HD DISPLAYS EVERYWHERE: WHAT IS THE DIFFERENCE?(WHAT TO LOOK WHEN DECIDING BETWEEN TWO DISPLAYS)

First things first, this post is mostly about mobile phone displays but I have explained the basics which apply for all kind of displays. 

So, every other phone you pick-up these days, or have a look at, has an HD display resolution. Every day, new companies are entering the Indian market with budget friendly phones with displays having HD resolution. Not only 720p, players like Zopo and UMi are coming up with Full HD resolution displays. So, how to differentiate between them? Well for that, lets understand some terms related to display technology.

PPI and Display Resolution:

Pixels

PPI stands for Pixels Per Inch. Now, as you may know, a display is made up of millions of tiny pixels which light-up in a certain order or manner, to give out different images and hence a video. So ppi is the number of these pixels which are present in every inch of your display. More the number of pixels, greater is the sharpness and crispness of the images and text on the display.
HINT: Human eye cannot differentiate pixels from one another over a ppi of 320.

The Display Resolution is nothing but the no. of pixels horizontally and vertically. Consider the following:

• WVGA RES: 800*480
• qHD RES: 960*540
• HD RES: 1280*720
• FULL HD RES: 1920*1080

So, now you would ask: Are the no. of pixels, the only deciding factor of the display quality? 

And the answer is : No.

Yes it's true that having more no. of pixels in a screen i.e. having a screen with greater PPI, translates to better images and crisper text, but other factors like display technology are also very important to consider before we may judge a displays quality. So let's first know what are the different types of screens which are present in the market right now:

LCD TECHNOLOGY:

This is the most used display technology used in mobile phones now-a-days. LCD stands for Liquid Crystal Display. That doesn't make sense. Basically it is worth knowing that the pixels are lighted with the help of either CCFL's or several LED's(kind of "bulbs). Mind you, LED displays are different from LCD display but now LCD displays come with LED backlight technology. If you want, I could write a different post to let you know the difference between both the technologies and the marketing gimmicks by TV companies. Just leave a comment down below and I will be on it. Anyways, back to business. Now you would generally find TFT LCD or IPS LCD written in the specs of any device. 

TFT AND IPS TECHNOLOGY: 

TFT stands for Thin Film Transistors. TFT is a type of LCD display which improves the image quality and contrast. TFT has different types and one of them is IPS. Though, whenever it is mention that it is a TFT display without mentioning whether it is IPS, then generally it is a TN panel.

TN vs IPS: 

TN stands for Twisted Nematic and IPS stands for In-Plane Switching. Without going into details, let's just come to the point.

IPS displays have better viewing angles and colour reproduction.This means that the colours are more vibrant and more natural as compared to a similar TN based display. Better viewing angles translate to a much better viewing and reading experience.  On the other hand, TN panels have much lower response time than IPS panels which is better for hard-core gamers, though the difference isn't much noticeable in Mobile devices.TN panels have very bad viewing angles and colours get washed out by even tilting the phone slightly. TN TFT panels are also significantly cheaper to produce. So, from this, it is clear that you should prefer an IPS panel display over a TFT(i.e. TN panel display). 

SUPER LCD 2 DISPLAY: Super LCD differs from a regular LCD in that it does not have an air gap between the outer glass and the display element. This produces less glare and makes the user feel "closer" to the display itself. Super LCD's benefits also include lower power consumption and improved outdoor visibility.Super LCD (SLCD) is a display technology used by numerous manufacturers for mobile device displays. It is mostly used by HTC, as seen in the newly launched HTC ONE has somewhat tackled these problems. 

AMOLED:
Amoled stands for Active-Matrix Organic Light Emitting Diode. These are a type of an O-LED displays which are known for producing highly saturated colours and a vibrant output. Watching videos and images is a joy on these displays. These consist of Pentile Matrix arrangement. These displays have lower brightness as compared to their LCD counterparts but also consume less power as these do not light any pixels when showing the black colour.

SLCD vs AMOLED:
Super LCD displays have much better outdoor visibility as compared to Amoled displays. These also consume less power when showing lighter colours like the background of a website, which is generally white. On the other hand, AMOLED displays don't light pixels at all when showing black colour thus saving a lot of battery. Also these produce more vibrant colours and a better viewing experience. 

One con of Amoled is that, a low res display using PENTILE Matrix, shows jagged text as compared to an SLCD display, though this difference is not much prominent in high res displays like HD Amoled and Full HD Amoled( the one on the Galaxy S4).

S3 vs HTC ONE X(AMOLED vs LCD)

RGB vs PENTILE MATRIX:

I think I should talk about this in a later post as PENTILE Matrix arrangement is a SAMSUNG proprietary. But the basic difference is that RBG contains RED,BLUE and GREEN sub-pixels whereas PENTILE contains RGBG, i.e. RED,GREEN,BLUE and GREEN sub-pixels, giving a kind of bluish-green tinge to the display.  

FINAL THOUGHTS:
So after so much explanation about the terms about the present display technology, here are a few points to consider in a display before you decide to buy a cellphone because it is the most important part of today's smart phones:

• HIGH PPI: The Resolution does not matter. PPI matters.  A certain res would be good enough for a smaller display size but the same cannot be said for a larger display size. For example, A 4 inch display with a WVGA resolution has a PPI of about 233 whereas a 5 inch display with the same WVGA resolution has a PPI of about 190 ppi. So you should choose a display with a higher PPI.
• Viewing Angles: Having a great PPI isn't everything. The viewing angles should also be good for a display to be able to give a truely enjoyable viewing experience. For example, The Sony Xperia Z has got a Full HD display with a PPI of 441 which seems to be great. And the PPI is great. But the viewing angles aren't as great as they should be on a Full HD display which ruin the show. If Sony had put in a better quality display with better viewing angles, then this cellphone would have been up there with the best. 

  

  The difference in viewing angles between HTC ONE and XPERIA Z

• DISPLAY TECHNOLOGY: This is also very important. Choose an LCD display if you need : Good Outdoor Visibility, More Natural Colours etc. In LCD always prefer an IPS display over an TN panel(generally marketed as TFT panel with no mention of IPS).
  Choose an AMOLED panel if you don't really want that great outdoor visibility but want good contrast levels and punchy colours along with better battery life. 

  

  Outdoor Visibility Comparision

  
  

So the decision should be totally based on your priorities. 

Check out my post about how to buy a cellphone to get help on how to get to know your priorities. If you have any queries about which cellphone to buy then you could ask me.

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