MATLAB: How to get the coordinates of a given pixel

Question

I was wondering if there was a method to get the X,Y coordinate of a pixel in an image? I have the pixels that I'd like to get the coordinates of, but as they aren't regions, a regionprops centroid doesn't help, and I need it to be done without user input, so I can't click on them with ginput.

Answer 1

Use bilinear interpolation, like interp2() if you want the exact value of fractional coordinates. However, it may be good enough for you to do a much simpler operation of just rounding the coordinates to the nearest integer and just getting the array element

grayLevel = grayImage(round(y), round(x));

Remember, like Walter said above, it's (y,x) not (x,y) because the first index is rows and y is the row.

You might also like the impixel() function, but I don't find that any more convenient than simple indexing.