title: Converting a bitmap to monochrome
body: <p>I am trying to save an image as monochrome (black&amp;white, 1 bit-depth) but I'm coming up lost how to do it.</p>
  
  <p>I am starting with a png and converting to a bitmap for printing (it's a thermal printer and only supports black anyway - plus its slow as hell for large images if I try to send them as color/grayscale).</p>
  
  <p>My code so far is dead simple to convert it to a bitmap, but it is retaining the original colour depth.</p>
  
  <pre><code>Image image = Image.FromFile("C:\\test.png");
  
  byte[] bitmapFileData = null;
  int bitsPerPixel = 1;
  int bitmapDataLength;
  
  using (MemoryStream str = new MemoryStream())
  {
      image.Save(str, ImageFormat.Bmp);
      bitmapFileData = str.ToArray();
  }
  </code></pre>