1. A computer-implemented method for using a geometry shader program to perform a Hough transform, comprising: executing a pixel shader program by a multithreaded processor to compute input data defining a Hough map that includes coordinate pairs in Hough space representing lines of an input image in image space, wherein the pixel shader program is configured to compute the input data for the Hough map by rendering a graphics primitive that covers the entire input image and by intersecting the lines of the input image with the graphics primitive to generate the coordinate pairs; executing the geometry shader program by the multithreaded processor to identify local maxima of the input data; and storing the local maxima in an output buffer.