Parsing field value inside this html code?

I have this code in my html:
<asp:Image runat="server" ID="imgProduct" src='<%# "images/ads/" + Eval("key1") + "/" + Eval("image1_path") %>' alt='<%# Eval("title") %>' />
Field "image1_path" has value "myPic.jpg". If possible, I need to parse this field within the html so that I can add "_3" to the name of the file, and then add the extension. The new string would be "myPic_3.jpg". 
I don't want to touch the codebehind or the database.
Is this possible?
Thanks.
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