In case of computer graphics the alpha compositing is a method that merges an image and a background to generate the look of the incomplete transparency. It is frequently useful to make image elements in many part passes as well as join the resulting several 2D images or designs into a single. After the final image is in a process is called compositing. In order to unite these image basics correctly, it is essential to remain a connected matte for every part. The matte is having the coverage information such as the shape of the geometry, that creating the possible discriminate among parts of the image. In this way, the geometry can be drawn and other parts of the image or design that are empty. For the store matte information, the idea of an alpha channel was initiated by Alvy Ray Smith in the late 1970s, and completely developed by the Tom Duff and Thomas Porter in 1984.
In the computer graphics, the alpha compositing is a process to combine the image with background to make appearance of the partial transparency. It is very useful to render the image elements in the separate passes, and combine resulting multiple 2Dimages in the single, and final image in the process named compositing. For instance, compositing is been used extensively while combining the computer rendered image with the live footage. To combine the image elements rightly, it is essential to keep the associated matte for every element. This matte has coverage information—shape of geometry to be drawn—making that possible to distinguish between the parts of image where geometry was in fact, drawn as well as other parts of image that are empty. This is generally referred as premultiplied alpha.