Methods and apparatus for temporal matte filtering. Temporal matte filtering methods are described that improve the temporal coherence of alpha mattes for a video sequence while maintaining the matte structures on individual frames. The temporal matte filter may implement a level-set-based matte averaging method. In the level-set-based matte averaging method, two or more input alpha mattes are obtained. Level set curves are generated for the two or more alpha mattes. An averaged level set is computed from the two or more level sets according to a distance-transform-based technique. A temporally smoothed alpha matte may then be reconstructed by interpolating pixel alpha values between the inner and outer level set curves of the averaged level set. The alpha mattes can be optionally warped towards a center frame according to an optical flow technique before the averaging operation performed by the temporal matte filter.
展开▼
