MATLAB: How to get the pixel value at centroid point

image processing

how i get the pixel value at the centroid of image
i did as below
cn = s(1).Centroid;
rc = round(cn);
pixelValue = img(rc(1),rc(2));
but in some cases error is shown as
Index exceeds matrix dimensions.
Error in exe_demo (line 73)
pixelValue = img(rc(1),rc(2))
But the centroid point is plotted correctly. How to get the pixel value at that point without error.

Best Answer

pixelValue = img(rc(2), rc(1));
The centroid coordinate order is X, Y, but image arrays are in the order Y, X.
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