First there should not autopostback="true" in your Radio button
<tr>
<td>
<asp:radiobutton id="Radio1" checked="true" runat="server" text="Text" groupname="rd" xmlns:asp="#unknown" />
</td>
<td>
<asp:radiobutton id="Radio2" runat="server" text="Image" groupname="rd" xmlns:asp="#unknown" />
</td>
</tr>
then using jQuery it will get like this:
$(document).ready(function () {
$('#Radio1').change(function () {
});
$('#Radio2').change(function () {
});
});