title: create a grayscale image
body: <p>I am reading binary data from one file that specifies intensity values across x and y coordinates (not a open-source image format) and want to convert it to a PNG image (or other widely supported format). I have the data loaded into an array (using the array module) where each element is a integer from 0 to 255. To save this to a PNG I can create a 3 item tuple of each element (x) like so:</p>
  
  <pre><code>t = (x, x, x)
  </code></pre>
  
  <p>add apply it across the array using the map(), then save the image using putdata(). However, the conversion to the array of tuples takes a long time (few minutes). Is there a way to specify the rgb value using only one integer (not a tuple). I guessing an alternative would be to use NumPy, but I don't know where to start, so any help in this regard would also be appreciated.</p>
  
  <p>Thanks in advance for the help.</p>