1. A computer implemented method comprising: automatically separating a video object from a background of a video sequence via a processor performing operations comprising: pre-segmenting frames of the video sequence into regions; selecting two model frames of the video sequence via a user interface, wherein each of the two model frames has a foreground representing the video object, and said background; constructing a 3-dimensional (3-D) graph from a 3-D volume of the frames temporally bounded by the two model frames, including associating regions on a single frame with adjacent regions on the same frame and associating the regions on the single frame with candidate corresponding regions on adjacent frames; segmenting the 3-D graph into associated foreground regions and associated background regions separated by a boundary according to a global color model, wherein the associated foreground regions represent the video object in the frames of the video sequence and wherein segmenting the 3-D graph into associated foreground regions and associated background regions is achieved by minimizing a plurality of energy functions of the 3-D graph, wherein: a first energy function represents the conformity of a color of a region to a foreground/background color model associated with the color information in the two model frame; a second energy function represents color differences between two adjacent regions in the same frame; and a third energy function represents color differences between two regions in two adjacent frames; specifying a video tube portion around a localized section of the boundary in the 3-D graph with the user interface, wherein the video tube comprises a subportion of a video frame and corresponding parts of at least one other video frame in the video sequence; and applying a local color model to a 2-dimensional (2-D) graph cut segmentation within the video tube portion to refine a localized boundary between the foreground regions and the background regions.