Change the Width parameter (or add it if not present already) to a percentage instead of a static value.
width="75%"
Here is code in source:
Please help me modify for banner resize automatic
Here, but I think it might be better to do this via the CSS instead.
<img src="~/images/banner/Banner_001.png" runat="server" width="75%" alt="Banner" style="border: 0;" id="imgBanner"/>