Why are wallpapers that are not stock not able to go full screen?

[maestol]

I have a galaxy note 4 and downloaded the new s6 wallpaper but when I add it I notice the top dims where the time and signal strength are. Then I noticed that any other wallpaper that I downloaded would have the same dimming effect on the top as well. The only ones that go full screen are those that come with the Note 4. Any way to fix that?

 

[maestol]

also occurs with the lock screen as well.

 

[maestol]

I tried various other wallpapers that i download from the internet and they all end up with the same dimming effect.