title: Finding size of reconstructed image in iradon in MATLAB
body: <p>Consider the following code:</p>
  
  <pre><code>P = Phantom(256);
  theta = 0:1:179;
  R = radon(P, theta);
  I = iradon(R, theta);
  </code></pre>
  
  <p>iradon.m calculates the size of the reconstructed image using</p>
  
  <pre><code>N = 2*floor(size(R,1)/(2*sqrt(2)))
  </code></pre>
  
  <p>But why this formula? It gives N as approximately equal to number of projections divided by square root of 2. But how will this give size of image? Is there any better way to find the size of image given R and theta?</p>