what is the algorithm used to generate those little gravatar identicon images?

Question

Naturally, one would suspect that the algorithm creates images that are:

• highly unlikely to produce the same identicon twice; and
• capable of ensuring that each identicon is sufficiently distinctive as to not appear too similar to any other identicon

Answer 1

Here's an implementation of it for Wordpress, and another one for Perl.

Answer 2

They are called Identicons. The Gravatar identicon image is based off of an MD5 hash of your email address. Here is an identicon implmentation if you are using .NET. There are other implementations listed in the Wikipedia article as well.

Important Update You may also be interested in Unicornicons.

Answer 3

Checkout Coding Horror, it has an algorithm based on IP Address similar to SO.

From Wikipedia:

An Identicon is a visual representation of a hash value, usually of the IP address, serving to identify a user of a computer system. The original Identicon is a 9-block graphic, which has been extended to other graphic forms by third parties some of whom have used MD5 instead of the IP address as the identifier. In summary, an Identicon is a privacy protecting derivative of each user's IP address built into a 9-block image and displayed next the user's name. A visual representation is thought to be easier to compare than one which uses only numbers and more importantly, it maintains the person's privacy. The Identicon graphic is unique since it's based on the users IP, but it is not possible to recover the IP by looking at the Identicon.

Answer 4

Easy way to display the gravatar for a given email address

http://meta.stackoverflow.com/questions/38944/what-is-the-easist-way-to-display-the-gravatar-for-an-email-address

Answer 5

Hi all,

I've been working on an enhancement to identicons. My version is able to rotate the identicon, and generate triangular, pentagonal, hexagonal and septagonal identicons.

For a preview, check out http://www.sambira.com/identicons.png

Anyone like to to help me offload this into the WWW? Will share the credit. Get in touch at michael.muriithi[at]yahoo[dot]co[dot]uk

Answer 6

Here is an Identicon implementation as a JQuery plugin using HTML5 and the Canvas element. If the browser supports Canvas the Identicon is drawn without an IMG and HTTP call to Gravatar, otherwise it defaults to the Gravatar IMG link.

Demo : http://francisshanahan.com/identicon5/test.html

jQuery Page: http://plugins.jquery.com/project/identicon5

Project Page: http://francisshanahan.com/index.php/identicon5