A digital image sequence consists of a set of pixels each describing the scene intensity at a specific location on a specific instance in time. In a natural scene these pixels are spatially and temporally correlated with each other. An image coding scheme utilizes these correlations in order to represent the image sequence more efficiently in this way allowing for a more cost-effective storage or transmission. In this chapter spatio-temporal subsampling will be discussed as a data reduction technique. Subsampling is in use as a data reduction method for the standardized HDTV transmission systems MUSE [1] and HD-MAC [2] which are completely based on this technique. Recent proposals use this technique in a combination with transform coding [3][4],