<ImageView android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:src="@drawable/your_image_name"/>

<ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/image_name" />

<ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/myimage"
    />

drawable-mdpi
drawable-hdpi
drawable-ldpi

<ImageView
    android:id="@+id/YourImageViewID"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/Your_Image_Name"
   />