Performance and Image Quality

The HTC One X is a nimble performer by any measure. From the home screen the camera app launches and is ready to shoot roughly one second after you tap its icon. Autofocus is very brisk even in lower light levels for subjects that have good contrast. With repeated tapping you can shoot consecutive images as fast as .3 seconds apart, although enabling a processor-intensive Effect like vignetting slows this rate down to about 1.5 seconds between shots. Simply put, in weeks of real-world use, we rarely found ourselves waiting on the camera to take a photo.

Continuous shooting

The One X has a continuous shooting option. Once enabled, the camera will take successive pictures in a single burst when you tap and hold the shutter button. Frame rates can vary from shot to shot, but in our tests the camera averages roughly 4 fps in a single burst. You have the option to limit this burst to 20 frames. While this feature is well suited to shooting moving subjects in well-lit conditions (as shown below), in lower light the lack of any shutter speed indication means that you can unknowingly end up with motion blur caused by a shutter speed that is too slow to freeze your subject.

In the sequence below, to ensure a shutter speed fast enough to freeze the subject, we manually set the camera to ISO 400 even though the bright daylight conditions would have easily allowed shooting a more static subject at ISO 100.

Image # 1
Image # 2
Image # 3
Image # 4

Overall, the feature works as advertised. Image quality is indistinguishable from single shot images. Something to watch out for though, if you're shooting moving subjects we recommend manually setting a higher ISO to ensure a shutter speed fast enough to keep everythign sharp. Focussing isn't an issue -  because of the small camera sensor's extreme depth of field, everything from a few inches away to infinity will be in focus. Note that the continuous shooting option is disabled when using any of the camera's Effects, which place heavy demands of their own on the processor.

Daylight

In bright sunlit conditions, the HTC One X is quick to focus and delivers generally pleasing, if not exceedingly accurate color. The camera's autoexposure system consistently delivers well-balanced exposures although the default processing is a bit contrasty, which can obscure some highlight and shadow detail. 

As we've seen with other smartphones though, noise is present even at low ISO sensitivities. This is especially noticeable in areas of plain tone. Where the camera disappoints is in the amount of artifacts such as stair-stepping and haloing found along edges. Viewed at 100%, the files appear noticeably oversharpened.

Even at low ISO values you can detect noise in smooth areas of the scene.
100% crop
Exposures are well-judged but sharpening-induced artifacts are more prominent than we'd like.
100% crop
The default contrast setting aims for a punchier image, which can lead more easily to highlight and shadow clipping.
100% crop

Low light, High ISO

As you'd expect, low light levels present a challenge for the One X. The overly crunchy output we see at base ISO is compounded by fairly aggressive noise reduction, which smears detail. The camera will automatically boost ISO to try and provide a hand-holdable shutter speed.

Image quality suffers as the ISO sensitivity increases, however, with increased noise and smearing of fine details. To be fair though, these flaws only really become obvious at view magnifications approaching 100%, as in the crops you see below. At the sizes most people will be sharing these images for online viewing, the results even at the maximum ISO are eminently usable.

This interior scene is lit by a combination of natural and artificial light. At a reported ISO 627, the One X delivers a fairly accurate white balance, but in the crop on the right you can see significant artifacts and edge halos.
100% crop
This twilight scene was shot at a reported ISO 955. The One X gives a pleasing exposure and acceptably neutral white balance. In the crop at right you can see that fine detail in the brickwork has been smeared.
100% crop
This scene is illuminated by a streetlight, a red neon sign in the window and an interior fluorescent light. As you'd expect, white balance suffers a bit in this challenging situation, with an overly warm color cast. Overall exposure is well-judged though. At a reported ISO 1238, noise reduction is quite aggressive and dark areas of the scene, like the leaves shown at right, are rendered with very little detail.
100% crop

Sharpness settings

With the disappointingly 'crunchy' results at the camera's default sharpness setting, we thought it would be useful to compare the results with the camera's less aggressive settings. The images below were all shot with the camera manually set to ISO 400.

Sharpness set to 0 (default)
100% crop
Sharpness set to -1
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Sharpness set to -2
100% crop

As you can see in the 100% crops, edge halos are significantly reduced at a -1 sharpness setting. At the minimum setting of -2, the file appears soft by comparison. If your imaging workflow includes any post-capture editing, however, this may indeed present the best starting place. For most users though, we see the -1 setting as the best compromise between perceived detail and image quality. Practically speaking though, the default setting is perfectly suitable for web viewing and social photo sharing.