La propiedad “filter” de CSS3 permite aplicar efectos de filtro comunes a un elemento, como la falta de definición, escala de grises, el brillo, el contraste . En esta articulo se demuestra el uso de uno de los efectos más conocidos, el blur en una imagen. Cuando el ratón pasa por encima de la imagen:

 

EJEMPLO:

CSS

<link href='https://fonts.googleapis.com/css?family=Josefin+Sans:400,700' rel='stylesheet' type='text/css'>

<style>

figure.blurfilter{
	margin: 0;
	padding: 0;
	display: inline-block;
	position: relative;
	overflow: hidden; /* hide overflowing elements by default */
}

figure.blurfilter img{
	display: block;
	width: 250px; /* width of image */
	height: auto;
	transition: all 0.4s 0.4s;
}

figure.blurfilter figcaption{
	position: absolute;
	display: block;
	text-align: left;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
	text-align: center;
	background: white;
	padding: 10px;
	z-index: 100;
	width: 90%;
	height: 90%;
	overflow: hidden;
	top: 5%;
	left: 5%;
  font-family: 'Josefin Sans', sans-serif; /* google font */
	font-size: 16px;
	opacity: 0;
	-moz-transition: all 0.4s;
	-webkit-transition: all 0.4s;
	transition: all .4s;
}


figure.blurfilter figcaption h3{
	border-bottom: 1px solid red;
	text-align: left;
	width: 90%;
	margin: 0;
}

figure.blurfilter figcaption p{
	text-align: left;
	margin-top: 10px;
	line-height: 1.5;
}

figure.blurfilter figcaption a{
	text-decoration: none;
}

/* Default effect */

figure.blurfilter:hover img{
  -webkit-filter: blur(30px); /* blur filter */
  filter: blur(30px); /* blur filter */
	-webkit-transform: scale(1.3);
	transform: scale(1.3);
	-moz-transition: all 0.4s;
	-webkit-transition: all 0.4s;
	transition: all 0.4s;
}

figure.blurfilter:hover figcaption{
	opacity: 1;
	box-shadow: 0 0 5px gray;
	-moz-transition: all .4s .4s;
	-webkit-transition: all .4s .4s;
	transition: all .4s .4s;
}

/* Semi transparent figcation background effect */

figure.semitransparent figcaption{
	background: transparent;
}

figure.semitransparent figcaption:before{
	content: '';
	display: block;
	position: absolute;
	left: 0;
	top: 0;
	width: 100%;
	height: 100%;
	z-index: -1;
	background: white;
	opacity: .5; /* render background semi transparent */
}

/* Rotate figcation effect */

figure.blurrotate figcaption{
	-webkit-transform: rotate(10deg);
	transform: rotate(10deg);
}

figure.blurrotate:hover figcaption{
	-webkit-transform: rotate(0);
	transform: rotate(0);
}

/* Slideup figcation effect */

figure.slideup figcaption{
	-webkit-transform: translateY(100%);
	transform: translateY(100%);
}

figure.slideup:hover figcaption{
	-webkit-transform: translateY(0);
	transform: translateY(0);
}

/* RotateX figcation effect */

figure.rotatex figcaption{
	-webkit-transform: rotateX(90deg);
	transform: rotateX(90deg);
}

figure.rotatex:hover figcaption{
	-webkit-transform: rotateX(0);
	transform: rotateX(0);
}

/* RotateY figcation effect */

figure.rotatey figcaption{
	-webkit-transform: rotateY(90deg);
	transform: rotateY(90deg);
}

figure.rotatey:hover figcaption{
	-webkit-transform: rotateY(0);
	transform: rotateY(0);
}

</style>


HTML
<figure class="blurfilter default">
	<img src="/IMAGEN" alt="An awesome picture">	
	<figcaption>
		<h3>Bcn Dos  Web</h3>
		<p>Soluciones para Tu Web. Blur Image Hover</p>
	</figcaption>
</figure>

<figure class="blurfilter semitransparent">
	<img src="/IMAGEN" alt="An awesome picture">	
	<figcaption>
		<h3>Bcn Dos Web</h3>
		<p>Soluciones para Tu Web. Blur Image Hover</p>
	</figcaption>
</figure>

<figure class="blurfilter blurrotate">
	<img src="/IMAGEN" alt="An awesome picture">	
	<figcaption>
		<h3>Bcn Dos  Web</h3>
		<p>Soluciones para Tu Web. Blur Image Hover</p>
	</figcaption>
</figure>

<figure class="blurfilter slideup">
	<img src="/IMAGEN" alt="An awesome picture">	
	<figcaption>
		<h3>Bcn Dos Web</h3>
		<p>Soluciones para Tu Web. Blur Image Hover</p>
	</figcaption>
</figure>

<figure class="blurfilter rotatex">
	<img src="/IMAGEN" alt="An awesome picture">	
	<figcaption>
		<h3>Bcn Dos  Web</h3>
		<p>Soluciones para Tu Web. Blur Image Hover</p>
	</figcaption>
</figure>

<figure class="blurfilter rotatey">
	<img src="/IMAGEN" alt="An awesome picture">	
	<figcaption>
		<h3>Bcn Dos Web</h3>
		<p>Soluciones para Tu Web. Blur Image Hover</p>
	</figcaption>
</figure>