = abs(U_real.^2);
 S2 = abs((Mask.*abs(fft_U)).^2);

It works but it is not very classy :s.

Result with the code :

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Ali Dordaee 2019-10-31

Could you please send me the whole coding if you have fixed it? I really appreciate it. this is my Email:

alidordaee@gmail.com

If you want, you can also send the coding as my answer on this website. thanks so much.

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Answer 1

Image Analyst 2016-3-22

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https://ww2.mathworks.cn/matlabcentral/answers/274939-diffraction-pattern-manipulation#answer_214624

在 MATLAB Online 中打开

There is nothing wrong or unclassy about that code, except that you don't need the outer abs on S2. There are alternative ways of getting the same thing but they're not necessarily better, like

S2 = abs(fft_U); % Initialize
S2(~Mask) = 0;   % Erase outside Mask
S2 = S2 .^ 2;    % Square.

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Regis Robles 2016-3-23

Yes, it is another way to do the same thing. But I want to know if it is possible to take only the center part of the fft_I = abs(fft_U.^2) matrix.

I want this because when I change some parameters in my program, the Mask matrix does not change and thus S2 = abs((Mask.*abs(fft_U)).^2) gives the wrong result. And in your way, it will be the same wrong result.

Image Analyst 2016-3-23

What does "take" mean? I can think of only two things: erase outside of it (which we've done), or to crop it out to its own image, which you can do by indexing or by using imcrop().

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Answer 2

Tanweepriya Das 2018-8-9

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https://ww2.mathworks.cn/matlabcentral/answers/274939-diffraction-pattern-manipulation#answer_332127

was the problem solved finally?

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Image Analyst 2018-8-9

Evidently not or else he would have marked my answer as "Accepted". Plus he never answered my question about what he means by take. However I doubt he's still working on it after 2 years.

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