two for loops problem

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yunwei hu
yunwei hu 2020-3-6
评论： yunwei hu 2020-3-6
Hi everyone,
here i want to get pixel intensity out of a 512*512 image.
i wrote two for loops, but in the end in matrix 'intensityValue', l got only the last set of data.
the background is to get the coordinates from x and y. corx and cory are 41*75 matrices.
Thanks !
fluo = imread('fluo0020.tif');
% imshow(fluo);
corx=[];
cory=[];
intensityValue=[];
for i=1:length(coordinate)
A = [coordinate ; coordinate(1,:)] ;
if mod(i, 2) == 1
x= int16(A(:,i));
y= int16(A(:,(i+1)));
corx=[corx,x];
cory=[cory,y];
end
% scatter(x,y);
% line(x,y);
% hold all
end
for ttt=1:length(x)
xc=x(ttt,:);
xy=y(ttt,:);
inten=fluo(xc,yc);
intensityValue =[intensityValue;inten];
end
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yunwei hu
yunwei hu 2020-3-6
i am still new to write the code.... it's true there not so much logic..
what l tried to get is the same corresponding values(the same row and column) from corx and cory, which l have uploaded. They are actually the x and y coordinates.
And from the two vuales, i get the intensity from the image.
the final intensityValue i expected is a 42*75 matrix
Thank you for your reply!
Ameer Hamza
Ameer Hamza 2020-3-6
Please check the one-liner in the answer to directly extract the value instead of writing a for loop.

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Ameer Hamza
Ameer Hamza 2020-3-6
编辑：Ameer Hamza 2020-3-6
You are directly use corx and cory variables to extract values from the matrix instead of the second for loop in your code.
intensityValue = fluo(sub2ind(size(fluo), cory, corx)); % cory is the row number and corx is the column number
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Ameer Hamza
Ameer Hamza 2020-3-6
As you can see, the image dimension is 512x512, and some elements of corx and cory are higher than 512. Therefore it is throwing an error. I guess that there is some issue in the calculation of the corx and cory in the first loop.
yunwei hu
yunwei hu 2020-3-6
Now i see.
i would check the data again.
thank you so much for your help!

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