it's not intended to replace photographs. in fact, one thing i would hope to do in the future is allow people to upload photographs. instead, it's meant to replace the auto-generated images that already exist that use IP addresses (like on stack-overflow, for example). those are really ugly; mine are much nicer (and more flexible).
while i was developing this approach i tried lots of ideas. it's actually quite hard to get images with (1) a wide range, to avoid "collisions", (2) attractive designs, and (3) coherent forms (that don't look like a random mess, making them easier to remember). one of the things that helps a lot in making these more distinctive/individual/memorable is the diagonal symmetry. another is the generally consistent hues within any one icon.
while i was developing this approach i tried lots of ideas. it's actually quite hard to get images with (1) a wide range, to avoid "collisions", (2) attractive designs, and (3) coherent forms (that don't look like a random mess, making them easier to remember). one of the things that helps a lot in making these more distinctive/individual/memorable is the diagonal symmetry. another is the generally consistent hues within any one icon.