In ASP.NET MVC how can use I Url.Content() from code?

VirtualPathUtility.ToAbsolute("~/url/");

public static string CustomImage(this HtmlHelper html)
{
    var Url = new UrlHelper(html.ViewContext.RequestContext);
}

public static string MyHelper(this HtmlHelper h)
{
      string url = h.ViewContext.HttpContext.Request.Url.AbsoluteUri;
}

string relativePath =
VirtualPathUtility.MakeRelative(Request.RawUrl, "~/myFolder/myImage.png");

string fullUrl = HttpContext.Current.Request.Url.AbsoluteUri;