Technically, it can be viewed as a method or procedure that determines whether a pixel is outside or inside of a specified region. The method is termed as clipping or clipping algorithm.

There are various applications ranging from surface visibility identification in three-dimensional view, drawing operation, to object creation using solid modeling method.

Based on application, clipping window boundaries is identified i.e. polygon.

A portion of two-dimensional scene that is chosen for display is termed as clipping window.

A region to which an object inside the clipping window is mapped is called viewport.

Read : What is window and viewport?

A line or an object can be partially or completely inside in a window.

If the given line or object is partially inside the clip region, then the portion which is outside the window would be removed.

Point Clipping:

In point clipping, a point (x,y) is checked whether it falls within the window or not.

• A point that lies inside the clipping window is considered as visible and no clipping is required for such case
•  If it lies outside the window, then it would be considered as  invisible

 Line Clipping:

A line clipping comes into play, where the extra portion of a given line that lies outside the window is cut off from the clip region. There is a popular line clipping algorithm named Cohen Sutherland algorithm.

• If a line intersects the clipping window, then the line is required to be clipped as it is considered as partially visible
• If a line falls inside the clipping window, then it is considered as visible
• Otherwise, invisible

 Polygon clipping:

Ploygon clipping also follows the same concept, it cuts out vertices of the polygon that is outside the windows. Sutherland–Hodgman algorithm and Weiler-Atherton polygon clipping algorithm techniques are used for clipping a polygon.

Clipping a polygon is a complex procedure, unlike line clipping where only two points need to map one another. In polygon clipping, a method may generate a sequence of vertices as output that can be represented as clipping boundaries.

• If a part of polygon intersects the clipping window, then a particular portion that lies outside the window is needed to be removed

Text Clipping:

It can be defined as a process where a string (a sequence of character) that falls outside the window is removed. 

There are various text clipping methods and its usage depends on character generation mechanisms. all-or-none clipping is the simplest method for clipping text corresponding to a window.