title: CGBitmapContextCreate: unsupported parameter combination
body: <p>I'm getting this error when creating a bitmap context:</p>
  
  <p>CGBitmapContextCreate: unsupported parameter combination: 8 integer bits/component; 24 bits/pixel; 3-component color space; kCGImageAlphaNone; 7936 bytes/row.</p>
  
  <p>Here's the code (note that the context is based on the parameters of an existing CGImage:</p>
  
  <pre><code>context = CGBitmapContextCreate(NULL,
                                  (int)pi.bufferSizeRequired.width,
                                  (int)pi.bufferSizeRequired.height,
                                  CGImageGetBitsPerComponent(imageRef),
                                  0,
                                  CGImageGetColorSpace(imageRef),
                                  CGImageGetBitmapInfo(imageRef));
  </code></pre>
  
  <p>Width is 2626, height is 3981. I've leaving bytesPerRow at zero so that it gets calculated automatically for me, and it's chosen 7936 of its own accord.</p>
  
  <p>So, where on Earth is the inconsistency? It's driving me nuts.</p>