Cage-based　constrained　deformation　can　generate　interpolations　for　given　images,　but　it　needs　large　amount　labor.　This　paper　proposes　an　automatic　interpolation　method　combining　curve　fitting　with　cage-based　constrained　deformation.　The　method　first　defines　cage　of　interested　regions　for　given　images　interactively,　then　calculates　motion　trajectory　for　each　vertex　of　the　cage　with　curve　fitting,　and　middle　cages　are　interpolated　along　the　fitted　trajectory.　The　last　step　is　computing　all　points＇　new　coordinates　inside　of　the　cage　and　filling　possible　holes.　With　this　method,　2D　transition　with　gradually　changing　images　can　be　generated,　and　the　generation　of　middle　cages　are　automatic　without　interaction.　The　method　provided　in　this　paper　has　wide　applications,　such　as　using　for　avoiding　sudden　vision　hopping　during　video　joining.　©　2010　Binary　Information　Press.