Understanding TV Resolution - Do You Need a 1080p 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 '720p HD Ready' 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 plasma, LCD and LED 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.
1920 x 1080 HD TV Resolution
Therefore, 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.
These are all considered to be high-definition screens.
You will often see these TVs referred to by various terms such as 1080p Full HD, HD ready or HD ready 1080p rather than the pixel numbers - but these terms can be a bit vague and it can be better to double-check the actual number of pixels if this is important to you.
1024 x 768 HD TV Resolution
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, 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).
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.
Unlike the native resolution (which is fixed), the image resolution can be different depending on how it is recorded and transmitted.
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.
The highest resolution high-definition image available is known as 1080p.
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 and by the PS3 and Xbox games consoles (and even then there are few games which are actually available in true 1080p resolution).
So remember, even if you buy a 1080p resolution TV, most of the sources of television that you will be watching will not be transmitting a 1080p image - and so you won't get the best out of your screen unless you are watching Blu-ray.
There are three types of high-definition images:
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, high-definition TV transmissions are restricted to either 1080i or 720p.
How Important is the Resolution of my HDTV?
The simple answer is that the native resolution of a particular HD screen isn't that important.
Whilst there are some circumstances where you will be able to see a difference between a 1080p and a 720/768 screen, in the real world this won't be a huge issue for most people.
Therefore it is not crucial that you buy a TV with a 1080p resolution.
42 inch 720p Plasma TV
Firstly, 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.
If you have a 1080p screen, then it is only Blu-ray players and a few PS3/Xbox games 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.
However, HD TV 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 dependant 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.
42 inch 1080p LCD TV
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.
When it comes to showing a 1080p resolution image on a 720p screen, then the processing will have to discard some of the information to reduce the number of lines for the TV.
While this obviously has some effect, as you are losing some of the detail, in the real world many people will struggle to tell the difference between 720p HD and 1080p HD because we are starting with such a good quality source resolution in the first place - although this partly depends on how far away from the screen you are when watching the images.
Most people will be able to tell the difference between an upscaled SD image and a true HD image, but differences between the three HD resolutions are harder to spot.
The factors that make a difference when it comes to the native resolution of your screen are:
To get the full benefit from a 1080p native resolution screen you need to be watching a true 1080p source, and then you need to be sitting relatively close to the screen - or you need to have a very large screen - or both!
The fact is that most peoples eyes won't be able to tell the difference between a 720p and a 1080p image from more than about 6 or 7 feet. 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.
TV Resolution Summary
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 1920 x 1080 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 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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