Aspect Ratio
Definition
Aspect ratio is the ratio of an image's width to its height. HD and UHD television use 16:9 (1.78:1), set by ITU-R BT.709 and BT.2020, and standard definition used 4:3 (1.33:1). Digital cinema mainly uses 1.85:1 (flat) and 2.39:1 (scope, often shot with anamorphic lenses). Social media add 1:1 (square) and 9:16 (vertical). LED walls and ribbon displays often have non-standard ratios, for example 8000×600 pixels, which require a media server canvas built to the real pixel dimensions. When content and screen ratios differ, the image is letterboxed or pillarboxed (black bars), cropped, or stretched.
In the field
Content in 16:9 shown on a non-standard screen is either letterboxed or cropped, and the choice is normally agreed with the creative team before the content is produced. Stretching distorts faces and logos, and clients usually notice it.
Related lessons
Sources
- ITU-R BT.709 : format d'image 16:9 pour la HD · itu.int
- ITU-R BT.2020 : format d'image 16:9 pour l'UHD · itu.int
- DCI, Digital Cinema System Specification : conteneurs image flat (1,85:1) et scope (2,39:1) · dcimovies.com
- Wikipédia, Aspect ratio (image) : 4:3, 16:9 et formats cinéma 1,85:1 et 2,39:1 (pointeur secondaire) · en.wikipedia.org