All four cameras can shoot HDR images, though, inevitably, they have somewhat different approaches to the topic. The iPhone 7, LG G5 and Galaxy S7 have on/off and auto positions on the HDR toggle. The Xperia XZ, on the other hand, can engage it itself in Superior Auto, or you can switch to Manual mode and flip the toggle yourself.
Then there's the matter of live preview - only the Galaxy S7 adjusts its viewfinder to reflect what the final image will look like. That, combined with the instant capture of an image suggests a software HDR implementation - a tonal curve, which dynamically gets adjusted to preserve both shadows and highlights for each particular scene. The alternative approach seems to be taken by the other three - capturing multiple shots at different exposures and combining them afterwards.
The iPhone 7 has very good dynamic range to begin with, but its HDR mode is oddly tuned and it doesn't necessarily help. Not only is it geared towards highlight preservation but in contrasty scenes it pushes the entire exposure down producing photos, which are darker than usual. The implementation is decidedly different than on the previous models and it's borderline illogical. You often end up with dark photos with pitch black shadows at the expense of well-preserved highlights.
The LG G5 is a bit more conventional in its HDR approach. It brightens up the shadows and tones down the highlights - what you'd expect it to. There's virtually no difference between auto and forced HDR - if the G5 automatically decides to engage HDR, it goes all the way.
Not so with the Galaxy S7. There's a noticeable difference between what you'd get with Auto HDR and HDR On, in a scenario where Auto does choose to engage it, of course. Auto's approach is to salvage the shadows - forget about those clipped clouds, they're gone.
There's also a lot that gets pulled up from the dark areas, though noise is an inevitable side effect. Full On HDR goes a step further and lightens up the midtones a bit - all this done without touching the highlights. The good part is that you can observe the effects live on screen, and choose the mode you prefer.
In comes the Xperia. In Manual mode with HDR off, the sky is a goner, but the shadows are safe (the quality of the rendered detail there is another topic). When Superior Auto mode recognizes a backlit scene, it triggers a specific scene mode called Backlight mode - or essentially Auto HDR. It produces virtually the same result as Manual mode with HDR On, and that result isn't very dramatic, nor is it in the right direction. The Xperia approach is to brighten up the shadows but it doesn't bother recovering the highlights, so it's a bit counterintuitive.
Next, you get the HDR On samples from each camera above for immediate comparison of what you'd get in a similar scenario.
HDR photos winner: Tie between the LG G5 and Galaxy S7. The HDR mode on the LG G5 salvages highlights and pulls up the midtones, while preserving detail and keeping noise in check. The Samsung top model takes a two-tiered approach with a strong, yet believable effect with HDR switched on, and a toned down version in HDR Auto. The convenience of having a live preview is undeniable as well.
Starting with the samples from the shootout, a few things are immediately visible, even from the thumbs - the Xperia XZ has a much colder white balance than the other three, and the iPhone 7's colors have faded into oblivion. And it was precisely the iPhone with this image that won the shootout.
Colors or no colors, the iPhone has preserved detail in the foliage a lot better than the Xperia XZ and the G5. That's in no small part due to the fact that it has exposed the scene more than a full stop brighter than them (EV7.1 vs. EV6 on both). Makes you appreciate then what the Galaxy S7 has achieved at EV6.3 (exposure value).
Looking the other way, we find that the Galaxy S7 has the upper hand in terms of sharpness, noise and detail preservation. The G5 is a close second in resolved detail, but it suffers badly from the inevitable extra noise that comes with ISO300.
Xperia aficionados often insist that in low light Sony cameras perform best when shooting in 8MP, and not in full resolution (23MP or so in this case). While the premise of having a 23MP camera (and having it advertised as such) only to use it in 8MP so you get better image quality is shaky, we figured we'd provide samples for folks to draw up their own conclusions. We've also added a third image - the first one downscaled to 8MP.
Low light photos winner: Galaxy S7. The Samsung top-dog creates sharp low-noise images in low light, while preserving colors. The G5 does a good job as well, only its less aggressive processing leaves plenty of noise.
When the light gets really low, sometimes the camera flash performance is the only difference between getting the shot and ruining it.
The iPhone 7 flash is noticeably brighter than the last generation but oddly, it literally pales in comparison to the competition. The subject in the center is well lit, but everything else in the scene is quite dark.
The G5 does the best job of lighting up the entire frame, and the Xperia isn't too shabby either, especially considering that it has a wider area to cover.
The Galaxy S7 does a decent job with light uniformity. Remember, these were all shot from the same distance from the subject (himself an arm's length from the camera and little under a meter away from the wall behind).
Upon closer inspection of the face, the iPhone 7, LG G5, and Galaxy S7 have resolved similar levels of detail. As previously observed in less than ideal lighting, the iPhone's colors have lost saturation, while here the G5's reds have shifted towards orange. The Xperia isn't looking great - that's as accurate as it would focus when it gets darker and it's a serious blunder for an otherwise very good camera.
Flash photos winner: Tie between the LG G5 and Galaxy S7. The S7 skin tones and colors are very well preserved, but the G5 scores points for its uniform light distribution and even scene light.