title: Adding poisson noise to an image with specific mean.
body: <p>How do I add Poisson noise with a specific mean of Poisson distribution in Matlab? The code below gives me a completely white image. </p>
  
  <pre><code>img = im2double(phantom(512));
  figure; imshow(img)
  mean = 1e9;
  R = poissrnd(mean, [512, 512]);
  J = img + R;
  figure; imshow(J);
  </code></pre>