合并Facebook个人资料照片

I develop an application on Facebook where I get all the friends profile photos of a person.

Then I would like to merge all those photos into one (a blank photo with fixed width and height).

For my application I use the Javascript Sdk. I think it's not possible to do it with javascript, so I think to use Ajax and to merge them with php.

A lot of applications do this (birthdays applications for instance).

Is there an other way to make it without using Ajax? And if I use Ajax, do I have to save my merged image on my server?

Thank you.