Incorrectly, a common assumption people make when looking at HD television screen information is to think that resolution guarantees a better picture quality. A higher resolution (on its own) does not mean this. There are several factors that will affect the picture quality and resolution is just one of them. The aspects together make up the image and how well it is displayed. This articles goes into more depth below. In the UK, the picture signal is known as PAL and is used for SD (standard definition) pictures - these are usually associted with DVD and broadcast TV. This has a resolution of 720x576 (720 pixels across, and 576). A pixel makes up a single "dot" shown on the screen and together these dots make up the entire picture. You can't buy a plasma or LCD screen with this resolution however. The screens resolution is usually a lot higher than this and is referred to as the native resolution.
This means that every screen must process the picture and scale it to meet the native one. The accuracy of the scaling here is very very important to the image quality. A very important question regarding HD televisions was wether the image was linear to the native resolution. That is - would the horizontal and vertical proportions be the same. If it wasnt linear the screen would create artefacts that would result in a worse image.
To highlight this, see the example below. If you have 3x42 inch screens with the following resolutions but lets assume identical otherwise:
screen1: 1280x720
screen2: 1024x768
screen3: 852x480
If we try and feed this televisions an HD signal which is outputted at a resolution of 1280x720 (720p) we can see the following.
Screen 1 is able to display the picture at 1:1 - that is each pixel of the HD signal can represented equally as each pixel on the screen.
Screen 2 would have to scale the image 80% horizontally (1024/1280) and 106% vertically (768/720). This means that each axis is going to have
different proportions and this will cause artefacts on the screen.
Screen 3 would have to scale the image 66% on both the horizontal and vertical axis (852/1280 and 480/720). Although not quite as good as
screen 1, as this is linear the Television can scale this with quite simple maths.
To summarise, Screen 1 would produce the best picture as no scaling is involved.
Screen 3, although it has the lowest resolution will display the picture well as it is linear.
Screen 2 would display the WORST picture, desite having a higher resolution to screen 3.
Bear in mind that these are moving images and not still pictures - the more artefacts on the screen, the more it notices.
Higher resolution screens will be more expensive due to the faster and more advanced processing needed to map an image to match the native resolution of the screen. This will be true for any pixel based display - think computer monitors. The pioneer and panasonic entry level screens are very good examples of SD screens that outperform most of the HD televisions around.
The consumer desire for bigger pictures means we need higher quality broadcasts, and is part of the reason for the birth of HD televisions. However, it isnt just the resolution that will depend on the picture quality. A high resolution set with poor image processing will be worse than a set with lower res/better processing. If you are looking at a sales brochure, your friend claims resolution is the deciding factor, or a salesman tries to talk over you, dont be fooled by the lingo and refer back to this article.
