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Full HD Flagship Smartphone Display Technology Shoot-Out

HTC One  –  Huawei Ascend D2  –  Sony Xperia Z

 

Dr. Raymond M. Soneira

President, DisplayMate Technologies Corporation

 

Copyright © 1990-2013 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

 

 

HTC One

Huawei Ascend D2

Sony Xperia Z

 

Introduction

A new generation of Smartphones with Full High Definition 1920x1080 displays have arrived, the same as your living room HDTV, but with a 5 inch screen size – that is very impressive! But, how good are these new displays, do you really need all of that sharpness and resolution, and will you be able to actually see the difference? Also, how do they compare with the Apple iPhone 5 and Samsung Galaxy S4? We’ll cover these issues and much more, with in-depth comprehensive display tests and analysis that you will find nowhere else.

 

With the iPhone 4 Retina Display, Apple pioneered the previous generation of Smartphone displays in 2010. This time the pioneers are all Android devices, with the iPhone still not even at the basic HD resolution of 1280x720. But there are rumors of higher resolutions and larger Apple Smartphones on the way, possibly even in the Phablet size class – we’ll see…

 

In this article we’ll examine three Flagship Full HD top-of-the-line Smartphones: the HTC One, Huawei Ascend D2, and the Sony Xperia Z, all with 5.0 inch or smaller screens. The LG Optimus G Pro has an excellent Full HD display that we have tested (for SID Information Display magazine), but it’s currently available only in a larger 5.5 inch size – a smaller 5.0 inch model is coming, which we plan on including when it becomes available. While Huawei is better known as a manufacturer of low cost Smartphones, their Ascend D2 is aimed at the premium top tier, and as you’ll see below, they managed to hit a home run with the display the first time at bat – that’s also very impressive!

 

The Shoot-Out

To examine the performance of these Flagship Full HD Smartphone displays we ran our in-depth series of Mobile Display Technology Shoot-Out Lab tests. We take display quality very seriously and provide in-depth objective analysis and side-by-side comparisons based on detailed laboratory measurements and extensive viewing tests with both test patterns and test images. To see how far Smartphones have progressed in just three years see our 2010 Smartphone Display Shoot-Out, and for a real history lesson see our original 2006 Smartphone Display Shoot-Out.

 

Results Highlights

In this Results section we provide Highlights of the comprehensive Lab tests, measurements, and extensive side-by-side visual comparisons using test photos, test images, and test patterns that are presented in later sections. 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. You can also skip these Highlights and go directly to the Conclusions.

 

Can You Actually See the Enhanced Full HD Sharpness and Resolution?

Apple started a major revolution in display marketing by introducing their “Retina Display” with 326 Pixels Per Inch (PPI) on the iPhone 4 in 2010. While not equivalent to the resolution of the human retina, people with 20/20 Vision cannot resolve the individual pixels when the display is held at normal viewing distances of 10.5 inches or more. This started a PPI and Mega Pixel war similar to what happened with Smartphone digital cameras, which is still an ongoing wild goose chase now into the stratosphere… Hopefully the same thing won’t happen with mobile displays. The real question is how high do we need to go before reaching a practical visual PPI limit?

 

True Retina Displays: As I have pointed out before, the effective resolution of the human retina is much higher than Apple’s Retina Display, and corresponds to somewhere around 600 PPI at a 10 inch viewing distance, which is the limit for the best human vision, around 20/10. That is well above the highest 468 PPI display that we test here, so the Full HD higher resolution and sharpness should be visually apparent. On the other hand, very few people have that level of 20/10 visual acuity. In fact, a fair fraction of the adult population does not have corrected (near) vision even to 20/20. Furthermore, ambient light decreases visual acuity because the reflected light glare from the screen reduces image contrast – and Smartphones are almost never viewed in the dark. So perhaps the extra sharpness won’t be apparent for many situations, especially casual viewing…

 

Enhanced Acuity: But if you want (or need) to take advantage of that extra display sharpness and resolution, you can. If you study and stare at the image on the screen, move it closer, or move it around, you’ll be able to make out considerably more fine image detail because you are building an integrated visual image map in the brain. So, when you are looking at an image with finely detailed graphics and small text, most people with reasonably good vision will be able to make out and appreciate the extra sharpness and image detail if they take the time to do so.

 

Photos and Videos: Unlike computer generated text and graphics that have precise pixel arrangements, photographic images are inherently fuzzy because the image detail is spread over multiple pixels, so you are less likely to detect a sharpness difference over basic 1280x720 HD, especially with jpeg images, which are all digitally compressed. That’s for still photos, but movies and videos have images that are continually changing so a fair amount of image detail is often visually lost due to its transitory nature (plus digital compression). So for photos, movies and videos the extra sharpness and resolution will be less apparent…

 

From the above discussion, there are lots of good and technically sound reasons for moving up to Full HD in a 5 inch Smartphone display. People with reasonably good vision will be able to see and appreciate the higher resolution, additional sharpness and image detail that it provides.

 

Overall Display Performance

In our Lab tests and measurements the three Smartphone displays, for the most part, delivered comparable and very good to excellent performance, including Brightness, Contrast Ratio (low ambient light), Contrast Rating for High Ambient Light, Reflectance, White Point, and Display Power Efficiency, which are analyzed in the Comparison Table. Below are a number of major issues where the displays performed very differently.

 

Color Gamut

In order to produce accurate image colors on-screen the displays need to match the Standard Color Gamut that is used to create virtually all current consumer content, which is named sRGB / Rec.709 (not the occasionally mentioned NTSC Gamut, which was defined in 1953 and has been obsolete for over 30 years). The Standard Gamut encompasses digital camera, HDTV, Internet, and computer content, including virtually all photos and videos. Note that standard consumer content does not include colors outside of the Standard sRGB / Rec.709 Gamut, so a display with a wider Color Gamut cannot show colors that are not in the original, and only produce inaccurate exaggerated on-screen colors.

 

Most LCDs until recently delivered only 55 to 65 percent of the sRGB / Rec.709 Color Gamut, but many newer Smartphones are producing close to 100 percent of the Standard Gamut, including the HTC One and Huawei Ascend D2 tested here. However, the Sony Xperia Z has a somewhat too large Color Gamut of 115 percent, which contributes to its many problems with color accuracy.

 

Viewing Angle Issues

The image brightness, contrast, and colors can vary significantly when the screen Viewing Angle changes by even ±30 degrees, which is quite common for Smartphones because it depends on how you hold it in your hand (with varying pitch). The angle can be even larger if the Smartphone is resting on a table or desk.

 

While all LCDs show large decreases in brightness with Viewing Angle (generally over 50 percent at ±30 degrees), it is now unusual for high-end LCDs with In Plane Switching (IPS) or similar technology to show substantial color and contrast shifts with Viewing Angle, which were shockingly large on the Sony Xperia Z. The problem is incredibly large increases in the background Black Level with small changes in Viewing Angle, which significantly washes out and degrades the image contrast and colors. This could be an LCD technology issue or possibly due to the use of a low grade polarizer in the panel. To double check this, we tested another similar model, the Xperia ZL, and it showed the same substantial degradation with Viewing Angle. On the other hand, both the HTC One and Huawei Ascend D2 have excellent viewing angle performance, with no visible color shifts. This Figure with screen shots illustrates the Viewing Angle performance for the three tested Smartphone displays. Measurement details are provided in the Viewing Angles Table below.

 

Color Accuracy and Calibration

Picture quality and Color Accuracy are especially important for these Full HD 5 inch displays because they are multimedia devices designed for viewing photos, videos, movies, HDTV and internet content. It takes careful display hardware design and careful factory calibration to produce top notch picture quality and color accuracy. Some manufacturers attempt to make their displays standout with image processing “enhancements” that exaggerate the colors and image contrast. The result is almost always distorted and over saturated colors and contrast. It is almost impossible to get the image processing “enhancements” to work well because of the incredible range and variety of images that can be displayed. The Huawei Ascend D2 avoids this sort of image processing and simply relies on standard accurate display calibration. Unfortunately, both the HTC One and Sony Xperia Z use excessive processing that results in distorted and over saturated colors and contrast.

 

Viewing Tests

Not surprisingly, all three displays were extremely sharp, and had bright screens with good image contrast, but only at zero degrees Viewing Angle for the Sony Xperia Z, which has large color and image contrast shifts with Viewing Angle as described above. Where all three displays diverged significantly was in their Color Accuracy and Calibration due to excessive image and color processing, which some manufacturers do intentionally to try to make their displays stand out. But the end result almost always produces distorted and over saturated colors and contrast as described above. In our extensive Viewing Tests with a large set of challenging test photos and test images the three Smartphone displays were incredibly different as we compared them side-by-side to each other and to a number of accurate calibrated displays. The Huawei Ascend D2 delivered every bit as good picture quality and color accuracy as the iPhone 5 and Galaxy S4, but the HTC One had noticeably and significantly inaccurate, distorted and over saturated colors and contrast. The Sony Xperia Z was significantly worse with its “Bravia Engine” On – turning it Off improved its picture quality a lot, but not enough.

 

It is surprisingly difficult to capture the magnitude of the differences seen live using camera screen shots. We’ve often used the following photo of a colorful barn door. This Figure with screen shots illustrates the differences in Viewing Test performance for the three Smartphone displays. When viewed live side-by-side the differences between the displays appear much greater.

 

HTC One

While it has an excellent LCD panel (made by Sharp), HTC has significantly degraded display performance by introducing unnecessary image and color processing in a poorly implemented attempt at making the display stand out. The result is distorted and over saturated colors and contrast. And unlike Sony, HTC does not provide an option to turn this processing off, which is a shame. Hopefully, such an option will become available in a future software upgrade.

 

Huawei Ascend D2

With the Ascend D2 Huawei appears to have taken the same successful solid approach for display performance as Apple. In our extensive side-by-side viewing test comparisons the Ascend D2 was virtually indistinguishable from the iPhone 5 and iPad Retina Display, two of the most accurate and high quality mobile displays we have ever tested. The Huawei Ascend D2 joins an elite group of Smartphones with world class displays.

 

Sony Xperia Z

The performance of the Sony Xperia Z flagship top-of-the-line Smartphone can only be described as extremely disappointing. First of all, the Xperia Z has awful viewing angle performance, which is common for low-end low-technology displays, but is inexcusable in an expensive flagship top-of-the-line product. Second, the “Bravia Engine” that they brag enhances picture quality instead significantly degrades it, introducing extremely gaudy, oversaturated and distorted colors – similar to what you’ll see if you turn the Color Control on your HDTV all the way up to maximum. At least they provide an option to turn the Bravia Engine Off, which improves things a lot, but not enough.

 

Comparison with the iPhone 5 Display

The Apple iPhone 5 is now more than half way through its product cycle, which is important to keep in mind for our comparison. However, the primary differences come down to its much smaller Screen Size (4.0 versus 4.7 to 5.0 inches), much lower Pixel Resolution (1136x640 versus 1920x1080), much lower total number of Pixels (0.7 versus 2.1 Mega Pixels), and much lower Pixels Per Inch (326 versus 443 to 468). On the plus side, the iPhone 5 has a much higher Peak Brightness (556 versus 421 to 491 cd/m2), a much lower Screen Reflectance (4.5 versus 5.6 to 6.5 percent), a much higher Contrast Rating for High Ambient Light (121 versus 65 to 88), and therefore much better screen visibility in high ambient light. All are major plus and minus differences.

 

But the most interesting and significant development is that one of the Full HD Smartphones that we tested here, the Huawei Ascend D2, delivers every bit as good a picture quality and color accuracy as the iPhone 5 (but at a much higher resolution and screen size). In fact, in side-by-side viewing tests the two are almost indistinguishable because they both have accurately calibrated displays, which makes it a tie in picture quality, unlike the HTC One and Sony Xperia Z, which are one or two steps below.

 

Comparison with the Galaxy S4 OLED Display

The Samsung Galaxy S4 is another important milestone display that we tested in a recent Shoot-Out article. Because OLED technology is significantly different from LCD technology there are many subtle performance issues that are examined in that article. The two most significant differences are: OLEDs provide perfect blacks but LCDs are currently significantly brighter. However, the Galaxy S4 has a much lower Screen Reflectance (4.4 versus 5.6 to 6.5 percent), and as a result, a somewhat higher Contrast Rating for High Ambient Light (65 to 108 versus 65 to 88). The Galaxy S4 also provides multiple Color Gamuts, including one that is very accurate, another for professional photography, and a larger one that is better in high ambient light. In terms of image sharpness, the Galaxy S4 also has Full HD 1920x1080 resolution – but there is one important difference, the LCD displays have 3 sub-pixels per pixel while the Galaxy S4 has a PenTile structure with only 2 sub-pixels per pixel. However, the very high 312 to 443 Sub-Pixels Per Inch together with its advanced sub-pixel rendering still results in a very visually sharp display. In the end, they each have their own particular strengths and weaknesses, so for the time being, it remains a tie between the high-end LCDs and OLEDs…

 

Conclusion:   One Very Impressive Full HD Smartphone Display…

It is amazing to hold a beautiful Full HD 1920x1080 mobile computer display and HDTV in the palm of your hand. But only one of the Smartphones tested here qualifies as a beautiful display – the Huawei Ascend D2, because it delivers superior picture quality with accurate colors and images. This Figure with screen shots illustrates the major points we make in the Conclusion with the measurement details in the Comparison Table below.

 

With the Ascend D2 Huawei appears to have taken the same successful solid approach for display performance as Apple. In our extensive side-by-side viewing test comparisons the Ascend D2 was virtually indistinguishable from the iPhone 5 and iPad Retina Display, two of the most accurate and high quality mobile displays we have ever tested. The Huawei Ascend D2 joins an elite group of Smartphones with world class displays. While Huawei is better known as a manufacturer of low cost Smartphones, their Ascend D2 is aimed at the premium top tier, so they managed to hit a home run with the display the first time at bat. My suggestion for Huawei, please keep it up…

 

I was expecting a lot better from the HTC One. While it has an excellent LCD panel (made by Sharp), HTC has significantly degraded display performance by introducing unnecessary image and color processing in a poorly implemented attempt at making the display stand out. The result is distorted and over saturated colors and contrast. And unlike Sony, HTC doesn’t provide an option to turn this processing off, which is a shame. Hopefully that will be an option in a future software upgrade. My suggestion for HTC, forget the display image processing tricks, which never work, and follow Apple and Huawei with solid and straightforward accurate display calibration…

 

The performance of the Sony Xperia Z flagship top-of-the-line Smartphone can only be described as extremely disappointing – even shocking, given that Sony was once the best display manufacturer in the world, famous for their beautiful and accurate picture quality – something they brag about on their Xperia Z web page – but is very far from reality for the Xperia Z. First of all, the Xperia Z has awful viewing angle performance, which is common for low-end low-technology displays, but is inexcusable in an expensive flagship top-of-the-line product. Second, the “Bravia Engine” that they brag enhances picture quality instead significantly degrades it, introducing extremely gaudy, oversaturated and distorted colors – similar to what you’ll see if you turn the Color Control on your HDTV all the way up to maximum. At least they provide an option to turn the Bravia Engine Off, which improves things a lot, but not enough. My suggestion for Sony, retrain your display engineering and marketing teams in the tradition of the former grand Sony Style…

 

The Next Generation of Smartphone Displays:

These are the trends in Smartphone displays that we expect to see in the upcoming generation of displays.

 

Sticking with Full HD:

Smartphone cameras are still involved in an absurd Mega Pixel war, so I hope that both manufacturers and consumers can instead agree on sticking with Full HD 1920x1080 Smartphone displays for a while. There are lots of good reasons to do so: there is a tremendous amount of Full HD 1920x1080 content available. Displaying that content at its native resolution (without the need to rescale up or down) results in the best possible image quality, plus rescaling requires processing overhead that uses (wastes) precious battery power.

 

Smaller Screens:

Screen sizes have been creeping up for years because of the marketing push to higher display resolutions. If we can stick with the 1920x1080 resolution then the increases in Pixels Per Inch can instead be used to begin decreasing screen sizes. Both HTC and LG have already started on this approach by introducing newer models that are smaller. The HTC One is 4.7 inches with 468 PPI that follows a 5.0 inch 440 PPI model. A 500 PPI Full HD display will be 4.4 inches, which may appeal to consumers that feel 5.0 inches is too large.

 

Better Picture Quality in High Ambient Light:

All current displays perform poorly in ambient light because the reflected light glare progressively degrades the on-screen colors and image contrast. With improved sensors and color management, displays will be able to compensate for the effects of ambient light by dynamically changing the Color Gamuts and Intensity Scales to automatically correct for reflected glare and image wash out from ambient light. For those interested, I have an advanced article on this topic in the July/August 2013 issue of the SID Information Display magazine.

 

DisplayMate Display Optimization Technology

All Smartphone and Tablets 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 help manufacturers with expert display procurement, optimization, and quality control so they don’t make mistakes similar to those that are exposed in our Display Technology Shoot-Out series. We can also improve the performance of any specified set of display parameters. This article is a lite version of our intensive in-depth 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.

 

HTC One

Huawei Ascend D2

Sony Xperia Z

 

Display Shoot-Out Comparison Table

Below we compare the displays on the HTC One, the Huawei Ascend D2, and the Sony Xperia Z based on a wide range of Laboratory measurement data and objective criteria. For additional background and information see the Flagship Smartphone Display Technology Shoot-Out between the OLED Samsung Galaxy S4 and the LCD Apple iPhone 5.

 

Categories

HTC One

Huawei Ascend D2

Sony Xperia Z

Comments

Display Technology

4.7 inch LCD

5.0 inch LCD

5.0 inch LCD

Liquid Crystal Display

Screen Shape

16:9 = 1.78

Aspect Ratio

16:9 = 1.78

Aspect Ratio

16:9 = 1.78

Aspect Ratio

All have the same shape as HDTV video content.

Screen Area

9.4 Square Inches

10.7 Square Inches

10.7 Square Inches

A better measure of size than the diagonal length.

Relative Screen Area

88 percent

100 percent

100 percent

Screen Area relative to the Ascend D2 and Xperia Z.

Display Resolution

1920 x 1080 pixels

Full High Definition

1920 x 1080 pixels

Full High Definition

1920 x 1080 pixels

Full High Definition

The more Pixels and Sub-Pixels the better.

Pixels Per Inch

468 PPI

Excellent

443 PPI

Excellent

443 PPI

Excellent

At a typical viewing distance of 12 inches from the

screen the 20/20 Vision sharpness limit is 286 PPI.

See this on the visual acuity for a true Retina Display

20/20 Vision Distance where Pixels

or Sub-Pixels are not resolved

7.3 inches

7.8 inches

7.8 inches

For 20/20 Vision the minimum Viewing Distance

where the screen appears perfectly sharp to the eye.

Gallery / Photo Viewer Color Depth

Full 24-bit color

No Dithering Visible

256 Intensity Levels

Full 24-bit color

No Dithering Visible

256 Intensity Levels

Full 24-bit color

No Dithering Visible

256 Intensity Levels

Many Android Smartphones and Tablets still have some

form of 16-bit color depth in the Gallery Photo Viewer

 

 

HTC One

Huawei Ascend D2

Sony Xperia Z

 

 

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

 

See Figure 1

Good Images

Photos and Videos

have too much color

and accurate contrast

 

See Figure 1

Very Good Images

Photos and Videos

have excellent color

and accurate contrast

 

See Figure 1

Good Images

Photos and Videos

have too much color

and variable contrast

 

See Figure 1

The Viewing Tests examined the accuracy of

of a large set of challenging photographic

images by comparing the Smartphone displays

to a calibrated studio monitor and HDTV.

 

See Figure 1

Variation with Viewing Angle

Lab Tests and Measurements

 

See Details Below

See Figure 1

Small Color Shifts

with Viewing Angle

 

Large Brightness Shift

with Viewing Angle

Small Color Shifts

with Viewing Angle

 

Large Brightness Shift

with Viewing Angle

Large Black Level Rise

with Viewing Angle

 

Large Brightness Shift

with Viewing Angle

All LCDs have a large decrease in Brightness

with Viewing Angle.

 

The Sony Xperia Z has a large increase in the

Black Level with Viewing Angle that reduces

contrast and washes out the images

Overall Display Assessment

Lab Tests and Measurements

See Details Below

Excellent LCD Panel

Excellent LCD Panel

Very Good LCD Panel

Poor Viewing Angles

The HTC One and Huawei Ascend D2 have

excellent LCD panels.

 

The Sony Xperia Z has poor Viewing Angles

that wash out the image at small viewing angles.

Overall Display Calibration

Lab Tests and Viewing Tests

Good Calibration

Too Much Processing

See Figure 1

Excellent Calibration

See Figure 1

Good Calibration

with Bravia Engine Off

See Figure 1

Poor Calibration

with Bravia Engine On

The Huawei Ascend D2 has a much more

accurate display calibration.

 

The HTC One and Sony Xperia Z have too

much processing and inaccurate colors.

Overall Display Grade

B+

Rank 2

A

Rank 1

B

Rank 3

The Huawei Ascend D2 has a much better display

than the HTC One and Sony Xperia Z.

 

HTC One

Huawei Ascend D2

Sony Xperia Z

 

 

Screen Reflections

All of these screens are large 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. Many Smartphones still have greater than 10 percent reflections that make the

screen much harder to read even in moderate ambient light levels, requiring ever higher brightness settings that waste

precious battery power. Hopefully manufacturers will reduce the mirror reflections with anti-reflection coatings and

matte or haze surface finishes.

 

Average Screen Reflection

Light From All Directions

Reflects 5.6 percent

Very Good

Reflects 6.5 percent

Very Good

Reflects 5.6 percent

Very Good

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

 6.5 percent

Very Good

 6.9 percent

Very Good

 6.7 percent

Very Good

These are the most annoying types of reflections.

Measured using a narrow collimated pencil beam

of light reflected off the screen.

 

HTC One

Huawei Ascend D2

Sony Xperia Z

 

 

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.

 

Measured Peak Brightness

100% Full Screen White

Brightness 491 cd/m2

Excellent

Brightness 421 cd/m2

Excellent

Brightness 478 cd/m2

Excellent

This is the Brightness for a screen that is entirely

all white with 100% Average Picture Level.

True Black Level

at Maximum Brightness

0.40 cd/m2

Very Good for Mobile

0.57 cd/m2

Very Good for Mobile

Black is 0.39 cd/m2

Very Good for Mobile

Black brightness is important for low ambient light,

which is seldom the case for mobile devices.

Dynamic Black Level

at Maximum Brightness

0.28 cd/m2

Very Good for Mobile

0.57 cd/m2

Very Good for Mobile

Black is 0.39 cd/m2

Very Good for Mobile

At low Average Picture Levels the Backlight

on the screen may be automatically dimmed.

Contrast Ratio

Relevant for Low Ambient Light

         1,228 True

    1,754 Dynamic

Very Good for Mobile

           739 True

           739 Dynamic

Very Good for Mobile

        1,226 True

        1,226 Dynamic

Very Good for Mobile

Only relevant for low ambient light,

which is seldom the case for mobile devices.

Actual Contrast Ratio is dominated by Ambient Light.

Contrast Rating

for High Ambient Light

88

Very Good

65

Very Good

85

Very Good

Defined as Maximum Brightness / Average Reflectance.

Screen Readability in Bright Light

Very Good  A–

Very Good  A–

Very Good  A–

Indicates how easy it is to read the screen

under high ambient lighting. Very Important!

See High Ambient Light Screen Shots

 

HTC One

Huawei Ascend D2

Sony Xperia Z

 

 

 

 

Colors and Intensities    

Figure 2.  Color Gamuts

Click to Enlarge

Figure 3.  Intensity Scales

Click to Enlarge

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. For LCDs a wider Color Gamut reduces the power efficiency and the Intensity Scale

affects both image brightness and color mixture accuracy.

 

White Color Temperature

Degrees Kelvin

 6,983 K

Very Good

User Adjustable

6,861 K  to  10,540 K

Excellent

6,760 K

Very Good

D6500 is the standard color of White for most

Content and needed for accurate color reproduction.

Color Gamut

Measured in the dark at 0 lux

See Figure 2

Close to Perfect

101 percent

See Figure 2

Close to Perfect

104 percent

See Figure 2

Somewhat Too Large

115 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

Reduction in Luminance with APL

4 percent

Very Good

None

Excellent

None

Excellent

This is the percent Brightness reduction with APL

Average Picture Level. Ideally should be 0 percent.

Intensity Scale and Image Contrast

See Figure 3

Very Smooth

Contrast is Excellent

See Figure 3

Very Smooth

Contrast is Excellent

See Figure 3

Contrast is Irregular See Figure 3

The Intensity Scale controls image contrast needed

for accurate image reproduction. See Figure 3

Gamma for the Intensity Scale

Larger means more Image Contrast

See Figure 3

2.15 to 2.20

Close to Perfect

2.27

Close to Perfect

 1.98 to 2.16

Somewhat Irregular

Gamma is the slope of the Intensity Scale.

Gamma of 2.20 is the standard and needed for

accurate image reproduction. See Figure 3

 

HTC One

Huawei Ascend D2

Sony Xperia Z

 

 

Viewing Angles

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

their large screen and multiple viewers. The typical manufacturer 176+ degree specification for LCD 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.

 

Note that the Viewing Angle performance is also very important for a single viewer because the Viewing Angle varies

based on how the Smartphone is held, and the angle can be very large if the Smartphone is resting on a table or desk.

 

Brightness Decrease

at a 30 degree Viewing Angle

61 percent Decrease

 

Very Large Decrease

 57 percent Decrease

 

Very Large Decrease

64 percent Decrease

 

Very Large Decrease

Most screens become less bright when tilted.

 

LCD brightness variation is generally very large.

Contrast Ratio

at a 30 degree Viewing Angle

606 True

Very Good for Mobile

415 True

Very Good for Mobile

146 True

Very High Black Level

Poor

A measure of screen readability when the screen

is tilted under low ambient lighting.

Primary Color Shifts

at a 30 degree Viewing Angle

Small Color Shift

Δ(u’v’) = 0.0061

 1.5 times JNCD

Small Color Shift

Δ(u’v’) = 0.0091

2.3 times JNCD

Small Color Shift

Δ(u’v’) = 0.0122

 3.1 times JNCD

JNCD is a Just Noticeable Color Difference.

IPS LCDs have smaller color shifts with angle.

Color Shifts for Color Mixtures

at a 30 degree Viewing Angle

Reference Brown (255, 128, 0)

Small Color Shift

Δ(u’v’) = 0.0027

0.7 times JNCD

Small Color Shift

Δ(u’v’) = 0.0093

2.3 times JNCD

Large Color Shift

Δ(u’v’) = 0.0520

13.0 times JNCD

JNCD is a Just Noticeable Color Difference.

Color Shifts for non-IPS LCDs are about 10 JNCD.

 

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.

 

HTC One

Huawei Ascend D2

Sony Xperia Z

 

 

Display Power Consumption

Figure 4.  LED Backlight Spectrum

Click to Enlarge

  

The display power was measured using a Linear Regression between Luminance and AC Power with a fully charged battery.

 

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 most challenging issue when increasing display resolution and PPI is the decrease in light output and display power

efficiency due to the proportional increase of the Active Matrix Thin Film Transistors (AM TFTs) that drive the display.

Since the thickness and weight of a Smartphone are crucial, the displays cannot use amorphous Silicon (aSi), which is

used in most Smartphones and Tablets, because it is very inefficient at high PPI, and instead need to use much higher

performance (and higher cost) Low Temperature Poly Silicon (LTPS) or (for Sharp displays) Continuous Grain Silicon (CGS).

All of the displays have very similar and very good Power Efficiency. For reference, the iPhone 5 with a much lower 326 PPI

has a Relative Display Power Efficiency of 0.90 watts, which is about 20 percent more power efficient than the 440+ PPI displays.

 

Maximum Display Power

Full White Screen

at Maximum Brightness

 1.05 watts

1.12 watts

1.21 watts

This measures the display power for a screen

that is entirely White at Maximum Brightness.

Relative Display Power Efficiency

same Luminance 421 cd/m2

same 5.0 inch screen area

1.03 watts

1.12 watts

 1.07watts

This compares the Average Power Efficiency

by using the same screen brightness and the

same screen area for all the displays.

 

The iPhone 5, with a smaller 326 PPI display,

has a Relative Power Efficiency of 0.90 watts.

 

HTC One

Huawei Ascend D2

Sony Xperia Z

 

 

Running Time on Battery

The running time on battery was determined with the Brightness sliders at Maximum, in Airplane Mode,

with no running applications, and with Auto Brightness turned off.

 

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.

 

Running Time

at Maximum Display Power

Not Yet Available

Coming Soon

Not Yet Available

Coming Soon

 Not Yet Available

Coming Soon

Display always On at Maximum power with

Airplane Mode and no running applications.

Categories

HTC One

Huawei Ascend D2

Sony Xperia Z

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.

 

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 help manufacturers with expert display procurement and quality control so they don’t make mistakes similar to those that are exposed in our Display Technology Shoot-Out series. We can also 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.

 

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 Smartphone 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. 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:  Samsung Galaxy S4 and iPhone 5 Display Technology Shoot-Out

 

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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