In controller:
public ActionResult MyImage()
{
byte[] image = .....;
return File(image, "image/png");
}
In view:
<img src="@Url.Action("MyImage", "ControllerName")" alt="my image" />
http://rayaspnet.blogspot.ca/2012/06/how-to-covert-string-to-image-in-mvc.html