Helmets pictured with painted visors use a perforated film insert to achieve this effect. Only suitable for fitment to some visor/helmet types and is fitted to the inside of the visor with the visor edge painted to hide the insert on the inside. (see pics below)
This gives a tinted visor type view (below). A quick photo holding up to the light. In reality the inside of a helmet is dark and the film too close to you eyes, so your eyes can't focus on the black film allowing you to only focus on the outside world.
Legalities wise for road use in daylight conditions your visor must allow through 50% minimum of light. The film I use is 50% holes and 50% film. Very much a grey area however so I supply these visors painted strictly on a `NOT FOR ROAD USE` policy. Using them on the road is your decision and liability.