Try with SVG filter.
img {
filter: blur(3px);
-webkit-filter: blur(3px);
-moz-filter: blur(3px);
-o-filter: blur(3px);
-ms-filter: blur(3px);
filter: url(#blur);
filter: progid:DXImageTransform.Microsoft.Blur(PixelRadius="3");
}
<img src="https://i.stack.imgur.com/oURrw.png" />
<svg version="1.1" xmlns="http://www.w3.org/2000/svg">
<filter id="blur">
<feGaussianBlur stdDeviation="3" />
</filter>
</svg>