The S4 packs a stonking 13-megapixel camera, which puts it side by side with the Xperia Z. The iPhone 5, S3 and Lumia all have 8-megapixel sensors, while the HTC One is bringing up the rear with only 4 megapixels. While that might seem laughable, HTC argues that its fewer pixels are physically bigger, resulting in better image quality overall. More megapixels certainly don't mean better photos, but we'll see later whether those claims are accurate
An important factor to note is the varying focal lengths of the phones. The HTC One has quite a wide-angle lens, whereas both the S4 and Xperia Z look much more 'zoomed in' in their shots. I point this out as their photos may look as though I stood in a different position when taking them. All phones were held in the same position each time, however, and all settings were firmly defaults.
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For the first test, I headed to Borough Market and found this delightful looking fruit selection. The S4 came out top here with rich colours, the sharpest image and best exposure. The One's effort was overly bright, while the 920's colours were poor and it didn't achieve a good focus.
Borough Market's sign, against the bright blue sky background is a good challenge for a camera's exposure metering. Again, the S4 did a great job of capturing a rich, deep blue, with pleasing clarity on the sign's words. The HTC One was still too bright, while the Xperia Z compensated too much for the bright light, resulting in a dark image overall.
Heading indoors, there wasn't much difference to be found between the 13 megapixels of the S4 or Xperia Z when images were viewed full screen. Both offered excellent image quality. The iPhone 5's colours were most appealing in this scene, but it lacked the clarity offered by some of its rivals.
The HTC One gave the sharpest results when looking at the whole image, but doesn't have anything like the same depth of information when you examine it full screen. It's good image quality for Facebook snaps, but not if you want to order large prints.
Moderate light with flash
Unless you only ever plan on using your phone in the glorious summer sun, you'll need a camera that can cope with fading light. I found a shadowy corner of the CNET UK office to see how the cameras cope with the lower light and how their flashes help illuminate the scene.
Without the flash, the S4 gave the most pleasing overall image. Both the Lumia 920 and Xperia Z's efforts came out a bit too yellow for my liking. With the flash however, the S3 gave the clearest image, although the flash was bordering on a little overpowering. The Xperia Z and 920 both suffered quite a bit from image noise.
The S4's overall image looked decent, so it's a shame that it couldn't focus as well as its competition on this test. Take the time to properly stabilise your shot and it should do well.
Venture into a dingy restaurant and even the best of cameras will struggle with the poor light. To see which of the phones would fare best at capturing a shot of your burger by candlelight, I set up a very poorly lit scene.
The Lumia 920 was the undisputed champion without the flash. Its image was bright, clear and didn't suffer too much from image noise -- unlike the awful attempts of the S3 and S4. The Lumia 920 was so good, in fact, that I had to double check I wasn't looking at the wrong image.
Low light with flash
Turn the flash on and things all change. The Lumia 920 still produced a well-balanced image overall, but the S4's shot was considerably sharper, particularly when you look full screen. Look closely around the red Saxa logo and you'll see that the Xperia Z's shot was rather poor.
High dynamic range (HDR) images combine multiple shots taken at different exposures in order to create an even exposure overall. It's particularly handy when shooting scenes with both dark and bright areas. The Nokia Lumia 920 doesn't have an HDR function as standard so it was left out of this test.
My favourite image from this test came from the Galaxy S3 -- it did a good job of toning down the bright sky, while keeping contrast and clarity on the building. The S4's looked similar, but I didn't like the zoomed-in view as much. The HTC One's made a rather bizarre attempt at rescuing the highlights, resulting in the odd dark splodge. The Xperia Z's auto-white balance gave overly warm results.
Although it couldn't match the Lumia 920's efforts in low light, the S4 generally did an excellent job in the tests. Its images were very crisp and had a good overall colour balance. It's a shame that it has such a narrow field of view, as it means you can't shoot a particularly wide scene -- landscape and architecture photographers might not be too impressed.
The S4 manages to produce sharper, more visually appealing images than the competition in nearly all of the tests. With the host of extra camera features -- Animation Photo, Best Face, Drama shot, etc -- it's arguably the best phone to consider right now if photography is your primary concern.