MVC - Resize an image

It turns out there is a helper class in the System.Web namespace for treating images. This class, WebImage, makes things like resizing e.g. a user profile picture when it is uploaded very easy:

public void FormatPicture(HttpPostedFileBase file) {
  WebImage image = new WebImage(file.InputStream);
  if (image.Width > 85 || image.Height > 85) {
    int w = image.Width;
    int h = image.Height;
    if (w > h) {
      w = 85;
      h = image.Height * w / image.Width;
    }
    else {
      h = 85;
      w = image.Width * h / image.Height;
    }
    image.Resize(w, h);
  }
  image.Save(PictureFilepath);
}

The HttpPostedFileBase file comes from the view model and contains the uploaded image from the file control. In this example the image is resized to a maximum of 85 pixels, with the smaller dimension interpolated, and stored.