Resolution independence

Resolution independence is where elements on a computer screen are rendered at sizes independent from the pixel grid, resulting in a graphical user interface that is displayed at a consistent size, regardless of the size of the screen.

As early as 1978, the typesetting system TeX due to Donald Knuth introduced resolution independence into the world of computers. The intended view can be rendered beyond the atomic resolution without any artifacts, and the automatic typesetting decisions are guaranteed to be identical on any computer up to an error less than the diameter of an atom. This pioneering system has a corresponding font system, Metafont, which provides suitable fonts of the same high standards of resolution independence.

The terminology device independent file format (DVI) is the file format of Donald Knuth's pioneering TeX system. The content of such a file can be interpreted at any resolution without any artifacts, even at very high resolutions not currently in use.

Apple included some support for resolution independence in early versions of OS X (formerly Mac OS X), which could be demonstrated with the developer tool Quartz Debug that included a feature allowing the user to scale the interface. However, the feature was incomplete, as some icons did not show (such as in System Preferences), user interface elements were displayed at odd positions and certain bitmap GUI elements were not scaled smoothly. Because the scaling feature was never completed, OS X's user interface remained resolution-dependent.

On June 11, 2012, Apple introduced the 2012 MacBook Pro with a resolution of 2880×1800 or 5.2 megapixels - doubling the pixel density in both dimensions. The laptop shipped with a version of OS X that provided support to scale the user interface twice as big as it has been previously been. This feature is called HighDPI mode in OS X and it uses a fixed scaling factor of 2 to increase the size of the user interface for high-DPI screens. Apple also introduced support for scaling the UI by rendering the user interface on higher or smaller resolution that the laptop's built-in native resolution and scaling the output to the laptop screen. One obvious downside of this approach is either a decreased performance on rendering the UI on a higher than native resolution or increased blurriness when rendering lower than native resolution. Thus, while the OS X's user interface can be scaled using this approach, the UI itself is not resolution-independent.

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