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Home Latest Articles TVs Kagoo Explains: Upscaling Part 1

Kagoo Explains: Upscaling Part 1

Updated 20 July 2020
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Welcome to ‘Kagoo Explains’ - a series of short articles de-mystifying some of the confusing terminology used to describe tech. This week we’re starting a two-part, in-depth look at upscaling, and how it can make your old movies really shine on a new TV!

Something is always left behind

Technology is constantly evolving and improving - new knowledge, improvements to existing systems and brand new innovations mean there is always a new horizon to chase, and some bleeding-edge tech to use as a handhold to pull up to the *next* breakthrough. It’s exciting, but for every tech that improves, two more are left in the dust.

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Television technology is no different - there have been massive improvements to display technology over the last few years, with 4K leading to 8K, OLED allowing limitless contrast and QLED creating beautifully deep colours. However the actual media you used to watch hasn’t changed. After all, a TV is only as good as what you watch on it - what good is a £5,000 TV if you only use it to watch reruns of the original 1964 Addams Family TV series?

The answer? Upscaling. At its most basic, upscaling is a technology that allows lower-quality digital media (such as old television shows, or movies that predate 4k) to be analysed and upgraded on the fly, producing a high quality, high resolution video that makes the most of your shiny TV. The end result is a noticeably improved picture quality - turning a small, smudgy recording into a crisp, high-detail video. It’s a bit magic!

Digital Resolution

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We’re going to talk a lot about HD, 4k and resolution - what exactly are they? Digital Resolution is a measurement of how many ‘pixels’ can be displayed on a single screen. A pixel is a single dot of colour - therefore the more pixels, the more detailed the image that can be displayed.

Resolutions are usually written as the width x height - that is, the amount of pixels going from left to right of the screen, then the amount from top to bottom. So a resolution of 1024 x 768 has effectively 1024 ‘rows’ of 768 pixels. 1024 x 768 = 786,432 pixels in the entire screen.

The key thing is that these are normally shortened to the most popular - SD (standard definition), HD (high definition), 4k, etc. Each one is a massive step up from the previous resolution - so 4K is 4 times as large as HD.

The Problem of Old vs New

When you try and watch an older movie on a newer TV, it is a smaller resolution than your TV - the digital ‘size’ of the video is smaller than what your TV is capable of showing. There are two options - the first is to display the video unchanged. This is undesirable, since the physical ‘size’ of the video will be smaller too - it would appear as a tiny image in the middle of a sea of black space.

So instead the TV tried to expand the image to fit the available area. However expanding a tiny video to fit a massive screen is also problematical - when the image expands it loses visual quality, as the system doesn’t know what to do with all the extra pixels it has to fill. You end up with an image that looks like an old video game - a cool aesthetic, but not the best for watching TV!

An example: If you have an old video in standard definition, that has 307,200 pixels (640 x 480). If you want to watch it on a 4k TV, it supports 8,294,400 pixels (3840 x 2160). So there are 7,987,200 pixels left to fill… that’s a lot of holes!

Filling in the Blanks

So when the TV expands the video, it tries to understand what *should* go in the missing areas of the video. This is what upscaling really is - the act of trying to analyse an image and filling in the missing information to provide the best image possible. It’s like if you completed a 100 piece jigsaw, then someone told you to use those to create a 5,000 piece puzzle. You’d have to get creative to design the remaining 4,900 pieces in a way that still showed the right picture!

There are several answers to this problem - and all of them involve maths:

  • The simplest of these is ‘Nearest Neighbor Interpolation’, which simply looks at the surrounding pixels, and takes a best guess at what should fill the blank by extrapolation. So a blank pixel surrounded by red would be coloured red. This is overly simplistic, and leads to awkward, low quality images.
  • Secondly ‘Bicubic Interpolation’ generates a guess that is ‘softer’ and has a smoother join with surrounding pixels, but lacking in detail.
  • Finally, ‘Bilinear Interpolation’ generates an image that is ‘sharper’ but more jagged, with more obvious ‘seams’ between the pixels.

Individual no method are perfect, but much like Captain Planet, they work best when used together. Therefore modern TVs use an adaptive mixture of all these methods, smoothing or sharpening the pixels as needed to create a high-quality image that looks natural on your screen.

A good start... but we can do better

The end result is that your small video is expanded to fill the large screen, and the missing pieces are filled in, leaving it looking clean and natural. Everything we’ve talked about is automatic and near-instantaneous - it happens on the fly as the video appears on your screen. If it works well, you barely notice it’s there. It’s not 100% foolproof - in the end upscaling is about educated guesswork - but the results are impressive, and it allows your old movies and television to live on and be enjoyed for years to come. If all this tech talk has got you interested in upgrading your TV, then head over to Kagoo for a comprehensive list of the Best TVs on the market!

In Part 2 we’ll be looking at the future of upscaling, and how machine learning and artificial intelligence are pushing the tech to new heights!

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