Add Image to HyperLink inside GridView in ASP.Net

You can either use this

<asp:TemplateField>
    <ItemTemplate>
        <asp:HyperLink ID="lnkRedirect" runat="server" NavigateUrl='<%# Eval("URL") %>'
Target="_blank">
            <img src='<%# Eval("URL") %>'  alt="Read online" />
        </asp:HyperLink>
    </ItemTemplate>
</asp:TemplateField>

Or

<asp:TemplateField>
    <ItemTemplate>
            <asp:ImageButton ID="imgRedirect" runat="server" ImageUrl='<%# Eval("Image_URL") %>'
            OnClick="Redirect" AlternateText="Read online" />
    </ItemTemplate>
</asp:TemplateField>

Thank You.