Help Lockscreen image size problem

[Fares1]

Hi, i'm trying to put a picture as my lockscreen image, but whenever i do, the high goes down, making the picture wider, it bothers me, is there any way to fix this? PS i have tried changing the dimensions, it just crops and then doesnt help

 

[Bandaid]

Lock screen size should be 480X800. Try mine out for size. Let me know how it goes.