Soap UI test design for Image Base64 String - What and How to test?

I have to test an API that allows user to create a profile and profile has a picture. Currently API taking picture value as base64 string.

Something like this.

<ImageContent>BASE64 STRING VALUE</ImageContent>

In UI code is decode this Base64 and shows image.

Now I have to write a test to test the API. Is there any Library available in SOAP UI Groovy Script that I can write and provide solid test around this?

I searched the Internet and found this, but its not the complete answer and decided to create this question.

reference link : http://ift.tt/1QpUMEX