One of the things we think Apple does better than other smartphone manufacturers is build great cameras into its phones. It's one of the reasons that iPhone is one of the most popular cameras in the world, period. Based on our experience, the iPhone 5S' camera produces better-looking photos than that on high-end Android phones like the Nexus 5 and HTC One M8, and it's a safe bet that the next iPhone will have yet another camera upgrade. Sony currently supplies the small CMOS camera in iPhones, and it's also the supplier of camera sensors on a variety of Android phones. The difference in photo quality between those devices, then, can partially be attributed to the lens system used. But photo quality is also tied to the imaging software built into the phone's OS. And on that front, Android may take a leap over iOS later this year.
While Apple is opening up manual camera controls to developers in iOS 8, one feature that's sorely lacking is support for RAW photo capture. And coincidentally, that's one feature that Google is bringing to Android L--support for camera apps to write raw pixel data from the camera sensor as a DNG (digital negative) file. While this may not sound like a big deal for most smartphone users, it is in fact a huge deal for photographers who are doing more than just taking photos to immediately share on social networks. As I've said before, the post-processing of a photo is just as important to the whole of the photography process as the act of snapping the shutter. The ability to save smartphone photos as RAW files instead of just JPEGs is the equivalent to an immediate and free upgrade to the camera, regardless of the sensor make.
To understand the benefits (and costs) of RAW, let's quickly go over the limitations of JPEG images. JPEG is a lossy file format, using image compression algorithms to reduce the file size of an image while retaining as much details as possible. Standard JPEG settings allow for a compression ratio of 10:1 from the original image without noticeable reduction detail, especially on small screens. JPEGs are also most commonly saved with 8-bit color profiles. That means that each of its RGB color channels top out at 256 gradiations. 256-degrees of brightness for each color channel is plenty for a photo, but camera sensors can actually record much more detail than that. Digital imaging chips can process light coming into sensors in 12 or 14-bits--light data that is lost when converting an photo to a JPEG. That extra data, when run through a RAW image processor, allows for more flexibility when editing and helps avoid image artifacts like light banding.
Another limitation to JPEGs is the inconsistency of compression engines between smartphones. The amount of compression used to save a photo in the iPhone is different than that of an Android phone, and can vary between camera apps. For example, a 13 Megapixel photo taken on the new OnePlus One Android phone is compressed to a file between 1-2MB at the highest quality setting. The iPhone 5S, using a 8MP sensor also made by Sony, saves JPEG photos that are also around 1.5MB each. (By comparison, the 14MP camera on the Phantom 2 saves 4-6MB JPEGs). So where did that extra megapixel data go? While some camera apps have JPEG quality settings, the amount of compression isn't always transparent, so you don't know if you're getting the best possible photo you can from your phone.
RAW image files eliminate that ambiguity, because it's just storing the unfiltered image data taken from the camera sensor. And the best part is that saving in RAW isn't a hardware limitation. All digital camera sensors have to pass that raw information through the phone's image processors--it's up to OS and camera software to give users a way to save that data before it gets lost in the JPEG output. The high-end Nokia Lumia phones have RAW photo capability, and previous phones like the Lumia 1020 were granted RAW file saving with a software update. DPreview ran a comparison of RAW and processed JPEG photos with the Lumia, and I ran own tests with a small-sensor camera to show you the image detail differences.