When it comes to buying a new TV it's difficult to separate the specs that matter from those that don't. However, one spec you should take notice of is the processing rate - particularly if you're a sports fan.
What is processing rate?
When watching TV the picture you see is actually a series of images shown at high speed to create a continuous moving image. Just like a flipbook or film reel.
The processing rate – aka the refresh rate – tells you how fast the images are flashing up on the screen.
In the technical specifications, you'll usually see it measured in hertz (Hz) – the higher the number, the more times per second the image refreshes on your screen. This makes the picture smoother and less blurry.
TV screen refresh rates are generally fixed at one of the following:
• 50Hz – gives a smooth picture and is good for general viewing
• 100Hz – the image handles fast action better
• 200Hz – ideal for fast-moving sports and gaming
How does a high processing rate make a difference?
When you're watching a TV show, film or sports event, the actual footage doesn't refresh itself at a higher rate than 60Hz – that's its limit.
But new 4K Ultra HD (UHD) TVs have processing rates well above 60Hz – some have even broken 1,000Hz.
Through a bit of technical trickery, these TVs create a smoother picture and cut down on motion blur.
Backlight flashing is one technique. This is where the TV’s backlight goes dark between video frames – it might sound strange, but your eye can't spot the change at this speed, so all you see is a smoother image.
Some TVs also use black-frame insertion, where, as the name suggests, black frames are inserted between each image. Again, the naked eye cannot spot this, and the image produced appears smoother.
Tip: You can tell if your TV has frame insertion by checking in the settings menu.
Should I have high or normal processing rates?
It depends on what you're watching. High processing rates are great for fast-moving sports, where players are constantly on the go.
Frame insertion on TVs with higher processing rates can make images on the screen seem smoother. It reduces motion blur making it easier to follow an end-to-end counter attack at Wembley, passing down the line at Twickenham or a long rally at Wimbledon.
When to turn off your frame insertion
Although this frame insertion technique can improve watching sports, it can hamper other types of programme – such as a movie or TV soap opera. Frame insertion can look jarring on images that are not fast moving.
So if you're watching something where people move as they do out on the street in the real world, then maybe disable the feature in your TV's settings so it runs at the regular 60Hz rate.
PQI, PMI and Hz
Some TVs have additional image processing technology built in, which helps to give you a smooth, stable image. Because of this, the manufacturers may use a different measurement system – designed to give you an idea of the full picture quality.
Each TV is given a number that takes into account factors like the how high the resolution is, colour, brightness, contrast, motion, noise reduction, screen panel and backlight refresh rate and immersivity – the higher the number, the better the picture quality.
These measurements differ by manufacturer, the main ones are:
• PQI (Samsung) – ranges from 100-2400
• PMI (LG) – ranges from 1000-2300
• Hz (LG and Sony) – ranges from 100-1300
Because the manufacturers use different criteria and calculations to work out these numbers, they’re not directly comparable. Instead they allow you to easily compare picture quality across the whole of the manufacturer’s range.
For example, a 100 score on the Samsung PQI scale doesn’t mean the picture will be bad – instead it means the TV sits at the lower end of the Samsung range, and may lack some of the picture enhancing features a TV that scores 2400 has.
