Average photo or photo mean

A couple of days ago I saw on the internet some photo statistics with average man and average woman from different regions around a world.

The average women face around the world

the_average_womans_face_around_the_world

The average mens face around the world

the_average_mens_face_around_the_world

An interesting question it’s How are made?

There are made using many layers of photos with opacity (alpha value). This means if we want to do mean of 3 photos we need to put 3 overlapping photos with 33% opacity for each. In many cases we can’t obtain a very sharp image. For example above photo results are photoshoped after overlapping.