After trying several different combination of tags I haven't had any luck getting photoshop to open my frankenDNG files. I poked around a bit on the the Adobe site and found the DNG SDK supports just about everything you would want to do with a DNG and additionally sports a very liberal license. It comes with an example implementation called ...

Lets say you had a TIFF 6.0 file and you wanted it to be recognized as a DNG (Adobe Digital Negative) for some particular reason. This seems like it should be trivially easy to do with the DotImage TiffFile framework. As far as I knew, there were only two caveats: The image must be in a 8 to 32 bit pixel format.The image must use Lossless Jpeg, ...