Taken with iPhone 11 ISO 500 | 1/30 sec | F1. 8 The bokeh-imitation effect that's all over your Instagram feed is a few generations old, but it's still a relatively young technology. Portrait Mode, as Apple calls it, is a computational feature that mimics the shallow depth of field closely associated with professional portrait photography.
The latest iteration in the iPhone 11 is a great leap forward and, when compared with Google's Pixel 3, shows that the search-engine giant is going to have to do something pretty special with the forthcoming Pixel 4.
Just to make sure you're caught up – phone sensors and the lenses they are coupled with are quite small, and inherently limited in their ability to create a blurry background behind a subject. Hence, portrait mode was born (Portrait Mode is Apple's proprietary name, but for the sake of simplicity I'll use it throughout this article to refer to all such modes).
Compared side-by-side with results from the iPhone 11, the Pixel 3 has been surpassed in many respects
Like so many first-generation technologies, portrait mode was a bit dodgy at first – subjects poorly separated from their backgrounds and results that were decent but not quite convincing. But no matter where you stand on its current state from "It's so terrible it's an insult to photographers" to "Eh, it's passable," there's no denying that it has steadily improved with each generation.
Apple, like most manufacturers, introduced Portrait Mode when it brought dual cameras to its devices. However, Google chose to offer it with a single camera, relying on dual pixel depth data, machine learning, and up-sampling to create that fake bokeh look. The results looked fine until, well, about now.
Compared side-by-side with results from the iPhone 11, the Pixel 3 has been surpassed in many respects. Here are the areas in which the iPhone 11 pulls clearly ahead of the Pixel – and where Google needs to do some catching up in the Pixel 4.
The nitty gritty details
Google achieves its portrait mode by digitally zooming in to mimic a longer focal length and creating a depth map by using dual pixels along with a learning-based algorithm to judge distance to a subject and separate it from its background, up-sampling the final result to a full 12MP resolution. Apple (and Samsung, Huawei, among others) instead use their telephoto camera, calculating depth with the help of the perspective offset between the telephoto and wide cameras – no cropping or up-sampling needed.
The images below demonstrate the difference – note that to match the subject's size in the frame using the two different focal lengths, the 3a image was taken from about a meter farther back than the iPhone 11.
Pixel 3 – 100% crop
iPhone 11 – 100% crop
Of course the vast majority of portrait mode images will be viewed on a phone or computer screen, where the difference in detail is much harder to spot. Still, looking at the images above at even a 50% crop shows a vast difference in the level of detail captured, and all things being equal we'd much rather have more detail than less.
Backlit subjects
We've previously noted the Pixel 3's fantastic ability to render high-contrast scenes, but one place this falls flat is with backlit portrait subjects. The camera's tendency to preserve highlight detail and push up shadows is normally what we'd prefer, but it doesn't work well when the shadows are your main subject.
Pixel 3a
iPhone 11
The resulting image shows that the Pixel does a poor job of rendering the cat's orange fur, giving him an overall 'crunchy' look in comparison to the more pleasing rendering by the iPhone. In our testing, the Pixel 3 has consistently shown this tendency to expose for highlights, even when it might do better to choose an exposure better suited to your human or feline subject, at the cost of highlight detail. Even tapping the subject's face doesn't adjust the exposure as much as we'd like.
Skin tones
The most sophisticated depth mapping in the world won't save an image from bad-looking skin tones, and this is one area where Google really needs to catch up. The subject below is lit by window light that's much cooler than the yellow lights of the kitchen behind him. It's a tricky situation for sure, but the iPhone has clearly made the right call to warm up the subject's skin tone rather than preserve the cool cast of the window light.
Pixel 3a
iPhone 11
To be fair, both of these phones are susceptible to producing noticeably different colors based on slight shifts in framing, or using a different camera mode like Night Sight. But over the course of much use, we've seen that the Pixel 3's standard camera mode renders skin tones particularly poorly by comparison.
Apple's face smoothing and skin tone rendering has a tendency to go too far in some situations, and there are times when we prefer the more faithful color rendering of the Pixel. It's also pretty easy to correct the Pixel's skin tone rendering in the phone's own Photos app, but we're betting that most people don't want to (and won't) take the time to color correct every portrait that they take.
Focal length flexibility for portrait mode
Taken with iPhone 11 | ISO 200 | 1/60 sec | F1. 8
Apple's XR introduced wide-angle portrait mode to the iPhone, but the 11 and 11 Pro improve on it with more accurate depth maps thanks to the availability of the ultra-wide lens. Thus, the 11 offers a very good wide Portrait mode via its standard lens, and the 11 Pro offers both telephoto and wide portrait options.
Whether you prefer the look of a telephoto or wide portrait is of course a personal preference, and I tend to prefer the wide portrait mode on the iPhone 11. I like an across-the-table environmental portrait, which usually requires backing up if I'm using the telephoto lens or the crop imposed by the Pixel 3.
Whether or not you like the crop, it being forced on you makes it less flexible and, in my book, I'd rather have that wide-angle – and I'm sure I'm not alone.
Your move, Google
To be fair, there are things we prefer about the Pixel 3's portrait mode. We find it's much less prone to obvious errors in cutting around human subjects than the iPhone 11. I also far prefer using Google Photos to Apple's iCloud, so the seamless integration with my photo archive is a big plus.
Healthy competition between two big tech companies keeps pushing phone camera technology forward at a rapid pace
We can also say with some certainty based on leaks and rumors that the Pixel 4 will address some of these shortcomings. We know that the device will offer more cameras, which will likely improve portrait mode. Whether we'll see improvements to skin tones or better handling of backlit subjects is less certain, though encouragingly, leaked photos do show better rendering of skin tones. All will be revealed soon, but one thing is for sure – healthy competition between two big tech companies keeps pushing phone camera technology forward at a rapid pace, and that's nothing but good news for the photo-taking public.
. dpreview.com2019-10-12 16:00
