Demystifying the myth of full HD smart phone screens

Published: April 6, 2013
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Photo: http://www.samsung.com/global/microsite/galaxys4/index.html

Photo: http://www.samsung.com/global/microsite/galaxys4/index.html Although the S4 is not the first phone to be equipped with an HD resolution, the terrific success of the S2 and S3 makes it an appealing get-as-soon-as-possible feature for Galaxy lovers.

2013 is witnessing a rapid growth in smart phone technology with a number of exciting features added to the phones.

Despite the amazing features in recent mobile phones that include, high speed quad core processors, large screen sizes, high-fidelity Graphic Processing Units (GPUs) and innovative designs, the mobile phones manufacturers are desperately trying to surpass each other.

A number of marketing tactics are being used to get us all excited, and persuade us to upgrade our phones.

Due to the tremendous advancements in hardware and software technology and the challenges posed by a very competitive market, the smart phone manufacturers are left only with the screen resolution to boast about and as an immediate eye-catching feature for a potential upgrade.

Samsung is already making a big deal about the full High Definition (HD) resolution of its Galaxy S4 introduced this month. Although the S4 is not the first phone to be equipped with an HD resolution, the terrific success of the S2 and S3 makes it an appealing get-as-soon-as-possible feature for Galaxy lovers.

If you are charmed by the HD resolution and intend on throwing extra money to upgrade your phone to S4, let us first analyse if a full HD smart phone screen is really worth draining your wallet.

Resolution is the prime determinant of a screen’s clarity. HD resolution refers to a High Definition screen having either 1280 x 720 pixels (720p) or 1920 x 1080 pixels (1080p/full-HD) spread along the width and height of the smart phone’s screen.

The pixel is the elementary area of illumination on the screen. The image displayed is composed of pixels. Therefore, higher the number of pixels, the sharper and crisper an image appears on the screen.

For an immediate comparison, you can check the resolution of your old smart phone (For example a Nokia 6600, 176 x 208 pixels) and that of a recent smart phone (like the Samsung Galaxy S3, 720 x 1280 pixels). You will immediately notice that the high resolution produces a much clearer and sharper image.

Nevertheless, resolution is not the only factor responsible for a sharper screen. Keeping the resolution the same and increasing the screen’s size separates the pixels, thus resulting in lost sharpness.

What really matters for determining a screen’s quality is the number of pixels packed in a given area. The term Pixel Per Inch (PPI) represents how many pixels there are in one inch of a screen’s area; the larger the number, the better the screen’s quality.

As an example, Nokia 6600 launched in 2003 has a PPI density of 130, whereas, Apple’s iPhone 4, sensationalised and marketed by the brand name Retina Display, has a PPI of 330. This produces a much sharper and vibrant image on the screen and makes other older phones look lacklustre.

Increasing the resolution does increase the PPI, provided that the screen size is not increased significantly. Two smart phones having the same screen sizes but different resolutions will have different figures for PPI.

Does it mean increasing the PPI indefinitely will produce even sharper images on the screen? The answer is no.

Our eyes can determine the quality of the contents on a screen if the pixels are distinguishable at the normal viewing distance. The reason why Apple called their iPhone 4 screen ‘Retina Display’ was that the 326 PPI pixel density was so high that individual pixels were indistinguishable to the human eye at the normal viewing distance. However, Retina Display is no longer an industry-leading figure.

HTC was one of the companies to develop a display beating that of the iPhone 4 with HTC Rezound (342 PPI). Nevertheless, if you compare the screens of Iphone 4 and HTC Rezound, I can bet you won’t be able to tell the difference.

The reason is that the human eye cannot distinguish the difference in PPI when the figure reaches a saturation point of about 300 (slightly exaggerated, otherwise some studies suggest a threshold of 250 PPI). Therefore, having a PPI of more than 300 will not make any difference to normal human eye unless you use a magnifying glass or have the screen pressed up against your eyeballs to see the subtle difference (of course you don’t want to do that).

Even for people with 20/20 vision, a full HD resolution would be a waste because most people’s eye can’t resolve sharpness above 250 PPI. The same goes for observing the photos quality. The pixel details in a photograph is always spread over more than one pixel and never perfectly aligned with the pixel structure of the display. So it will not matter whether you view the photographs on a 1080p or 720p display; they will appear the same. If you come across a smart phone having a PPI above 350, safely take it as a marketing stunt. It is not going to make the smart phone’s screen any sharper.

Consequently, a full HD (1080p) resolution is no better looking than 720p resolution in smart phones. A full HD resolution is only better for tablets, laptop screens, or monitors where the human eyes can resolve such a high resolution. The smart phones having 720p resolutions and sizes ranging from 4.3 to 4.7 inches have PPIs within the range 312 to 341. This PPI range is more than enough.  Therefore, Samsung’s claim to give a sensational screen experience is pretty pompous.

Whereas, a full HD resolution necessitates using larger screen size (at least 5 inches) which is pretty annoying for small-sized phones lovers.

Another issue is the increased power consumption. The extra features in electronic devices don’t come for free. The price usually has to be paid in terms of high power consumption. A full HD display makes more demand from the processor and the GPU, which in turn needs more power to help it cope.

Although, the S4 has much improved battery (2600 mAh) as compared to the S3 (2100 mAh), it is still not sure if we can get improved battery life as well. We must not forget that the Apple iPad 4’s screen has a higher than 1080p resolution (2048 x 1536, but a PPI of 264), and a battery rated as 11666 mAh, while the iPad2 has a less than 720p resolution (1024 x 768, 132 PPI). Yet both provide the same 10-hours of use before needing a recharge.

The only advantage of a full HD screen in smart phone is that it gives more space for user interface elements such as button and text. For example, a webpage can fit to the screen, but the size of the contents decreases due to high resolution. In most of the cases, the viewer has to zoom in the contents to view them easily.

Due to these reasons, I still prefer to stick to my Xperia S with 720p resolution and a PPI of 341.

Read more by Umair here

Umair Khan

Umair Ali Khan

A researcher in Alpen-Adria University, Austria, Umair is currently pursuing his PhD degree from the same university. His interests include writing and behavioural analysis.

The views expressed by the writer and the reader comments do not necessarily reflect the views and policies of The Express Tribune.