XA Ultra (Black) Lockscreen Wallpaper problem

[mtnguyen027]

The thing is my BLACK lockscreen wallpaper of the default black theme displaying not really BLACK. 

However,  I have checked the BLACK display and it works normally:

[MarlonUk1]

That is how it is supposed to be.  It is not pure black but grayish black

[mtnguyen027]

I try with XA and it's pure black
I hv searched a lot, mate

[MarlonUk1]

     I meant it is how it supposed to looked with your device, unless you can find another XA Ultra and not compare it with just an XA      

 Xperia X                                              Xperia XZ