Watching 4K content on a 4K TV is a visual extravaganza you must experience first-hand to appreciate it. Besides portraying 4K content in its actual resolution, 4K TVs can also show lower-res content better than expected.
In other words, Full HD content will look sharper on a 4K television than it would on a 1080p TV, thanks to a technological phenomenon that takes place in the background, called “4K upscaling”.
What is 4K upscaling? Does it make non-4K content look like actual 4K? Or is it an overrated feature or a gimmick that TV manufacturers predicate the sales of their 4K TVs on?
Keep reading to learn the basics of 4K upscaling, how it stacks up against native 4K and more.
- What is 4K Upscaling?
- What is the Difference Between Upscaled 4K and Native 4K?
- What are Upscaled 4K’s Limitations?
- Is Upscaling to 4K Worth It?
What is 4K Upscaling?
4K upscaling is the process of making Full HD or 720p content appear sharper or more pixel-dense on a 4K TV than on a native 1080p television.
The upscaling process helps a 4K TV fill up its digital canvas when showing low-resolution content. When 1080p content is not upscaled to 4K on a 4K television, it will occupy only one-fourth of the screen (since 4K is four times the size of Full HD).
A 4K television uses a set or combination of interpolation algorithms to achieve this feat. The algorithms append pixels to a given HD image to boost its resolution. A Full HD image is made to acquire six million pixels through upscaling, turning into a 4K picture in the process.
Upscaling is not unique to 4K televisions. Even Full HD TVs can upscale HD (720p) content to Full HD so the content can occupy the screen entirely.
Are Only TVs Capable of 4K Upscaling?
Contrary to general perception, 4K upscaling can be performed by a range of devices besides your TV, such as a 4K Blu-ray player. However, the other devices’ efforts are redundant since your 4K TV is already shouldering that responsibility.
If your 4K TV is poor at upscaling compared to your Blu-ray player, the upscaling at the Blu-ray player level would seem like a genuinely significant enhancement.
Talking about other kinds of devices that come with native upscaling, the Xbox One X and S, too, are equipped with upscaling capabilities. The PlayStation 4 Pro doesn’t employ inbuilt upscaling, however. What it does instead is resort to “checkerboard rendering”.
To learn more about checkerboard rendering, how it works and compares to native 4K, etc., watch this video:
Similarly, home theater receivers, source switchers, etc., could also have integrated 4K upscaling capabilities. The picture quality adjustment settings can be likened to those on a 4K TV or projector.
Kindly note, your TV must be 4K to support the third-party upscaling capabilities mentioned above. If the TV’s native resolution is 1080p, you would be confined to that, or no external input would make an impact.
Is 4K Upscaling An Automatic Process?
You cannot configure the upscaling manually on a 4K TV, Blu-ray player, or gaming console. The particular device usually springs into action by itself, adding additional lines or pixels representing a 4K image’s resolution.
If the upscaling weren’t computerized, 1080p content would look small on your large 4K TV, with the remaining portion of the display filled with black bars or images. And that would look odd.
What is the Difference Between Upscaled 4K and Native 4K?
As mentioned above, 4K upscaling improves original input resolution, usually or preferably Full HD. After the upscaling, the video resolution becomes 3840 x 2160 from 1920 x 1080.
Native 4K, on the other hand, means the resolution is 4K or 3840 x 2160, to begin with.
Which is Better of the Two?
Upscaled and native 4K seem the same on paper since both are 3840 x 2160 pixels. Native 4K, however, is better of the two—like how optical zoom on a camera is always better than digital zoom.
4K upscaling is done through image interpolation or using fake pixels. There are three kinds of interpolation to upscale 1080p to 4K content: nearest neighbor, bicubic, and bilinear.
Also called the point sampling process, nearest-neighbor interpolation is the simplest of the three methods and, therefore, the most common 4K upscaling technique too.
When nearest-neighbor interpolation is used, a grid of white pixels is attached to an image, and a mathematical guess is made as to what color the blank pixels should be filled with based on four neighboring pixels.
For example, if the blank pixel is surrounded by blue pixels, it will turn blue. If the surrounding pixels are black and blue, the empty pixel could assume the dark blue hue.
No doubt, the process is relatively straightforward. But the output could be replete with several digital artifacts, jagged outlines, and blur—particularly with fast-paced videos.
And the distortion and blurring, if any, would become quite noticeable when viewed from up-close. In short, the result would be far from how native 4K looks.
How Does Upscaled 4K Compare to Native 1080p?
Despite all its issues, upscaled 4K generally looks better than Full HD content playing on a traditional 1080p screen. That’s because nearest-neighbor interpolation isn’t the only upscaling method your 4K TV resorts to.
The upscaling is usually the product of the various (aforementioned) techniques put together. In other words, bicubic interpolation smoothens the images, while bilinear assists with the sharpening effects.
With the bicubic technique, every pixel attached to a picture looks at 16 nearby pixels to assume a color, resulting in an unmistakably soft image. Bilinear interpolation takes only two adjacent pixels into account and churns out a sharp picture based on the information.
With the combination of these methods and some color and contrast effects thrown in for good measure, your 4K television produces visuals that do not look very different from a native 4K image, and they are certainly better than native 1080p content.
What are Upscaled 4K’s Limitations?
4K upscaling does an excellent job of making 1080p content look like 4K. But, as stated earlier, it’s still not comparable to native 4K images.
Interpolation is not a standard procedure with uniform steps, or its implementation may not be the same across different 4K TVs. Since there’s quite a bit of guesswork involved, there’s always some room for errors.
Moreover, a proper implementation doesn’t always guarantee impeccable visuals.
If the input signal comprises poor color, excessive video noise, harsh edges, etc., the upscaling process could make the visuals look worse instead. “Ghosting”, for instance, could be an issue—particularly with inexpensive 4K TVs.
Such artifacts are more prominent when 720p content is upscaled to 4K, or your 4K TV is relatively large.
Is Upscaling to 4K Worth It?
Upscaling to 4K is usually worth it. Though the amount of legwork your 4K TV does to execute the process may sound far-fetched, the result is impressive. And with premium 4K TVs, the upscaling is hardly noticeable.
If you usually sit a fair distance away from your TV, the 4K upscaling would be almost indiscernible. Not to mention, the upscaling would impress you a great deal if you don’t set your expectations too high.
Will upscaled 4K look like native 4K from a distance? Maybe not. But then the difference would be marginal, as mentioned above.
If, however, you’re someone who consumes most of their content in native 4K, you’ll be able to ascertain upscaling is at play. Also, the issues with upscaling older or 720p content would be more obvious.
Also, as alluded to above, the TV size determines how worthwhile the upscaling is. The results would be a lot more jarring if you’re trying to 4K-upscale HD content on a 65-inch or 85-inch television.
Long story short, 4K upscaling is quite compelling if the TV is equipped with a capable scaler, is not too big, and the original content is 1080p. Also, the further you sit away from the TV, the more impressive the 4K upscaling results would usually seem.
Do monitors have 4K upscaling?
Most monitors usually do not support 4K upscaling since they don’t have the dedicated scalers essential for the process. Standalone monitors generally display the content in its original resolution and/or stretch it to fit the screen if required. Not to mention, the result is usually a pretty jagged video or image.
Upscaling is essentially a stopgap solution in the absence of actual 4K content.
The current image standard is 4K, but most content is still produced in 1080p. 4K TVs, therefore, do everything within their might to make existing content look as close to 4K as possible so that there are no unoccupied spaces on display.
Some 4K TVs do a splendid job in that pursuit, and quite a few leave a bit to desire. But at the end of it all, or irrespective of how different 4K TVs go about the processing, visuals upscaled to 4K generally look better than HD or 1080p content.
And with 4K TVs and their upscaling technologies improving with time, upscaled 4K is bound to get better in the future. Maybe someday, it could come eerily close to native 4K quality.
Catherine Tramell has been covering technology as a freelance writer for over a decade. She has been writing for Pointer Clicker for over a year, further expanding her expertise as a tech columnist. Catherine likes spending time with her family and friends and her pastimes are reading books and news articles.