title: Rawpy raw image pattern
body: <p>I'm trying to read and demosaic raw images in Python using the RawPy module. Unfortunately the module does not provide simple demosaic method, but a complete postprocess function which is not suitable for my case since I want to keep the floating point images, instead of using 8bit uint. I also do not want to get gamma applied, or any other postprocessing, so I end up demosaicing them manually. When I use the <em>raw_pattern</em> method of RawPy object where I have loaded the dng image I get this:</p>
  
  <pre><code>In[23] : raw_image.raw_pattern
  Out[23]: array([[0, 1],
                  [3, 2]], dtype=uint8)
  </code></pre>
  
  <p>But Adobe's DNG documentation says</p>
  
  <pre><code>Digital Negative Specification
  September 2012
  CFAPlaneColor
  ...
  Value  
  See below
  Default 
  0, 1, 2 (red, green, blue)
  </code></pre>
  
  <p>And I get confused where does that <strong>3</strong> come from?
  If there is another way to demosaic raw image It's also suitable, since it's easy for me to replace this part of the project.</p>
  
  <p>Thanks is advance!</p>