Philips Cinema 21:9 TV

21:9 (2.3:1) 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 of 2.35:1 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.

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

${\displaystyle {\tfrac {4}{3}}\cdot {\tfrac {4}{3}}\cdot {\tfrac {4}{3}}={\tfrac {64}{27}}}$

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