try this
<asp:datalist id="ItemsList" onitemdatabound="Item_Bound" runat="server">
<itemtemplate>
<asp:image id="Image1" runat="server" />
</itemtemplate>
On Item_Bound event you can control data binding dynamically
void Item_Bound(Object sender, DataListItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Item ||
e.Item.ItemType == ListItemType.AlternatingItem)
{
YourDataSourceClass obj= (YourDataSourceClass )(e.Item.DataItem);
Image img= (Image)e.Item.FindControl("Image1");
img.ImageUrl=obj.ImageUrl;
}
}