1. Square Image:

decor-image
            
                <img class="img-square" src="image url" alt="square image">
            
        

2. Round Image:

decor-image
            
                <img class="img-round" src="image url" alt="round image">
            
        

3. Responsive Image:

decor-image
            
                <img class="img-responsive" src="image url" alt="responsive image">