Sorry think I was a bit confusing and maybe I am a bit confused about what you are explaining.
What I meant was not how did you confirm that what you have input is 10 bit but how did you confirm that the data you have on the machine is valid 10 bit data and not in 8 bit form. I found that even if I input 10 bit data the imaqdx driver was only capturing at 8 bit.
Now I'm thinking about it I'm remembering that the decklink card creates a WDM streaming device in device manager. I can use this as a device to get information directly in to OpenCV but this was not giving me the full resolution of the picture I was inputting and was only 8 bit.