The default driver.
In theory the default driver is capable to deliver
the raw-image buffer. I wrote a version which catches the
raw-image buffer and I wrote a simple DNG-File export.
Sadly there is a bug in a gstreamer-component. Even if
the buffer has the full 2592x1968 pixel data (this is the
raw resolution of the camera chip), the gstreamer plugin
only copies at image capture resolution (2576x1960).
That means there are some missing lines at the bottom of the
raw-image.
But the gstreamer plugin (gstv4l2camsrc) is open as well, so it could be fixed.

Nicolai