The use of correlation-based techniques to perform stereoscopic matching enables real-time frame rates to be achieved. The disparity maps produced are not as accurate as those produced using more sophisticated methods. This paper presents three ideas aimed at decreasing the computation time of standard correlation-based techniques. The reduction in computation time is achieved using two different methods. Firstly, the number of comparisons is reduced using MPEG-2 motion vectors to narrow the disparity search range to an optimised region and identifying areas of a scene which have remained static between frames so the previous disparity can be used. The second approach is an implementation of stereo using the above ideas on a GPU. The increases in error and frame rate can be controlled depending on the requirements of the application.