AJAX :: ModalPopupExtender / Datalist Original Image Come In Modalpopupextender After Click

I have a DataList that contains some Thumbnail Image(Image Button).

Now I want when i click on any Item in datalist the original image come in modalpopupextender.

How I can do this?

<asp:DataList
ID="dlImgGallery"
runat="server"
RepeatColumns="3"
Width="100%"
onselectedindexchanged="dlImgGallery_SelectedIndexChanged"
DataKeyField="Id"
>
<ItemTemplate> <table
style="width:100%;">
<tr>
<td
></td>
<td
class="style3">
<asp:ImageButton
ID="ImageButton1"
runat="server"
ImageUrl='<%# Eval("Img_URL") %>'
BorderColor="#0098DB"
BorderStyle="Double"
BorderWidth="3px"
onclick="ImageButton1_Click1"
/>
</td>
<td
class="style3">
</td>
</tr>
</table> <br
/>
<cc1:ModalPopupExtender
ID="mpe"
runat="server"
BackgroundCssClass="ModalBackColor"
TargetControlID="ImageButton1"
PopupControlID="Panel8"
CancelControlID="btnCancel"
ondatabinding="mpe_DataBinding">
</cc1:ModalPopupExtender>
</ItemTemplate>
</asp:DataList>and
my panel that shows as modalpopu
<
asp:Panel
ID="Panel8"
runat="server"
onload
="Panel8_Load">
<asp:Button
ID="btnCancel"
runat="server"
Text="Cancel"
/>
<br
/>
<asp:Image
ID="Image1"
runat="server"
Height="102px"
Width="124px"
/>
</asp:Panel>

Now where I can to write code that when i click on item in datalist Original Image show in modal popup extender?