Twixtor enables you to speed up, slow down or frame rate convert your image sequences with visually stunning results. In order to achieve its unparalleled image quality, Twixtor synthesizes unique new frames by warping and interpolating frames of the original sequence... employing RE:Vision's proprietary tracking technology that calculates motion for each individual pixel.

The "Download" link provides the Adobe After Effects and Premiere Pro, but it's available for other applications on this page.