In this article we describe a family of technologies designed to enhance live television sports broadcasts. Our algorithms provide a means for tracking the game object (the ball in baseball, the puck in hockey); instrumenting broadcast cameras and creating informative graphical visualizations regarding the object's trajectory. The graphics are embedded in the live image in real time in a photo realistic manner. The demands of live network broadcasting require that many of our effects operate on live video streams at frame-rate (60 Hz) with latencies of less than a second. Some effects can be composed off-line, but must be Preprint submitted to IEEE MultiMedia Magazine complete in a matter of seconds. The final image sequence must also be compelling, appealing and informative to the critical human eye. Components of our approach include:(1) Instrumention and calibration of broadcast cameras so that the geometry of their field of view is known at all times, (2) Tracking items of interest such as balls and pucks and in some cases participants (e.g., cars in auto racing), (3) Creation and transformation of graphical enhancements such as illustrative object highlights (e.g., a glowing puck trail) or advertisements to the same field of view as the broadcast cameras and (4) Techniques for combining these elements into informative on-air images. We describe each of these technologies and illustrate their use in network broadcast of hockey, baseball, football and auto racing. We focus on vision based tracking of game objects.