Uni-View ( I think that's how they are spelt) - these were a godsend in our old house (albeit a little pricey) they were how to best to explain "sheet" blinds available in any colour - we went for cream - which when pulled down you could see daylight and shadowy people going around from a distance if you looked closely, but from the outside you could see nothing - absolutely nothing! not even shadows walking about in our house at night time. They were really classy and were fitted to each window so were made to measure. I wish we had brought them to our new house as they were one of the best blinds I've ever bought!
They were made of really heavy material too, they just felt so classy when you raised or lowered them.
They were cutting edge technology when we bought them, perhaps now they are more widely sold?
I know one shop near us that did them and that was 10 years ago. May be worth a look at them to see if it's what you're after?