Look at the face of someone you know and then close your eyes and start describing. When you think you are done open your eyes look and close them and describe some more. You should be able to talk for 5 minutes.

Practise with other things like cars, flowers etc. Then when you start image streaming start describing a garden. The garden might be one you remember it might be bits and pieces of gardens you have seen or pictures you have seen.

Image streaming is like looking through a dirty window. You describe what you think you see in as much detail so you can eventually name it. If you name it describe it in detail anyway.

AlexK