Miguel Idalgo

Chroma keys
Good afternoon we are Nataly Maldonado, Ana Sofia Bustamante and Carolina Moreno Vidallana and we are going to explain how does chroma keys works.
It’s a special effect/post productiontechnique for composing (layering) two images or video streams together based on color hues (chroma range).
A color range in the top layer is transparent, reveling another image behind. The chromakeying technique is commonly use in a video production and post –production.
Green and Blue backgrounds are more commonly use because they differ most distinctly in hue from most humans skin colors.It is commonly used for weather forecast broadcast, were a news presenter appears to be standing in front of a large map during live televisionewscast. ‘Imagine if the news presenter wears blue clotheshis clothes we also be replaced with the background video.
The advance state of technology and much commercially available computer software such as Pinnacle Studio, Adobe Premier, and dozens ofother computer programs.
STEP 1: The background footage is shot first, and the actor or model is filmed carrying out their actions against a blue screen.
STEP 2: To simply place the foreground shotoverlapping the background shot, as added light will create a ghostly image with a blue-tinged background.
STEP 3: The actor of model must be separated from the background and placed into aspecially-mode ‘hole’ in the background footage.
A special film is used that creates a black and-white negative image-black background with a subject-shaped hole in the middle. This is called a ‘female matte’.The blue screen shot was then rephotographed again , this time through a red and green filter so that only the foreground image was cast on film ,creating a black silhouette on an exposed (Clear)background .This is called ‘male matte’.
The background image is then rephotographer through the male matte, and the shot rephotographed through the female matte. An optical inter with two projectors, a...