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I know that my avatar is based on my email address, but how can I predict the kinds of shapes and the color of my avatar based on my email address?

What characteristics (characters, I assume) of the hash equal what shapes, colors etc?

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possible duplicate of How is the default user avatar generated? – Pops Nov 9 '10 at 2:30
    
@popularDemand - Nope, I know that. The factor is my email hash. I want to know how that has is translated and what characteristics of the hash equal what colors, shapes etc. – Moshe Nov 9 '10 at 2:33
    
Relevant link from the dupe: en.wikipedia.org/wiki/Identicon – Pops Nov 9 '10 at 2:33
    
@PopularDemand - NOT A DUPE! – Moshe Nov 9 '10 at 2:33
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@Pop: There's gotta be a better way - I spent a lot of time composing an answer only to discover that the question isn't original. – uɐɯsO uɐɥʇɐN Nov 9 '10 at 2:40
    
@GeorgeEdison - @Pop? hehe. – Moshe Nov 9 '10 at 2:41
up vote 1 down vote accepted

The way Gravatar works, the hash of your email address is used to form the parameters to their image generating function. These are passed to a special URL which returns an image:

Example:

Email: bob@test.com
Hash: ebf3a1ca1e3ca553e2bd873b3cd96390
URL: http://gravatar.com/avatar/ebf3a1ca1e3ca553e2bd873b3cd96390?d=identicon

The default Gravatars for StackExchange are Identicon images (notice the d parameter in the URL above), so given your email hash and the function that generates the images, yes - you can predict what it will look like.


Edit: the source code for Identicon can be found here: http://downloads.wordpress.org/plugin/wp-identicon.zip

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I'd like to know how the image generating function works. – Moshe Nov 9 '10 at 2:41
    
@Moshe: The source code is here. – uɐɯsO uɐɥʇɐN Nov 9 '10 at 2:43
    
Please add to the answer. – Moshe Nov 9 '10 at 2:50
    
@Moshe: I added it. – uɐɯsO uɐɥʇɐN Nov 9 '10 at 3:32
    
The MD5 hash is just used as the seed for the pseudo random number generator. At least that's how it works for MonsterId and Unicornify; I assume Identicons work the same way. – balpha Nov 9 '10 at 8:28

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