solo lo adaptas a tu codigo php
Código:
<img src="imagen.jpg" width="100" height="100" border="0" style="-moz-opacity:1;opacity:1;filter:alpha(opacity=100);cursor:hand;" onmouseover="this.style.MozOpacity=0.2;this.style.opacity=0.2;this.filters.alpha.opacity='20'" onmouseout="this.style.MozOpacity=1;this.style.opacity=1;this.filters.alpha.opacity='100'">