U2515H, Whites not uniform on monitor

For a while now I have noticed some strange streaks across my Dell U2515H on white backgrounds, I do a lot of work on Photoshop and it has been quite a pain, i have had the monitor for about 8 months and thought it was just IPS glow, but after some research it seems to be non uniform back-lighting, i was just wondering if this is normal and if it is covered in dells warranty, if anyone knows i would be most grateful if they could advise me.

Many Thanks, Gabriel.

The picture below was taken while the monitor was on the built in diagnostics.