Understanding TV Resolution - Do You Need a 1080p or 4K HDTV?

TV resolution is one of the things that you will often see quoted when you are looking to buy a new television.

Now, you won't actually see it called this, you will just see terms like '1080p Full HD' and '4K Ultra HD' thrown about - but with little explanation as to what they actually mean - and why they are important.

So are they important? Let us take a look and find out.

What Is the Native Resolution?

All flat screen TVs have a native resolution - so that includes LED, OLED, plasma and LCD televisions.

It can be defined as the physical size of the screen - measured by the amount of pixels.

Every flat screen TV is made up of a grid of small pixels - and each pixel can be lit independently and set to a different colour - which is how the TV image is built.

In theory, the more pixels there are then the better the picture will be - as we will be able to see more detail. However, as we will see later, in reality it isn't quite as simple as that.

Now, you don't see each individual pixel at work as they are too small to see from a distance, but if you go up very close to your TV screen you will see how the image is built from this grid of small coloured dots - and when you walk away from the screen, these small dots merge into one and all you see is one big image.

In fact, this is one of the important concepts to understand about TV screen resolutions - that the further away you are from the screen, then the less detail your eyes will actually be able to see (more on this later).

So:

• the native resolution of a flat screen TV screen is a fixed number
• it is defined by the physical number of pixels the screen has
• as a general rule, the more pixels a screen has (higher resolution), then the sharper and more detailed the picture will be.

High-Definition TV Screens

A TV screen that is said to have a resolution of 1920 x 1080 (a common native resolution of HDTV screens), will have a grid of 1,920 pixels across the screen (horizontal) and 1,080 pixels down the screen (vertical).

In total, this means it has 2,073,600 individual pixels (1,920 x 1,080).

A TV screen with this number of pixels is often said to be 1080p. This means it has a 1920 x 1080 grid of pixels - and that it can display a progressive scan image.

Depending on the design of the screen, and the shape of the pixels (they can be round, square or rectangle), you may see other native resolutions for HD flat screen TVs such as 1280 x 720, 1366 x 768 or 1024 x 768.

A 1920 x 1080 native resolution screen will often be referred to as 'Full HD', whereas an 'HD Ready' screen will generally be the be the lower resolution 1280 x 720 or 1024 x 768 screens.

These are all considered to be high-definition screens.

So you will often see these TVs referred to by these various terms such as 1080p Full HD, HD ready or HD ready 1080p rather than the pixel numbers - and these terms can be a bit vague so it can be better to double-check the actual number of pixels if this is important to you.

Ultra HD 4K Resolution TV Screens

In recent years there has been a progression to even higher resolution screens - welcome to the world of Ultra HD!

Ultra HD can be known by a further wonderful array of 'marketing' terms. You will see reference to 4K, Ultra High Definition, Ultra HD 4K, SUHD and many more - however they all refer to the same increased resolution of new flat screen TVs.

If you find all the features of new TVs confusing, don't forget to check out my buying guide to the best OLED and LED TVs in 2018.

Ultra HD televisions have a native resolution of 3840 x 2160, which is over 4 times the resolution of a Full HD screen - a total of 8,294,400 pixels to be precise.

What Is the Image Resolution?

The image resolution is the number of pixels in the picture that is being sent to the television.

It is useful to understand that the image resolution is not the same thing as the native resolution of the TV (as discussed above).

Unlike the native resolution of a TV (which is fixed), the image resolution can be different depending on how it is recorded and transmitted.

TV and video image resolutions can be broadly split into three main categories - standard definition, high-definition and ultra high-definition.

Standard Definition Video Images

A standard definition TV transmission (the most common type of TV picture - which is slowly being replaced by high-definition transmissions), will have a visible resolution of either 480i or 576i - depending on where you are in the world.

Therefore, a 4:3 480i image is made up of 640 pixels across the image and 480 pixels down (a total of 307,200 pixels).

The 'i' at the end means that this transmission has an interlaced image, which was a method introduced to cut down the amount of bandwidth that it took to transmit an image, but which also has an adverse effect on the quality of the image.

Standard definition DVDs in NTSC regions have a similar 480 lines of vertical resolution (576 lines in PAL regions) - but are transmitted with progressive scan and so this resolution is known as 480p.

High-Definition Video Images

One of the best quality high-definition resolution images is known as 1080p. This is common in Blu-ray players and some streaming services.

This image will be recorded with 1920 horizontal pixels and 1080 vertical pixels of information. The result is over two million pixels of resolution which means it will be much sharper and clearer than the 480i image - which only has 307,200 pixels of information.

The 'p' means that the image is also recorded using progressive scan, which results in a better image quality than with interlaced scan.

At present, a 1080p image can only be transmitted by a small number of sources - by Blu-ray players like the Sony BDPS3700 streaming Blu-Ray disc player pictured here, by the Sony Playstation 3/4, Xbox 360/One and Wii U games consoles or by some streaming services such as Netflix, Amazon Prime Video and YouTube.

So remember, even if you buy a 1080p resolution TV, many of the sources of television that you will be watching will not be transmitting a full 1080p image - and so you won't get the best out of your screen unless you are watching Blu-ray, gaming or streaming from certain online providers.

There are three types of high-definition images:

• 1080p - 1920 x 1080 pixels and progressive scan
• 1080i - 1920 x 1080 pixels and interlaced scan
• 720p - 1280 x 720 pixels and progressive scan
  

These are all regarded as high-definition image resolutions, and they will all look fantastic on your HD flat panel TV - even though they have different amounts of pixel information.

Due to the amount of bandwidth required, many high-definition TV transmissions are restricted to either 1080i or 720p.

4K UHD Video Images

Ultra high-definition 4K resolution images are known as 2160p.

A 4K image will be recorded using progressive scan and have a minimum resolution of 3840 x 2160 pixels - so 8.3 million pixels with a 16:9 aspect ratio.

The source of 4K video is very limited at present. The Ultra HD Blu-ray specification will finally allow Blu-ray technology to provide 4K video on your Ultra HD 4K TV. There are now a few Ultra HD Blu-ray players on the market like the OPPO UDP-203 Ultra HD Blu-ray Disc Player pictured below.

Other than that, we are limited to a few streaming services which have some 4K content - Netflix, Amazon Prime Video, YouTube and Vimeo. 

In August 2015, BT Sport in the UK launched a 4K channel showing their Premier League and European football matches in Ultra HD.

How Important Is the Resolution of My HDTV?

The simple answer is that in many cases the native resolution of a particular HD screen isn't that important.

Why?

In short, because to see the best quality image on your TV, the transmitted image resolution should be the same as the native resolution of your TV - and much of the time it won't be. Also, you will need to be sat fairly close to the TV to be able to appreciate the increased resolution.

The factors that make a difference to how good your TV picture looks in your room are:

• The size of the screen
• The distance you sit from the screen
• The resolution of your source images
• The quality of the TVs processing
  
• The contrast ratio and colour accuracy of the picture
  

To get the full benefit from a 1080p or 4K native resolution screen you need to be watching a true 1080p or 4K source, and then you need to be sitting relatively close to the screen - or you need to have a very large screen. Or both!

Image and Native Resolution

Just remember most of the images you watch on your 1080p screen will not be transmitted in 1080p, and so they will have to be processed by the TV to display properly. Similarly, you may have a 4K TV but most of the images you watch will not currently be transmitted in Ultra HD.

When the image resolution is different to the native resolution of your TV, your television will scale the image to fit the screen. This scaling is performed better by some TVs than others - and this will have an effect on the quality of the picture you see.

If you have a 1080p screen, then it is only Blu-ray players, PS4/Xbox games and some streaming services that send a true 1080p image - and so it is only these sources that will benefit the most from a 1080p screen because there is no scaling or processing required.

The story is the same for 4K UHD TVs. Because there are limited sources of 4K content, you may find that other factors are more important than the screen resolution.

The contrast ratio and colour accuracy are widely accepted to be more important to picture quality than purely higher resolutions.

This is why OLED TVs such as the  LG Electronics OLED55C7P 55-Inch 4K Ultra HD Smart OLED TV pictured here are so well received as they have the best contrast ratios available today.

Most terrestrial, cable and satellite HDTV transmissions either come in 1080i or 720p formats, and so the TV will either have to de-interlace (for the 1080i) or upscale (for the 720p) in order to display them on the screen. Either way, both of these processes can affect the quality of the image you see - and how good these sources look on your 1080p TV are more dependent on the quality of the transmission and the processing in the TV, rather than its native resolution.

Similarly, a standard definition image with 480 lines would have to be upscaled to either 720 lines or 1080 lines depending on the native resolution of your screen. The TV effectively adds in extra information to the low resolution images to enable them to be seen on the bigger screen.

Therefore, because this image starts with such a relatively poor resolution, then you will not gain anything by having a higher resolution 1080p screen. An upscaled DVD will look pretty good on any HD screen, regardless of the native resolution of the TV, just not as good as a true HD source.

Distance from the Screen

The fact is that most people's eyes won't be able to tell the difference between a 720p and a 1080p image from more than about 6 or 7 feet. The same goes for 1080p and 4K.

A rough rule of thumb is that if you are further away than 1.5 times the diagonal screen size, then you will struggle to tell the difference between the various HD resolutions.

So unless you plan on sitting five or six feet away from the screen - or you have a very large TV - then your eyes just won't be able to appreciate the extra resolution between different high-definition images on a 720p or 1080p screen - or a 4K Ultra HD screen for that matter.

The article on TV viewing distance covers this in more detail.

Conclusion

You can now see why the native resolution of a TV can make a difference - but it is not something that should be your biggest concern when choosing which TV to buy.

The TV resolution can have an effect on the picture quality you see - but this is also dependent on a number of other things too.

Because a TV has to handle a number of different image resolutions, the quality of the internal processing can be as important as the native resolution of the screen - and as most people will find it hard to tell the difference between different resolutions of HD material, you shouldn't get too hung up on the number of pixels of the screen that you buy.

It is widely understood that the contrast ratio and colour accuracy of the TV are more important to picture quality than the native resolution of the screen - and there are also other factors to take into account such as the distance you will be sitting from the screen, how big the screen is and how good your eyes are!

As newer models of television are released, more and more of them are either 1920 x 1080 (HD) or 3840 x 2160 (UHD) resolutions as standard - so there are less choices to be made in this area than there used to be.

However, if you do have a choice to make, a 1080p or 4K resolution TV won't necessarily give you a better image than one with a slightly lower native resolution - so don't think you have to pay extra money just to get the 'best'.

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