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iPad mini Display Technology Shoot-Out

Apple iPad mini  –  Amazon Kindle Fire HD  –  Google Nexus 7

 

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

 

 

Amazon Kindle Fire HD

Google Nexus 7

Apple iPad mini

 

Introduction

The iPad mini has finally arrived – Apple’s much anticipated response to the incredibly successful 7 inch Tablets pioneered by Amazon and Barnes & Noble, and more recently by Google with its Nexus 7. So far they are the only Tablets that have made a dent in Apple’s near monopoly on Tablets. At first Apple declared them too small to be useful, but consumers clearly wanted something more portable than a full size 10 inch Tablet, and also a lot less costly. Millions were sold – and that got Apple’s attention. Over the past year there have been increasingly credible accounts of a small iPad prototype being developed by Apple, but there was no guarantee that it would turn into an actual product until Apple’s official announcement.

 

In a short period of time mini Tablets have evolved into first tier products with excellent displays. It shows how demand can drive the state-of-the-art very quickly. Apple has made displays their most prominent marketing feature because they determine the quality of the visual experience for everything on a Tablet or Smartphone – including Apps, web content, photos, videos, and its camera. So how good is the display on the iPad mini? And how does it compare to the displays on the leading Amazon Kindle Fire HD and Google Nexus 7 Tablets? And how does it compare to the displays on the full size iPads? We’ll tell you here…

 

The Shoot-Out

To evaluate and analyze the display on the iPad mini we ran our comprehensive series of Mobile Display Technology Shoot-Out tests and compared it to the Amazon Kindle Fire HD and Google Nexus 7, and also to the iPad 2 and new iPad 3. We take display quality very seriously and provide in-depth objective analysis of side-by-side comparisons based on detailed laboratory measurements and extensive viewing tests with both test patterns and test images.

 

The discussions and analysis here deal primarily with the iPad mini. For parallel in-depth discussions and analysis of the Amazon Kindle Fire HD and Google Nexus 7 see our 7 Inch Tablet Display Technology Shoot-Out. Our iPad Display Technology Shoot-Out compares the iPad 2 and the new iPad 3. For earlier “popular” full size Tablets see our 10 Inch Tablet Display Technology Shoot-Out.

 

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 Comparison Table in the following section summarizes the lab measurements in the following categories:  Screen ReflectionsBrightness and ContrastColors and IntensitiesViewing AnglesDisplay Backlight Power ConsumptionRunning Time on Battery. You can also skip the Highlights and go directly to the Conclusions.

 

Sharpness and Resolution:

Pixel resolution has been the number one topic of discussion for the iPad mini – both before and after launch. Many people were expecting a Retina Display like the new iPad 3, but that would have required a 326 Pixels Per Inch display with more than 4 times the screen area of the iPhone 5. That is currently out of the question for both cost and manufacturing volume and yield since it would need to be Low Temperature Polysilicon. Given that Apple has been sticking with either 1024x768 or 2048x1536 iPad displays for compatibility reasons, that meant the iPad mini had to be 1024x768 with 163 Pixels Per Inch. But that’s now considered to be rather on the low side.

 

While screen Resolution gets lots of attention from both consumers and marketers – it’s really only critical for providing visually sharp text – but that applies for most applications running on a Tablet. The $199 Amazon Kindle Fire HD and Google Nexus 7 both have considerably sharper displays with 216 Pixels Per Inch, and they both delivered considerably sharper text. We’ll discuss below how Apple can improve image sharpness on the mini iPad.

 

Screen Reflectance:

The screens on almost all Tablets and Smartphones are mirrors good enough to use for personal grooming. Even in moderate ambient lighting the contrast and colors can noticeably degrade from ambient light reflected by the screen, especially objects like your face and any bright lighting behind you. So low Reflectance is very important in determining real picture quality, especially on the smaller and more portable Tablets. The lower the better… This article shows how screen images degrade in bright Ambient Light.

 

Screen Reflectance on the iPad mini is a surprisingly high 9.0 percent. On the Nexus 7 the Reflectance is a much lower 5.9 percent, while on the Kindle Fire HD it is 6.4 percent. As a result, the iPad mini reflects 53 percent more ambient light than the Nexus 7 and 41 percent more than the Kindle Fire HD. That’s quite a big difference… Screen visibility and readability in high Ambient Light depends on both the Maximum Brightness and Screen Reflectance, which we evaluate with a Contrast Rating for High Ambient Light. On the Kindle Fire HD it is 58 percent higher than the iPad mini and 47 percent higher on the Nexus 7.

 

Color Gamut and Color Accuracy:

While the display PPI and pixel Resolution seem to get most of the attention, it is the display’s Color Gamut together with the Factory Display Calibration (below) that play the most important role in determining the Wow factor and true picture quality and color accuracy of a display. The Color Gamut is the range of colors that a display can produce. If you want to see accurate colors in photos, videos, and all standard consumer content the display needs to closely match the Standard Color Gamut that was used to produce the content, which is called sRGB / Rec.709. Most of the previous generations of LCD Tablets and Smartphones had smaller Color Gamuts around 60 percent of the Standard Gamut, which produces somewhat subdued colors. But that’s been changing due to both technology and competition.

 

While the iPad 2 and iPhone 4 had reduced 61-64 percent Color Gamuts, the Amazon Kindle Fire HD and Google Nexus 7 both deliver a much larger 86 percent Color Gamut, and the new iPad 3 and iPhone 5 have full 100 percent standard Color Gamuts. So it was a surprise and a major disappointment for the iPad mini to arrive with an antiquated smaller 62 percent Color Gamut.

 

Factory Display Calibration:

The raw LCD panel hardware first needs to be adjusted and calibrated at the factory with specialized firmware and software data that are downloaded into the device in order for the display to produce a usable image – let alone an accurate and beautiful one. This is actually a science but most manufacturers seem to treat it as if it were a modern art form, so few Tablets, Smartphones, and even HDTVs produce accurate high quality images.

 

Apple has been a leader in accurate display calibration – the new iPad 3 and iPhone 5 have among the best and most accurate factory calibrations we have ever measured in a consumer product, including high-end HDTVs. The iPad mini follows that tradition – it has an accurate White Point and a very accurate Intensity Scale, except for a 5 percent compression near the Peak Intensity, which we discuss in more detail below.

 

Viewing Tests:

Using our extensive library of challenging test and calibration photos, we compared the iPad mini to a calibrated professional studio monitor and to the new iPad 3, which has a virtually perfect Factory Calibration and Color Gamut.

 

In spite of its smaller Color Gamut, the iPad mini delivered fairly accurate picture quality and color accuracy. This is due to color management processing that is generally absent from Tablets and Smartphones. However, the iPad mini display is still unable to produce very saturated colors, like fire engine red, which was not as vibrant and appeared with a noticeable shift towards orange. Very saturated purples are also especially difficult to reproduce on LCD displays with a reduced color Gamut. For example, the iPad mini appeared almost identical to the iPad 2 in this screen shot comparing the latter to the new iPad 3.

 

 

iPad mini Conclusions:

The iPad mini is certainly a very capable small Tablet, but it does not follow in Apple’s tradition of providing the best display, or at least a great display – it has just a very capable display. What’s more, the displays on existing mini Tablets from Amazon and Google outperform the iPad mini in most of our Lab tests as documented below in the Shoot-Out Comparison Table. Some of this results from constraints within the iPad product line, and some to realistic constraints on display technology and costs, but much of it is due to a number of poor choices and compromises.

 

Lower Screen Resolution:

Many people were expecting a Retina Display like the new iPad 3, but that would have required a 326 Pixels Per Inch display with more than 4 times the screen area of the iPhone 5. That is currently out of the question for both cost and manufacturing volume and yield since it would need to be Low Temperature Polysilicon. Given that Apple has been sticking with either 1024x768 or 2048x1536 iPad displays for compatibility reasons, that meant the iPad mini had to be 1024x768 with 163 Pixels Per Inch. But that’s now considered to be rather on the low side, especially given that the $199 Amazon Kindle Fire HD and Google Nexus 7 both have considerably sharper displays with 216 Pixels Per Inch. So Apple, the inventor of Retina Display marketing, now has a significant competitive shortfall on this very issue…

 

Improving Screen Sharpness:

Apple could have increased the iPad mini Screen Resolution in the same way as it did for the iPhone 5 – simply having older Apps running Letterboxed inside a higher resolution display, which would have been a great way to provide a higher Pixels Per Inch display. iOS and newer Apps would have used the full higher Resolution – that didn’t happen. While screen Resolution gets lots of attention from both consumers and marketers – it’s really only critical for providing visually sharp text – but that applies for most applications running on a Tablet. As we have pointed out a number of times, the best way to increase visual text sharpness on any display is by using Sub-Pixel Rendering, which Apple should now implement in order for the iPad mini to become competitive on visual sharpness…

 

Viewing Widescreen Content:

All of the iPads have a 4:3 Aspect Ratio screen, rather than the 16:10 or 16:9 Aspect Ratios found on most other Tablets. One advantage of the iPad’s more square 4:3 screen shape is that it lends itself better for use in both Landscape and Portrait viewing modes. Another is that a 4:3 screen is often better suited for reading because it has the same Aspect Ratio as content on 8.5x11 inch documents. But another major application for mini Tablets is viewing widescreen video content with Aspect Ratios of 16:9 (and higher for many movies). On the iPad mini 16:9 content is viewed Letterboxed with only 1024x576 Resolution, which is getting pretty close to Standard Definition video rather than true High Definition 1280x720 video on most other mini Tablets like the Amazon Kindle Fire HD and Google Nexus 7. A much better screen resolution choice for the iPad mini would have been 1280x960, because it could then deliver true HD video content, satisfactory Letterboxing for older 1024x768 Apps, plus much sharper text for reading…

 

Higher Screen Reflectance:

The iPad mini is the most portable of the iPads so it will often be used under brighter ambient lighting than full sized Tablets. As a result it’s more important for the mini to have a low Reflectance screen, otherwise reflections from the higher ambient lighting will reduce screen visibility and wash out the images and colors. Most displays are now coming with lower Reflectance screens. The Amazon Kindle Fire HD and Google Nexus 7 managed to accomplish this, even at their low price points, but the iPad mini comes with an unusually high Reflectance – it reflects 53 percent more ambient light than the Nexus 7 and 41 percent more than the Kindle Fire HD. This is another poor choice and another significant competitive shortfall…

 

Smaller Color Gamut:

The previous generations of LCD Tablet and Smartphone displays had smaller Color Gamuts in order to improve their screen Brightness, Power Efficiency, and Battery Running Times. But that’s been changing due to both technology and competition. Full standard Color Gamut displays not only deliver more accurate and vivid colors, but are better in high ambient lighting because the additional color saturation improves image contrast. While the iPad 2 and iPhone 4 had reduced 61-64 percent Color Gamuts the new iPad 3 and iPhone 5 have full 100 percent standard Color Gamuts. So it was a surprise and major disappointment for the iPad mini to arrive with an antiquated smaller 62 percent Color Gamut, especially considering that the Amazon Kindle Fire HD and Google Nexus 7 both managed to deliver considerably larger 86 percent Color Gamuts. That’s another poor choice and another significant competitive shortfall…

 

The Next Generation of Tablet Displays:

Mini Tablets fill an important need and will undoubtedly continue to grow in market share, so it’s very important for manufacturers to understand how to optimize their smaller displays in brighter ambient lighting environments to deliver both top picture quality and long battery running time. See our new iPad 3 Shoot-Out Conclusion for a discussion of the many improvements that are needed for the next generation of both full size and mini Tablet displays.

 

 

DisplayMate Display Optimization Technology

All Tablet and Smartphone 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.

 

Amazon Kindle Fire HD

Google Nexus 7

Apple iPad mini

 

Display Shoot-Out Comparison Table

Below we compare the displays on the iPad mini, Amazon Kindle Fire HD, and Google Nexus 7 based on objective measurement data and criteria. Note that all of the tested Tablets were purchased independently by DisplayMate Technologies through standard retail channels.

 

For additional background and information see our 7 Inch Tablet Display Technology Shoot-Out that analyzes the Amazon Kindle Fire HD and Google Nexus 7 in depth, and the iPad Display Technology Shoot-Out that analyzes the iPad 2 and new iPad 3. For earlier “popular” full size Tablets see our 10 Inch Tablet Display Technology Shoot-Out.

 

Categories

Amazon

Kindle Fire HD

Google

Nexus 7

Apple

iPad mini

Comments

Screen Diagonal Size

Display Technology

7.0 inches

IPS LCD

7.0 inches

IPS LCD

7.9 inches

IPS LCD

Liquid Crystal Display

In Plane Switching

Screen Shape

16:10 = 1.60

Aspect Ratio

16:10 = 1.60

Aspect Ratio

4:3  =  1.33

Aspect Ratio

The iPad screen has the same shape as 8.5x11 paper.

Screen Area

22.0 Square Inches

22.0 Square Inches

29.6 Square Inches

A better measure of size than the diagonal length.

Relative Screen Area

74 percent

74 percent

100 percent

Screen Area relative to the iPad mini.

Display Resolution

1280 x 800 pixels

1280 x 800 pixels

1024 x 768 pixels

The more Pixels and Sub-Pixels the better.

Active Display Area

1280 x 800 pixels

1280 x 736 pixels

1024 x 768 pixels

The Nexus 7 reserves 64 pixels for a navigation bar.

Pixels Per Inch

216 ppi

Very Good

216 ppi

Very Good

163 ppi

Relatively Low

At 12 inches from the screen 20/20 vision is 286 ppi.

See this on the visual acuity for a true Retina Display

20/20 Vision Retina Display

down to this Viewing Distance

20/20 “Retina Display”

to 15.9 inches Viewing

20/20 “Retina Display”

to 15.9 inches Viewing

20/20 “Retina Display”

to 21 inches Viewing

For 20/20 Vision the minimum Viewing Distance

where the screen appears perfectly sharp to the eye.

Pixels Per Square millimeter

Text letters are 2D objects

72 ppmm2

72 ppmm2

41 ppmm2

Image elements like text letters are seen as

2D objects drawn as a small area of pixels.

Sub-Pixel Rendering

Improves Sharpness

No

Pixel Rendering

No

Pixel Rendering

No

Pixel Rendering

Sub-Pixel Rendering improves visual image

sharpness for text and graphics.

Small Text Readability

Very Good

Very Good

Somewhat Fuzzy

Perceived visual sharpness reading small text such

as on The New York Times website front page.

Gallery / Photo Viewer Color Depth

Full 24-bit color

No Dithering Visible

256 Intensity Levels

Dithered 24-bit color

False Contouring

Full 24-bit color

No Dithering Visible

256 Intensity Levels

Many Android Tablets and Smartphones still have some

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

 

Kindle Fire HD

Nexus 7

iPad mini

 

 

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

Very Good Images

Photos and Videos

have accurate color

and accurate contrast

Good Images

Photos and Videos

have washed out

color and contrast

Very Good Images

Photos and Videos

have good color

and good contrast

The Viewing Tests examined the accuracy of

photographic images by comparing the displays

to a calibrated studio monitor and HDTV.

Variation with Viewing Angle

Small Color Shifts

with Viewing Angle

 

Large Brightness Shift

with Viewing Angle

Small Color Shifts

with Viewing Angle

 

Large Brightness Shift

with Viewing Angle

Small Color Shifts

with Viewing Angle

 

Large Brightness Shift

with Viewing Angle

IPS LCDs have Small Color Shifts.

TN LCDs have Large Color Shifts.

 

All LCDs have Large Brightness Shifts

Viewing the Screen with

Polarized Sunglasses

Extinction in

Landscape

 

View in Portrait

Extinction in

Landscape

 

View in Portrait

No Extinction But

Bluish Color Caste in

Landscape

Polarized Sunglasses are increasingly popular,

which often makes the screen invisible black for

certain orientations.

Overall Display Assessment

Lab Tests and Viewing Tests

Very Good Display

Very Good Calibration

Very Good Display has

Poor Calibration

Washed Out Images

Bugs that need Fixing

Good Display has

High Reflectance

Smaller Color Gamut

Very Good Calibration

Lab and Viewing Test Assessments

Major Display Weaknesses

Nothing Major But

Increase Color Temp

Increase Gamma

Poor Display Calibration

Higher Reflectance

Smaller Color Gamut

Notable Display Weaknesses

Major Display Strengths

Display Calibration

Larger Color Gamut

Lowest Reflectance

Larger Color Gamut

Display Calibration

Notable Display Strengths

Current Overall Display Grade

A–

 B–

 B

Our Overall Assessments based on all criteria

 

Kindle Fire HD

Nexus 7

iPad mini

 

 

 

 

Screen Reflections

Figure 1.  Screen Reflection Photos

Click to Enlarge

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. The 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. Hopefully

manufacturers will reduce the mirror reflections with anti-reflection coatings and haze surface finishes.

 

The Kindle Fire HD and Nexus 7 significantly outperform the iPad mini with much lower Reflectance.

The iPad mini reflects 53 percent more ambient light than the Nexus 7 and 41 percent more than the Kindle Fire HD.

Cover Glass

with Air Gap or Bonded to Display

See Figure 1

Cover Glass Bonded

No Air Gap

Cover Glass Bonded

No Air Gap

Cover Glass Bonded

No Air Gap

A Cover Glass with an Air Gap is easier to

manufacture. Optical Bonding reduces both

external and internal Reflections. See Figure 1

Average Screen Reflections

Percentage of Reflected

Light From All Directions

Reflects 6.4 percent

Very Good

Reflects 5.9 percent

Very Good

Reflects 9.0 percent

Relatively High

Measured using an Integrating Hemisphere that

produces a uniform anisotropic light distribution.

Specular Mirror Reflections

Percentage of Light Reflected

See Figure 1

Reflects 7.6 percent

Very Good

 Reflects 7.2 percent

Very Good

Reflects 12.1 percent

Poor

These are the most annoying types of reflections.

Measured using a narrow collimated pencil beam of

light reflected off the screen. See Figure 1

 

Kindle Fire HD

Nexus 7

iPad mini

 

 

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.

 

All of the Tablets have comparable Brightness and Contrast Ratio, but Contrast Ratio is only relevant for low ambient light.

The iPad mini has a much lower Contrast Rating for High Ambient Light than most Tablets in our Display Shoot-Outs.

Measured Maximum Brightness

is the Peak Luminance for White

Brightness 434 cd/m2

Very Good

Brightness 372 cd/m2

Good

Brightness 388 cd/m2

Good

Maximum Brightness is very important for mobile

because of the typically high ambient light levels.

Black Level

at Maximum Brightness

Black is 0.51 cd/m2

Very Good for Mobile

Black is 0.40 cd/m2

Very Good for Mobile

Black 0.46 cd/m2

Very Good for Mobile

Black brightness is important for low ambient light,

which is seldom the case for mobile devices.

Contrast Ratio

Relevant for Low Ambient Light

851

Very Good for Mobile

930

Very Good for Mobile

843

Very Good for Mobile

Measured in absolute darkness.

Only relevant for low ambient light,

Contrast Rating

for High Ambient Light

68

Very Good

63

Very Good

43

Relatively Low

Visual Contrast in High Ambient Lighting.

Defined as Maximum Brightness / Average Reflectance.

Screen Readability in Bright Light

Very Good    A–

Very Good    A–

Good    B

Indicates how easy it is to read the screen

under high ambient lighting. Very Important!

See High Ambient Light Screen Shots

 

Kindle Fire HD

Nexus 7

iPad mini

 

 

 

 

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.

 

The Nexus 7 has a major problem with its Intensity Scale due to a poor Factory Calibration. We have discussed this

in more detail in this Display News article. The iPad mini suffers from the same problem of Peak Compression but on

a much smaller scale. See Figure 3 for more information.

 

The iPad mini is well calibrated but its Color Gamut is at the low end of what we have seen in Tablets and Smartphones.

Some important issues regarding the Color Gamut are explained in Figure 2 and the Intensity Scale in Figure 3.

White Color Temperature

6,380 degrees Kelvin

Close to Standard

6,708 degrees Kelvin

Close to Standard

6,711 degrees Kelvin

Close to Standard

D6500 is the standard color of White for most content

and necessary for accurate color reproduction.

Color Gamut

See Figure 2

86 percent of Std

Gamut Very Good

See Figure 2

86 percent of Std

Gamut Very Good

See Figure 2

62 percent of Std

Gamut Too Small

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 Contrast or Backlight

None

Excellent

Below 10 percent APL

Very Good

None

Excellent

Many manufacturers manipulate the Intensity Scale

and Backlight based on image content. That results

in inaccurate colors and images.

Intensity Scale and Image Contrast

See Figure 3

Very Smooth

Contrast is Excellent

See Figure 3

Irregular and Convex

Saturation and Clipping

See Figure 3

5% Peak Compression

Contrast is Very Good

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

Gamma 2.16

Gamma is Excellent

Gamma 1.70  to  2.44

Convex Highly Variable

15% Peak Compression

Gamma 2.15

Gamma is Very Good

5% Peak Compression

Gamma is the slope of the Intensity Scale.

Gamma of 2.20 is the standard and needed for

accurate image reproduction. See Figure 3

 

Kindle Fire HD

Nexus 7

iPad mini

 

 

Viewing Angles

The variation of Brightness, Contrast, and Color with viewing angle is especially important for Tablets 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 Tablets. IPS LCDs generally do well.

 

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

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

All of these Tablets have LCDs that perform very well with similar Viewing Angle performance.

Brightness Decrease

at a 30 degree Viewing Angle

52 percent Decrease

Falls to 208 cd/m2

 

Very Large Decrease

53 percent Decrease

Falls to 175 cd/m2

 

Very Large Decrease

50 percent Decrease

Falls to 194 cd/m2

 

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

602

Very Good for Mobile

662

Very Good for Mobile

495

Very Good for Mobile

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’) = 0.0047

1.2 times JNCD

Small Color Shift

Δ(u’v’) = 0.045

1.1 times JNCD

Small Color Shift

Δ(u’v’) = 0.0037

0.9 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’) = 0.0069

1.7 times JNCD

Small Color Shift

Δ(u’v’) = 0.0068

1.7 times JNCD

Small Color Shift

Δ(u’v’) = 0.0067

1.7 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.

 

Kindle Fire HD

Nexus 7

iPad mini

 

 

Display Backlight Power Consumption

Figure 4.  LED Backlight Spectrum

Click to Enlarge

  

The Display Backlight power does not include the power used by the LCD itself or by the display electronics.

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 iPad mini falls in between the Nexus 7 and the Kindle Fire HD in Backlight Power Efficiency.

Display Backlight Power

at Maximum Brightness

2.1 watts

1.4 watts

2.3 watts

Lower power consumption is important for energy

efficiency and improving running time on battery.

Display Backlight Power Efficiency

same Peak Luminance 388 cd/m2

same 7.9 inch screen size area

2.5 watts

2.0 watts

2.3 watts

This compares the Relative Power Efficiency

by looking at the same screen brightness and

screen area.

 

Kindle Fire HD

Nexus 7

iPad mini

 

 

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.

 

The Nexus 7 has the longest Running Time at Maximum Brightness for any Tablet we have tested.

Since the display consumes the most device power, the Running Times at lower Brightness settings will be longer.

Running Time

At the Maximum Brightness Setting

6.6 hours

9.1 hours

6.1 hours

Display always On at the Maximum setting with

Airplane Mode and no running applications.

Categories

Kindle Fire HD

Nexus 7

iPad mini

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 Tablet and Smartphone 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 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. 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:  7 Inch Tablet Display Technology Shoot-Out

Article Links:  new iPad and iPad 2 Display Technology Shoot-Out

Article Links:  10 Inch Tablet Display Technology Shoot-Out

 

Article Links:  Tablet 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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