Hi Fred,
I did not heared the format of RGGB12.
But for which format is better to save into tiff file, I think there is no different.
Like you have a serial of number need to remember, you can new a txt file to save them , you also could new a doc file to save them. For the data, doc or txt is no different.
For the data type, I think you should following your needs.
Thanks
Chad