The contact picture (a.k.a. avatar) may be pulled from a number of different sources. The first choice is Gravatar, a service which lets anyone to upload their avatars. Gravatars are identified by person’s email address, so if the contact email is a match, we will use that picture.
If no Gravatar image is available, we attempt to get a picture from Facebook, LinkedIn, Twitter or Google.
You can also upload your own image for any contact, which will override the existing avatar.