A jump scare (often shortened to jumpscare) is a technique often used in horror films, haunted houses, video games, and Internet screamers, intended to scare the audience by surprising them with an abrupt change in image or event, usually co-occurring with a frightening sound, mostly loud screaming. Common in film since the 1980s, the jump scare has been described as "one of the most basic building blocks of horror movies". Jump scares can surprise the viewer by appearing at a point in the film where the soundtrack is quiet and the viewer is not expecting anything alarming to happen, or can be the sudden payoff to a long period of suspense. Some critics have described jump scares as a lazy way to frighten viewers, and believe that the horror genre has undergone a decline in recent years following an over-reliance on the trope, establishing it as a cliché of modern horror films.
Chroma key compositing, or chroma keying, is a special effects / post-production technique for compositing (layering) two images or video streams together based on color hues (chroma range). The technique has been used heavily in many fields to remove a background from the subject of a photo or video – particularly the newscasting, motion picture and videogame industries. A color range in the foreground footage is made transparent, allowing separately filmed background footage or a static image to be inserted into the scene. The chroma keying technique is commonly used in video production and post-production. This technique is also referred to as color keying, colour-separation overlay (CSO; primarily by the BBC), or by various terms for specific color-related variants such as green screen, and blue screen – chroma keying can be done with backgrounds of any color that are uniform and distinct, but green and blue backgrounds are more commonly used because they differ most distinctly in hue from most human skin colors. No part of the subject being filmed or photographed may duplicate the color used as the backing.