Determine if images been deployed with DCT

I read through the documentation of DCT and some questions came up.
I start docker without having DCT enabled and deploy some images.
Then I decide to enable DCT so that I can only continue to deploy signed images.
What will happen to the unsigned ones that have already been deployed? Will they just continue running?

Can I somehow determine (within the image and from the outside host) if the image running is singed or unsigned (assuming that the described scenario is possible)?

Thank you