Is there a tool to re-project a particular view back onto the original panorama?

I have a full spherical panorama and I capture a view using krtransform e.g.

ktransform view "Pano1.jpg" "View.jpg" 2 100 0 130

I then edit that view by sketching in PhotoShop and I then want to re-project the image back onto the full spherical panorama. Is there a tool that will reproject a given view back into an equirectangular spherical?

I have managed to use Hugin to achieve this with a fair degree of accuracy, but its not a perfect match and it strikes me that I have all the inputs that you would need to map it exactly if I had the right tool.

Any help would be appreciated,

Thanks,
Ken