New Post: please help

using (MagickImage image = new MagickImage("test.bmp"))
{
  image.ColorFuzz = new Percentage(20); // -fuzz 20%
  image.Opaque(new MagickColor("#c62122"), MagickColors.Black); // -fill black -opaque "#c62122"
  image.Threshold(new Percentage(1)); // -threshold 1%
  image.Write("convert.bmp");
}

using (Bitmap bitmap = new Bitmap("input.bmp"))
{
  using (MagickImage image = new MagickImage(bitmap))
  {
    return image.ToBitmap();
  }
}