1. A method for estimating a complexity of a picture, the method comprising: receiving a metric of a complexity of a picture generated from a motion-compensated processor or analyzer, a motion compensator, a spatial processor, a filter, or from a result generated from a previous coding pass, wherein the complexity comprises a temporal, a spatial, or a luminance characteristic; and estimating the metric of the complexity of the picture comprising: determining if the picture is correlated with a future or past picture; and determining if the picture or an area of the picture masks artifacts more effectively than areas of the picture or the future or past picture that do not mask the artifacts.