Understanding Video Resolutions

Understanding Video Resolutions

SD. HD. Full HD. Quad HD. UHD. 4K. DCI4K. Something-point-something-K. Video resolutions are confusing enough for consumers but as a content creator they are even more confounding. Here at BorrowLenses, we carry cameras that shoot everything from 720p HD all the way out to 6K. That variety can be somewhat confusing when you’re trying to sort out just which camera you need to rent and what resolution to actually shoot at once you’ve rented it. And that’s before you begin diving into the world of aspect ratios, too.

This article will try and demystify that morass a bit. Here goes.

What’s a Resolution? For That Matter, What’s an Aspect Ratio?

Let’s start with understanding exactly what we mean by “resolution.” Every digital video file has certain set dimensions, measured in the number of pixels. When you see something like “1920 X 1080” or 1080p, that is referring to the dimensions of that picture. In this example, it’s 1920 pixels wide, by 1080 pixels high.

In the image below (and all the other examples included), I’ve taken a “true” 4K frame from a video shot on a Panasonic GH4 and outlined the various resolutions in red boxes for reference and comparison.

Full HD 1080p cutout of a DCI 4K Image

Full HD 1080p cutout of a DCI 4K Image

Then there’s aspect ratio to consider. Most TV programming, as well as a lot of what you see online, is in the aspect ratio of 16:9.

If you divide 1920 by 1080, your are left with 16/9 as your end result – that is the ratio of horizontal pixels to vertical pixels. This particular aspect ratio is also known as “Widescreen” and is currently the most used on TV and the web.

Feature films, however, are a whole other ballgame, as we’ll soon see.

For the purposes of a running reference, we’ll use the table below and update it as we progress through the various resolutions.

SD (480p) frame outline in a DCI 4K Image

SD (480p) frame outline in a DCI 4K Image

 

Resolution Pixel Size Aspect Ratio Other Names
SD (Standard Definition) 640 x 480 4:3 480p

HD Resolutions

Let’s start with understanding what exactly “HD” means. Fortunately, this one’s kinda easy.

“HD” really only applies to two specific resolutions: 1920 X 1080 and 1280 X 720 pixels. In both cases, the aspect ratio is 16:9.

Full HD, HD, and SD resolutions in outlined in a frame from 4K video.

Full HD, HD, and SD resolutions in outlined in a frame from 4K video.

This was the big upgrade from SD, or Standard Definition, which was typically 640 X 480 pixels in size and in the 4:3 aspect ratio.

So now our updated table looks like this:

Resolution Pixel Size Aspect Ratio Other Names
SD (Standard Definition) 640 x 480 4:3 480p
HD (High Definition 1280 x 720 16:9 720p
Full HD 1920 x 1080 16:9 1080p

Beyond HD

Once we start talking about resolutions larger than HD, things get… muddled.

More than HD, Less than 4K

2K, HD, and SD framelines

2K, HD, and SD framelines

Here’s something interesting: while the buzzword these days for video capture is “4K” (more on that later), it’s a little-known fact that most of the cameras used to film the big Hollywood blockbusters (like the Arri Alexa) do not film in 4K. Rather, they film in 2K, or a resolutions that are usually 2048 pixels wide. One of the cameras that we carry, the Arri Amira, shoots in this resolution exactly.

Resolution Pixel Size Aspect Ratio Other Names
SD (Standard Definition) 640 x 480 4:3 480p
HD (High Definition 1280 x 720 16:9 720p
Full HD 1920 x 1080 16:9 1080p
2K 2048 x 1152 1:1.77 N/A

One caveat, as you’ll see in the camera tables below, is that some cameras shoot slightly more than 2K, but still less than 4K.

Cameras that Record Less Than 4K, more than 1080p
Camera Recording Resolution
Arri Amira 2K (2048 x 1152)
Blackmagic Cinema Camera 2.5K (2432 x 1366)

The Buzzword These Days: 4K

UHD, Full HD, HD, and SD resolutions in outlined in a frame from 4K video.

UHD, Full HD, HD, and SD resolutions in outlined in a frame from 4K video.

“4K” is the thing a lot of TV and camera manufacturers are throwing around as “The Next Big Thing.” Cameras as small and inexpensive as the Panasonic G7, to much larger systems like the Sony FS7, all include 4K shooting in their list of specifications.

What isn’t particularly clear is just what “4K” means. The answer: it depends.

Strictly speaking, 4K refers to a video frame that’s at least 4000 pixels wide. Right off the bat, that’s kind of confusing to some folks, as we are used to seeing resolution expressed in terms of the vertical pixel account (1080p, 720p, etc.). Once you get into the world of Ultra-HD and 4K, however, we start talking about resolution in terms of its horizontal size.

For example, if you’ve browsed the BorrowLenses website, you’ve seen that in the category of cameras that can shoot beyond 1080p, we carry bodies that have resolutions ranging from 2K all the way to 6K. This is because a number of these cameras were designed to be capable of shooting for feature films, meant to be projected onto a theater display.

4K, UHD, Full HD, HD, and SD resolutions in outlined in a frame from 4K video.

4K, UHD, Full HD, HD, and SD resolutions in outlined in a frame from 4K video.

Before the advent of 4K, the standard for digital film cameras was – and still is for a lot of them – 2K, or 2048 pixels wide. In fact, this is what the Arri Amira camera that we carry shoots at. With 4K now here, that horizontal size has now been standardized to a resolution of 4096 pixels wide. The 4K DCI standard specifically calls for a resolution of 4096 x 2160 pixels, which amounts to an aspect ratio of 1:1.85.

Let’s talk about that aspect ratio for a moment. When we start talking about video shot specifically for theater projection or to mimic the look of something shot for that purpose, we start expressing aspect ratios in a slightly different manner.

Here, we express aspect ratio in terms like 1:1.9, which is DCI 4K. What that means is that for every one pixel of height that a video frame has, it will have 1.9 pixels in width. For DCI 4K, this is technically 1.896296296 pixels wide for every 1 pixel in height, but hey, math. We round up.

You will also often see aspect ratios like 1:2.40 or 1:2.39, which are anamorphic aspect ratios, but will have the same number of horizontal pixels (either 4096 for DCI 4K or 3840 for UHD) and will calculate the vertical height based on that.

Coming back to the discussion about resolutions, then we have the so-called “4K” standard for TVs, which actually stops just short of being an actual 4000+ pixels wide. At 3840 X 2160 pixels (as in the image above), this ends up with an aspect ratio of 16:9, which is the same aspect ratio for HD TVs. Of course, “4K” sounds a lot sexier and, well, number-y than UHD, which is why manufacturers go ahead and stick that logo on their boxes.

YouTube was the first streaming service to support streaming in UHD and they refer to it as 2160p, which is actually more accurate than 4K, and is in keeping with the familiar naming scheme implemented for HD video.

YouTube allows for files up to 2160p in resolution.

YouTube allows for files up to 2160p in resolution.

So now our final table of resolutions looks like this:

Resolution Pixel Size Aspect Ratio Other Names
SD (Standard Definition) 640 x 480 4:3 480p
HD (High Definition 1280 x 720 16:9 720p
Full HD 1920 x 1080 16:9 1080p
2K 2048 x 1152 1:1.77 N/A
UHD 3840 x 2160 16:9 Sometimes called “2160p” and often mistakenly referred to as “4k”
DCI 4K 4096 x 2160 1:1.9 Just 4K (the “DCI” part is sometimes dropped)
Cameras that Record 4K
Camera Recording Resolution
AJA Cion UHD (3840 x 2160) and DCI 4K (4096 x 2160)
Blackmagic Micro 4K Studio Camera UHD (3840 x 2160)
Blackmagic Ursa Mini 4K (4000 x 2160)
Blackmagic 4K Production Camera UHD (3840 x 2160)
Blackmagic Blackmagic URSA 4K Digital Cinema Camera UHD (3840 x 2160)
Canon C500 4K DCI (4096 x 2160) and UHD (3840 x 2160)
Canon 1DC 4K DCI (4096 x 2160)
Canon XC–10 Professional Camcorder UHD (3840 x 2160)
Sony FDR-AX1 Digital 4K Video Camera UHD (3840 x 2160)
Panasonic GH4 4K DCI (4096 x 2160) and UHD (3840 x 2160)
Sony PXW-X70 4K Ready XDCAM Camcorder UHD (3840 x 2160)
Sony NEX-FS700 4K Ready Camera UHD (3840 x 2160)
Sony PXW-FS7 XDCAM Super 35 Camera System DCI 4K (4096 x 2160) and UHD (3840 x 2160)
Sony Apha a7S (with an external 4K-capable recorder) UHD (3840 x 2160)
Sony Alpha a7R II UHD (3840 x 2160)

Conclusion

Okay, feel better about knowing a bit more about video resolutions? Good. Because pretty soon, 6K and 8K are coming down the pipeline and promise to muddy these waters even more.

Thing is, right now the majority of the world delivers in 1080p. Yet some folks like YouTube and Netflix are also delivering 4K to consumers, and I just bought a Dell 4K 27″ monitor for less than $600, so the sense I and a number of folks get is that the transition to 4K is going to come a lot sooner than the transition from SD to HD. Even folks who deliver in 1080p often shoot in 4K, either to future-proof their footage or to be able to pan and zoom around it.

From a resolution standpoint, unless your workflow calls for superfast turnaround (like Electronic News Gathering [ENG]), you can’t go wrong shooting in 4K, even if you intend to master in 1080. My 3-year-old Macbook Pro can just about keep up with the footage from the GH4 and the a7S/Shogun combo, so computing power shouldn’t be too much of an issue.

Bottom line: If you can shoot in 4K, do it. Hopefully, this article and the tables/figures it contains will help make sense of the resolution soup.

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Sohail Mamdani is a writer, filmmaker, and photographer based in the San Francisco Bay Area. Follow him on Twitter or find him at anymedium.com.

10 Comments

  1. Let’s throw another element of confusion into the mix: PIXEL Aspect Ratio. While nowadays everything pretty much assumes a square pixel, anyone still working in (or just curiously exploring the legacy of) SD formats will see that 720×480 is the DVD spec for SD resolution and somehow is still 4:3 even though the math doesn’t work out. That’s because the pixels themselves are 0.9 proportioned rectangles rather than squares. So you first have to adjust for the pixel aspect ratio before calculating the image aspect ratio.

    Just to mess with your heads more. And give you an appreciation for modern square pixels.

    Reply
      • Where does GoPro 4 fit in all this?

        Reply
  2. Hey Sohail.
    Nice article! It would be good to include Panasonic GH4 under the list of “Cameras that Record 4K” – I noticed you did mention it a couple of times in the article (and use a frame from it for your comparison) – I am investing in one soon purely for the 4K video mode.

    Reply
    • Whoa. I don’t know how I overlooked the GH4!!! Fixing article now…

      Reply
  3. I’ve tried 4K on several occasions. The trouble is that the files are huge, slow to edit, and take forever to upload to YouTube. Add that most people look at the results on much less than 4K screens. As an amateur videographer I find 1080p to be more practical.

    Reply
  4. Nice article, however it didn’t answer the one question I’ve been hopelessly trying to answer for some time now: Why did DCI choose 4096 x 2160 as their 4K resolution? It isn’t 16:9, 1:85,or 2:39, so it’s always subject to some sort of cropping (as DCP standards require). Unless this resolution has something to do with anamorphic? By the way – there’s an error in your text. You state that the DCI 4K standard is 4096 x 2160 (true) which “amounts to an aspect ratio of 1:85” (not true). The 1:85 cinema 4K standard is 3996 x 2160. Can anyone tell me what value the full 1:9 aspect has? Thanks.

    Reply
  5. Great article. You should fix your screenshots though. They all show a 1920×1020 label, instead of 1920×1080, as they should.

    Reply
  6. Great article. Learned a great jdeal

    Reply

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