Aspect ratio

Aspect ratio describes an image's shape by comparing its width with its height. A 1920 × 1080 image and a 3840 × 2160 image both have a 16:9 ratio: one contains more pixels, but their overall proportions are the same. Apple’s aspect-ratio definition

BetterDisplay uses this relationship when filtering display modes and generating compatible scaling choices. A matching ratio helps preserve the shape of an image; it does not mean that the two images have the same resolution.

Rotation can swap width and height. Cropping or stretching a stream is another separate choice, so the shape of streamed content need not follow the selected display mode.

See Display Mode for the related options.