Blur outside, not inside

Hello, I'm a basic user ... and not familiar with masks ! VP Prof v 8.52

On a video/photo, I want to blur the outside of a rectangle or oval, the inside remaining sharp. No problem if I want to blur the inside.

How to do it ? Thanks !

Load the image onto track 1 and apply the BLUR effect

Load the image onto track 2, immediately above track one

Create the mask and UNcheck the Mask Inside box

Add a TRANSPARENCY effect and set the Opacity and Feathering sliders as desired

Click the Sequence tab or Display Dual Previews (via the OPTIONS | GENERAL tab) to see the result

Thanks, Borate ...

I'll try to apply that in the next days.