Okay, my previous post was probably a bit heavy-handed…
This is not a new question here, recall this thread: How to create synthetic RAW image?. And there, we regarded how hard is this challenge. @Whirlwind, in this thread you’ll find some approaches to inserting synthetic image arrays into DNG containers, but they’re not straightforward.
There’s clearly a need for this sort of thing, a ‘tiff2dng’ tool that would not only insert the image array but also set the metadata appropriately. I downloaded the Adobe DNG API today, but I won’t get a chance to do much right now, trying to put a bow on rawproc 0.7.