Any procedure which identifies that portion of a picture which is either inside or outside a region is referred to as a clipping algorithm or clipping. The region against which an object is to be clipped is called clipping window.
Any procedure which identifies that portion of a picture which is either inside or outside a region is referred to as a clipping algorithm or clipping. The region against which an object is to be clipped is called clipping window.
Examples
In 2D graphics for example, if the user of an image editing program is modifying an image and has "zoomed in" the view to display only the top half of the image, there is no need for the program to spend any CPU time doing any of the calculations or memory moves needed to display the bottom half. By clipping the bottom half of the image and avoiding these calculations, the program runs faster.
In 3D graphics, in a city street scene the computer may have model, texture, and shader data in memory for every building in the city; but since the camera viewing the scene only sees things within, say, a 90° angle, or field of view, the computer does not need to transform, texture, and shade the buildings that are behind the camera, nor those which are far enough to the side that they are off the screen. The clipping algorithm lets the rendering code skip all consideration of those buildings, and the program runs faster
(From wikipedia)
