# 21:9 aspect ratio

21:9 (2.33:1) is the approximated screen aspect ratio of the true value 64:27 (2.370:1) in comparison to the common ratio of 16:9 (1.77:1). It is designed to show films recorded in CinemaScope or the modern anamorphic format of 2.39:1. The main benefit of this screen ratio is the absence of the black bars at the top and bottom of the screen when viewing content in this format, and a constant display height when displaying other content with a lesser aspect ratio.

The 64:27 aspect ratio is the logical extension of the existing video aspect ratios 4:3 and 16:9, as it is the third power of 4:3, where 16:9 of traditional HDTV is 4:3 squared. This allows electronic scalers to use an easily implementable 4:3 (1.33:1) scaling factor.

$\tfrac{4}{3} \cdot \tfrac{4}{3} = \tfrac{16}{9}$

$\tfrac{16}{9} \cdot \tfrac{4}{3} = \tfrac{64}{27}$

The term "21:9" was chosen as a marketing term, probably first used by Philips. Due to its common denominator, 21:9 is more relatable to 16:9, the aspect ratio of regular HDTVs, rather than the correct 64:27 or 21$\tfrac{1}{3}$:9. If it actually were 21:9, the fraction could be expressed more elegantly in the reduced form as 7:3.

## Constant height

A 21:9 TV allows to display all content at equal height, allowing for a more balanced viewing experience.

16:9 TV 21:9 TV
16:9 content
21:9 content

## Film formats and 21:9

Format Aspect ratio
Cinemascope (1950s–1970s) 2.35:1
"21:9" (64:27) 2.370:1
Anamorphic, modern cinema widescreen format 2.39:1

## Standardisation

### HDMI

As of May 2013, video timings in this 64:27 aspect ratio are supported by the technical specification that defines video timings for the HDMI interface, CEA 861-F:[1]

• 1280×720p, anamorphic pixel aspect ratio of 4:3
• 1680×720p, near-square pixel aspect ratio of 64:27
• 1920×1080p, anamorphic pixel aspect ratio of 4:3
• 2560×1080p, square pixel aspect ratio
• 3840×2160p, anamorphic pixel aspect ratio of 4:3

All of the above timings are supported at frame rates of 23.97/24, 25, 29.97/30, 50 and 59.94/60 Hz, as well as 100 and 119.88/120 Hz for the non-UltraHD timings.

An additional resolution of 5120×2160p ("5K") could be added at a later time to provide a non-anamorphic UltraHD signal in 21:9. Variations of the 8K UltraHD resultions could also be considered, at 7680×4320p anamorphic and 10240x4320p non-anamorphic.

### Blu-ray

The Ultra HD Blu-ray specification was reportedly[2] include support for anamorphic video in a 64:27 aspect ratio as well. Eventually, this feature was not included in the final specification.[3] The company Folded Space is working on a proprietary solution, MFE,[4] to put anamorphic 21:9 video onto Blu-rays in a way compatible with standard players.

## Consumer Devices

### Flat panel TV

All Blu-ray Disc content with 1920 horizontal resolution has 1080 vertical resolution, though in the case of widescreen formats wider than 16:9, the image appears on 16:9 displays with letterboxing. The Cinema TV eliminates the black bars by scaling the 1920 horizontal resolution to its full width of 2560 and the 800+ pixels of cinemascope images (actual pixel counts vary[5][6]) is scaled to 1080 with the black space cropped. The result is an image which fills the screen, but does not provide higher quality due to the use of scaling.[7] Despite the intention being to fill the screen with a non-letterboxed image, the zoom mode can result in some cropping at the edges.[8] Content with the full image at 1920×1080 can be displayed in the center of the screen with pillarboxing, and should the viewer choose to not display cinemascope content at full width, it appears windowboxed.

### Philips

The Philips 'Cinema 21:9 TV' was the first LCD television of this aspect ratio.[9] The first model launched was a 56-inch screen size, although it was no taller than a conventional 16:9 42-inch television. Models released in 2010 and 2011 had a screen sizes of 50 and 58 inch.

Early reviews have claimed that it is "one of the coolest TVs" to enter the market for some time.[8] This set was previewed in the UK in advance of its release date of 18 June 2009. Pre-release launch events were held at numerous Philips retailers throughout June 2009.

The online advertising campaign surrounding the Cinema 21:9 TV, titled Carousel, went on to win the most prestigious award in the advertising industry, the Grand Prix at the Cannes Lions International Advertising Festival.[10]

In 2012, Philips stopped production on all its 21:9 televisions due to lack of demand.[11]

### Vizio

Vizio has since followed suit with their own Cinema TVs with identical resolution, similarly marketed as "21:9" in the United States.[12][13]

The 58-inch TV with a panel resolution of 2560×1080p has been sold in 2012 and 2013, and has since been discontinued. A planned 50-inch model never made it to market.

### LG

LG has a number of computer monitors with a panel resolution of 2560x1080 or 3440x1440 and a 21:9 aspect ratio, the 29EA93, 29EA73, 29LN450W and 34UM95. The 34UC97 is the curved version of the 34UM95.[14] The latter one features a TV tuner and is marketed as a Television Set. Other monitor manufacturers, such as Asus, Dell,[15] NEC and AOC, have since followed suit.

At the CES 2014, LG presented the 105UC9,[16] a 105-inch curved LCD TV with a 5120×2160p panel, one of the first two UltraHD 21:9 screens.

### Samsung

Also at CES 2014, Samsung presented a 105-inch curved LCD TV[17] with 5120×2160p as well, the other first UltraHD 21:9 screen.

### Front projection

Besides projectors outfitted with anamorphic lenses, which optically scale 1920×1080p to a 21:9 aspect ratio, Digital Projection,[18] Projection Design[19] and Avielo[20] have released projectors that utilise 2560x1080 pixels of a 2560×1440 DLP chip with a spherical lens.