Display and content quality are forever improving and you’ll see a lot about 4K and UHD video resolutions. What exactly are 4K and UHD video resolutions, though? And how do they impact your filming or viewing? Let’s take a look.
What is 4K video?
This is a little frustrating, but it’s a generic term. ‘4K’ can actually refer to a variety of things, and certainly any resolution with a pixel count of around 4,000 (horizontally).
4K video is a term used to describe video with a horizontal resolution of approximately 4,000 pixels. It's a significant upgrade from traditional 1080p HD, offering a much sharper and more detailed viewing experience. While there are different standards, the most common 4K video dimensions for consumers are 3840 x 2160 pixels. This means the video has 3840 pixels across the width and 2160 pixels from top to bottom, resulting in a stunningly clear picture.
What does 4K mean?
The ‘4’ in 4K is the horizontal pixel count, like you saw above, and the ‘k’ stands for ‘kilo,’ meaning one thousand. In other words, 4 thousand pixels. Easy!
Sometimes people refer to 2160p as 4K, and based on what you’ve learned so far I’m sure you’d say, ‘aha, the vertical pixels’ which is right… but, the p doesn’t stand for pixels. It stands for progressive scan, which means all the pixels appear at the same time, as opposed to interlaced which loads alternate rows of pixels to save bandwidth.
What is UHD?
UHD, or Ultra High Definition, is a display standard that’s often used interchangeably with 4K. UHD has the same pixel count as 4K, but 4K is actually a subset of UHD, which is why you sometimes see references to 4K UHD. When you go to the cinema, you see a film in Cinema 4K, which is actually a little over 4000 pixels horizontally. Cinema 4K is really only referring to professional digital content for theatres, and 4K is for more regularly consumed media displays, like TVs.
In a nutshell: even though they’re not quite the same thing, UHD and 4K are quite often used interchangeably, and that’s fine… mostly!
The evolution of 4K resolution size and UHD
To appreciate the significance of 4K and UHD resolutions and what they mean today, you need to know how they’ve evolved. They were once thought of as cutting-edge and pretty much only used in professional settings, but now they’re much more mainstream. That’s mostly thanks to advancements in technology, affordability, and an increasing demand for higher-quality content.
Early to Mid 00s: 4K resolution size and UHD resolutions can be traced back to the early 2000s when the film industry began to experiment with higher-resolution digital cameras. These innovations eventually made their way to consumer devices and displays. HDTV and Full HD were starting to become more mainstream.
2012: 4K was mostly used in theatres, and high-end professional video production initially but, UHD was adopted more broadly because we were all used to the term from HD!
2013: Video makers started to embrace 4K and UHD resolutions, recognising that technology is improving at such a rate that the content will need to stand up in terms of quality, as those changes happen. 4K and UHD displays became popular and households started to adopt them, mostly because equipment costs had come down.
2016-19: The rise of streaming platforms like Netflix, Amazon Prime, and Disney+, has played a significant role in consumption of 4K content. Although Netflix was an early streaming adopter – 2007!- it didn’t get going in the way we understand it now until 2016, closely followed by Prime and then many, many more streaming services. Each one of these has gradually structured itself based on tiers that increase in cost with an increase in quality, and now that high quality is expected, they're starting to charge more for ad-free viewing.
4K resolution size for video makers and video watchers!
Want to watch in 4K?
Upgrade your equipment
To really get the most out of 4K/UHD content, you need to make sure that your TV or monitor supports it. Did you know that your cable can also affect quality? You should use high-end HDMI or Display Port cables for the best results.
Internet speed
If you’re streaming in 4K, you’ll need a fast and stable internet connection. Check that your internet can handle the increased bandwidth, otherwise you’ll get issues like lagging and buffering.
Calibrate your display
Properly calibrating your display ensures that you're getting the best colour and contrast. Many TVs and monitors offer built-in calibration tools, or you can use calibration devices.
Content settings
Check to see if your device's settings are configured to display content in 4K. This includes settings related to resolution, picture quality, and any additional features like high dynamic range (HDR).
Want to create in 4K?
Why shoot in 4K?
Shooting in 4K future-proofs your content (at least short term) and gives you extra wiggle-room in post-production for things like cropping and zooming in, without losing quality*. You’ll also get extended colour depth so you can get more out of your correction and grading.
*Only if your output is less than 4K. If you’re outputting in 4K then you won’t benefit from this and would need to shoot at a higher resolution to get more flexibility in post.
Upgrade your equipment
You’ll need a camera capable of shooting 4K but perhaps an even bigger consideration is storage. Filming in such high resolutions will take up a lot of space, both in-camera and on your editing device.
Use high-quality lenses
The increased resolution of 4K will reveal all those little anomalies that were hidden or at least passable at lower resolutions. Use lenses with good optical quality and sharpness.
Editing software
Your video editing software will need to support 4K for you to be able to edit the footage. Most major editing suites support 4K now, even the subscription-tiered ones… though these may cost more.
4K resolution size and pixel count
We’ve talked about the pixel count of 4K video resolution, but we haven’t really touched on why that matters yet. Here are some of the main reasons that 4K is considered a better viewing experience than Standard Definition or even High Definition.
Clarity: With approximately 8.3 million pixels, 4K video resolution offers a level of clarity that brings out fine details, textures, and sharpness in images and videos. You can really see this on large TVs – the differences might be harder to spot on smaller screens.
Smooth viewing: The higher pixel count helps with smoother and more realistic motion. It minimises pixelation and reduces jagged artefacts – also known as stair-steps – that can be seen in lower resolutions.
Scaling: 4K content can be easily scaled down to lower resolutions without a significant loss of quality, making it versatile for various display sizes and devices.
Future-proof: As 4K content becomes more widespread, having a 4K display means your setup should still handle immediate future advances in the tech. Though we also know that sometimes they come so thick and fast that there is no real future-proofing!
- Improved gaming experience: The added clarity and realism that 4K res brings to gaming experiences can mean gameplay is more immersive and enjoyable.
Technical gubbins: 4K and UHD
If you’re someone who likes to get into the nitty gritty of tech features, then you might like some key technical stuff. If you aren’t, this bit is short, so skip right over it.
Aspect ratio: 4K/UHD resolutions typically stick to a 16:9 aspect ratio; the standard for modern displays. Cinemas are different, using very wide aspect ratios, something we’ll save for another day.
Bit depth and colour depth: Bit depth in imaging is the number of ‘bits’ that represent the colour or brightness of each pixel that a display can reproduce. It’s closely related to colour depth, but not the same, as bit depth is a more general term used in audio as well as imaging, but colour depth is the number of bits representing colours in digital images. In addition to the high pixel count, 4K and UHD support increased colour depth, which essentially means you get a broader range of colours and more vibrant images. You’ve probably more often heard this called High Dynamic Range (HDR).
Refresh rate: Refresh rate is the number of times per second that a display, like a TV or computer monitor, updates or ‘refreshes’ the images on the screen. It's usually measured in Hertz (Hz). A higher refresh rate like 60Hz, 120Hz, or 240Hz, means the screen updates the images more frequently. This generally means smoother and more fluid motion, great for both videos and games. A lot of mid to higher end displays are now using 120Hz upwards rather than the previous 60Hz, but the latter is perfectly fine for everyday stuff like browsing the web.
Compression: Streaming 4K content can be data-intensive and appropriate codecs are needed to do a good job of packing and unpacking that information.
Beware: Not all 4K is created equal
Cameras and promises
Cameras quite often advertise themselves as able to capture 4K but it isn’t always as cut and dried as that. A lot of cameras use heavy compression to keep file sizes down, which can lead to a loss of details, colour accuracy, and overall quality. Sensor size matters too – smaller image sensors like those in compact cameras, don’t capture as much dynamic range and colour information as more professional-grade ones.
Some cameras apply aggressive in-camera processing that can compromise the integrity of raw image data. They might have limited colour profiles, or not have the high data rates and bitrates needed for good quality 4K capture. All of these are things to consider when it comes to filming in 4K.
“Upscaling”
Upscaling, is the process of increasing the resolution of a lower-resolution video like HD or Full HD to match a higher resolution, such as 4K. The problem with this idea is that while upscaling can enhance the appearance of lower-resolution content on a 4K display, it can’t ever create new details or quality that wasn’t there in the first place. The effectiveness of upscaling depends on the quality of the upscaling technology and the specific characteristics of the content being upscaled. Garbage in, garbage out! Here are some ways upscaling happens:
Interpolation involves estimating the values of new pixels that need to be added to the image to increase its size. There are various interpolation methods, like bilinear and bi-cubic, that base newly generated pixels on the surrounding ones in the lower-resolution image. There’s also frame interpolation that increases the frame rate of low-res videos.
Scaling algorithms are used to intelligently resize the image while reducing artefacts and keeping sharpness and detail. Deep learning neural network stuff is starting to be applied in some places, to understand the content being upscaled and generate it more accurately without a loss in quality.
Edge enhancement is basically sharpening the edges of an upscaled image
Noise reduction and detail enhancement do what you’d imagine… reduce noise and enhance details! They try to preserve image quality.
Summary: What is 4K resolution?
Understanding what is 4K video and UHD resolutions are important for both film-makers and consumers. Here's a quick look at our main points:
4K is a resolution with four times the pixel count of Full HD: 3840 x 2160 pixels. The "K" in 4K stands for ‘kilo’ (so, thousand) representing approximately 4,000 horizontal pixels. UHD, or Ultra High Definition, is usually used interchangeably with 4K even though 4K is a subset of UHD.
For filmmakers, 4K captures sharp, detailed imagery at a resolution that supports extended colour depth (though it isn’t a given that that’s the case). 4K also offers the possibility for cropping and zooming in post-production without compromising quality if you’re outputting at a lower resolution.
For consumers of 4K UHD, it can deliver an immersive home theatre experience, making films or gaming more engaging. It looks great on larger screens and most major streaming platforms offer 4K video.
Be wary of the term ‘upscaling’—while it can enhance the viewing experience, it's not a true substitute for native 4K content and in some cases can lead to a loss of quality.
Conclusion
4K and UHD are changing the way we consume and create content. Film-makers benefit from the exceptional detail and post-production flexibility, while those of us who enjoy watching film and TV shows can enjoy a fantastic theatre-like experience fin our own homes, for relatively little cost.
About this page
This page was written by Marie Gardiner. Marie is a writer, author, and photographer. It was edited byGonzalo Angulo. Gonzalo is an editor, writer and illustrator.
