title: .Net Core unable to use Bitmap
body: <p>I am working on a Web Service using .Net Core 2.1.</p>
  
  <p>I have a byte array containing all pixels values (in grey scale), a width, a height. I want to create a bitmap from theses parameters.</p>
  
  <p>There is my code (from a working .Net Framework 4 project) :</p>
  
  <pre><code>public FileResult PostSealCryptItem(Byte[] matrix, int width, int height)
  {
      Bitmap bmp = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
      for (int y = 0; y &lt; height; y++)
          for (int x = 0; x &lt; width; x++)
              bmp.SetPixel(x, y, Color.FromArgb(ToArgb(matrix, x, y)));
  
      Byte[] data = BitmapToByteArray(bmp);
      FileContentResult result = new FileContentResult(data , "image/png");
  
      return result;
  }
  </code></pre>
  
  <p>But in .NET Core, I've the error :</p>
  
  <blockquote>
    <p>The type or namespace name 'Bitmap' could not be found (are you missing a using directive or an assembly reference?) </p>
  </blockquote>
  
  <p>I've try to add reference to System.Drawing but it did not work.</p>