Prefer to store a link to the avatar which any client can pick up.
Expanding on this...
How about this - all accounts automatically own the alias <account number>
This alias is locked to the account.
You use this alias to store in URI format a hierarchy of parameters for the person who owns the account - this can be set and managed though the clients - one of these is the avatar.

Yes, this would be the solution - if that alias of account number was locked and only the account itself can own it, then we can do this. If it is squattable, then it isn't possible to do.

CFB, what are your thoughts?

I like it

Quoting myself... hah... Here's a better flow...

1. Nominate an account to act as the "avatar account". It's purpose is to receive AM and maybe define an alias to the account number.
2. Send an AM with the FileReader.readAsDataURL encoded image to the avatar account.
3. To find an avatar for an account look for the most recent transaction from the account to the avatar account.
4. Take encoded image and set to value of <img src="AM_DATA_HERE">. More on data urls
5. Rejoice.

* Avatars can be updated by sending a new AM to the avatar account.

nxt: 4915862015826193000

With locked alias account id's, we open a whole new ability to have an actual profile to go along with an account. could be very useful down the road.

Well if <account number> is currently squattable you could always release a 'special' that is not available in the current code like @<account number> or pick a prefix string that no-one knows when you do the code update guys

Just call getAccountTransactionIDs for the account then loop and find the first one where recipient == avatar_account.

Squatting is allowed. Let's find another way.

Erm what's the processing time for every thousand transactions... sounds a bit like avatar mining

Ok, let's wait for Jaguar.