background Image gone compressed when keyboard is open : I am making signup page using this image background.

[Background image][1]

  [1]: https://i.stack.imgur.com/huxGd.png

It Look like:
[Signup page][2]
  [2]: https://i.stack.imgur.com/XGvyJ.jpg

but when i focus edittext and keyboard is opened, background image is compressed. how can i resolve this.