1. A system for detecting hand posture using parts based template matching to detect individual human fingers, comprising: a processor; an image capture system configured to capture multiple images of a scene, where: each image is a frame of video data comprising intensity information for a plurality of pixels; and the image capture system comprises a reference camera configured to capture a sequence of frames of video comprising a reference and an alternate frame of video data; memory containing: a hand tracking application; and a plurality of templates that are rotated and scaled versions of a finger template; and wherein the hand tracking application configures the processor to: obtain a reference frame of video data and an alternate frame of video data from the image capture system; identify corresponding pixels within the reference and alternate frames of video data as pixels that occupy the same pixel location in each of the reference and alternate frames of video data; identify at least one bounded region within the reference frame of video data containing pixels having corresponding pixels in the alternate frame of video data having corresponding pixels with intensity values that differ by a predetermined amount; and detect at least one candidate finger within the at least one bounded region in the reference frame of video data, where each of the at least one candidate finger is a grouping of pixels identified by searching within the at least one bounded region in the reference frame of video data for a grouping of pixels that match one of the plurality of templates.