Display

As we briefly discussed in our look at the specifications, the Galaxy S6 line introduces a newer generation of AMOLED displays, which is said to increase maximum luminance to 600 nits. Samsung claims that this was achieved with the use of new materials, which is likely necessary in order to sustain power efficiency improvements. It doesn't seem that AMOLED is uniquely suited to high resolution, but rather that Samsung Display Corp. is managing to dramatically improve how they make AMOLED displays with every year that offset power consumption increases from higher resolution displays.

To find out how Samsung did, we use SpectraCal's CalMAN 5 Ultimate, in addition to X-Rite's i1Pro2 Basic to characterize displays as accurately as possible.

Display - Max Brightness

From the results Samsung's claims of a 600 nit display are valid in this case, which is a 100% APL white display. It's important to note that achieving this requires the use of auto-brightness, and that manual brightness is limited to a much lower brightness to reduce power usage, here the S6 sees similar maximum brightness as the S5. The S6 edge disappointingly only achieves 272 nits in this mode, a rather low value. I saw color balance shift dramatically in auto-boost mode, which suggests that this operating mode is likely less efficient than manual brightness. As an explanation, we've seen that colors are controlled in AMOLED by voltage while brightness is controlled by PWM (pulse width modulation). As with most recent AMOLED displays, there's no DC bias to the pixels so the contrast really is infinite instead of just a very large number when displaying black.

Galaxy S6

Galaxy S6 edge

Display - White Point

Display - Grayscale Accuracy

Moving on to grayscale, we can see that Samsung has done a pretty good job of controlling the white point and gamma across the saturation sweep, even if green is slightly dominant in both displays. We can also see that there is variation across displays as the S6 edge is closer to neutral while the S6 sample tends a bit warmer.


Galaxy S6


Galaxy S6 Edge

Display - Saturation Accuracy

In the saturation sweep, both displays do an incredible job. I really don't have anything else to say here, because there's really no way to improve on the level of calibration Samsung has done on this display. Unless Samsung calibrates every single display in production, which is wildly impractical and effectively impossible to do, this is as good as it gets for a mass-produced device. Improving past this point will also be incredibly difficult to perceive, which means there's no real reason to go any further.


Galaxy S6


Galaxy S6 edge

Display - GMB Accuracy

In the Gretag MacBeth ColorChecker, we can get an idea for overall color accuracy, which paints a picture similar to the saturation test. The only real problem I've noticed with these displays are the viewing angles, which can produce color shifting when the display is tilted. This is a bit of an issue on the edge variant as I can see that the edges of the display appear somewhat green when viewed head on, but otherwise there are no real issues to be seen here.

Overall, from a color standpoint it’s looking like Samsung has made one of the best displays available on the market today. Color accuracy is at the point where it’s pretty safe to say that the calibration doesn’t have clear color errors, and the peak brightness of the display is incredibly high. The 1440p resolution helps to compensate for the PenTile subpixel layout so in practice it’s effectively impossible to make out any pixels or the subpixel pattern. The contrast remains infinite as with most modern AMOLED displays, and overall it’s really hard to find any issue with the Galaxy S6’s display at first.

However while the S6 edge seems to be without any issues, the S6 does have some odd display issues that can be seen in direct sunlight as seen in the photo above. To be clear about this the photo above is a simple white screen, which should make the image completely homogeneous but instead there are two visible vertical lines and another jagged horizontal line that appear across the display. Inspection under a light microscope doesn’t really reveal what’s causing this, but the defect is quite visible in practice as seen in the photo above. I suspect that defects are rare, and in any condition other than direct sunlight I can’t see this visual problem.

While trying to see what this kind of defect looked like under a microscope, I also went ahead and took some photos of the subpixel pattern. As far as I can tell, it looks like the green subpixels have a bit more variance than what we’re used to as they tend towards oblong shapes rather than circles, which is likely due to the much tighter pixel density. It seems that this variance may cause some color shifting in certain units, which seems to remain a potential problem with Samsung's AMOLED displays. The pixel fill factor still remains surprisingly low when compared to LCDs, which usually have much higher active area. Due to the subpixel arrangement and some other differences in the display design, color shifting also remains higher than one would expect from LCD displays that are found in phones like the iPhone 6.

The final test that I managed to run on the Galaxy S6 is the brightness vs APL test, which shows the advantage of AMOLED’s emissive nature as it can dynamically increase brightness if the entire display isn’t showing a white screen. As a result, this means that in low APL scenarios like dark movie scenes and app themes it’s possible to see a maximum brightness closer to 700 nits or higher. However, in practice the display’s practical brightness is closer to 600 nits.

Overall, the display is still one of the best on the market, but I would be a bit concerned about fill factor for VR applications as that was a problem on the Note 4. Issues like purple smearing have been resolved, but there are still some problems with the display such as color shifting with changes to viewing angles and some variability in display quality from unit to unit. With this generation I suspect Samsung is either meeting or exceeding the best LCDs in quality, and with the next generation of AMOLED it’s likely that high end smartphones will have to migrate to AMOLED to remain competitive.

Battery Life and Charge Time System Performance
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  • h3ck - Friday, May 8, 2015 - link

    Because even though media, books, music and other content is cloud based and easy to access, applications are getting increasingly larger and you still want to have space for local content in general. I went with the 64GB myself, but I also use a Dash Micro. If you don't know what that is, it's amazing > http://www.amazon.com/Dash-Micro-MicroSD-Android-U... Reply
  • elchepe - Saturday, May 23, 2015 - link

    I don't know what world you're living in, but most people take cheap loads of pictures and videos these days. Considering the megapixel count on the S6 and other flagship, expandable memory certainly becomes a necessity. There are plenty of people who know the woes of being unable to update their iPhones because there's not enough space available. Reply
  • deputc26 - Friday, April 17, 2015 - link

    I would like to see an APL vs. Brightness graph for maximum manual brightness. Using 100% APL unjustifiably biases the test against AMOLED screens. 60-80% APL would correspond much better to real world scenarios. Reply
  • Brett Howse - Saturday, April 18, 2015 - link

    Check the display page again. Reply
  • deputc26 - Saturday, April 18, 2015 - link

    "Manual" brightness, not automatic. I checked the display page again and was disappointed. Reply
  • melgross - Saturday, April 18, 2015 - link

    The problem amoled has, is if brightness remains too high for too long, the display will burn out after a time. The real max brightness is around 350nits, the same as before. In fact, Samsung is taking a big chance with the max brightness here. I predict that we'll be seeing display life significantly shortened for a number of people who spend a lot of time outdoors with their phones.

    The life of all LEDs is directly dependent on their temperature. Amoled needs low temps to work, unlike metal based LEDs, used for LCD screen back lights. Their innefficiency means that a lot of power is required for maximum brightness, which leads to overheating. That's why manual brightness on these is the same its been for the last three generations.
    Reply
  • Brett Howse - Saturday, April 18, 2015 - link

    @deptuc26: So you are concerned about 100% APL being biased against AMOLED but want to see the manual brightness where the scores are lower? I'm confused. You seem to contradict yourself there. Reply
  • melgross - Saturday, April 18, 2015 - link

    No, not at all. I'm pointing out that while Samsung has a new brightness setting for outside, you can't use it for regular use. That because using it more than occasionally will damage the display. This is like redlining a car engine. You can do it, but don't do it too often. Reply
  • deputc26 - Saturday, April 18, 2015 - link

    Values for both Manual brightness and automatic brightness are given at 100% APL in charts in the review. This is unrealistic, no one walks around with a pure white screen. The review partially makes up for this error by including a "APL vs brightness" graph for automatic brightness. It does not include such a graph for manual brightness leaving the attentive reader wondering what the brightness would be at a realistic APL and leaving the inattentive reader with a false impression. Reply
  • Uplink10 - Saturday, April 18, 2015 - link

    Because then people would not buy 64GB or 128GB phones which are very overpriced. They would just buy 32GB/16GB phone and additional MicroSD card. Why? Because of greed. Reply

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