compositing

Compositing is the process of combining visual elements from separate sources into a single image, used to create scenes that could not be filmed in reality or to integrate digital assets with live-action footage. It is central to visual effects in film, television, and digital media, as well as photography and advertising.

In digital compositing, imagery is arranged in layers with transparency defined by alpha channels. Elements can include live-action plates, computer-generated imagery (CGI), matte paintings, titles, and particle effects. The compositing pipeline often follows blocking, tracking, keying, rotoscoping, color correction, and final grading to achieve believable integration.

Key techniques include chroma keying (green or blue screen) to remove backgrounds, rotoscoping to isolate foreground elements, and matte painting to extend environments. 3D elements can be rendered and then composited with 2D plates, requiring light and shadow matching, color correction, motion shadows, reflections, and occlusion handling.

Typical tools are specialized compositing software, such as Nuke, Adobe After Effects, and Fusion. The term encompasses both the technical methods and the artistic decisions that influence realism, continuity, and audience perception.

Historically, compositing began with optical printers and matte paintings in cinema and evolved to digital methods in the late 20th century. Today, it is a foundational technique in creating convincing visual narratives.