background - Android, remove custom button border -

I used this selector code for my custom button (simple.xml)

  & Lt; ? Xml version = "1.0" encoding = "UTF-8"? & Gt; & Lt; Selector xmlns: android = "http://schemas.android.com/apk/res/android" & gt; & Lt; Item android: state_focused = "true" Android: state_pressed = "false" android: drawable = "@drawable / focus" /> & Lt; Item android: state_focused = "true" Android: state_pressed = "true" android: drawable = "@draubable / centered" /> & Lt; Item android: state_focused = "false" Android: state_pressed = "true" android: drawable = "@drawable / pressed" /> & Lt; Item Android: Dragon = "@ Drable / Default Button" /> & Lt; / Selector & gt;  

But on my image batting, I do not know how to remove the limit, I just want to show my images and not the button around the border.

Thanks

I

  & lt; ImageButton Android: id = "@ + id / imagebutton" Android: src = "@ mapped / simple" Android: layout_width = "wrap_content" Android: layout_height = "wrap_content" /> With  

:

  & lt; Image button Android: id = "@ + id / imagebutton" Android: background = "@ sketch / simple" Android: layout_width = "Wrap_content" Android: layout_height = "wrap_content" />  

more work