Intuit Practice Management, powered by Karbon pulls in your contact's profile images so that you can have each photo displayed for each contact.
You are able to edit your contact's profile image by going to the details tab > clicking edit in the Basics section > and then clicking on your contact's current avatar, it'll give you an option select from photos that Karbon has pulled up or you can choose to upload a photo of your own.
Further reading:
Where is the contact image and data sourced from?