  The conversion of traditional film into stereo 3D has become an important
problem in the past decade. One of the main bottlenecks is a disocclusion step,
which in commercial 3D conversion is usually done by teams of artists armed
with a toolbox of inpainting algorithms. A current difficulty in this is that
most available algorithms are either too slow for interactive use, or provide
no intuitive means for users to tweak the output. In this paper we present a
new fast inpainting algorithm based on transporting along automatically
detected splines, which the user may edit. Our algorithm is implemented on the
GPU and fills the inpainting domain in successive shells that adapt their shape
on the fly. In order to allocate GPU resources as efficiently as possible, we
propose a parallel algorithm to track the inpainting interface as it evolves,
ensuring that no resources are wasted on pixels that are not currently being
worked on. Theoretical analysis of the time and processor complexiy of our
algorithm without and with tracking (as well as numerous numerical experiments)
demonstrate the merits of the latter. Our transport mechanism is similar to the
one used in coherence transport, but improves upon it by corrected a "kinking"
phenomena whereby extrapolated isophotes may bend at the boundary of the
inpainting domain. Theoretical results explaining this phenomena and its
resolution are presented. Although our method ignores texture, in many cases
this is not a problem due to the thin inpainting domains in 3D conversion.
Experimental results show that our method can achieve a visual quality that is
competitive with the state-of-the-art while maintaining interactive speeds and
providing the user with an intuitive interface to tweak the results.
