How to plot radial profile of a diffraction pattern?

My goal is to radially average a diffraction pattern (please see the attached image) obtained from femtosecond laser and then convert it to pixel vs intensity graph.

Answer 1

[Sergey Loginov]

Better use accumarray based profiling! it is much much faster:

https://www.mathworks.com/matlabcentral/fileexchange/101480-very-fast-radial-profile

Answer 2

[KSSV]

YOu got the image in hand.

1. Use imread to get the pixles of the image i.e to read the image.

2. USe imfindcircles to find the circles on the image.

3. Once you have circle in hand, you can get the pixel values lying inside the circle, to get the average.

Answer 3

[Hugo Trentesaux]

Or you can program a function like this to do the averaging :

function profile = radialAverage(IMG, cx, cy, w)
    % computes the radial average of the image IMG around the cx,cy point
    % w is the vector of radii starting from zero
    [a,b] = size(IMG);
    [X, Y] = meshgrid( (1:a)-cx, (1:b)-cy);
    R = sqrt(X.^2 + Y.^2);
    profile = [];
    for i = w % radius of the circle
        mask = (i-1<R & R<i+1); % smooth 1 px around the radius
        values = (1-abs(R(mask)-i)) .* double(IMG(mask)); % smooth based on distance to ring
        % values = IMG(mask); % without smooth
        profile(end+1) = mean( values(:) );
    end
end