Santa Claus, also known as Saint Nicholas, Saint Nick, Kris Kringle, Father Christmas, or simply Santa (Santy in Hiberno-English), is a legendary figure of Western Christian culture who is said to bring gifts to the homes of well-behaved ("good" or "nice") children on Christmas Eve (24 December) and the early morning hours of Christmas Day (25 December). The modern Santa Claus grew out of traditions surrounding the historical Saint Nicholas, a fourth-century Greek bishop and gift-giver of Myra, the British figure of Father Christmas and the Dutch figure of Sinterklaas (himself also based on Saint Nicholas). Some maintain Santa Claus also absorbed elements of the Germanic god Wodan, who was associated with the pagan midwinter event of Yule and led the Wild Hunt, a ghostly procession through the sky.
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.