Compositing: what is it?
The compositing is the combination of visual elements separated into individual images to create the effect of the single scene. It is the most advanced technique for manipulating images with the aid of computer graphics. This is why it is very often used both in cinema and on television. Live action shooting techniques are: chroma key, blue screen or green screen. Living in the digital age, the images used for the realization of this technique are mostly digital images. However, we find first forms of pre-digital compositing as early as the late 1800s in Georges Méliès’ films.
Compositing: how it works
Compositing is based on a basic principle that is the replacement of an image with other material from other images. However, it must be taken into account that in digital compositing like corporate film production, software considers areas that have a specific color as the areas to be replaced, so they must be well lit and without shadows. At that point, each pixel of that particular color is replaced with a pixel from another image, aligned so precisely that they will appear to be part of the original itself.
Several compositing techniques are used. In “camera” compositing all the images are filmed together from the same shot to give the effect of a single representation. The elements are arranged in perspective in order to give the idea of belonging to a single image. For this type of compositing glass painting and the projection of images on a screen are used.
The chroma key is instead one of the most used techniques to superimpose figures. This technique recognizes the color of the areas to be eliminated and replaces it with other images, symbols or scenographies. This happens for example in the television programs of the transmissions of the time. The presenter is in fact filmed in front of a blue or green screen and the software substitutes the weather maps for the color of the screen.
The chroma key is used to represent subjects or objects on virtual backgrounds that can be of two types: using material already used previously or using material created entirely digitally.
Compositing: green screen
For the chroma key effect to work, the background must be green (green screen) or bright blue (blue screen). In reality, the green color is almost always used, the latter having gradually replaced the blue screen. The background must also be well lit, in order to make the color homogeneous in all its points. To avoid the effect of fringing, i.e. cutting the edges, it is better to use the rain backlight source. The subject in the foreground obviously must not wear clothes of the same color as the background otherwise we would encounter the “laundry” effect of the chroma key.
THE team of experienced videomakers obviously knows all the tricks to create the best movies and photographs that best suit your needs. Videos and photos will talk about you in the way you have always wanted but never realized.