Jan Porter, one of the best match anglers in the world was famous for wearing bright red clothing when fishing.
Bob Nudd wears a bright white hat.
John Wilson can often be seen in a bright red jumper.
One of the carp mags did an article on this very subject, using a diver, camera, fish eye lens and people dressed in various clothing. If the anglers where infront of a tree/bush then virtually any dark colour was hard to see. Dark red, brown, blue, grey, green etc.
When the angler stood with the sky behind them any light colour seemed to work, but blues, greys and yellows were the hardest to see.
They also did an angler in a boat, and basically, if the angler sat down, then the fish if they where within about 15 metres of the boat could not see the angler due to the refraction caused by the water.
I tend to wear drab clothing more to hide froim other anglers then from the fish, as I find that there are many "social" anglers that will often decide that the bit of water next to you is the best bit to fish
..lol