When people think of tablets, they think of iPads. To some people, the word “tablet” basically means “iPad.” So it’s a big deal when Apple creates a new one. With the new iPad Pro, Apple’s finally created a tablet that’s supposed to be professional grade, but does that self-imposed accolade stand up under extensive testing?
The key element for a great tablet has always been a truly innovative and top performing display, and the best leading edge tablets have always flaunted these beautiful high tech screens.
For 2015, there is a new broad product line of iPads – from the small mini 4 up to the new large Pro model, with display sizes that span almost 3 to 1 in screen area. The displays have different applications and performance criteria that we will measure and analyze below. The differences and similarities in performance between the 3 iPad displays are really interesting and surprising.
The tablet revolution began with the launch of the first iPad in 2010, and over the years the iPad displays have taken the lead with several major innovations, but they have also periodically lagged behind the displays on competing tablets. Looking back, the iPad displays have gotten major performance enhancements every two years (just like the iPhones but without the S designations). To understand the various performance aspects of the latest iPad displays we’ll first take a look at how they have evolved.
For 2010, the original iPad had a leading edge 1024x768 display with 132 pixels-per-inch (ppi) and a small-ish 62 percent color gamut that had noticeably lower color saturation. The next cutting edge development for tablet displays arrived in 2012 on the iPad 3, which not only doubled the resolution and ppi up to what Apple classifies as a “Retina Display,” but also provided a much larger 99 percent color gamut, which delivered full color saturation images.
Up through 2013 all of the iPads had relatively high screen reflections, primarily from an air gap between the outer cover glass and the display, resulting in a high reflectance of 8.7 percent of the ambient light falling on the screen, which was reduced with each succeeding generation down to 6.5 percent for the iPad Air 1 in 2013. That may seem like a small percentage difference, but it is their ratio that matters. So 6.5 percent reflects 25 percent less ambient light than 8.7 percent.
The next cutting edge development for tablet displays arrived in 2014 on the iPad Air 2, which received a very innovative low reflectance screen that reflects just 2.5 percent of the ambient light by using a new anti-reflection AR coating (together with eliminating the air gap). While this was overlooked by most consumers, reviewers, and (even) manufacturers, it was a major enhancement that reduced the reflected light glare from the screen by a very impressive 62 percent compared to the iPad Air 1 (and even more for the earlier iPads).
Reflected ambient light washes out the on-screen images, reducing both their contrast and color saturation. Since (almost) no one looks at the screen in absolute darkness, that 62 percent decrease in reflectance significantly increases the actual on-screen image contrast that you see in typical ambient light by an incredible factor of 2.6 times, and that also improves on-screen color saturation. Stated another way, the earlier iPads had less than 38 percent of the visual display contrast compared to the iPad Air 2 in typical ambient light. The difference is very easy to see in side-by-side visual comparisons, particularly when the displays are turned off so you just see the light reflected by the screens.
A lower screen reflectance also allows you to reduce the display brightness setting in ambient light, which saves power and increases running time on battery. Lowering screen reflectance is a major display performance improvement for real world viewing conditions.
The much anticipated smaller 7.9 inch iPad mini 1 launched in 2012, but the mini’s display performance has always lagged behind the full-size, 9.7-inch iPads by one to two generations. In 2013, the mini 2 was upgraded to a Retina Display but still only received the lower 62 percent color gamut, which also continued for the mini 3 in 2014. The mini screen reflectance was even higher than the full size iPads. The iPad mini was treated like the runt of the litter, but it has now found favor and been transformed into a beautiful leading edge display on the new iPad mini 4.
For 2015, all of the current iPad displays have all of the enhancements mentioned above. The iPad Air 2 continues on as the current 9.7-inch model, the new 7.9 inch iPad mini 4 has received a slew of major display performance improvements, and there is the brand new iPad Pro with a much larger 12.9 inch display that is intended primarily for professional and advanced imaging applications (and promoted as a laptop replacement).
The differences and similarities in performance between these 3 current iPad displays are really interesting and surprising. We’ll cover these issues and much more, with in-depth comprehensive display tests, measurements and analysis.
To examine the performance of the iPad mini 4, the iPad Air 2, and iPad Pro displays we ran our in-depth series of Mobile Display Technology Shoot-Out lab tests and measurements in order to determine how these latest LCD tablet displays have improved. We take display quality very seriously and provide in-depth objective analysis based on detailed laboratory tests and measurements and extensive viewing tests with both test patterns, test images, and test photos. To see how far mobile displays have progressed in just five years see our 2010 Smartphone Display Shoot-Out, and for a real history lesson see our original 2006 Smartphone Display Shoot-Out.
In this results section we provide highlights of the comprehensive DisplayMate Lab tests and measurements and extensive visual comparisons using test photos, test images, and test patterns that are covered in the advanced sections. The main Display Shoot-Out Comparison Table summarizes the iPad mini 4, the iPad Air 2, and iPad Pro Lab measurements in the following categories: Screen Reflections, Brightness and Contrast, Colors and Intensities, Viewing Angles, LCD Spectra, Display Power.
You can also skip these highlights and go directly to the iPad Conclusions.
All of the iPads have similar high performance IPS LCDs, but with different performance enhancements. The iPad Air 2 and iPad Pro both have photo aligned LCDs, which provides higher contrast ratios than the traditional and more common mechanical alignment on the iPad mini 4. On top of that, the iPad Pro has a metal oxide TFT backplane that increases the light throughput for the panel and therefore increases its power efficiency, which is particularly important for such a large mobile LCD panel with a backlight that needs lots of battery power to keep all of its LEDs shinning.
All of the iPads have Retina Displays, which means that their pixels are not resolved with normal 20/20 vision at their typical viewing distances. The smaller iPad mini 4 has a higher 326 pixels-per-inch (ppi) because it is typically viewed closer than the larger iPad Air 2 and iPad Pro, which have 264 ppi. All the iPads appear perfectly sharp at their typical viewing distances.
Because the iPad Pro has a much larger screen size, its ppi results in a significantly higher resolution of 2732 x 2048 pixels, versus 2048x1536 pixels for the iPad mini 4 and iPad Air 2. All of the iPads have a horizontal to vertical screen aspect ratio of 4:3, which is the same as standard 8.5 x 11-inch paper documents (with 0.5 inch borders). Their most important and significant difference is the almost 3 to 1 range in screen area.
Display Brightness and Contrast Ratio
All of the iPads have fairly high maximum brightness, from 415 cd/m2 (nits) for the iPad Air 2, to 424 nits for the iPad Pro, and 450 nits for the iPad mini 4. High screen brightness is only needed when in high ambient light, so most of the time the brightness should be set lower than the maximum.
The display’s maximum contrast is the ratio between its peak white brightness (luminance) and its darkest black luminance, one of the more important measures of LCD performance quality. All of the iPads have fairly high true contrast ratios, from 967 for the iPad mini 4, to 1,064 for the iPad Air 2, up to a very impressive 1,631 for the iPad Pro, the highest we have ever measured for an LCD tablet display. Note that some manufacturers list a much higher (dynamic) contrast ratio for their LCDs, but that is just meaningless marketing puffery. See the Brightness and Contrast section for measurements and details.
Color Gamut and Absolute Color Accuracy
Good color accuracy is particularly important for tablets because they provide much larger images than smartphones. Their accuracy has been steadily improving as the result of providing close to 100 percent color gamuts and more manufacturers are now using fully automated color calibration with instruments at the factory instead of having assembly workers visually tweaking the colors.
Producing high absolute color accuracy is incredibly difficult because everything on the display has to be done just right. In order to deliver accurate image colors, a display needs a 100 percent sRGB / Rec.709 Standard color gamut that is used for producing virtually all current consumer content for digital cameras, HDTVs, the internet, and computers, including photos, videos, and movies. The iPad mini 4 has a very accurate 101 percent color gamut, while the iPad Air 2 and iPad Pro have slightly too large 105 to 107 percent color gamuts, primarily from over saturated Blue primaries, which reduces their color accuracy. See this Figure for the measured Color Gamuts.
In order to produce high absolute color accuracy a display also needs an accurate (pure logarithmic power-law) intensity scale, and an accurate white point. The new iPads have fairly accurate intensity scales with gammas fairly close to the 2.2 standard, however, they all have slightly bluish white points, with color temperatures of 7,109K to 7,355K, which is still (marginally) very good but reduces their overall color accuracy somewhat because the white point also affects all of the low saturation colors in the color gamut. See this Figure for a plot of the measured intensity scales and the Colors and Intensities section for measurements and details.
The iPad mini 4 has a very impressive absolute color accuracy with average/maximum color errors of 1.9 and 4.2 JNCD – tied for first place in absolute color accuracy with the Microsoft Surface Pro 4. The iPad Pro is somewhat less accurate but still (just barely) very good with average/maximum color errors of 2.6 and 6.6 JNCD. The iPad Air 2 has noticeably lower absolute color accuracy with average/maximum color errors of 3.9 and 8.8 JNCD, which are visually noticeable and could be unacceptable for some color critical applications (like medical imaging, high-end digital photography, product sales demonstrations, and advertising proofs, for example).
See this Figure for an explanation and visual definition of JNCD and the Color Accuracy Plots showing the measured display color errors. See the Color Accuracy section and the Color Accuracy Plots for measurements and details.
Screen Reflectance and Performance in Ambient Lighting
The screens on all displays are mirrors that reflect light from everything that is illuminated anywhere in front of the screen (especially anything behind the viewers), including lamps, ceiling lights, windows, direct and indirect indoor and outdoor sunlight, which washes out the on-screen colors, degrades image contrast, and interferes with seeing the on-screen images. The lower the screen reflectance the better. In fact, decreasing the screen reflectance by 50 percent doubles the effective contrast ratio in ambient light, so it is very important.
To visually compare the differences in screen reflectance for yourself, hold any tablets or smartphones side-by-side and turn off the displays so you just see the reflections. Those reflections are still there when you turn them on, and the brighter the ambient light the brighter the reflections.
A major innovation for all of the current iPads is an anti-reflection AR coating on the cover glass that reduces ambient light reflections by about 3:1 over most other tablets and smartphones (including the previous iPads), and about 2:1 over all of the very best competing tablets and smartphones.
Right now all 3 current iPads are the unrivaled record holders for display performance in ambient light as a result of their record low screen reflectance of 2.0 to 2.6 percent, significantly lower than the 4.5 to 6.5 percent reflectance found in all other current competing tablets. The iPad mini 4 is the best at 2.0 percent, with the iPad Air 2 at 2.5 percent and the iPad Pro at 2.6 percent.
Our contrast rating for high ambient light quantitatively measures screen visibility under bright ambient light – the higher the better. As a result of its high brightness and very low reflectance, the iPad mini 4 has a contrast rating for high ambient light of 225, by far the highest that we have ever measured. The iPad Air 2 has 166 and the iPad Pro has 163. See the Screen Reflections and Brightness and Contrast sections for measurements and details.
Viewing Angle Performance
While tablets are primarily single viewer devices, the variation in display performance with viewing angle is still very important because single viewers frequently hold the display at a variety of viewing angles, plus they are large enough for sharing the screen with others. The angle is often up to 30 degrees, more if it is resting on a table or desk.
The iPads all have IPS LCD displays, so we expected them to show very small color shifts with viewing angle, and our lab measurements confirmed their excellent viewing angle performance, with no visually noticeable color shifts.
The display’s contrast ratio also changes with viewing angle, and at 30 degrees the iPad Pro maintained its high contrast ratio with 1,015 in portrait mode and 974 in landscape mode, the highest we have ever measured for an LCD tablet. The iPad Air 2 and iPad mini 4 contrast ratios at 30 degrees were both in the 400 to 650 range, which are much lower but still very good for mobile displays.
However, all LCDs do have a strong decrease in brightness (luminance) with viewing angle, and all of the iPads showed (as expected) a 55 to 60 percent decrease in brightness at a modest 30-degree viewing angle. See the Viewing Angles section for measurements and details.
The iPads all provide very nice, pleasing and accurate colors and picture quality. The very challenging set of DisplayMate Test and calibration photos that we use to evaluate picture quality looked Beautiful, even to my experienced hyper-critical eyes.
But in side-by-side visual comparisons of all 3 iPads, it was clear that the iPad mini 4 provided the best and most accurate colors and image contrast over a very wide range of photo and image content – the result of its high color accuracy and very accurate intensity scale. See Figure 2 and Figure 3 and the Colors and Intensities section for quantitative details.
Display Power Efficiency
There are many factors that affect a display’s power efficiency, including the type of the white LEDs that are used, the optics and optical films in the backlight, the circuit technology in the LCD backplane, and the pixels per inch.
After measuring the power used by each display, we scaled them all to the same screen brightness (luminance) and the same screen area in order to compare their relative power efficiencies. The display power efficiencies for the iPad mini 4 and iPad Pro are 22% to 33% higher than the iPad Air 2.
The iPad Pro is the most power efficient of the iPads for two reasons: it has a metal oxide backplane, which increases the light throughput for the panel, and the display uses a lower refresh rate when the images remain static (like during our power measurements). See the Display Power section for measurements and details.
The primary goal of this Display Technology Shoot-Out article series has always been to publicize and promote display excellence so that consumers, journalists, and even manufacturers are aware of and appreciate the very best in displays and display technology. We point out which manufactures and display technologies are leading and advancing the state-of-the-art for displays by performing comprehensive and objective scientific lab tests and measurements together with in-depth analysis. We point out who is leading, who is behind, who is improving, and sometimes (unfortunately) who is back pedaling—all based solely on the extensive objective careful lab measurements that we also publish, so that everyone can judge the data for themselves as well.
The conclusions below summarize all of the major results. See the main Display Shoot-Out Comparison Table for all the DisplayMate Lab measurements and test details, and see the Results Highlights section above for a more detailed introduction and overview with expanded discussions and explanations.
The new product line of iPads now includes small, medium, and large displays, with sizes that span almost 3 to 1 in screen area. The displays have different applications and performance criteria. The differences and similarities in performance between the 3 iPad displays are really interesting and surprising.
The nicest surprise this year is the tremendous improvement in the display quality and performance of the iPad mini 4 after the poor showings of previous minis – the mini 4 is now very impressive and breaks many tablet display performance records. The iPad Pro has also made a strong entrance and first appearance.
As we analyze in detail below, the iPad mini 4 and iPad Pro both deliver uniformly consistent all around top-tier display performance: two of a small number of displays to ever to get all green (very good to excellent). Ratings in all test and measurement categories (except for brightness variation with viewing angle, which is the case for all LCDs) since we started the Display Technology Shoot-Out article Series in 2006, an impressive achievement for a display. The iPad Air 2 missed the all green performance cut as the result of its lower yellow absolute color accuracy (discussed below).
Right now, all the iPads are the unrivaled record holders for display performance in ambient light as a result of their record low screen reflectance of 2.0 to 2.6 percent, significantly lower than the 4.5 to 6.5 percent reflectance found in all other current competing tablets. As a result, the iPads provide by far the highest on-screen image contrast in ambient light and the highest contrast rating for high ambient light of all current tablet displays. In theNext Generation of Displays section below we’ll explain how the display performance in ambient light can be further significantly improved.
Below we individually cover and analyze the display performance of iPad mini 4, iPad Air 2, and iPad Pro displays.
iPad mini 4
The iPad mini 4 is close to being a textbook perfect LCD display in all of the lab measurements and viewing tests. Among the iPads it takes first place and is marked “Best” in every single test category except contrast ratio – where it has a “very good” but not the highest contrast ratio of 957 in 0 lux (because Apple didn’t provide a Photo Aligned LCD like on the Air 2 and Pro).
Among all existing Tablets of any size, the iPad mini 4 takes first place and breaks performance records in many of the most important test categories including: lowest screen Reflectance (2.0 percent), highest contrast rating in high ambient light (225), a near perfect log-straight intensity scale and gamma of 2.22, and the highest absolute color accuracy (average/maximum color errors of 1.9 and 4.2 JNCD – tied for first place with the Microsoft Surface Pro 4). If Apple hadn’t intentionally made the display’s white point so bluish (7,109K instead of 6,500K) then the color errors would have been even smaller.
There is just one qualification. if you will be viewing dark content or need perfectly dark black levels, then an OLED display like the Samsung Galaxy Tab S 8.4 will perform much better than an LCD display.
The iPad mini is small but has a gorgeous display – unquestionably the best and most accurate LCD tablet display that we have ever tested. If a 7.9 inch display is big enough, the iPad mini 4 is the best. See the Display Shoot-Out Comparison Table for all of the measurements and details.
iPad Air 2
The iPad Air 2 has a “very good” display overall, but for almost all of the tests and measurements it came in somewhat behind both the iPad mini 4 and Pro – both are new for 2015 while the Air 2 was introduced in 2014, and the unit we tested was our original from 2014. It is certainly possible that the 2015 iPad Air 2 production units have been improved, but we have not seen that on previous iPad and iPhone models carried over from year to year.
While the iPad Air 2 performed very well overall, it did not take first place in any of the tests, which is actually a nice demonstration of the steady improvements in displays and display technology from year-to-year. It came in a solid second place only once, with a contrast ratio of 1,064, 11 percent higher than the mini 4 (which lacks a photo aligned LCD) but 35 percent behind the record high 1,631 for the iPad Pro. In all other tests it was either tied for second or a close behind third.
The one category where the iPad Air 2 received a disappointing yellow grade, was in absolute color accuracy, where it had average/maximum color errors of 3.9 and 8.8 JNCD, which are visually noticeable and could be unacceptable for some color critical applications (like medical imaging, high-end digital photography, product sales demonstrations, and advertising proofs, for example). If better absolute color accuracy is important then for this screen size consider the Samsung Galaxy Tab S 10.5 with average/maximum color errors of 2.1 and 4.0 JNCD or the Microsoft Surface 3 with 2.2 and 4.5 JNCD.
If absolute color accuracy is not critical then the iPad Air 2 has a “very good” all around medium size tablet display. See the Display Shoot-Out Comparison Table for all of the measurements and details.
The iPad Pro is a large tablet, with almost double the screen area of the iPad Air 2, and almost triple the area of the iPad mini 4. Many professional and imaging applications need or can benefit from a large display that you can easily carry around, lay flat on a table, just hold, or rest on your lap. But to qualify as a professional grade display it needs to provide top image quality and accuracy.
The iPad Pro display performed very well in all of our tests and measurements, earning “very good” to “excellent” in all test categories, performing not quite as well as the iPad mini 4. But it came in or tied for second place in every test except true contrast Ratio in 0 lux, where it is the definitive winner and marked “best” with a record 1,631.
But in two test categories the Pro display was not quite stellar. First, since 2012 all of the iPad and iPhone displays have had near perfect log-straight intensity scales (something that no other manufacturer has yet been able to match), but on the iPad Pro there is a significant intensity scale bump and irregularity at and below 45 percent signal as shown in this Figure, a surprising calibration issue for an Apple display (but still better than most competing tablets).
Second, in absolute color accuracy the iPad Pro just barely qualified for a “very good” green rating, just 6 percent from the cutoff, where it has average/maximum color errors of 2.6 and 6.6 JNCD, much better than the iPad Air 2, but no where near as good as the iPad mini 4, as shown in this Figure. If better absolute color accuracy is important, then for this screen size consider the Microsoft Surface Pro 4 with average/maximum color errors of 1.9 and 4.1 JNCD – tied with the iPad mini 4 for the most color accurate tablet that we have ever tested.
The displays on the competing iPad Pro and Surface Pro 4 are both “very good” to “excellent” in all test categories. The most significant performance differences are the iPad Pro’s much lower screen reflectance (2.6 versus 5.6 percent) and the Surface Pro 4’s much better absolute color accuracy (listed above).
If you need a large professional-grade tablet with “very good” to “excellent” image quality and accuracy, the iPad Pro delivers a top-tier professional display. See the Display Shoot-Out Comparison Table for all of the measurements and details.
Right now the iPads are the unrivaled record holders for display performance in ambient light as a result of their record low screen reflectance of 2.0 to 2.6 percent, significantly lower than the 4.5 to 6.5 percent reflectance currently found in all other current competing tablets.
Apple has taken an important first step towards improving display performance in ambient light. But essentially all displays are still designed to work best in absolute darkness, but they all significantly degrade in even modest levels of ambient light. However, Microsoft has also taken an important initial step with the Surface 3 providing its best color accuracy in typical indoor 300 lux ambient light rather than in absolute darkness like everybody else.
The best performing LCD and OLED displays are now delivering impressive sharpness, brightness, low reflectance, high color accuracy, accurate image contrast, and great viewing angles. So what comes next? Essentially all published display specifications and factory calibrations are based on performance in absolute darkness 0 lux, but mobile displays (and even TVs) are seldom viewed in the dark. Even low levels of ambient light significantly affect the image and picture quality. For example, the 100 percent sRGB color gamut specified by many manufacturers only applies at 0 lux. At 500 lux, which corresponds to typical indoor office lighting, the on-screen colors are washed out by the reflected ambient light, typically reducing the on-screen Color gamut from 100 percent down to 80 percent, plus the image contrast is also significantly affected. And it gets worse as the ambient light levels increase.
The most important improvements for both LCD and OLED displays will come from improving their image and picture quality and screen readability in real world ambient light, which washes out the screen images, resulting in reduced image contrast, color saturation, and color accuracy. The key will be in lowering screen reflectance and then implementing dynamic color management with automatic real-time modification of a larger color gamut and intensity scale based the measured ambient light level in order to have them compensate for the reflected light glare and image wash out from ambient light as discussed in our 2014 Innovative Displays and Display Technology and SID Display Technology Shoot-Out articles.
The higher the ambient light level, the larger the color gamut that the display needs in order to compensate for the loss of color saturation from the reflected ambient light. All LCDs will need Quantum Dots in order to implement the necessary large color gamuts.
The displays, technologies, and manufacturers that succeed in implementing this new real world high ambient light performance strategy will take the lead in the next generations of mobile displays.
Below we examine in-depth the LCD displays on the Apple iPad mini 4, the iPad Air 2, and iPad Pro based on objective lab measurement data and criteria. For comparisons and additional background information refer to these comparable Tablet displays: Microsoft Surface Pro 4 Display Technology Shoot-Out, the Microsoft Surface 3 Display Technology Shoot-Out, and the Samsung OLED Tab S Display Technology Shoot-Out.
For comparisons with the other leading tablet, smartphone, and smartwatch displays see our Mobile Display Technology Shoot-Out series.
Click this link to see the complete Data Comparison Table.
About the Author
Dr. Raymond Soneira is President of DisplayMate Technologies Corporation of Amherst, New Hampshire, which produces display calibration, evaluation, and diagnostic products for consumers, technicians, and manufacturers. See www.displaymate.com. He is a research scientist with a career that spans physics, computer science, and television system design. Dr. Soneira obtained his Ph.D. in Theoretical Physics from Princeton University, spent 5 years as a Long-Term Member of the world famous Institute for Advanced Study in Princeton, another 5 years as a Principal Investigator in the Computer Systems Research Laboratory at AT&T Bell Laboratories, and has also designed, tested, and installed color television broadcast equipment for the CBS Television Network Engineering and Development Department. He has authored over 35 research articles in scientific journals in physics and computer science, including Scientific American. If you have any comments or questions about the article, you can contact him at email@example.com.
About DisplayMate Technologies
DisplayMate Technologies specializes in proprietary advanced scientific display calibration and mathematical display optimization to deliver unsurpassed objective performance, picture quality and accuracy for all types of displays including video and computer monitors, projectors, HDTVs, mobile displays such as Tablets and Smartphones, and all display technologies including LCD, LCD, 3D, LED, LCoS, Plasma, DLP and CRT. This article is a lite version of our intensive scientific analysis of Tablet and Smartphone mobile displays – before the benefits of our advanced mathematical DisplayMate Display Optimization Technology, which can correct or improve many of the display deficiencies. We offer DisplayMate display calibration software for consumers and advanced DisplayMate display diagnostic and calibration software for technicians and test labs.
For manufacturers we offer Consulting Services that include advanced Lab testing and evaluations, confidential Shoot-Outs with competing products, calibration and optimization for displays, cameras and their User Interface, plus on-site and factory visits. We help manufacturers with expert display procurement, prototype development, and production quality control so they don’t make mistakes similar to those that are exposed in our Display Technology Shoot-Out series. See our world renown Display Technology Shoot-Out public article series for an introduction and preview. DisplayMate’s advanced scientific optimizations can make lower cost panels look as good or better than more expensive higher performance displays. If you are a display or product manufacturer and want to turn your display into a spectacular one to surpass your competition then Contact DisplayMate Technologies to learn more.
This article has been republished with permission from DisplayMate.com, where it can be read in its entirety. Follow DisplayMate on Twitter to learn about these developments and our upcoming display technology coverage.
Top image by Michael Hession