1. A method, comprising: dividing frames of a video sequence into regions prior to applying a 3-D graph cut segmentation for designating an outline of a video object in the video sequence; constructing a 3-dimensional graph including embedding temporal coherence in the 3-dimensional graph by forming associations between corresponding regions in adjacent video frames; applying the 3-D graph cut segmentation to the 3-dimensional graph according to a global color model to derive a binary segmentation representing the outline of the video object; and applying a 2-D graph cut segmentation to at least some of the binary segmentation according to a local color model to obtain a refined outline of the video object.