UP-resing HD to 4K?

Editing a film that was mostly shot in 4K. But about 1/3 of the footage was shot in HD. I want to try and experiment ... to see how good I can make the HD look in 4K. I had been planning to finish the film in HD, down-resing the 4K. But watching how fast the 4K market is taking off ... and the fact that all the remaining shooting of the film will be in 4K ... thus my interest.

Just wondering if there is any new software out there designed specifically for 'improving' resolution if one wants to try and up-res? Like Neat Video does for cleaning up noise, for instance.

I'm also helping on an IMAX film that was shot in 4K. Some of the material looks remarkably good on the big screen. Some doesn't. So I'm also looking around for my IMAX friends - to see if there might be anything for cleaning or improving the lesser quality images.

All ears,

Ben

Boris Continuum Complete UpRez may be good although I haven't used it personally.
[www.borisfx.com]