ABSTRACT
Chroma key, known as bluescreen, greenscreen, or process photography, is a method of producing mattes for compositing. The basic principle is the same for all processes and for both film and video: by including an area of a pure color in the scene, that color can then be made transparent, and another image can be substituted for it. Day-for-night is an important technique when it was very difficult to actually shoot at night on location, such as the zoo scenes in the film Mank. Flicker-free ballasts are available that minimize the possibility of flicker even under high-speed conditions. They utilize two basic principles: square-wave output and high frequency. Some microphones are omnidirectional, meaning that they pick up sound from every direction around them. Other mics are a little bit directional, meaning that they are much more sensitive to sound coming toward the front of the mic than anywhere else.
