#clientes img{
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;
}
#clientes img:hover{
-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;
}