Aspect ratio refers to the proportional relationship between an image’s width and height, expressed as width to height, or W:H. Most high-definition displays, including the modern day panel PC, are widescreen offering a 16:9 aspect ratio, which represents a width of 16 units relative to a height of nine units. Older standard-definition displays like cathode-ray-tube TVs or even the early generation industrial panel PC offer a narrower 4:3 aspect ratio, which represents four units of width relative to three units of height.
Some are confused by the concept at first, incorrectly assuming it refers to a display width of 16 inches relative to a height of nine inches. Some also wonder what if anything this has to do with a television that measures 42 inches diagonally from corner to corner, i.e., a 42” HDTV. Although a display may, indeed, measure 16 inches wide by nine inches high, this isn’t the reason for the 16:9 aspect ratio. In truth, ‘W’ and ‘H’ have nothing to do with specific measurements. Rather, the term 16:9 is an expression of proportionality.
Computing dimensions: 42” capacitive touch panel example
Consider a 42-inch-diagonal capacitive touch panel. Using the good ol’ Pythagorean Theorem, A2
, we can calculate the touch panel pc measurements very easily. We know that the display’s proportional width-to-height ratio is 16:9 and that the screen’s measurement, diagonally across its face, is 42 inches. Dispensing with algebraic detail, we use math to calculate the display’s physical dimensions, expressed in the following formulae:
Measured display width = (diagonal * width) / √(width2
Measured display height = (diagonal * height) /√(width2
Now, let’s plug in our known values, where the diagonal measurement is 42 inches, the proportional width is 16 and proportional height 9:
Measured display width = (42 * 16) / √(162
) = > 36.6
Measured display height = (42 * 9) / √(162
) = > 20.59
The answer: our 42” diagonal 16:9 widescreen capacitive touch panel has a display whose physical dimensions are 36.6” wide and 20.59” high. We can even verify it using simple division and comparing the results: both 16 ÷ 9 and 36.6 ÷ 20.59 do, in fact, equal 1.78 (expressed as 1.78:1).
How aspect ratio affects panel display
Now that we know what aspect ratio means, let’s consider how it affects screen display. We have the film industry to thank for today’s screen aspect ratios. The earliest films were a shot on stock that had a 4:3 aspect ratio (expressed as 1.33:1). Early television-set makers followed suit, adopting 4:3, as did the eventual manufacturers of our first computer monitors. Acting on fears that television might supplant and render obsolete the movie-theater experience, the film industry soon embarked on a campaign to differentiate itself by shooting movies on expanding array of wider film stocks.
The trend produced a variety of panoramic formats, culminating in 1952 with the release of Cinerama’s 2.59:1 aspect ratio, a width well more than double its height. Various wide-screen aspect ratios eventually congealed into the industry’s two current standards, 1.85:1 and 2.39:1.
In the late 1980s the television industry again followed suit, broadening its standard format to 1.78:1 – wider than the original 1.33:1 but not as wide as the 1.85:1 cinematic aspect ratio. Thus, the current 16:9 standard was born.
Even after its creation however, it took time for the TV and computer panel display industries to adopt it. The 4:3 standard continued to dominate throughout the next decade and into the early 2000s as the industrial panel pc used in factory-floor automation and medical and industrial industries had custom applications married to their 4:3 aspect ratio. Unfortunately, this led to unforeseen issues once 4:3 displays ceased to exist. Eventually, the growing availability of widescreen content led to increased production of widescreen televisions. Ultimately, computer displays followed their lead – but not entirely.
The computer industry goes its own way
Instead of adopting the 16:9 standard, the computer industry opted for a slightly narrower aspect ratio of 16:10, used predominantly in laptops and LCD/LED monitors from 2003 to 2006. A desire to accommodate widescreen TV and movie content was one of the reasons. However, the industry settled on 16:10 instead because it offered the unique advantage of permitting the full, un-cropped, side-by-side display of two 8.5-inch x 11-inch paper-sized documents. Given the slightly taller display, now even large-format computer-aided-design renderings could fit comfortably on a single screen.
The new 16:10 aspect ratio’s lifespan was brief, however, as manufacturers eventually abandoned it in favor of 16:9. Not all users welcomed the change, though. The blog sixteenbyten.com argued that the switch represented a 10-percent loss in screen height. Lance Ulanoff on pcmag.com further contended:
The switch from 4:3 to 16:10 took away some of that depth on my [monitor’s] screen, but the tradeoff was enough room to run apps side by side. The 16:9 aspect ratio offers no more width, just less screen real estate.
So why the need to change? Could it be that since most contemporary movie and TV content fits within 16:9, it only makes sense for our computer monitors and displays to do so as well? Writing on pcmag.com, Michael Miller offered one explanation:
There are two reasons here. First (and the one they’ll tell consumers) is, that this ratio matches the HD formats used in televisions. Second (and the one that really counts) is, that these displays are more efficient to make, so they cost the display makers less money.
Matthew Humphries on geek.com continued: “It makes sense to produce panels of the same aspect ratio, simplifying the production line and being more exonomic
Dealing with early industrial touch panels
Regardless of where in the debate we stand, most users simply want to be able to view content natively and use applications as designed. Accordingly, many users must deal with 16:9 screen issues caused by displaying 4:3 applications which were originally designed for the older 4:3 industrial touch panel PC and not widescreen displays. To view them properly, legacy applications as well as classic film and TV content require the use of a technique called pillar boxing. Instead of filling the entire field of a 16:9 display, 4:3 legacy applications and content span only the screen’s height, with vertical black bars creating empty voids to the right and left of the image. The result is a horizontally centered image embraced by two vertical black bars. In this case, because the 4:3-designed application or content no longer is being displayed in its native size relative to the panel’s display, it makes the onscreen image smaller and harder to view.
An alternative to pillar boxing is to expand a 4:3 image horizontally to fill the width of a 16:9 display. Stretching in this way, however, distorts the onscreen image and can make the text, controls, and graphical user interface more difficult to operate, particularly on a panel pc, as well as cause old TV shows and movies to appear unaesthetic.
Understanding aspect ratio and the long journey to its present-day standards help us determine the ideal size for a display’s intended use. For many, 16:9 is perfectly suited for their content and applications. Some prefer 16:10 and feel that the additional real estate at screen’s top and bottom are easier to use and promote greater productivity. Still others are bound to a 4:3 aspect ratio due to legacy applications that aren’t redeveloped cheaply or easily. One thing is certain, however. Display aspect ratios will continue to evolve and we have to understand why so that we’re prepared to design the best, new displays for content and applications of the future.