Simple helper renderer

UmbImage.cs

using umbraco.NodeFactory;

namespace Sample.Web.UI
{
	public class UmbImage : System.Web.UI.HtmlControls.HtmlImage
	{
		public string Field
		{
			set
			{
				string mediaUrl = Node.GetCurrent().GetOptionalMediaUrl(value); //Extension method. Could be more defensive
				base.Src = mediaUrl;
			}
		}
	}
}