title: How do I interpret the result of a 2D fourier Transform on an Image?
body: <p>I am having trouble understanding the result of the 2D Fourier transform on images. Are the indices in the resulting matrix the horizontal and vertical frequencies respectively, of the image? How can I extract the frequencies that are present in the image from the matrix?
  As I recall in the 1D case if one were to Fourier transform a signal, one would get a spectrum representing the Magnitude of each frequency in said signal. How does it work for images? How do I interpret the result?
  Sample code:</p>
  
  <pre><code>img = imread(image);
  A = rgb2gray(img);
  X = fft2(A);
  </code></pre>
  
  <p>How do I interpret the X matrix in this case for example?
  Thanks in Advance! </p>