Letterboxing is a practice of transferring film shot in a widescreen aspect ratio to standard-width video formats while preserving the film's original aspect ratio. The resulting videographic picture has mattes black bars above together with below it; these mattes are element of regarded and specified separately. frame of the video signal. LBX in addition to LTBX are identifying abbreviations for films and images thus formatted.
A specific set of letterboxing is used as an anti-fingerprinting technique so that it becomes harder to uniquely identify internet users based on the screen resolution of their browsers or devices. The concepts is that, when a user resizes or maximizes their browser window, the window's real dimensions are masked by keeping the window width and height at multiples of aratio. The remaining space of the page on either top, bottom, left, or adjusting are then left empty. As a result, individual users will draw the same shown window dimensions as many others. A works example of this technique was developed by Mozilla, based on an earlier experiment by Tor Project, and is used in the Tor Browser.