If you’ve been reading Maximum PC for a while, you know that we use Displaymate ’s suite of calibration tools to test all the monitors, projectors, and displays that come through the Maximum PC Lab. You might also know that Dr. Raymond Soneira has penned a few stories for Maximum PC and our new personal technology channel, Maximum Tech .
A few months ago, we asked Dr. Soneira for his thoughts about evaluating the displays on smartphone devices. Back then he told us that he was working on an extensive comparison as well as a methodology for testing. He just published his results, and we’re happy to excerpt them for you below.
A key element in the success of all smartphones and mobile devices is the quality and performance of their display. There have been lots of articles comparing various smartphone LCD and OLED displays and technologies, but almost all simply deliver imprecise off-the-cuff remarks like “the display is gorgeous” with very little in the way of serious attempts at objective or accurate display performance evaluations and comparisons – and many just restate manufacturer claims and provide inaccurate information, performance evaluations and conclusions. This article objectively compares the display performance of five leading smartphone LCD and OLED displays based on extensive scientific lab measurements together with extensive side-by-side visual tests, incisive evaluations and comparisons, nicely summarized in the Comparison Table and Results Highlights below.
The term “Super” is marketing puffery being used by some manufacturers, but we have adopted it generically to differentiate the highest performance display technologies. Since smartphones are being used to view photos, videos and a wide range of multimedia content we have evaluated their picture quality on the same terms as HDTVs. In fact, one of the smartphones that we tested has better picture quality than most living room HDTVs – so the bar is already quite high for smartphones. But there is still plenty of room for improvement and we will show and tell you where – we have included images that have been mathematically processed to correct color and imaging errors on each smartphone so you can compare them to the originals. Part II of this series will be on glare, screen reflectance, ambient lighting and sensors, automatic screen brightness controls and using them to improve picture quality, screen readability, viewing comfort, reduce display power and increase battery run time. Now let’s see how these leading smartphone’s perform…
The Comparison Table below covers a wide range of display data on the Google Nexus One, Samsung Galaxy S, Apple iPhone 3GS, Motorola Droid and the Apple iPhone 4, but here are some of the highlights and conclusions culled from the Table:
Since its introduction the iPhone has been one of the wonders of the modern tech world for many reasons – but its display was never one of them – up until the iPhone 4, where it finally got the display it deserved. The iPhone 4 display, nicknamed the Retina Display, is an outstanding “Super” LCD delivering top performance in many of our test categories – it has the brightest and sharpest display, but on the other hand its color gamut is too small, producing under saturated somewhat washed-out colors, and its image contrast is too high, which produces punchier images and also partially compensates for its smaller color gamut. These were most likely intentional tradeoffs made by Apple to increase screen brightness, power efficiency and battery run time.
None-the-less the iPhone 4 earned our Best Mobile Display Award in the DisplayMate Best Video Hardware Guide. We include a dedicated comparison with the iPhone 3GS below. “Retina Display” is a great marketing name, and it is the sharpest smartphone display available, but quantitatively it is a factor of two lower than the acuity of the human Retina. Click here for a discussion on the Retina Display. Finally, Part II of this series will discuss some major flaws in the iPhone 4’s Automatic Brightness control, which hopefully will be corrected in the near future through a software update.
The Galaxy S has Samsung’s next generation premium OLED display marketed as a “Super AMOLED” display. The AM stands for Active Matrix, but all smartphone displays have that. What is particularly impressive is how rapidly Samsung has been improving their OLED technology, and the Galaxy S delivered top performance in many of our test categories. Some of areas where it fell short were the result of manufacturer calibration and OS issues rather than fundamental problems with the OLED technology itself. Google confirmed that some of the display problems we discovered are caused by Android 2.1.
While OLED is still a relatively young display technology that has not yet been perfected to the performance levels of the very best mature LCDs, the Galaxy S is already an impressive display for an upcoming and rapidly evolving technology, so it earned our Best New Mobile Display Technology Award in the DisplayMate Best Video Hardware Guide. There are comparisons with ”Super” LCDs and “non-Super” OLEDs below. Part II will also discuss problems with the Automatic Brightness control on the Galaxy S, which should also apply to other Android phones.
All of the tested LCDs were considerably brighter than the OLED displays – however, that may change in the near future as OLEDs continue to improve… While “Super” OLEDs have roughly 50 times the Contrast Ratio of “Super” LCDs, when a display is set properly to its optimum screen brightness that superior Contrast Ratio is visually insignificant except under dark ambient lighting, which is seldom the case for mobile displays. While OLEDs love to flaunt their vivid colors and large color gamut, that produces gaudy and over saturated pictures – someday they will turn those down and get it right… While the iPhone 4’s sharpness is something of an overkill (it’s that high for App compatibility) the PenTile arrangement of the OLEDs has only two sub-pixels per pixel instead of the usual three, so it sometimes appears more pixilated than its stated resolution implies – it’s excellent for photographic images but is noticeably degraded for colored (red, blue and magenta) text and graphics.
While all OLEDs behave considerably better with changes in viewing angle than “Super” LCDs, smartphones are primarily single viewer devices and the user can easily orient the phone for the best viewing angle. LCDs are currently more power efficient for brighter images and OLEDs are more efficient for darker images. But for typical web and app content, which typically use bright backgrounds, the power balance is still decisively in the favor of LCDs by more than 2 to 1 in our tests – again, that should change as OLEDs continue to improve… The big question remaining for OLEDs (and not covered by our tests) is whether the previous uneven aging over time for the red-green-blue OLED sub-pixels has been solved.
“Super” OLEDs do indeed perform considerably better than “non-Super” OLEDs. What is particularly impressive is how rapidly Samsung has been improving their OLED technology. The “Super” OLED is a much more refined display with many fewer artifacts and a much better factory calibration. Samsung advertises that the Galaxy S Super OLEDs are 20 percent brighter and use 20 percent less power than “non-Super” OLEDs, and have a screen reflectance of just 4 percent, down from 20 percent for “non-Super” OLEDs. In our lab tests the Galaxy S has a screen reflectance of 4.4 percent, is 25 percent brighter and uses 21 percent less power than the “non-Super” OLED in the Google Nexus One – meeting or exceeding all of Samsung’s specs. Particularly impressive is the very low screen reflectance, which is among the lowest we have ever measured – outdoors it can have a significant impact on screen visibility. The over-saturated gaudy colors are still there – they need to be properly managed and can be used constructively in a calibrated fashion to counteract the effects of glare from ambient light (Part II).
The iPhone 4 display is a tremendous step forward over the iPhone 3GS and earlier models. It has double the resolution, a 26 percent brighter screen, 24 percent lower screen reflectance, and 64 percent greater Contrast under bright ambient light, plus it has 8 times the Contrast under dim ambient light. On the other hand, the iPhone 4 has the same reduced color gamut as the iPhone 3GS, producing under saturated somewhat washed-out colors. The iPhone 3GS has very low image contrast, which adds to the display’s washed-out appearance. The iPhone 4 has gone to the other extreme and has too much image contrast, which gives its images a punchier look and also partially compensates for its smaller color gamut. Lastly, the iPhone 4 display consumes only half the power of the iPhone 3GS display.
The original Droid, launched in October 2009, remains the number one smartphone in terms of overall picture quality and accuracy, close to what you see in a calibrated studio monitor and actually better than most living room HDTVs – just a lot smaller, but still impressive none-the-less. It earned the Best Mobile Picture Quality Award in the DisplayMate Best Video Hardware Guide but only for Android 2.0. Google confirmed that the some of the display problems we discovered afterwards were caused by upgrading to Android 2.1.
About the Author
Dr. Raymond Soneira is President of DisplayMate Technologies Corporation of Amherst, New Hampshire, which produces video calibration, evaluation, and diagnostic products for consumers, technicians, and manufacturers. See
. He is a research scientist with a career that spans physics, computer science, and television system design.