Android - Insertar imagen android studio

<LinearLayout

    <Button

        android:id="@+id/buttonCreateAccount"

        android:layout_width="wrap_content"

        android:layout_height="50dp"

        android:layout_marginBottom="20dp"

        android:textSize="20dp"

        android:shape="rectangle"

        android:text="Confirmar registro / Save record"

        android:background="@color/mcmgreen"

        android:layout_marginTop="40dp"

        android:layout_gravity="center_horizontal|bottom"/>

        android:layout_marginTop="40dp"

        android:background="@drawable/rounded"

</LinearLayout>

<LinearLayout

    android:layout_width="fill_parent"

    android:layout_height="fill_parent"

    android:orientation="vertical" >

    <ImageView

        android:id="@+id/imageview"

        android:layout_width="fill_parent"

        android:layout_height="fill_parent"

        android:scaleType="fitXY"

        android:src="@drawable/ic_launcher"/>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent" >

<Button

android:id="@+id/buttonCreateAccount"

android:layout_width="match_parent"

android:layout_height="50dp"

android:layout_marginBottom="20dp"

android:textSize="20dp"

android:shape="rectangle"

android:text="Confirmar registro / Save record"

android:background="@color/mcmgreen"

android:layout_marginTop="40dp"

android:layout_gravity="center_horizontal|bottom"

android:layout_marginTop="40dp"

android:background="@drawable/rounded"

/>

<ImageView

android:id="@+id/imageview"

android:layout_width="200dp"

android:layout_height="200dp"

android:layout_centerHorizontal="true"

android:layout_below="@+id/buttonCreateAccount"

android:scaleType="fitXY"

android:src="@drawable/ic_launcher"/>

</RelativeLayout>