.pic_box {
width: 300px;
height: 300px;
font-size: 0;
text-align: center;
}
.pic_box:after {
display: inline-block;
width: 0;
height: 100%;
content: ‘.‘;
vertical-align: center;
overflow: hidden;
}
<div class="pic_box">
<img scr=" "/>
</div>
