iPhone 4 vs. a compact camera

Does the iPhone 4's camera have the capability to replace a compact camera for everyday snapshots?

A few months ago when the iPhone 4 was first announced, I wrote an article entitled "Will the iPhone 4 kill the compact camera?". Suffice to say there was a strong reaction from readers in the comments, espousing that even the thought of such a thing occurring was a ludicrous idea and that Apple fanaticism had swept through the sentiment of the piece. (For the record, I only own one Apple product, an iPod Classic 160GB.) But what most failed to realise is that it wasn't necessarily the iPhone 4's camera specifically that was the subject of the argument; it simply signalled a major paradigm shift crossing over to the mainstream, something that has been occurring in photography for a few years now.

Pitting the iPhone against a compact camera seemed like an easy test, until it came down to choosing a camera that the iPhone (or any other mobile phone camera) could easily replace in most day-to-day situations. We used the Canon IXUS 105 as the litmus test: 4x optical zoom, a 12.1-megapixel sensor and the best image quality for its class. Though the image sensor isn't the same as the iPhone (backlit CMOS), other compacts using that sensor are still too expensive and not as widespread, which would negate the point.

We put both cameras through a series of tests and shooting situations, scaling back the IXUS 105 to 5 megapixels in the image settings and leaving everything else on automatic. To give the iPhone 4 a decent chance we used the Camera+ app, which adds image stabilisation to the camera.

Each image is presented with the iPhone's picture at the top, and the IXUS's image at the bottom, both with 100 per cent crops inset. As undoubtedly the main destination for digital images is the computer or phone screen, we've scaled the images to a resolution suitable for web display. No editing has been done on these images apart from reducing their size and re-saving as a JPEG.

The iPhone's image (top) clearly has a slightly more punchy feel to it than the Canon's (bottom), though this isn't unusual as many mobiles purposely increase the saturation to give pictures more vibrancy. A similar effect could have been achieved by choosing the vivid colour mode from the menu of the Canon. The 100 per cent crops of both images are quite similar, though the iPhone appears to have a few more digital artefacts and over-processing on close inspection.

Still, at reduced magnification the images are remarkably similar so this one is a clear draw.

This is where most compact cameras struggle, let alone mobile phone cameras. At dusk, just before the sun sets completely, the iPhone and Canon present their shots taken without flash. This is where the image stabiliser kicks in, and the colour cast from the automatic white balance seems to be playing havoc in both shots. The iPhone's colour is closer to the actual colour of the sky, but the Canon wins this one easily with the sharpness of the lens.

The challenge where the iPhone really shows its weaknesses is with zoom. Possessing no optical zoom, relying instead on interpolated digital zoom, we didn't expect the iPhone to perform particularly well against the Canon. At 4x zoom (the extent of the Canon) the iPhone's image is reasonably smeary even at a reduced resolution, but would still be usable for web with some noise reduction applied.

It's the most useful addition to the iPhone's camera, but in reality the results are a little lacklustre. It doesn't help matters that it's just a lowly LED flash either; as you can see, the results speak for themselves.

The iPhone's flash also presented another problem in certain situations, and that was lens flare. We found that having the phone in a case or bumper seemed to exacerbate the effect, but even shooting at certain angles left light blotches across photos.

Normally, most mobile phones display horrendous overexposure of brightly lit areas. In this challenge, sunlight is streaming directly into the lens.

Apart from the obvious change in field of view (given the focal length of each lens is different), the results of this test are remarkably similar. Both blow out the highlights from the light being cast through the tree, and both display a small amount of lens flare in the top right, with the iPhone's image showing this a little more clearly.

So, does the iPhone have the capability to replace a compact camera? Yes and no. Certainly, the iPhone, or any other mobile phone with a respectable camera function, has the capability to take the place of a basic compact camera for snapshots designed for web use. Plus, there's no camera on the market today with the image-sharing capacity and Wi-Fi/3G connectivity to match the iPhone.

But at the same time, purists looking for the best image quality and fully featured functionality can't go past a dedicated, high-end compact with manual controls. The potential of future mobile phone cameras, like Nokia's N8, means that cameras and mobiles are only getting closer.