.grises img {
-webkit-filter: grayscale(0%);
-moz-filter: grayscale(0%);
-ms-filter: grayscale(0%);
-o-filter: grayscale(0%);
filter: none;

-webkit-transition: all 0.5s ease;
-moz-transition: all 0.5s ease;
-ms-transition: all 0.5s ease;
-o-transition: all 0.5s ease;
transition: all 0.5s ease;
}

.grises img:hover { 
filter: url('#grayscale'); /* Versión SVG para IE10, Chrome 17, FF3.5, Safari 5.2 and Opera 11.6 */
-webkit-filter: grayscale(100%);
-moz-filter: grayscale(100%);
-ms-filter: grayscale(100%);
-o-filter: grayscale(100%);
filter: grayscale(100%); /* Para cuando es estándar funcione en todos */
filter: Gray(); /* IE4-8 and 9 */

-webkit-transition: all 0.5s ease;
-moz-transition: all 0.5s ease;
-ms-transition: all 0.5s ease;
-o-transition: all 0.5s ease;
transition: all 0.5s ease;
}


* {
  -moz-box-sizing: border-box;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

.item {
  position: relative;
  
  border: 0px solid #333;
  margin: 2%;
  overflow: hidden;
  width: 340px;
}
.item img {
  max-width: 100%;
  
  -moz-transition: all 0.3s;
  -webkit-transition: all 0.3s;
  transition: all 0.3s;
}
.item:hover img {
  -moz-transform: scale(1.1);
  -webkit-transform: scale(1.1);
  transform: scale(1.1);
}