Why do police wrap a blanket around people in mug shots in Texas?

I think it has to do with new automatic identification software that gets confused by colored shirts and different designs. And while most of this software is in its early stages of implimentation into society, it has been proven to be very effective by tracking people by facial recognition anywhere they are in the world. Just watch the fifth element. It's coming. Not to mention that the goal of the State is to have everyone's mugshot by 2020. This has inspired a contract to arrest for any reason. Know your rights. But also fight for them.