How do I fix this?? White halftones appearing

[Jamesgray1009]

Hi

I just turned my imac back on to find these white/faded halftones around the edges and to some extent in the middle of my screen.

I was using it early and this wasn't happening and I haven't accidentally nocked or even moved the computer so I'm wondering what the issue is??

Any advice would be great!

Thanks
James

 

[Jamesgray1009]

Another picture