Lowest level of unprocessed (raw) camera data accessible on the iphone?

If someone wanted access to unprocessed camera sensor data on the iPhone, is there a way to use the API to get at it?

I'm particularly interested in the data before it's开发者_Python百科 white balanced, as well as brightness metics.

eg, An interesting app would be a rough color temperature meter for photographers using gelled strobes.

On option is that you can manually lock the color temperature processing and exposure level (via standard AV API call) after aiming the camera at an appropriately lit neutral gray card. Then examine the differentials under alternate lighting.