Keystone - Projector Video Correction

Square up browser videos for your projector with vertical and horizontal perspective correction, fine controls and shortcuts.

Put your projector where it fits. Square up the video in your browser. Keystone compensates for the trapezoid-shaped picture you get when a projector sits below, above or beside the screen. Adjust two sliders in a compact popup while your video keeps playing. PRECISE PERSPECTIVE CORRECTION • Narrow the top or bottom edge, and the left or right edge. • Use a projective transform rather than a simple squeeze. • Fine-tune with 0.1%, 0.5% or 1% steps. • See an approximate tilt angle for a 1.2:1, 16:9 projector setup. • Preview a local still frame where the browser allows it, with a geometric fallback for restricted video. ADJUST WITHOUT INTERRUPTING PLAYBACK • Use keyboard shortcuts with a brief on-screen readout. • Set your own bindings at chrome://extensions/shortcuts. • Correct dynamically added videos and accessible embedded players. • Keep your settings across tabs and browser restarts. • Turn correction off without losing your setup, or reset either axis. LOCAL AND OPEN SOURCE No account, ads, analytics or network requests. Settings stay in your browser. The popup's temporary video preview is processed in memory and is never saved or uploaded. The correction itself uses CSS, without processing video frames in JavaScript. Keystone is the browser companion to Keystone for IINA. Its source code, privacy policy and contribution guide are available on GitHub. WHICH EDGE SHOULD I NARROW? • Projector below the screen: narrow the top. • Projector above the screen: narrow the bottom. • Projector to the left: narrow the right. • Projector to the right: narrow the left. BEFORE YOU INSTALL Keystone corrects HTML video, not your entire desktop or the projector's menus. Settings apply globally to supported videos. Chrome's built-in pages, restricted frames and closed shadow roots are inaccessible. Protected video may limit correction or previews. Native video fullscreen may ignore transforms; use a player's container-based fullscreen where available. Picture-in-picture is not corrected. Digital correction reduces effective resolution on the narrowed side. Website access is needed to locate and transform videos, including accessible player iframes. You can restrict site access through Chrome's extension settings. Source code: https://github.com/lenadweb/keystone-video-extension