Rétroprojection

Rétroprojection is a term used in various fields, most commonly in animation and filmmaking, to describe a process that involves projecting an image onto a surface, and then filming or photographing that surface. This technique allows for the integration of live-action elements with animated or pre-recorded backgrounds. In traditional animation, a painted background scene would be projected onto a screen, and then the animated characters would be filmed performing in front of it. This created the illusion that the animated characters were interacting within a real environment.

The term can also be found in other contexts, such as in medical imaging, where it refers to the reconstruction of a three-dimensional image from a series of two-dimensional projections. This is a fundamental principle in technologies like computed tomography (CT) and positron emission tomography (PET) scans. In essence, retroprojection involves taking what has been captured or created and projecting it back into a different context or format to achieve a desired outcome, whether that is artistic integration or scientific reconstruction. The core idea remains the transformation and manipulation of projected imagery.