res/drawable/default_image.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
       android:shape="rectangle">

  <!-- these are the dimensions of the original default_image.png -->
  <size
      android:width="215dp"
      android:height="210dp" />

  <solid
      android:color="#ccc" />

</shape>