The distinction between horror and terror is a standard literary and psychological concept applied especially to Gothic and horror fiction. Terror is usually described as the feeling of dread and anticipation that precedes the horrifying experience. By contrast, horror is the feeling of revulsion that usually follows a frightening sight, sound, or otherwise experience. It is the feeling one gets after coming to an awful realization or experiencing a deeply unpleasant occurrence. In other words, horror is more related to being shocked or scared (being horrified), while terror is more related to being anxious or fearful. Horror has also been defined as a combination of terror and revulsion.
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.