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Smartphone “Super” LCD-OLED Display Technology Shoot-Out
iPhone 4 – Samsung Galaxy S
– Motorola Droid – iPhone 3GS – Google Nexus One
Dr. Raymond M. Soneira
President, DisplayMate Technologies
Corporation
Copyright © 1990-2010 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
Introduction and Series Overview
A key element in the success of all smartphones and mobile
devices is the quality and performance of their display. There have been lots
of articles comparing various smartphone LCD and OLED displays and
technologies, but almost all simply deliver imprecise off-the-cuff remarks
like “the display is gorgeous” with very little in the way of serious
attempts at objective or accurate display performance evaluations and comparisons
– and many just restate manufacturer claims and provide inaccurate
information, performance evaluations and conclusions. This article objectively compares
the display performance of five leading smartphone LCD and OLED displays
based on extensive scientific lab measurements together with extensive
side-by-side visual tests, incisive evaluations and comparisons, nicely
summarized in the Comparison Table and Results Highlights below. The term
“Super” is marketing puffery being used by some manufacturers, but we have
adopted it generically to differentiate the highest performance display
technologies. Since smartphones are being used to view photos, videos and a
wide range of multimedia content we have evaluated their picture quality on
the same terms as HDTVs. In fact, one of the smartphones that we tested has
better picture quality than most living room HDTVs – so the bar is already
quite high for smartphones. But there is still plenty of room for improvement
and we will show and tell you where – we have included images that have been
mathematically processed to correct color and imaging errors on each
smartphone so you can compare them to the originals. Part II of this series will be on glare, screen
reflectance, ambient lighting and sensors, automatic screen brightness
controls and using them to improve picture quality, screen readability, viewing
comfort, reduce display power and increase battery run time. Now let’s see
how these leading smartphone’s perform…
The Comparison Table below covers a wide range
of display data on the Google Nexus One, Samsung Galaxy S, Apple iPhone 3GS,
Motorola Droid and the Apple iPhone 4, but here are some of the highlights
and conclusions culled from the Table:
iPhone 4 – “Super” LCD
Since its
introduction the iPhone has been one of the wonders of the modern tech world
for many reasons – but its display was never one of them – up until the
iPhone 4, where it finally got the display it deserved. The iPhone 4 display,
nicknamed the Retina Display, is an outstanding “Super” LCD delivering top
performance in many of our test categories – it has the brightest and
sharpest display, but on the other hand its color gamut is too small,
producing under saturated somewhat washed-out colors, and its image contrast
is too high, which produces punchier images and also partially compensates
for its smaller color gamut. These were most likely intentional tradeoffs
made by Apple to increase screen brightness, power efficiency and battery run
time. None-the-less the iPhone 4 earned our Best
Mobile Display Award in the DisplayMate Best Video Hardware Guide. We include a
dedicated comparison with the iPhone 3GS below. “Retina Display” is a great
marketing name, and it is the sharpest smartphone display available, but
quantitatively it is a factor of two lower than the acuity of the human
Retina. Click here for a discussion on the Retina Display.
Finally, Part II of this series will discuss some major flaws in
the iPhone 4’s Automatic Brightness control, which hopefully will be
corrected in the near future through a software update.
Samsung Galaxy S – “Super” OLED
The
Galaxy S has Samsung’s next generation premium OLED display marketed as a
“Super AMOLED” display. The AM stands for Active Matrix, but all smartphone
displays have that. What is particularly impressive is how rapidly Samsung
has been improving their OLED technology, and the Galaxy S delivered top
performance in many of our test categories. Some of areas where it fell short
were the result of manufacturer calibration and OS issues rather than
fundamental problems with the OLED technology itself. Google
confirmed that some of the display problems we discovered are caused by
Android 2.1. While OLED is still a relatively young display technology that
has not yet been perfected to the performance levels of the very best mature
LCDs, the Galaxy S is already an impressive display for an upcoming and
rapidly evolving technology, so it earned our Best New
Mobile Display Technology Award in the DisplayMate Best
Video Hardware Guide. There are comparisons with ”Super” LCDs and “non-Super”
OLEDs below. Part II
will also discuss problems with the Automatic Brightness control on the
Galaxy S, which should also apply to other Android phones.
“Super” LCD versus “Super” OLED
All of
the tested LCDs were considerably brighter than the OLED displays – however,
that may change in the near future as OLEDs continue to improve… While
“Super” OLEDs have roughly 50 times the Contrast Ratio of “Super” LCDs, when
a display is set properly to its optimum screen brightness that superior
Contrast Ratio is visually insignificant except under dark ambient lighting,
which is seldom the case for mobile displays. While OLEDs love to flaunt
their vivid colors and large color gamut, that produces gaudy and over
saturated pictures – someday they will turn those down and get it right…
While the iPhone 4’s sharpness is something of an overkill (it’s that high
for App compatibility) the PenTile arrangement of the OLEDs has only two
sub-pixels per pixel instead of the usual three, so it sometimes appears more
pixilated than its stated resolution implies – it’s excellent for
photographic images but is noticeably degraded for colored (red, blue and
magenta) text and graphics. While all OLEDs behave considerably better with
changes in viewing angle than “Super” LCDs, smartphones are primarily single
viewer devices and the user can easily orient the phone for the best viewing
angle. LCDs are currently more power efficient for brighter images and OLEDs
are more efficient for darker images. But for typical web and app content,
which typically use bright backgrounds, the power balance is still decisively
in the favor of LCDs by more than 2 to 1 in our tests – again, that should
change as OLEDs continue to improve… The big question remaining for OLEDs
(and not covered by our tests) is whether the previous uneven aging over time
for the red-green-blue OLED sub-pixels has been solved.
“Super” OLED versus “non-Super” OLED
“Super”
OLEDs do indeed perform considerably better than “non-Super” OLEDs. What is
particularly impressive is how rapidly Samsung has been improving their OLED
technology. The “Super” OLED is a much more refined display with many fewer
artifacts and a much better factory calibration. Samsung advertises that the Galaxy S Super OLEDs are 20
percent brighter and use 20 percent less power than “non-Super” OLEDs, and
have a screen reflectance of just 4 percent, down from 20 percent for
“non-Super” OLEDs. In our lab tests the Galaxy S has a screen reflectance of
4.4 percent, is 25 percent brighter and uses 21 percent less power than the
“non-Super” OLED in the Google Nexus One – meeting or exceeding all of
Samsung’s specs. Particularly impressive is the very low screen reflectance,
which is among the lowest we have ever measured – outdoors it can have a
significant impact on screen visibility. The over-saturated gaudy colors are
still there – they need to be properly managed and can be used constructively
in a calibrated fashion to counteract the effects of glare from ambient light
(Part II).
iPhone 4 versus iPhone 3
The
iPhone 4 display is a tremendous step forward over the iPhone 3GS and earlier
models. It has double the resolution, a 26 percent brighter screen, 24
percent lower screen reflectance, and 64 percent greater Contrast under
bright ambient light, plus it has 8 times the Contrast under dim ambient
light. On the other hand, the iPhone 4 has the same reduced color gamut as
the iPhone 3GS, producing under saturated somewhat washed-out colors. The
iPhone 3GS has very low image contrast, which adds to the display’s
washed-out appearance. The iPhone 4 has gone to the other extreme and has too
much image contrast, which gives its images a punchier look and also
partially compensates for its smaller color gamut. Lastly, the iPhone 4
display consumes only half the power of the iPhone 3GS display.
Motorola Droid – “Super” LCD
The
original Droid, launched in October 2009, remains the number one smartphone
in terms of overall picture quality and accuracy, close to what you see in a
calibrated studio monitor and actually better than most living room HDTVs –
just a lot smaller, but still impressive none-the-less. It earned the Best
Mobile Picture Quality Award in the DisplayMate Best Video Hardware
Guide but only for Android 2.0. Google confirmed
that the some of the display problems we discovered afterwards were caused by
upgrading to Android 2.1.
Google Nexus One – “Non-Super” OLED
Its
“non-Super” OLED display got lots of attention when it was introduced in
January 2010, but in terms of objective picture quality and overall display
performance it behaves like a rushed and unfinished prototype for early
adopters instead of a production quality display. Decidedly in last place for
the five smartphone displays tested. Google
confirmed that some of the display problems we discovered are caused by
Android 2.1.
And the
Winner is…
There is
no decisive winner as each of the three “Super” displays significantly
outperforms the others in more than one important area and significantly
underperforms in other areas. The iPhone 4 by far has the brightest and
sharpest display and is the most power efficient of the displays. The
Motorola Droid by far has the best picture quality and accuracy. The Samsung
Galaxy S by far has the lowest screen reflectance and largest Contrast for
both bright and dark ambient lighting, and the best viewing angles. On the
flip side, the iPhone 4 has a weak color gamut and viewing angles, the
Motorola Droid has weak screen reflectance and viewing angles, and the
Samsung Galaxy S has lower brightness, excessive color saturation, higher
power consumption and some sharpness issues. Each of these “Super” displays
is none-the-less impressive and deserves an award: the iPhone 4 performed
better overall so it earned the DisplayMate Best
Mobile Display Award, the Motorola Droid earned the Best
Mobile Picture Quality Award, and the Samsung Galaxy S earned the Best New
Mobile Display Technology Award. Each of these displays has lots of room
for improvement and can leapfrog the others in their next iteration with appropriate
action…
DisplayMate Display Optimization Technology
All of
these “Super” displays can be significantly improved and optimized on many
different levels. This article is a lite version of our intensive scientific
analysis of smartphone and mobile displays – before the benefits of our
advanced mathematical DisplayMate
Display Optimization Technology, which can correct or improve many of the
deficiencies – including higher calibrated brightness, power efficiency,
effective screen contrast, picture quality and color and gray scale accuracy
under both bright and dim ambient light, and much more. If you are a display or product manufacturer and want our
expertise and technology to turn your display into a spectacular one to
surpass your competition then Contact DisplayMate
Technologies to learn more.
Below we compare the
displays on the Google Nexus One, Samsung Galaxy S, Apple iPhone 3GS,
Motorola Droid and the Apple iPhone 4 based on objective measurement data and
criteria. Note that we are testing and evaluating the displays with whatever
hardware, firmware, OS and software are provided by the smartphone
manufacturers. Note that the Categories in the Table are not intended to have
equal weighting in case you plan on scoring the results. For details, measurements, in-depth explanations and
analysis see the Article Links below for the individual dedicated articles for each
smartphone.
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Categories
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Google
Nexus One
Article Link
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Samsung
Galaxy S
Article Link
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Apple
iPhone 3GS
Article Link
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Motorola
Droid
Article Link
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Apple
iPhone 4
Article Link
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Comments
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Display Technology
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3.7 inch
PenTile OLED
Active
Matrix
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4.0 inch
PenTile Super
OLED
Active
Matrix
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3.5 inch
LCD
Active
Matrix
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3.7 inch
IPS LCD
Active
Matrix
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3.5 inch
IPS LCD
Active
Matrix
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Technologies are Organic Light Emitting Diodes
and In Plane Switching Liquid Crystal Displays.
All the smartphone displays have an Active Matrix.
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Display Resolution
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800 x 480
pixels
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800 x 480
pixels
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480 x 320
pixels
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854 x 480
pixels
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960 x 640
pixels
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The more Pixels and Sub-Pixels the
better
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Pixels Per Inch
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252 ppi
Very Good
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233 ppi
Very Good
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163 ppi
Good
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265 ppi
Very Good
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326 ppi
Excellent
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At 12 inches from the screen 20/20 vision
is 286 ppi.
Best human vision is about 20/10 vision or
572 ppi.
See this link
on the acuity for a Retina Display
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Number of Red+Blue Sub-Pixels
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0.38
Million
Less Sharp
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0.38
Million
Less Sharp
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0.31
Million
Less Sharp
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0.82
Million
Sharp
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1.23
Million
Very Sharp
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PenTile OLEDs have only 2 sub-pixels per
pixel
instead of the 3 that are used in most displays.
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Hardware Color Depth
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24-bit
color
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24-bit
color
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18-bit
color
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24-bit
color
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24-bit
color
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24-bit color produces 16.8 Million screen
colors
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Displayed Color Depth
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16-bits on-screen
Browser and
Gallery
Android
2.1
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16-bits with
Dithering
to 24-bits
Browser
and Gallery
Android
2.1
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18-bits
with
Dithering
to 24-bits
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Full
24-bits
Browser
and Gallery
Android 2.0
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Full
24-bits
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Android 2.1 produces 16-bit on-screen
color causing
false image contours and color-intensity
artifacts.
See this link for
Google’s comments on this topic
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Viewing Tests
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Gaudy
Images
Photos and
Videos
have too
much color
and too
much contrast
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Good
Images
Photos and
Videos
have too
much color
and
accurate contrast
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Subdued
Images
Photos and
Videos
have too
little color
and too
little contrast
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Excellent
Images
Photos and
Videos
have
accurate color
and
accurate contrast
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Good
Images
Photos and
Videos
have too
little color
and too
much contrast
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The Viewing Tests examined the accuracy
of
photographic images by comparing the
displays
to a calibrated studio monitor and HDTV.
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Photo and Image Comparison Tests
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Click Link for
Comparison Images
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Click Link for
Comparison Images
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Click Link for
Comparison
Images
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Click Link for
Comparison
Images
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Click Link for
Comparison Images
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Visually compare images that are mathematically
processed to correct a number of imaging flaws
with the original images for each
smartphone.
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Suggestions and Conclusions
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Suggestions
and
Conclusions
for
Google
Nexus One
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Suggestions
and
Conclusions
for
Samsung
Galaxy S
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Suggestions
and
Conclusions
for
Apple
iPhone 3GS
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Suggestions
and
Conclusions
for
Motorola
Droid
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Suggestions
and
Conclusions
for
Apple
iPhone 4
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Our Conclusions and Suggestions for
improvement for each smartphone.
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Overall Display Assessment
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Rushed Prototype
Needs
Updates
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Excellent
Display
DisplayMate Award
Best New
Technology
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Dated Display
Needs a
Makeover
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Excellent
Display
DisplayMate Award
Best
Picture Quality
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Excellent
Display
DisplayMate Award
Best
Mobile Display
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Three of these high-end smartphones with “Super”
LCD and OLED top performance displays
received
DisplayMate Best Video Hardware
Guide Awards.
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Brightness and Contrast
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Measured Maximum Brightness
is the Peak Luminance for White
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Brightness
292 cd/m2
Full
Screen 229 cd/m2
------
No Google
Brightness
Specs
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Brightness
365 cd/m2
Full
Screen 305 cd/m2
------
No Samsung
Brightness
Specs
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Brightness
428 cd/m2
Excellent
------
No Apple
Brightness
Specs
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Brightness
449 cd/m2
Excellent
------
No
Motorola
Brightness
Specs
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Brightness
541 cd/m2
Excellent
-------
Apple
Advertises
500 cd/m2
typical
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Maximum Brightness is very important for
mobile
because of the typically high ambient
light levels.
For these OLEDs the Maximum Brightness
is lower
when the screen is mostly bright or white.
Apple exceeds their advertised value –
impressive!
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Black Level
at Maximum Brightness
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Black 0.0035
cd/m2
Outstanding
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Black <
0.005 cd/m2
Outstanding
|
Black 3.1
cd/m2
Very High
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Black 0.31
cd/m2
Very Good
for Mobile
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Black 0.48
cd/m2
Very Good
for Mobile
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Black brightness is important for low
ambient light,
which is seldom the case for mobile
devices.
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Contrast Ratio
Relevant for Low Ambient Light
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65,415
to 83,430
Outstanding
------
Google
Advertises
100,000
typical
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Greater
than 61,000
Outstanding
------
Samsung
Advertises
50,000
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138
Poor
------
No Apple
Contrast
Specs
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1,436
Very Good
for Mobile
------
No
Motorola
Contrast
Specs
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1,117
Very Good
for Mobile
------
Apple
Advertises
800
typical
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Only relevant for low ambient light,
which is seldom the case for mobile
devices.
Don’t confuse our measured objective
values with
the often inflated manufacturer Contrast
specs.
Samsung and Apple exceed their
advertised values!
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Screen Reflectance
of Ambient Light
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Reflects
15.5 percent
Relatively
High
------
No Google
Reflectance
Specs
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Reflects
4.4 percent
Excellent
------
Samsung
Advertises
Reflects 4
percent
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Reflects
9.2 percent
Good
------
No Apple
Reflectance
Specs
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Reflects
12.1 percent
Good
------
No
Motorola
Reflectance
Specs
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Reflects
7.0 percent
Very Good
------
No Apple
Reflectance
Specs
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Reflectance is the most important spec
for mobile
because of the typically high ambient
light levels.
Samsung matches their advertised value.
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Screen Bright Contrast Rating
for High Ambient Light
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Bright
Contrast 15 - 19
Very Low
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Bright
Contrast 69 - 83
Excellent
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Bright
Contrast 47
Very Good
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Bright
Contrast 37
Good
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Bright
Contrast 77
Excellent
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Indicates how easy it is to read the
screen
under high ambient lighting. Very
Important!
Defined as Maximum Brightness / Reflectance
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Colors and Intensities
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White Color Temperature
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8,870
degrees Kelvin
White is
Too Blue
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9,688
degrees Kelvin
White is
Too Blue
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6,977
degrees Kelvin
Close to
D6500
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6,752
degrees Kelvin
Close to
D6500
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7,781
degrees Kelvin
White Slightly
Too Blue
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D6500 White is the standard for most
content
and necessary for accurate color
reproduction.
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Color Gamut
See Figure 1
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Gamut Too
Large
141
percent
See Figure 1
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Gamut Too
Large
138
percent
See Figure 1
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Gamut Too
Small
60 percent
See Figure 1
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Standard
Gamut
97 percent
See Figure 1
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Gamut Too
Small
64 percent
See Figure 1
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sRGB / Rec.709 is the color standard for
most
content and needed for accurate color reproduction.
Too Large is visually worse than Too
Small.
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Picture Color Saturation
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Very High
Gaudy
Colors
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Too High
Gaudy
Colors
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Very Low
Subdued
Colors
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Excellent
Beautiful
Colors
|
Too Low
Subdued
Colors
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Picture Color Saturation depends on both
the
Color Gamut and the Intensity Scale
Gamma.
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Intensity Scale and Image Contrast
See Figure 2
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Mostly Too
High
and Very
Irregular
|
Very Good
Close to
Standard
|
Very Low
and
Concave
|
Excellent
Very
Accurate
|
Good
But Too High
|
The Intensity Scale controls image
contrast needed
for accurate image reproduction. See Figure 2
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Gamma for Intensity Scale
See Figure 2
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Poor 1.82
to 2.55
Very
Irregular
|
Very Good
2.36
Close to
Standard
|
Poor Less
than 1.90
Too Low
|
Excellent
2.24
Close to
Standard
|
Good 2.68
But Too
High
|
Gamma of 2.2 is the standard and needed
for
accurate image reproduction. See Figure 2
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Viewing Angles
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Brightness Decrease
at a 30 degree Viewing Angle
|
28 percent
decrease
to 166
cd/m2
From
Absorbing Layer
|
28 percent
decrease
to 221
cd/m2
From
Absorbing Layer
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63 percent
decrease
to 161
cd/m2
Very Large
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64 percent
decrease
to 160
cd/m2
Very Large
|
57 percent
decrease
to 235
cd/m2
Very Large
|
Screens become less bright when tilted.
OLED variation is due to screen
absorbing layers.
LCD brightness variation is generally
very large.
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Contrast Ratio
at a 30 degree Viewing Angle
|
Extremely
High
Not
Measured
|
Extremely
High
Not
Measured
|
44
Extremely
Low
|
280
Low
|
556
Very Good
for Mobile
|
A measure of screen readability when the
screen
is tilted under low ambient lighting.
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Color Shift
at a 30 degree Viewing Angle
|
Δ(u’v’)
= 0.0262
7 times
JNCD
|
Δ(u’v’)
= 0.0229
6 times
JNCD
|
Δ(u’v’)
= 0.0418
10 times
JNCD
|
Δ(u’v’)
= 0.0020
½ times
JNCD
|
Δ(u’v’)
= 0.0096
2 times
JNCD
|
JNCD is a Just Noticeable Color Difference.
IPS LCD has a smaller color shift with
angle.
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Display Power Consumption
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|
Display Power for White Screen
at Maximum Brightness
|
0.91 watts
|
1.13 watts
|
0.81 watts
|
0.87 watts
|
0.42 watts
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Lower power consumption is important for
energy
efficiency and improving run time on
battery.
|
|
Display Power for White Screen
same Peak Luminance 229 cd/m2
same 3.7 inch screen area
|
0.91 watts
|
0.72 watts
|
0.46 watts
|
0.46 watts
|
0.19 watts
|
iPhone 4 is considerably more power
efficient for
the same size equal brightness full white
screens.
|
|
Display Power for
NASA Sunset on
Mars Photo
same Peak Luminance 229 cd/m2
same 3.7 inch screen area
|
0.25 watts
|
0.20 watts
|
0.46 watts
|
0.46 watts
|
0.19 watts
|
OLEDs use much less power when there is
darker
screen content. This is the display power
for
the NASA
Sunset on Mars Photo.
|
|
Display Power for Black Screen
at Maximum Brightness
|
0 watts
|
0 watts
|
0.81 watts
|
0.46 watts
Dynamic
Black
|
0.42 watts
|
OLED is zero because it is emissive
technology.
Droid Dynamic Contrast reduces power for
Black.
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Categories
|
Google
Nexus One
Article Link
|
Samsung
Galaxy S
Article Link
|
Apple
iPhone 3GS
Article Link
|
Motorola
Droid
Article Link
|
Apple
iPhone 4
Article Link
|
Comments
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