Digital Negative is a new iPhone app which promises to save photos in Adobe’s DNG format. That is, it promises RAW images from your iPhone’s sensor. Leaving aside the debate of whether or not this is a good idea (more on that in a second), can an App Store app really get access to the raw, unprocessed data from the sensor? The answer is no, but to the developer’s credit, it goes just about as far as is possible.
A RAW file is literally the raw data from the image sensor, before it is even turned into color and luminance values, or let alone an actual image. This is what makes it so powerful – your RAW-capable editor (Lightroom, Aperture) can interpret that data any way it likes before turning into an image. And DNG is just a file format for RAW data. The thing is, you can also wrap up a JPG as a DNG if you like.
The Digital Negative app, then, actually just takes the Red, green and blue values from the pixels and stores those in its DNG files. This is the closest to the metal that Apple will let you get and, while not really RAW, it does improve on JPG files which have all kinds of image data thrown out by their compression algorithms.
I haven’t bought the app, because if I want RAW pictures I dig out my Micro Four Thirds camera. But all the reviews say that the image quality is good, but the app itself is clunky. Still, you could just use it for capture and share the results with Lightroom or Aperture – but if you’re going to do that, why not just use a camera that can do it properly?
Finally, a bit about that RAW conversion. The reason the iPhone’s camera is so far ahead of other phone cameras isn’t hardware (although that part is more than taken care of in the 4S and 5), but software. The image processing performed by the iPhone camera is what turns the raw soup of numbers into amazing, low-noise images which are full of depth and detail. If you start dicking around with your own RAW processing, then you’d better make it better than Apple’s version. Take a look at the difference in the noise-reduction of Lightroom (great) and Aperture (not great) if you don’t believe me.
The app is available, and costs just $2. Which is, admittedly, quite a lot less than buying a new camera.