bootstrap 4 center image

class="mx-auto d-block"

<img class="img-fluid" src="" alt=""> //This will make your image responsive

/* used mx-auto d-block */

<img class="mx-auto d-block" src="https://www.w3schools.com/bootstrap4/paris.jpg" alt="https://www.w3schools.com/bootstrap4/paris.jpg"/>

<div class="text-center">
	<img src="{{source}}"/>
</div>