Camera Architecture

When the OnePlus One was released one of its most notable features was its camera. At its price, being able to include Sony's IMX214 camera sensor was quite notable. This time around OnePlus is playing in a higher price bracket, and the stakes have been raised due to greater competition. With that being said, the camera is definitely one of the areas I see executed poorly on many non-flagship phones, either due to a poor camera sensor, or more frequently, a poor ISP and inadequate image processing.

  OnePlus One OnePlus 2
Front Camera Resolution 5MP
Front Camera Sensor Omnivision OV5648
(1/4", 1.4µm)
Front Camera Aperture f/2.0 f/2.0
Rear Camera Resolution 13MP
Rear Camera Sensor Sony IMX214
(1/3.06")
Omnivision OV13860
(1/2.6")
Rear Camera Focal Length 28mm eff
Rear Camera Aperture f/2.0

The OnePlus 2 retains the OV5648 front-facing camera from the OnePlus One, along with the same lens arrangement. The rear camera now uses an OmniVision sensor as well, which is a departure from the Sony sensor used on the OnePlus One. While some may see this as a downgrade due to Sony's reputation as a great camera sensor manufacturer, I don't think there's any inherent downgrade in moving to an OmniVision sensor. On top of that, we're actually talking about an increase in sensor size from a 1/3.06" format to a 1/2.6" format, which represents a move from 1.12 to 1.3 micron pixels. These aren't as large as those found in a device like the Nexus 5X, but they're larger than the standard 1.12 micron pixels used in the sensors for most flagship smartphones. OnePlus's decision represents another OEM deciding to increase pixel size to improve sensitivity rather than increasing spatial resolution.

Still Image Testing

Due to some less than optimal weather in my area I'll be using the photo comparisons that Josh has taken for his reviews when evaluating the OnePlus 2. In a way this is good, as it means that the OnePlus One is available for comparison, which is a very relevant topic in this circumstance due to its issues with image processing. However, it does mean that the Nexus 5X isn't available in the comparison, which is an unfortunate but worthwhile compromise in this case.

To begin, I'll start with discussing the image quality when taking photos in the daylight with the OnePlus 2, followed by looking at how it fares during the night.

Daytime Photography

When taking photos during the day, the OnePlus 2 exhibits some improvements over its predecessor, but some regressions as well. The OnePlus One had some notorious processing issues, and one of the most prominent was how chroma noise would be plainly visible even in scenes with ample lighting. In this scene one can notice that the noise across the frame has been reduced dramatically. While this is good in a sense, OnePlus seems to have gone a bit overboard. Looking at the grass and the textures of the walkway one can see that the amount of detail is reduced compared to the OnePlus One. This is easily visible in the grass, where the heavy noise reduction has turned it into a featureless green smear.

As far as sharpness goes, the OnePlus 2 is definitely an improvement over the OnePlus One in the areas where noise reduction hasn't caused havoc. Examining the tree in the top left of the frame makes this quite apparent, with the OnePlus 2 maintaining the sharpness of the individual branches, and the OnePlus One producing a much fuzzier rendition.

Overall, if I had to choose between the OnePlus One and the OnePlus 2 as a day time camera, I would probably go with the OnePlus 2 simply due to the fact that the chroma noise in the photos taken with the OnePlus One is incredibly distracting. OnePlus definitely has room to improve their processing by toning down the noise reduction a bit in order to better preserve the detail of leafy foliage and grass. I think that phones like the Nexus 5X that offer better image quality at this price point, but they come with their own caveats as well such as having to use HDR+ mode on the Nexus 5X which greatly lengthens the capture time.

Low Light Scene 2

In night time photography the OnePlus 2 makes further gains over its predecessor. When looking at the shot it's immediately obvious how much more detail is retained on the OnePlus 2, and there's none of the distracting chroma noise and smearing that exists in the OnePlus One's photo. When comparing the OnePlus 2 to other smartphones it becomes clear that it's not as good as the latest flagship devices like the Galaxy Note5 and the LG G4, but it still ends up being fairly good, and bests smartphones like the iPhone 6.

It's clear that OnePlus was aware of the problems with image processing on the OnePlus One, and the quality of photos taken with the OnePlus 2 is much better. They definitely have room to improve by toning down noise reduction which would allow them to preserve more fine details in foliage, but as it is now the camera still outputs fairly good images for a phone of this price.

Video Recording

The OnePlus 2 offers three modes for recording video. There's a 720p mode, a 1080p mode, and a UHD mode. I'll just be focusing on the latter two, as at this point almost no smartphones offer any additional benefits by recording in their 720p mode other than smaller file sizes in return for lower quality.

When recording UHD video, the OnePlus 2 puts up a notification letting you know that the capture time is limited to ten minutes. I'm glad that OnePlus, like most vendors, has thought to do this so you don't run into situations where your video stops recording without you even knowing like can happen with the new Nexus phones. As for the video itself, it's a 42Mbps 3840x2160 file recorded at 30fps, with a 96Kbps stereo audio stream. The video is encoded using the H.264 Baseline profile, which makes the OnePlus 2 another device in a trend of Android phones that use an H.264 profile that can't take advantage of space-saving features like B-frames and CABAC which would allow for smaller files or higher bitrates at the same file size.

The video is adequate from a pure visual quality perspective, but the visibly changing FOV and jerky motion caused by the use of OIS for stabilization is very difficult to overlook. It surprises me that almost every smartphone manufacturer continues to implement OIS video stabilization in such a simplistic manner, as it makes the video quite unpleasant to watch.

As for the 1080p video, it's a 20Mbps H.264 baseline stream with the same audio encoding as the UHD footage. Since you're not really gaining anything as far as stabilization goes due to the jerkiness of the footage when the OIS resets, I would stick to the UHD recording mode unless you need to record footage longer than 10 minutes in length, or if you want to save space. I suspect that most buyers will be purchasing the 64GB model of the OnePlus 2 where this won't pose a problem anyway.

Display Analysis Software
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  • LiverpoolFC5903 - Tuesday, December 15, 2015 - link

    Sorry for sounding thick! So basically even though ALL the cores are operating synchronously, indvidual cores in a cluster can be into different power states and/or shut off altogether?

    How does this compare with something like a Snapdragon 801 where all 4 cores run at different frequencies depending on the workload?
  • phoenix_rizzen - Tuesday, December 15, 2015 - link

    The cores in the S810 work the same way as in the S801.

    There's 3 ways that ARM's big.LITTLE setup works:
    1. Cluster migration: either the A57 cluster is active, or the A53 cluster is active. The OS only ever sees 1 cluster of cores (so an S810 would appear as a 4-core SoC). This is done in hardware on the SoC itself.
    2. Core migration: each A57 core is paired with an A53 core. Either the A57 or the A53 is active in each pair, never both at the same time. But an A57 from pair 1 can be active while an A53 from pair 2 is active, while the other two pairs are offline, for example. The OS only ever sees 1 cluster's worth of CPUs (so the S810 would appear as a quad-core). I believe this is done in hardware on the SoC itself.
    3. Forget the name of this one, but all cores in all clusters are available for scheduling, and it's up to the OS to manage everything. 1 core can be online, 2 cores can be online, all the way up to all 8 cores can be online. And the kernel scheduler determines whether a process runs on an A53 core or an A57 core.

    The first big.LITTLE SoCs from Samsung (the Exynos 54xx-something) used method 1. The latest big.LITTLE SoCs from everyone (Exynos 7xxx, Snapdragon 810/808, MediaTek Helios, etc) uses method 3.
  • LiverpoolFC5903 - Wednesday, December 16, 2015 - link

    Thanks mate, but as Andrei pointed out, my question was a different one. But useful information all the same.
  • Andrei Frumusanu - Tuesday, December 15, 2015 - link

    Please ignore phoenix's comment, he seems to have misunderstood the question at hand.

    The Snapdragon 801 behaves as you say, they each have individual frequencies, meaning they're all on their own clock domain. Also each core has their own power domain, meaning each core can be individually turned off.

    The difference again is that ARM CPUs such as the A57 in the S810 have all the same clock domain. However even if they all have the same clock they can still be individually powered off as the power domains are individual as well.

    As to how it compares, it has both benefits and disadvantages. But there seems to be no clear winner.
  • LiverpoolFC5903 - Wednesday, December 16, 2015 - link

    Thank you Andrei, its pretty clear to me now! Synchronous cores (A57, standard ARM cores) have the same clock domain which means cluster frequency remains the same. However, individual cores within each cluster can be powered off based on need and workloads.

    And Krait based quadcores have different clock domains for each core as well as different power domains.

    Understood.
  • WoodyPWX - Tuesday, December 15, 2015 - link

    Nice and honest review as always, thank you! A Lumia 950xl review would be awesome.
  • victorson - Tuesday, December 15, 2015 - link

    I love Anand and the insight in the reviews, but sometimes you guys throw something that even the more experienced reader will find hard to understand. "As always, all devices are calibrated to 200nits except when their brightness curves necessitate testing above that value." Could you kindly elaborate on what is that supposed to mean to those of us who are interested in display quality, but don't have a PhD on the matter? :)
  • Ryan Smith - Tuesday, December 15, 2015 - link

    As close to 200nits as we can get. If we can't hit 200 exactly, then it's the first value over that which we can hit.
  • kasakka - Tuesday, December 15, 2015 - link

    The sandstone black back cover is one of the best things about Oneplus phones. It really helps keeping a big phone like that firmly in your hands. By comparison the Oneplus X or iPhone 6S really needs a cover because they are very slippery.

    Where Oneplus went wrong with the Two was the Snapdragon 810 and that it's not that much of an upgrade from the One. As a One owner, the only things I'd like from it are LTE band 20, better speaker and vibration motor and the fingerprint reader which is positioned very poorly. On phones this size they should be in the back like on the Nexus phones because reaching down to that bottom area when using with one hand is quite annoying. I use the onscreen buttons on my One because of the same reason.

    I really hope they manage a better design with the inevitable Oneplus Three. I like that they haven't jumped on the 1440p bandwagon because that doesn't really give any benefit in phones at this screen size. Just more pixels to push.
  • lid - Tuesday, December 15, 2015 - link

    Thank you for providing LTE band information! It has always been a deciding factor for me, since I travel constantly. This phone doesn't seem great for anyone who frequently visits the EU from the US (since the US version is missing LTE band 3), or vice versa (since the EU version is missing LTE bands 2/4).

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