  Depth-image-based rendering (DIBR) oriented view synthesis has been widely
employed in the current depth-based 3D video systems by synthesizing a virtual
view from an arbitrary viewpoint. However, holes may appear in the synthesized
view due to disocclusion, thus significantly degrading the quality.
Consequently, efforts have been made on developing effective and efficient hole
filling algorithms. Current hole filling techniques generally
extrapolate/interpolate the hole regions with the neighboring information based
on an assumption that the texture pattern in the holes is similar to that of
the neighboring background information. However, in many scenarios especially
of complex texture, the assumption may not hold. In other words, hole filling
techniques can only provide an estimation for a hole which may not be good
enough or may even be erroneous considering a wide variety of complex scene of
images. In this paper, we first examine the view interpolation with multiple
reference views, demonstrating that the problem of emerging holes in a target
virtual view can be greatly alleviated by making good use of other neighboring
complementary views in addition to its two (commonly used) most neighboring
primary views. The effects of using multiple views for view extrapolation in
reducing holes are also investigated in this paper. In view of the 3D Video and
ongoing free-viewpoint TV standardization, we propose a new view synthesis
framework which employs multiple views to synthesize output virtual views.
Furthermore, a scheme of selective warping of complementary views is developed
by efficiently locating a small number of useful pixels in the complementary
views for hole reduction, to avoid a full warping of additional complementary
views thus lowering greatly the warping complexity.
