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Samsung Galaxy OLED Display Technology Shoot-Out

Galaxy S I  –  Galaxy S II  –  Galaxy S III

 

Dr. Raymond M. Soneira

President, DisplayMate Technologies Corporation

 

Copyright © 1990-2012 by DisplayMate Technologies Corporation. All Rights Reserved.

This article, or any part thereof, may not be copied, reproduced, mirrored, distributed or incorporated

into any other work without the prior written permission of DisplayMate Technologies Corporation

 

 

Galaxy S I

Galaxy S II

Galaxy S III

Introduction

Organic Light Emitting Diodes, OLEDs, are the first new display technology in over 10 years that appears destined to play an increasing and eventual commanding role in the marketplace. And they are finally ready to go big time – OLED HDTVs are expected to arrive by early 2013 when LG and Samsung will begin shipping their first 55 inch flagship models – they will draw crowds but initially few will be able to afford the first generation price tags. On much smaller and affordable scales, Samsung has for several years been supplying most of the OLED displays found on a rapidly increasing number of Smartphones and a few Tablets.

 

The first famous OLED Smartphone was the Google Nexus One, launched in January 2010, which included a Samsung early generation OLED display. But by far the most successful series of OLED Smartphones has been Samsung’s own Galaxy S series that launched in mid 2010 – Galaxy S I with a 4.0 inch screen in June 2010, Galaxy S II with a 4.5 inch screen in June 2011, and the just released Galaxy S III with a 4.8 inch screen in June 2012. All are called “Super AMOLED” – some are Plus and others are PenTile – we’ll explain the differences below.

 

Not surprisingly, all new display technologies initially start near the back of the pack in performance compared to the established and more refined products – IPS LCDs in this particular case. Not surprisingly, the Google Nexus One came in last place in our Smartphone Display Shoot-Out. But six months later the Samsung Galaxy S I did a lot better and we gave it a DisplayMate Best Video Hardware Award for the Best New Display Technology. In this Shoot-Out we will examine in-depth the display performance of the three Galaxy S generations to see how OLEDs have been evolving and improving over time. This article will be a combination of objective praise and critical analysis of OLED displays.

 

OLED versus LCD and LED

Most Smartphones, Tablets, Laptops, Computer Monitors, and HDTVs currently use LCD display technology, which is a transmissive technology that requires a Backlight to produce the light for the image. That Backlight is being made increasingly with LEDs. Many manufacturers advertise their LCD displays and HDTVs that have LED Backlights as LED displays and HDTVs, but that is very misleading because the LEDs are just the Backlight for the LCD. There are actually no consumer LED displays or HDTVs. On the other hand, OLED displays are emissive devices that don’t require a Backlight because every pixel and sub-pixel gives off its own colored light to produce the image. That lack of a Backlight and its complex optics means that OLEDs are a lot thinner than LCDs and is also the reason why OLEDs will eventually become a lot cheaper to manufacture than LCDs.

 

OLED, PenTile AMOLED, Super AMOLED, Super AMOLED Plus, and HD Super AMOLED

The marketing terminology and puffery for displays varies among manufacturers and is confusing… The Google Nexus One was listed as having an “AMOLED” display. The AM stands for Active Matrix, but that prefix is unnecessary because all current LCD and OLED Smartphones, Tablets, Laptops, and HDTVs use an Active Matrix. All subsequent generations of Samsung OLEDs are called “Super AMOLED” in the same way that you’ll often see “Super LCD” advertised as well. Not all manufacturers use the “Super” terminology so it’s best just to ignore it as advertising puffery. “HD AMOLED” means that the pixel resolution of the display is High Definition 1280 x 720 pixels or higher. But here is where it gets complicated and confusing – if you see “Plus” that means that the display has the traditional 3 Red, Green and Blue sub-pixel arrangement that is found in almost all display technologies. If you don’t see “Plus” on Samsung devices that means that the display has only 2 sub-pixels per pixel (a Minus) – half of the pixels have Green and Red sub-pixels and the other half have Green and Blue sub-pixels, so Red and Blue are always shared by two adjacent pixels. This technology is called “PenTile.” PenTile screens have only half the total number of Red and Blue sub-pixels as the traditional 3 sub-pixel displays, so they aren’t as sharp as traditional displays with the same pixel resolution and their highly advertised screen PPIs are not comparable. This is especially noticeable with colored text and graphics. PenTile uses Sub-pixel Rendering and Anti-Aliasing that partially compensates for this shortfall. PenTile displays have some advantages: they are easier to manufacture and therefore cost less, and for OLEDs the Red, Green and Blue sub-pixels are sized differently and that improves Blue aging somewhat (see below). For now, OLED displays over 250 PPI use PenTile technology. It’s expected that the next generation of OLEDs will be called “HD Super AMOLED Plus” and they will have the standard 3 sub-pixels per pixel.

 

The Shoot-Out

To compare the performance of the Galaxy S series of OLEDs we ran our in-depth series of Display Technology Shoot-Out tests on the Galaxy S I, Galaxy S II, and Galaxy S III. We take display quality very seriously and provide in-depth objective analysis side-by-side comparisons based on detailed laboratory measurements and extensive viewing tests with both test patterns and test images. For additional background, context, and comparisons see our in-depth new iPad Display Shoot-Out and the previous generation Smartphone Display Shoot-Out.

 

Galaxy S I

Galaxy S II

Galaxy S III

Results Highlights

In this Results section we provide Highlights of the comprehensive lab measurements and extensive side-by-side visual comparisons using test photos, test images and test patterns that are presented in later sections. The next section below provides OLED Power Saving and Aging Advice. The Comparison Table in the following section summarizes the lab measurements in the following categories:  Screen ReflectionsBrightness and ContrastColors and IntensitiesViewing AnglesDisplay Power ConsumptionRunning Time on Battery.

 

New Issues for a New Technology:  OLED is a very different new display technology and so both manufacturers and consumers will have to learn about its particular performance requirements and idiosyncrasies. The new issues for OLEDS are just as challenging and significant as when we shifted from CRTs to LCDs. An excellent source of information about OLEDs is www.oled-info.com. As the discussion below shows, manufacturers still have a lot to learn…

 

OLED Engineering versus Galaxy Marketing:  This is actually a combined Shoot-Out – we are looking at an OLED display implemented within Samsung Galaxy Marketing goals and requirements. One of the most important is to make the Smartphone as thin and light as possible. Unfortunately, the battery is a major contributor to both thickness and weight so it bears the brunt of this limitation. OLED displays still require more power on the average than comparable LCDs. And unfortunately, the Galaxy S I,II,III battery runtimes (below) are shorter than most other Smartphones that we have tested. As a result, Power Management is the single biggest issue confronting OLED displays. The power constraints on all of the Galaxy S Smartphones have significantly impacted many display performance issues, particularly on the Galaxy S III. This is undoubtedly a strategic marketing decision, but it would be nice if the Galaxy S III were also available in a slightly thicker and heavier version with a bigger battery. In particular, that would help its OLED display really shine if there were fewer imposed power constraints that affect its calibration and performance…

 

OLED Progress Report:  Based on our Lab tests and measurements below there has been a rapid and significant improvement in OLED performance within the Galaxy S I,II,III series, particularly the power efficiency, which is extremely important. The OLED displays themselves are excellent, but their overall performance has been compromised by the calibration and implementation choices that have been made for the Galaxy S series, which are discussed in detail throughout this article.

 

OLED Aging:  All display technologies age to varying degrees. The current generation of Blue OLEDs age much faster than the Red and Green OLEDs. The current 50 percent aging Brightness for Blue is specified by the manufacturers at 20,000 hours while Red and Green are both over 200,000 hours. People generally don’t hold onto their Smartphones for very long: for example, 2 years at 4 hours per day is about 3,000 hours. That would actually be enough time for the Blue aging to become visually noticeable, but there is also some built-in automatic aging compensation that adjusts the drive levels to help counteract the aging effects. In the past users have documented OLED aging with screen shots, but there have been continuing improvements, so it’s hard to say how large the visual aging effects are for the current generation of OLEDs. We include some advice on reducing aging effects and improving the power efficiency of OLEDs below.

 

Comparison with the Best LCDs:  The premium IPS LCDs used in many top performing Smartphones and Tablets (including the iPhone 4s and iPads) are the benchmark competition for these OLED displays. IPS LCDs remain significantly brighter and still have a higher overall power efficiency, but typically have a smaller Color Gamut, a higher Black Level, a larger Brightness decrease with Viewing Angle, and some Motion Blur. OLEDs are still more expensive than LCDs, although that will change over the next several years. While LCDs are not very power efficient, they are still more power efficient than OLEDs for producing bright images (although the public perception is the reverse – that’s why OLED displays are dimmer and why you don’t see any large OLED Tablets). There has been quite a significant improvement within the Galaxy S I,II,III series and this will undoubtedly continue until OLEDs eventually become more efficient than LCDs. For comparison with LCDs see our in-depth new iPad Display Shoot-Out.

 

Screen Brightness:  The Maximum and Peak Brightness for the Galaxy S III are significantly lower than the S II and S I, and they are in turn lower than most LCDs. Fortunately, the Screen Reflectance of the Galaxy S series is among the lowest we have ever measured and that helps overcome much of the Brightness shortfall. A more troubling issue with current OLEDs is the variation in Brightness that occurs with image content, called the Average Picture Level, APL. Bright images with high APL have their screen Brightness reduced by up to 30 percent, which introduces undesirable Brightness variations with content. Another side effect is that the Brightness of images can change significantly in shifting between Portrait and Landscape modes. On the Google Galaxy Nexus, a close cousin of the Galaxy S III, the effect is so large for high APL that the Brightness (Luminance) of Green is greater than White, which is very wrong.

 

Color of White for OLEDs:  Providing an accurate White is very important for getting accurate colors in images, particularly photos and videos. The Standard White for digital photography and essentially all consumer content is called D6500, which is the color of Daylight and corresponds to a Color Temperature of 6,500 degrees Kelvin. Whites with a higher Color Temperature appear too blue and lower too yellow. White for the Galaxy S series ranges from 10,200 Kelvin for the S I down to 7,900 Kelvin for the S III, among the bluest Whites we have ever measured. This gives all images something of a cold bluish cast. But what is positively shocking about increasing the Blue content of all images is that Blue OLEDs have only about one tenth the power efficiency of Red and Green OLEDs (see below), so the additional Blue produces a significant waste of precious power that has very little effect on the total screen Brightness. Perhaps even more shocking is that the Blue OLEDs age at a much faster rate than the Red and Green OLEDs, so the higher Color Temperature accelerates the aging process – a very bad idea. Using the Standard D6500 White would improve color accuracy, improve battery run time, and reduce aging…

 

Color Saturation and Accuracy:  OLEDs have a large native Color Gamut, much bigger than LCDs, but bigger isn’t always better. In order to accurately reproduce the colors in photos, videos and other images the display needs to match the Standard sRGB / Rec.709 Color Gamut that is used to generate most consumer content. The Color Gamut of the Galaxy S I,II,III is 138 percent of the Standard, which produces oversaturated colors that can appear comic book like and gaudy in some instances. Photos appear with way too much color. It’s similar to turning the Color Control way up on your HDTV. Unfortunately, none of the Galaxy S Smartphones have a similar Color Saturation control that would allow users to correct this or adjust it to their satisfaction, so you’re stuck unless there is a software update that corrects this. An accurate factory color calibration would fix it – but the exaggerated images sometimes make these Smartphones standout in a crowd, so it undoubtedly helps boost retail store sales. But eventually when you want to see accurate renderings of your photos and images, you’re out of luck. Note that Apple is emphasizing very high color accuracy in their latest displays – hopefully Samsung will follow the lead…

 

Irregular Color Gamut and Power Implications:  Not only is the Galaxy S I,II,III Color Gamut set way too large, but it is also very irregular – Green is much more saturated compared with either Red or Blue, as shown in Figure 2. This imbalance has a tendency to give images a Green accent and color cast. But correcting the Gamut so that it matches the Standard has power efficiency implications because Green is significantly more power efficient than either Red or Blue, and they must be added as calibration color mixtures for the Color Gamut adjustments, so the power consumption for a calibrated OLED display will be higher. See below.

 

Viewing Angle Performance:  In principle, OLEDs shouldn’t have any variation in Brightness or Color with Viewing Angle. But they do – they are still better than LCDs but show significantly larger Brightness and Color Shifts than might be expected. The Color Shifts are actually about double that for IPS LCDs, but are still satisfactory. This is due primarily to the anti-reflection layer, although the touch screen and cover glass also affect Viewing Angle performance. The root cause is the greater optical path absorption at larger Viewing Angles. It’s still satisfactory, but larger than expected. However, at very large Viewing Angles (greater than 45 degrees) the screens on the Galaxy S I,II,III take on a distinctly strong blue color shift and cast.

 

OLED Power Efficiency:  While LCDs are not very power efficient, they are still currently more power efficient than OLEDs for producing bright high Average Picture Level APL images. For dark low APL images OLEDs are very efficient and LCDs very inefficient. So OLED Power Efficiency and Power Management strategies become very important for bright images because they are using lots of battery power (and generating heat). By far the most significant issue is that Green OLEDs are 12 times more power efficient than Blue OLEDs and 1.8 times more efficient than Red OLEDs at producing visible light (Luminance) for a given amount of display power (Watts). In fact, Blue OLEDs consume more power than Green OLEDs but generate only 9 percent of Green OLED Brightness (Luminance). This tremendous imbalance means that images with lots of Green content are much more power efficient. It also means that color mixtures all come with a power penalty. In fact, color calibration of an OLED display so that it matches the sRGB / Rec.709 Standard would require complex color mixtures that will have noticeably higher power demands, which may make OLED calibration challenging in the near future for mobile displays until the OLED efficiencies (or battery power) increase significantly.

 

Galaxy S I, Galaxy S II, and Galaxy S III Power Efficiency Comparisons:  From our Luminance, Power, and screen Area measurements we can compare the relative display power efficiencies of the three Galaxy S generations. In going from the S I to the S II there was a 29 percent improvement in display power efficiency, and in going from the S II to the S III there was a 43 percent improvement in display power efficiency. From S I to S III there was a total of 59 percent improvement in display power efficiency – that’s in just 2 years – very impressive!

 

OLED Galaxy S III and iPhone LCD Power Efficiency Comparisons:  Typical full screen text applications (on a white background) have an Average Picture Level APL of 90 percent or more, so we expect LCDs to do better. On the other hand, typical full screen video and photographic images have an APL of 20 percent or less, so we expect OLEDs to do better there. From our Luminance, Power, and screen Area measurements we can determine exactly which is better, when, and by how much. Comparing the Galaxy S III and the iPhone 4, images with less than 28 percent APL are more power efficient on the Galaxy S III, and greater than 28 percent are more efficient on the iPhone 4 – so the Galaxy S III is somewhat more efficient for videos and significantly less efficient for text applications. But the iPhone 4 uses an LCD with Low Temperature Poly Silicon that is significantly more efficient than typical LCDs with amorphous Silicon, such as the iPhone 3GS – where the crossover is a lot higher at 69 percent APL, so it’s a split decision there depending on the application mix…

 

Aggressive Power Management:  The smaller battery and bigger power needs of the larger OLED screens requires aggressive display power management. The Galaxy S I has the least Power Management and the Galaxy S III has the most. First of all, the Maximum and Peak Brightness for the Galaxy S III are set significantly lower than the S II and S I, and they are in turn lower than most LCDs. Fortunately, the Screen Reflectance of the Galaxy S series is among the lowest we have ever measured and that helps overcome much of the Brightness shortfall. Also to save power, images with a high Average Picture Level APL are automatically dimmed by up to 30 percent. An Automatic Brightness control based on the Ambient Light level is also important for display power management, but it is implemented poorly (see below). These issues combined with the Power Efficiency effects discussed above could all be better implemented with a Display Power Management Slider – set it low and the display receives aggressive power management – set it high and the display delivers optimum performance.

 

Significantly Improved Battery Running Times:  The large improvement in OLED power efficiency and the much more aggressive Power Management has produced a 75 percent increase in Battery Running Time for the Galaxy S I to II to III, from a poor 3.2 hours to a very good 5.6 hours. For comparison, note that the iPhone 4 has a running time of 7.8 hours with a screen Brightness of 541 cd/m2 while the Galaxy S III has a running time of 5.6 hours with a screen Brightness of 224 cd/m2. The running times are based on a full brightness all white screen with no running applications. As the Average Picture Level APL decreases the Battery Running Times for OLEDs will increase.

 

Screen Reflectance:  Ambient light reflecting off the screen washes out the image, its contrast and colors. Increasing the screen Brightness is one way to overcome this problem but it uses precious battery power (and speeds up the OLED aging process). A much better method is to lower the screen Reflectance. Because of the way the LCD optics works they already have some built-in anti-reflection – not so for OLEDs, so they have a much more difficult Reflectance problem. Fortunately, Samsung has risen to the challenge because the Galaxy S OLED displays all have Reflectance of 5 percent or less – among the lowest we have ever measured. The Nokia Lumia 900 is the only other Smartphone to come in under 5 percent Reflectance. This is quite impressive – it’s done by using advanced optics, a Quarter Wave Plate under the cover glass suppresses the reflections. This is super important for OLEDs because of the brightness, power, and aging issues discussed above. Samsung has done an excellent job here. However, the Lab measurements indicate that the Reflectance is getting slightly worse from I to II to III, rather than better…

 

Automatic Brightness:  It is particularly important for Smartphones to accurately and automatically adjust their screen brightness according to the current highly variable Ambient Lighting conditions. This maintains screen visibility while minimizing the battery power needed to do so. Because OLEDs have significant power management issues this is especially important for them. Unfortunately, the Galaxy S Smartphones all perform poorly here (as do almost all Android devices – Apple does slightly better but still poorly). The Galaxy S I,II,III results are similar to the results in our Automatic Brightness Shoot-Out. An innovative application for the OLED’s large native Color Gamut and high Color Saturation is to (only) fully use it when there is High Ambient Light, which will help compensate for the washed out image colors and will even allow lower screen Brightness to be used under those conditions – but before that happens Automatic Brightness and Color Calibration will need to be properly implemented.

 

Polarized Sunglasses:  Most LCDs and some OLED displays can have screen viewing interference problems with polarized sunglasses – the image can become invisible Black at some screen orientations and angles. The Galaxy S I, Galaxy S II, and Galaxy Nexus have Quarter Wave Plate optics that result in a screen extinction at a 45 degree orientation, so their screens can be read in both Landscape and Portrait orientations, which is good. However, the Galaxy S III screen shows multi-colored circular rings with polarized sunglasses, which are quite pronounced at large Viewing Angles, so the Galaxy S III is not good with polarized sunglasses.

 

Google Galaxy Nexus:  The Google Galaxy Nexus is also made by Samsung and has an OLED display that is very similar to the Galaxy S III. However, its Brightness is set much higher than the S III, but it then has a much higher variation in Brightness with the APL of image content as discussed above – it is more than a 2:1 variation, which is way too large. In fact, the effect on the Galaxy Nexus is so large that for high APL the Brightness (Luminance) of Green is greater than White, which is very wrong. Hopefully, Google will correct that with an Android software update…

 

 

OLED Power Saving and Aging Advice

There is a lot that individual users can do to reduce the power consumption of OLEDs and also reduce potential aging effects:

 

The obvious recommendation for all display technologies is to appropriately adjust the screen Brightness for the current level of Ambient Light – that should be done by the Automatic Brightness control, but as indicated above it is poorly implemented and close to useless on virtually all Smartphones including the Galaxy S series. Hopefully that will be corrected in future versions of Android. When adjusting screen Brightness also take into account that applications like reading require higher visual acuity and need more Brightness than when looking at photo and video content.

 

Unlike LCDs, display power on OLEDs depends entirely on the image content – brighter images use more power. In particular, wallpapers and screen backgrounds can have a considerable impact on OLED power consumption.

 

Because of differential aging, setting your wallpaper to all Black is most likely a bad idea because the fixed arrangement of Home Screen icons may eventually affect screen uniformity, so ghost images of the icons might become noticeable.

 

For all text based reading applications it is a really good idea to set the standard Black text on a White background to Reverse Video, White text on a Black background. Not only does that use a lot less power but it improves screen viewability in bright Ambient Lighting. Start by setting Google’s search page to a Black background. Do the same for Email and other Apps and websites wherever possible.

 

Setting your wallpaper to a bright beach scene will use a lot more power than a subdued indoor photo. A more subtle but more important issue is that color has a major impact on display power consumption because the Green OLEDs provide 10 times more Brightness per watt than Blue OLEDs. In fact, Blue OLEDs consume more power than Green OLEDs but deliver only about one tenth of the Brightness. So give preference to images and wallpapers with Greens and try to avoid images with lots of Blue.

 

 

Conclusion:   Great OLED Displays… But Compromised by Galaxy Marketing Constraints…

All of the Galaxy S OLEDs performed very well in our Lab Tests and Measurements. The results indicate that there has been a rapid and significant 2:1 improvement in OLED performance, particularly the power efficiency within the Galaxy S I,II,III series in just 2 years, which is very impressive. LCDs like the iPhone 4 are still considerably more power efficient than the latest OLEDs for bright image content with white backgrounds, which includes most text based and web applications. On the other hand, OLEDs are much more power efficient for full screen videos and photos, which generally have low Average Picture Levels.

 

The OLED displays themselves are excellent, but their overall performance has been compromised by the implementation choices that have been made in marketing the Galaxy S series. In particular, the power constraints have significantly compromised many display performance issues, particularly in the Galaxy S III, in order to deliver a very thin and light phone with very good battery running times. This is undoubtedly a strategic marketing decision, but it would be nice if the Galaxy S III were also available in a slightly thicker and heavier version with a bigger battery. That would help its OLED display really shine, particularly if there were fewer imposed power constraints that affect its display performance. In addition, OLED displays all currently suffer from a lack of accurate Color Calibration, something that LCDs have gotten very good at, particularly the new iPad, which is almost accurate enough to be used as a professional studio reference monitor, so its photos, videos, and image content appear beautiful and accurate. Hopefully, the same will happen for OLED displays in the near future…

 

Even with these compromises and performance issues the latest Galaxy S III has an impressive OLED display. If and when Samsung and Google implement the suggestions that we have made it will turn into an outstanding display. That and future models indicate a very promising and exciting future for OLEDs…

 

Lots of Room for Improvement by Samsung and all of the other OLED Smartphone and Tablet Manufacturers:

While Samsung has zeroed in on OLED power efficiency and done an excellent job of it, there are still plenty of other very important display issues that need to be addressed by all of the OLED Smartphone and Tablet manufacturers along with Google for the Android OS. Here are just a few:  1. Variable Display Power Management:  The Power Efficiency effects discussed above could all be better implemented with a Display Power Management Slider – set it low and the display receives aggressive power management – set it high and the display delivers optimum performance.   2. Accurate Color Calibration:  The OLED Color Gamut is not only substantially larger than the sRGB/ Rec.709 Standard, but it is also very irregular – Green is much more saturated compared with either Red or Blue, as shown in Figure 2. This imbalance has a tendency to give images a Green accent and color cast. The display also needs a Standard D6500 White Point – using D6500 would improve color accuracy, improve Battery Running Time, and reduce Blue aging. Note that Apple is emphasizing very high color accuracy in their latest displays – hopefully Samsung and other manufacturers will follow the lead.   3. Screen Reflectance:  Samsung has done an excellent job here, but the Lab measurements indicate that the Reflectance is getting slightly worse from Galaxy S I to II to III – it definitely needs to get better. The typically large screen reflections can make the screen much harder to read even in moderate ambient light levels, requiring ever higher brightness settings that waste precious battery power. Manufacturers need to significantly reduce the mirror reflections with anti-reflection coatings and haze surface finishes. This article shows how Smartphone and Tablet screens degrade as the Ambient Light increases from 0 to 40,000 lux.   4. Ambient Light Sensor:  The forward facing Ambient Light Sensor on virtually all Smartphones and Tablets measures the brightness of your face instead of the surrounding Ambient Light, which is what is needed to accurately set the screen’s Automatic Brightness.   5. Automatic Brightness:  The Automatic Brightness controls on all Smartphones and Tablets that we have measured are positively awful and close to functionally useless. As a result they often get turned off, which reduces battery run time and increases eye strain. This article explains how to do it properly.   6. Display User Interface:  The User Interface for most Smartphone and Tablet displays consists of a Brightness slider and an Automatic Brightness checkbox. People have very different visual preferences that should be accommodated with a display Pizzazz control that is similar to the functionality provided by the audio Equalizers found on most Smartphones and Tablets.

 

 

DisplayMate Display Optimization Technology

All Smartphone and Tablet displays can be significantly improved using DisplayMate’s advanced scientific analysis and mathematical display modeling and optimization of the display hardware, factory calibration, and driver parameters. We can improve the performance of any specified set of display parameters. This article is a lite version of our intensive scientific analysis – before the benefits of our DisplayMate Display Optimization Technology, which can correct or improve all of these issues. If you are a display or product manufacturer and want to significantly improve display performance for a competitive advantage then Contact DisplayMate Technologies.

Galaxy S I

Galaxy S II

Galaxy S III

Display Shoot-Out Comparison Table

Below we compare the displays on the Samsung Galaxy S I, Galaxy S II, and Galaxy S III based on objective measurement data and criteria.

All of the units are USA T-Mobile retail products purchased new and tested as supplied without any modifications or installed optional software.

For additional background, context, and comparisons see our in-depth new iPad Display Shoot-Out and previous generation Smartphone Display Shoot-Out.

 

Categories

Samsung

Galaxy S I

Samsung

Galaxy S II

Samsung

Galaxy S III

Comments

Display Technology

4.0 inch

PenTile OLED

4.5 inch

RGB OLED

4.8 inch

PenTile OLED

Organic Light Emitting Diode

PenTile and RGB are the Sub-Pixel layouts

Samsung Marketing Name

Super AMOLED

Super AMOLED Plus

HD Super AMOLED

Super means second generation with advanced features.

AM means Active Matrix but is not necessary.

Plus means RGB Sub-Pixels, without Plus is PenTile.

Screen Shape

16:10  =  1.60

Aspect Ratio

16:10  =  1.60

Aspect Ratio

16:9  =  1.78

Aspect Ratio

Ratio of the Height to Width in Portrait mode.

Screen Area

7.1 sq inches

8.9 sq inches

9.8 sq inches

Screen area in square inches.

Relative Screen Area

100 percent

27 percent larger

than the Galaxy S I

39 percent larger

than the Galaxy S I

Screen area compared to the Galaxy S I.

Display Resolution

800 x 480 pixels

800 x 480 pixels

1280 x 720 pixels

The more Pixels and Sub-Pixels the better.

Pixels Per Inch

PenTile 233 PPI

Good

207 PPI

Very Good

PenTile 306 PPI

Very Good

PenTile displays have non-standard Pixels.

Sub-Pixels Per Inch

    Red 165 SPPI

Green 233 SPPI

    Blue 165 SPPI

    Red 207 SPPI

Green 207 SPPI

   Blue 207 SPPI

    Red 216 SPPI

Green 306 SPPI

   Blue 216 SPPI

PenTile displays have only half the number of

Red and Blue Sub-Pixels as RGB displays.

 

Note that the Galaxy S II and Galaxy S III have

approximately the same Red and Blue SPPI.

Total Number of Sub-Pixels

    Red 192 KSP

Green 384 KSP

    Blue 192 KSP

    Red 384 KSP

Green 384 KSP

    Blue 384 KSP

    Red 461 KSP

Green 922 KSP

    Blue 461 KSP

Number of Kilo Sub-Pixels for Red, Green and Blue.

On-Screen Displayed Color Depth

Full 24-bit color

256 Intensity Levels

Full 24-bit color

256 Intensity Levels

Full 24-bit color

256 Intensity Levels

24-bit displays produce images with relatively

smooth and artifact free colors and intensities.

Gallery  Viewer Color Depth

16-bit color

Full 24-bit color

256 Intensity Levels

Full 24-bit color

256 Intensity Levels

Most Android Tablets and Smartphones still have

only 16-bit color depth in the Gallery Photo Viewer.

 

Galaxy S I

Galaxy S II

Galaxy S III

 

 

Overall Assessments

This section summarizes the results of all of the extensive Lab measurements and viewing tests performed on all of the displays.

 

Viewing Tests

Good Images

Photos and Videos

have too much color

and irregular contrast

 

Medium Color Shifts

with Viewing Angle

Good Images

Photos and Videos

have too much color

 too much contrast

 

Medium Color Shifts

with Viewing Angle

Good Images

Photos and Videos

have too much color

 and good contrast

 

Medium Color Shifts

with Viewing Angle

The Viewing Tests examined the accuracy of

photographic images by comparing the OLED

displays to an accurate calibrated display.

Display Hardware Performance

Lab Tests and Measurements

Very Good

OLED Display

Excellent

OLED Display

Excellent

OLED Display

All of the Galaxy S OLEDs performed very well in

the Lab Tests and Measurements.

Overall Display Calibration

Lab Tests and Viewing Tests

Good

Needs Improvement

Good

Needs Improvement

Good

Needs Improvement

Numerous Power Management and Color Calibration

issues need correction or improvement.

Overall Display Grade

Good  B

Very Good  B+

Very Good  B+

All the OLED displays suffer from effects that result from restricting display power and lack of color calibration.

 

Galaxy S I

Galaxy S II

Galaxy S III

 

 

 

 

Screen Reflections

Figure 1.  Screen Reflection Photos

Click to Enlarge

All of these screens are mirrors good enough to use for personal grooming – but it’s actually a very bad feature…

We measured the light reflected from all directions and also direct mirror (specular) reflections, which are much more

distracting and cause more eye strain. 10 – 15 percent reflections can make the screen much harder to read even

in moderate ambient light levels, requiring ever higher brightness settings that waste precious battery power.

 

The Galaxy S displays all have Average Screen Reflectance of 5 percent or less – among the lowest we have measured.

The Nokia Lumia 900 is the only other Smartphone to come in under 5 percent Reflectance. This is quite impressive –

it’s done by using advanced optics, a Quarter Wave Plate under the cover glass suppresses the reflections.

Samsung has done an excellent job here. However, the Lab measurements indicate that the Reflectance is getting slightly

worse from I to II to III, rather than better.

 

Average Screen Reflection

Light From All Directions

Reflects 4.4 percent

Excellent

Reflects 4.7 percent

Excellent

Reflects 5.0 percent

Excellent

Measured using an Integrating Hemisphere.

The best value we have measured is 4.4 percent

and the current worst is 14.8 percent.

Mirror Reflections

Percentage of Light Reflected

5.7 percent

Very Good

6.1 percent

Very Good

7.1 percent

Very Good

These are the most annoying types of reflections.

Measured using a narrow collimated pencil beam

of light reflected off the screen.

 

Galaxy S I

Galaxy S II

Galaxy S III

 

 

Brightness and Contrast

The Contrast Ratio is the specification that gets the most attention, but it only applies for low ambient light, which is seldom

the case for mobile displays. Much more important is the Contrast Rating, which indicates how easy it is to read the screen

under High Ambient Lighting and depends on both the Maximum Brightness and the Screen Reflectance.

 

The increasingly aggressive Power Management in going from the Galaxy S I to II to III has resulted in a progressive decrease

in screen Brightness. The Contrast Rating for High Ambient Light has also decreased in going from the Galaxy S I to II to III.

 

All of the Galaxy S OLED displays show a significant variation in Brightness with Average Picture Level, APL.

The Maximum Brightness on Full Screen White, which has 100% APL, is 16 to 29 percent lower than the Peak Brightness with

a small 1 percent APL. This effect introduces undesirable Brightness variations with content and is done to limit display power.

Another side effect is the Brightness of images can change significantly in shifting between Portrait and Landscape modes.

 

Measured Maximum Brightness

100% Full Screen White

Brightness 305 cd/m2

Good

Brightness 289 cd/m2

Good

Brightness 224 cd/m2

Poor

This is the Brightness with a Full White Screen,

which has 100% Average Picture Level.

Measured Peak Brightness

1% of Full Screen White

Brightness 365 cd/m2

Very Good

Brightness 405 cd/m2

Very Good

Brightness 283 cd/m2

Good

This is the Brightness for a screen that has

only a tiny 1% Average Picture Level image.

Brightness Reduction

at High Average Picture Level

16 percent

29 percent

21 percent

This is the percent Brightness reduction with Average

Picture Level. Ideally it should be 0 percent.

Black Level

at Maximum Brightness

Less than 0.005 cd/m2

Outstanding

Less than 0.005 cd/m2

Outstanding

Less than 0.005 cd/m2

Outstanding

Black Brightness is important for low ambient light,

which is seldom the case for mobile devices.

Contrast Ratio

Relevant for Low Ambient Light

Greater than 61,000

Outstanding

Greater than 58,000

Outstanding

Greater than 45,000

Outstanding

Only relevant for low Ambient Light,

which is seldom the case for mobile devices.

Defined as Maximum Brightness / Black Brightness.

Contrast Rating

for High Ambient Light

 Bright Contrast 69 - 83

Bright Contrast 61 - 86

Bright Contrast 45 - 57

Defined as Maximum or Peak Brightness /

Average Reflectance.

Screen Viewability in Bright Light

Very Good

Very Good

 Very Good

Indicates how easy it is to read the screen

under high Ambient Lighting. Very Important!

See High Ambient Light Screen Shots

 

Galaxy S I

Galaxy S II

Galaxy S III

 

 

 

Figure 2.  Color Gamuts

Click to Enlarge

Figure 3.  Intensity Scales

Click to Enlarge

Figure 4.  Screen Shots

Click to Enlarge

Colors and Intensities    

 

 

 

 

 

 

 

The Color Gamut, Intensity Scale, and White Point determine the quality and accuracy of all displayed images and all

the image colors. Bigger is definitely Not Better because the display needs to match all the standards that were used

when the content was produced. The Intensity Scale affects both image brightness and color mixture accuracy.

 

The most significant issue for the OLEDs is the excessive Color Gamut and Color Saturation. The Color Gamut is also

very irregular – Green is much more saturated compared with either Red or Blue, as shown in Figure 2.

This imbalance has a tendency to give images a Green accent and color cast.

 

White Color Temperature

For a Full White Screen

10,177 degrees Kelvin

White is Too Blue

8,656 degrees Kelvin

White is Too Blue

7,860 degrees Kelvin

White is Too Blue

D6500 is the standard of White for most content

and necessary for accurate color reproduction.

Color Gamut

See Figure 2

Gamut Too Large

138 percent of Std

See Figure 2

Gamut Too Large

 136 percent of Std

See Figure 2

Gamut Too Large

139 percent

See Figure 2

sRGB / Rec.709 is the color standard for most

content and needed for accurate color reproduction.

 

Note that Too Large a Color Gamut is visually

worse than Too Small.

Dynamic Brightness

16 percent

29 percent

21 percent

This is the percent Brightness reduction with Average

Picture Level. Ideally it should be 0 percent.

Dynamic Contrast

No

Excellent

No

Excellent

No

Excellent

Many manufacturers manipulate the Intensity Scale

based on image content. That results in inaccurate

colors and images.

Intensity Scale and Image Contrast

See Figure 3

Fairly Smooth But

Contrast is Irregular

Very Smooth But

Contrast is Too High

Very Smooth

Contrast is Good

The Intensity Scale controls image contrast needed

for accurate image reproduction. See Figure 3

Gamma for the Intensity Scale

Larger means higher Image Contrast

See Figure 3

2..12  to  2.48

Gamma is Irregular

2.60

Gamma Too High

2.38

Slightly Too High

Gamma is the slope of the Intensity Scale.

Gamma of 2.2 is the standard and needed for

accurate image reproduction. See Figure 3

 

Galaxy S I

Galaxy S II

Galaxy S III

 

 

Viewing Angles

The variation of Brightness, Contrast, and Color with viewing angle is important for Smartphones because of the

different ways they are typically held. For LCDs, the typical manufacturer 176+ degree specification Viewing Angle

is nonsense because that is where the Contrast Ratio falls to a miniscule 10. For most LCDs there are substantial

degradations at less than ±30 degrees, which is not an atypical viewing angle for Smartphones.

 

The Brightness Decrease for the OLEDs at a 30 degree Viewing Angle is 28 percent, larger than expected, but about

half the value for LCDs. On the other hand, the Color Shifts for OLEDs are about double that for IPS LCDs, which is

again larger than expected, but still satisfactory. The cause is primarily due to the anti-reflection optics used for the

OLEDs. In addition, at very large Viewing Angles (greater than 45 degrees) the screens on the Galaxy S I,II,III take on

a distinctly strong blue color shift and cast.

 

Brightness Decrease

at a 30 degree Viewing Angle

28 percent Decrease

Surprisingly Large

26 percent Decrease

Surprisingly Large

28 percent decrease

Surprisingly Large

Screens become less bright when tilted.

For OLEDs this is due to the anti-reflection layers.

 

LCDs have larger Brightness variations, 58 percent.

Contrast Ratio

at a 30 degree Viewing Angle

Extremely High

Not Measured

Extremely High

Not Measured

Extremely High

Not Measured

A measure of screen readability when the screen

is tilted under low Ambient Lighting.

Primary Color Shifts

at a 30 degree Viewing Angle

Medium Color Shift

Δ(u’v’) = 0.0237

5.9 times JNCD

Medium Color Shift

Δ(u’v’) = 0.0227

5.7 times JNCD

Medium Color Shift

Δ(u’v’) = 0.0234

5.9 times JNCD

JNCD is a Just Noticeable Color Difference.

 

IPS LCDs have smaller Color Shifts, 2.5 times JNCD.

Color Shifts for Color Mixtures

at a 30 degree Viewing Angle

Reference Brown (255, 128, 0)

Medium Color Shift

Δ(u’v’) = 0.0191

4.8 times JNCD

Medium Color Shift

Δ(u’v’) = 0.0173

4.3 times JNCD

Medium Color Shift

Δ(u’v’) = 0.0168

4.2 times JNCD

JNCD is a Just Noticeable Color Difference.

 

Reference Brown is a good indicator of color shifts

with angle because of unequal drive levels and

roughly equal luminance contributions from

Red and Green.

 

IPS LCDs have smaller Color Shifts, 2.5 times JNCD.

 

Galaxy S I

Galaxy S II

Galaxy S III

 

 

Display Power Consumption

Figure 5.  OLED White Spectrum

Click to Enlarge

  

Since the displays have different screen sizes and maximum brightness, the values were also scaled to the

same screen brightness (Luminance) and screen area in order to compare their relative power efficiencies.

 

The large improvement in OLED power efficiency has produced an almost a 2:1 improvement in the total

Display Power Efficiency from the Galaxy S I to II to III. These results are consistent with the measured

Battery Running Times, below.

 

Maximum Display Power

2.4 watts

2.1 watts

1.3 watts

Lower power consumption is important for energy

efficiency and improving running time on battery.

Display Power Efficiency

same Peak Luminance and

same screen area as Galaxy S III

2.5 watts

1.8 watts

1.3 watts

This compares the Power Efficiency by

looking at the same screen Brightness

and screen area as the Galaxy S III.

Relative Display Power Efficiency

100 percent

39 percent Better

92 percent Better

The Relative Power Efficiency with respect

to the Galaxy S I.

 

Galaxy S I

Galaxy S II

Galaxy S III

 

 

Running Time on Battery

The running time on battery was determined with the Brightness sliders at the Maximum setting, with a

Full White Screen, in Airplane Mode, with no running applications, and with Auto Brightness turned off.

This is the maximum display load, which has a White background, but there are no running applications.

As the Average Picture Level APL decreases the Battery Running Times for OLEDs will increase.

 

Note that Auto Brightness can have a considerable impact on running time but we found abysmal performance for

both the iPhone and Android Smartphones in our BrightnessGate analysis of Ambient Light Sensors and Automatic

Brightness. They all need a more convenient Manual Brightness Control as described in the BrightnessGate article.

 

The large improvement in OLED power efficiency and the much more aggressive Power Management has produced

a 75 percent improvement in Battery Running Time from the Galaxy S I to II to III. These results are consistent with

the measured Display Power Consumption, above.

 

For comparison, note that the iPhone 4 has a running time of 7.8 hours with a screen Brightness of 541 cd/m2 while

the Galaxy S III has a running time of 5.6 hours with a screen Brightness of 224 cd/m2.

 

Running Time

at Maximum Display Power

3.2 hours

4.4 hours

5.6 hours

Display always On at the Maximum setting with

Airplane Mode and no running applications.

Categories

Galaxy S I

Galaxy S II

Galaxy S III

Comments

 

 

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 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 dtso.info@displaymate.com.

 

About DisplayMate Technologies

DisplayMate Technologies specializes in proprietary sophisticated 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 smartphones and tablets, and all display technologies including LCD, OLED, 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 supplier display spec and quality control evaluations, and on-site and factory visits. 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. For more information on our technology see the Summary description of our Adaptive Variable Metric Display Optimizer AVDO. 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.

 

Article Links:  Smartphone Displays Under High Ambient Lighting Shoot-Out

Article Links:  Automatic Brightness Controls and Light Sensors

 

Article Links:  Mobile Display Shoot-Out Article Series Overview and Home Page

Article Links:  Display Technology Shoot-Out Article Series Overview and Home Page

 

 

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