ASPECT RATIO:
DISPLAY + IMAGE

What is aspect ratio?

It certainly isn’t an intuitive term, but let’s see if we can break it down, and extract some meaning.

An ‘aspect’ is a part, or feature, of a larger… something..

A ‘ratio’ is a quantitative relationship between two comparable values - a proportion - that is usually reduced to the lowest common denominator.

That probably doesn’t help a lot, or at least not when we try to piece the two together.

Basically, aspect ratio is the proportion of width to height of an image or display. So the ‘aspect’ of the image that we’re concerned with is just the length of a given side. The ‘ratio’ then puts those lengths into a proportion.

HOW do We figure it out?

The aspect ratio is the size or resolution reduced to its smallest whole integers, OR reduced to reflect the ratio’s relation to 1 unit. Typically speaking, people usually reduce the ratio if the short side were 1, but you can do whichever makes sense for what you’re trying to figure out.

I frequently think of aspect ratio as it relates to units, or squares; like big pixels. This also helps me to think of the compositional properties of any given aspect ratio.

Reducing to whole integers

For example, a ‘full frame’ camera sensor is 36mm wide and 24mm tall. To figure out the aspect ratio of the sensor, we just need to reduce the lengths of the sides.

36x24 reduces to 3:2 because both sides are divisible by 12. We can’t reduce the ratio any further while maintaining whole integers on both sides. In case you’ve forgotten, integers are whole numbers; no fractions, no decimal places necessary.

So, each unit is basically a 12x12mm square. The sensor is 3 units wide by 2 units tall.

reducing to 1

To figure out the ratio to 1, we just need to decide which side we want to reduce to 1, then divide both sides by that amount. As mentioned above, people usually reduce the ratio to make the short side 1 in the ratio. Since we’re dealing with 3:2, the short side is 2 units. Dividing 3 by 2 gives us 1.5. Dividing 2 by 2 gives us, well, 1. So a 3:2 ratio reduced to 1 is 1.5:1.

If we were to reduce the long side to 1, we would get 1:0.666(repeating).

Reducing resolution

You can figure out the aspect ratio of any given resolution by doing the same thing. Just reduce each side as much as possible while maintaining whole integers. For example, Ultra High-Definition resolution, is 3840x2160 in pixel resolution. If we divide each side by 240, we’ll get the aspect ratio 16:9.

Unless you’re really gifted at mental math, you probably didn’t see 3840x2160, and think, “ah, that’s divisible by 240.” So let’s work through reducing it in a way that’s more in line with how you might do it in the future:

• 3840x2160 divided by 2 gives us 1920x1080

• 1920x1080 divided by 2 gives us 960x540

• 960x540 divided by 2 gives us 480x270

• 480x270 divided by 3 gives us 160x90

• 160x90 divided by 10 gives us 16x9!

If the unit size matters to you, you could figure that out by multiplying all of our common values (what we divided by).

• 2x2=4

• 4x2=8

• 8x3=24

• 24x10=240

Then if we take 16:9, and divide each of those sides by 9, we’ll get 1.777:1. This helps us more easily understand just how wide the aspect ratio is, with 1 as our reference, since we know that’s a square.

If you only ever want to know a resolution’s ratio to 1, the work becomes much easier. Just divide one side by the other. More specifically, dividing the long side by the short side will tell you how wide or tall the ratio is. For example, 3840/2160 is 1.777(repeating).

Width:height (X:Y)

And like resolution, aspect ratio should be written width-by-height, so x:y.

If you haven’t totally purged your mind of every last remnant of math, you might recall that the x-axis runs horizontally (left and right), and the y-axis runs vertically (up and down).

Sometimes you’ll notice that people will just write the aspect ratio with the longer side first, but that only tells us how wide/tall the aspect ratio is. If we write aspect ratio as x:y, then the orientation (landscape or portrait) can easily be figured out, too.

Helpful adjectives: Display + Image

Most of what we’re covering in this article is also known as ‘display aspect ratio’ or ‘image aspect ratio’, depending on the context of the use.

Display aspect ratio is the term used when defining the aspect ratio of displays, such as computer monitors, TVs, phones, projectors, etc.

Image aspect ratio is the appropriate term when we’re talking about the ratio of a source image, whether digital or physical. We view images with many different image aspect ratios on our displays.

These added terms help us to understand the subject, and I think people would be less confused by aspect ratio, in general, if these terms were more commonly lumped together.

Image aspect ratio is also sometimes referred to as ‘picture aspect ratio’, but that’s too easily confused with ‘pixel aspect ratio’, so let’s all avoid using that one.

DISPLAY ASPECT RATIOS

Luckily for us, there really aren’t that many current display aspect ratios, or at least they don’t stray too far from each other anyways.

Let’s start, however, by taking a step back into the 20th century.

4:3

The first standard display aspect ratio - of silent films, nonetheless - was 4:3 (1.333:1). That is, 4 units wide by 3 units tall.

This didn’t stay the standard in cinema for long, however. The inclusion of a sound track on the film meant giving up a bit of real estate, so to speak, which resulted in the Academy Ratio (1.37:1), which was still pretty close to 4:3, visually.

Decades later, 4:3 also became the standard for the home television set. Televisions would keep this aspect ratio for about half a century.

Meanwhile, these other things were invented, called computers. By the mid-90’s, computers were fairly commonplace in the home. Computer monitors also adopted the 4:3 standard, and thus the rise of the internet happened on 4:3 cathode-ray tubes. What a time to be alive. Sorry, youngsters.

16:9

Advances in ‘flat panel’ display technologies - which were cheaper to produce, lighter, simpler, and superior in most ways to CRT displays - culminated with the adoption of a new standard aspect ratio as well.

We were entering the ‘High-Definition’ world.

It was decided to create a new aspect ratio that was somewhat of a ‘happy medium’ between the old 4:3 standard and the wider aspect ratios that had become commonplace in cinema, decades prior. Some people ultimately landed on the 16:9 aspect ratio, which still reigns supreme as the most widespread display aspect ratio today.

If we’re imagining square units again, this would be 16 units wide by 9 units tall.

As mentioned, 16:9 came to prominence with the rise of ‘High-Definition’ televisions, starting with the then-cutting-edge screen resolution of 1280x720. The aspect ratio has stuck ever since; through 1920x1080, now 3840x2160, and soon 7680x4320.

Our phones are mostly in variations of 9:16, which is of course the same aspect ratio, only portrait-oriented. Some models might have a slightly taller or shorter aspect ratio, but no mainstream device deviates too far from 9:16 (yet).

CLAMSHELLS: A WAY MORE FUN NAME FOR DUAL-SCREEN PHONES

The 9:16 phone norm might be upset soon, however, with the rise of the clamshell dual-screen design.

Samsung’s Z Fold 2 has a total aspect ratio of 5:4 with both screens. Microsoft’s Surface Duo is 3:2 with both.

Who knows how long it will be before a ‘standard’ aspect ratio is settled on for clamshells.

What aspect ratio do you think makes sense for these types of devices?

WHEN IMAGE ASPECT RATIO AND DISPLAY ASPECT RATIO DON'T GET ALONG…

In today's digital landscape, we're quite used to images not filling our entire displays. Open Instagram, and you'll likely see several square images in your timeline, even though you're not viewing the app on a square display. Likewise, we’ll click open images and graphics on social media, which just blacks out the rest of your screen until you hit the back button.

We don't think much about it, but once upon a time, it was a high priority to maximize a display by adapting the image aspect ratio to fit.

Pan-and-scan

When 4:3 TVs were still the norm, there was an ongoing debate about how to display the wider images of film. The relatively common 2.39:1 aspect ratio of film was and is significantly wider than the ubiquitous 4:3 displays in everyone's homes at the time.

In an effort to utilize the full 4:3 display aspect ratio, a process was developed which ultimately became known as 'pan-and-scan'. This process included enlarging the wide, cinematic image to fill the full 4:3 frame. But what about all the image that gets cropped off the sides?

Well, this became a job in-and-of-itself. Basically, it was decided which part of the frame was most fundamentally important to the viewer at any given moment, and the enlarged image would be panned over enough to contain that subject or action within the 4:3 screen. If this seems like it would be a meticulous process, that's because it was!

Full screen vs wide screen

This was such a common practice that DVDs (digital video discs; the predecessors to modern Blu-rays) were sold in two different variants: full screen and wide screen.

The pan-and-scan version of the film was dubbed 'full screen', because it used the full 4:3 display aspect ratio of a TV.

You could also buy a DVD that featured the original image aspect ratio of the film, known as 'widescreen'. But how do they fit a wide image on a taller display?

They did this by adding mattes to the top and bottom of the image, effectively covering about half the screen with the black matting. This technique of adding mattes to the top and bottom of the image is known as 'letterboxing'.

Once 16:9 became commonplace, it was no longer necessary to offer two formats of every home video release since the display aspect ratio is wider, and much closer to the two most common cinematic aspect ratios: 2.39:1 and 1.85:1. Displaying the cinematic image aspect ratio with letterboxing became the norm.

4:3 image on 16:9 Display

But what about all that 4:3 content made for TV over the decades?

When viewing 4:3 content on a 16:9 display, mattes are added to the left and right side of the image. This process is known as 'pillarboxing'. An example of this can be seen earlier in the article, in the It’s Always Sunny In Philadelphia image.

A box in a box

Every now and then, if you book a really shitty hotel somewhere, you might be lucky enough to get a room that, for whatever reason, only gets an SD signal. This SD signal will most certainly be in the 4:3 format, meaning it only fills the center portion of your display (which is surely some small, plasticky 16:9 HDTV from a brand you’ve never heard of). And since practically everything is shot for 16:9 these days, you’re seeing a 16:9 image letterboxed into a 4:3 SD signal, which is pillarboxed on the 16:9 TV. So, ultimately you’re watching a much smaller 16:9 signal in the middle of your TV, and then you’re forced to touch the remote to use that weird digital zoom option in the display menu, which only blows up that tiny SD signal, making it look that much more awful.

If this hasn’t happened to you several times in your life, then we are living very different lives, and I simultaneously envy and pity you.

SOME image aspect ratio STANDARDS

The above details the most prominent display aspect ratios of modern times. But what are some other image aspect ratios?

1:1 (square)

When a lot of young folk think of a square image, they probably think of Instagram, which is fair. Being such a popular social media platform that only supported square photos for its first several years, that's certainly an understandable association to make.

You might be surprised to learn, though, that images have been taken and exhibited in the square aspect ratio for well over 100 years. Many medium and large format cameras of yesteryear used square film.

6x6 medium format film cameras, for example, exposed the image into film that was 6cm along each edge.

The infatuation with the square aspect ratio carried over into more commonplace and domestic uses, too. Polaroids and other instant film cameras prominently featured a square image area. Fujifilm continues to produce instant film cameras that expose on a square image area with their aptly named Instax Square line of products.

Another highly common use of square imagery can be found in the music industry. Vinyl records - themselves circular in shape - were stored and distributed in square sleeves. These sleeves featured artwork in the square aspect ratio.

Cassette tapes deviated from this format, but were relatively short lived.

CDs returned to the square aspect ratio for album artwork.

Even with digital streaming - which theoretically allows artists to release album artwork in whatever image aspect ratio they want - artists continue to release and display album artwork in the square image aspect ratio, with exceptions few and far between.

5:4 (1.25:1)

This is still one of the most common formats for picture frames, which is absolutely baffling considering the format was based on old-school 8x10" large format cameras, which haven't been used much in the last 100 years.

4:3 (1.333:1)

Aside from the aforementioned cinema, television, and consumer display history that 4:3 has, the aspect ratio is still relatively commonplace in other areas.

Most notably, many digital cameras use 4:3 sensors. The Micro Four-Thirds system, featuring Panasonic and Olympus cameras, uses a 4:3 sensor that's roughly 18x13.5mm in size.

Fujifilm, Hasselblad, and Pentax also make digital medium format cameras that feature 44x33mm sensors! Humongous by digital standards.

4:3 is also a relatively popular format for posters and artwork (although isn’t quite as common as 3:2).

1.37:1 - The Academy Ratio

This aspect ratio isn’t really seen much anymore outside of Wes Anderson’s The Grand Budapest Hotel, but 1.37:1 was the formal ‘Academy Ratio’ for film once sound was added. Prior to this, silent films were in 4:3.

7:5 (1.4:1)

This is another common aspect ratio for picture frames, even though no modern digital camera (that I’m aware of) shoots native 7:5.

Basically, it’s the middle ground between 4:3 and 3:2.

3:2 (1.5:1) - The Popular One

This is one of the most common aspect ratios when it comes to imagery.

First, this is the aspect ratio of APS-C and 35mm ‘Full Frame’ cameras, which combined account for a significant chunk of all digital cameras. As such, the native image aspect ratio that these cameras produce is also 3:2.

In addition to that, the majority of posters and wall imagery are in the 3:2 ratio, with 24x36 and 27x40 being two of the most common large poster sizes.

Postcards are usually 6x4”, which is of course 3:2.

Finally, the display aspect ratio of my beloved Microsoft Surface is 3:2.

16:9

We’ve talked enough about the prominence of 16:9 as a display aspect ratio, but it’s a common image aspect ratio, too, for that very reason.

If you want to view an image, edge-to-edge, on a high resolution display, chances are very good that the display is 16:9, or very close to it. So it makes sense that a lot of people shoot and edit for 16:9 images.

1.85:1 - A cinema ratio

This is one of the standard cinema aspect ratios, alongside the wider 2.39:1. This was the standard ‘spherical’ format (NOT anamorphic, which we’ll discuss below).

1.85:1 isn’t as popular or common now as it once was, but a lot of Spielberg greats were released in this aspect ratio, including E.T. and Jurassic Park.

The taller 1.85:1 ratio arguably makes Jurassic Park a more engaging viewing experience, as it allows the camera to be placed closer to tall dinos while keeping them mostly or entirely in the frame.

17:9 (1.888:1) - DCI (Digital Cinema Initiatives)

This isn’t a common aspect ratio for many finished works, but a number of modern mirrorless and cinema cameras can shoot in DCI 2K or 4K. These formats have more pixels horizontally than the common display formats Full HD and UHD (Ultra High-Definition), which are both 16:9.

DCI 4K, for example, is 4096x2160 in pixel resolution, compared to UHD’s 3840x2160. Same number of vertical pixels, but an extra bunch on the ends.

At the theater, films are projected with a width of 2048 or 4096 pixels. If the film is 1.85:1, it will be very slightly pillarboxed to fit the display. More likely, however, the film will be closer to 2.39:1, and will have letterboxing across the top and bottom of the image.

2:1 - Balanced

This isn’t really a standard ratio for much of anything, but I personally find it to be an aesthetically pleasing ratio. A 2:1 ratio contains an image with the same proportions as two side-by-side squares.

2.35:1 or 2.39:1 (often rounded to 2.4:1) - The Anamorphics

The most common cinema ratio today is 2.35:1/2.39:1. If these seem like highly specific and arbitrary numbers, it’s because they kind of are.

This aspect ratio is the result of using 35mm film with anamorphic lenses, which is a whole can of worms, but here we go. Basically, you’re using an anamorphic lens to stretch an image onto a larger surface area of film or sensor, so that you can squeeze it back to look right later. Different anamorphic lenses have different ‘squeeze’ ratios. These squeeze ratios affect the overall anamorphic effect, or ‘look’, but also affect the final image aspect ratio.

The theory behind anamorphic lenses was that the overall image quality would be better, since you’re recording onto more film area, but in practice the whole stretch-squeeze-desqueeze-squeeze process that anamorphic films went through degraded the image quality enough that films shot with regular ‘spherical’ lenses are technically better looking.

Anamorphic lenses do create a highly desirable aesthetic effect, however, which is why everyone continued doing it.

When shooting with anamorphic lenses, bokeh - the look and quality of light sources and other out of focus elements - becomes more oval in shape, as opposed to the circular nature of spherical lenses. Anamorphic lenses also produce unique flare, streak, and ghost properties compared to their spherical counterparts.

Anamorphic remains highly popular today among directors and cinematographers of all genres.

Even the wide 2.39:1 ratio is popular among young cinematographers-to-be who aren’t using anamorphic lenses, but want their video to have that cool wide look.

WHAT’S THE NEXT STEP IN ASPECT RATIOS?

The first major shift in display aspect ratios was from the original 4:3 tube TVs in the 20th century to the 16:9 flat panels that rose to prominence at the start of the 21st century.

How long before 16:9 is supplanted by another aspect ratio?

What will that aspect ratio be?

How will that aspect ratio rise to such ubiquity? What devices will drive that change? Phones? Tablets? Something we haven’t even seen yet?

Will we see a shift from landscape to portrait for our TVs and monitors?

Which aspect ratio do you think makes the most sense for the next step?

Personally, I think it would make sense to adopt square aspect ratio displays for our clamshell design dual-screen devices. Then we could use just one-half of that to experience something in landscape or portrait, and the 2:1 ratio of the half would work well with most things that the square display doesn’t work for.

Or perhaps you could even reverse this, and make it a square device that opens to reveal a larger 2:1 clamshell display. This would perhaps be more convenient for mobile gaming or streaming, but maybe not as much for apps or browsing the internet.

Your guess is as good or better than mine, but at the end of the day, neither of us will likely have much of a say in it, so try your best to enjoy the ever-confused times we live in while they last.