private void AddImageToPDF(string imagePath, ref PdfDocument doc)
{
    Image MyImage = Image.FromFile(imagePath);
    AddImageToPDF(MyImage, ref doc);
}

private void AddImageToPDF(Image image, ref PdfDocument doc)
{
    try
    {
        int numPages = doc.Pages.Count;
        using (Image MyImage = image)
        {
            for (int _pageIndex = 0; _pageIndex < MyImage.GetFrameCount(FrameDimension.Page); _pageIndex++)
            {
                MyImage.SelectActiveFrame(FrameDimension.Page, _pageIndex);

                XImage img = XImage.FromGdiPlusImage(MyImage);
                img.Interpolate = true;

                var page = new PdfPage() { Orientation = img.PixelWidth > img.PixelHeight ? PageOrientation.Landscape : PageOrientation.Portrait };
                doc.Pages.Add(page);

                using (var xg = XGraphics.FromPdfPage(doc.Pages[_pageIndex + numPages]))
                {
                    xg.DrawImage(img, 0, 0);
                }
            }
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.Message);
    }
}

    /// <summary>
    /// check if the image exists, or if the image is png
    /// if the image is png then I just read the images bytes
    /// else I convert the image from whatever type she is to png and then read the bytes
    /// </summary>
    /// <param name="imageName">the name of the image that is about to be read</param>
    /// <returns>byte array of the image data </returns>
    public static byte[] GetBytesFromImage(string imageName)
    {
        byte[] bytes = null;

        string imagePath = "..\\..\\Imagens";
        imageName = imageName == "" ? "some_default_image.jpg" : imageName;
        string fpath = imagePath + imageName;


        if (File.Exists(fpath) && imageName.EndsWith("png"))
        {
            using (MemoryStream ms = new MemoryStream())
            using (FileStream imageStream = new FileStream(fpath, FileMode.Open, FileAccess.Read))
            {
                imageStream.CopyTo(ms);
                bytes = ms.ToArray();
            }
        }
        else
        {
            using (MemoryStream image = new MemoryStream())
            using (System.Drawing.Image bmpImageToConvert = System.Drawing.Image.FromFile(fpath))
            using (System.Drawing.Image bmpNewImage = new Bitmap(bmpImageToConvert.Width, bmpImageToConvert.Height))
            using (Graphics gfxNewImage = Graphics.FromImage(bmpNewImage))
            {
                gfxNewImage.DrawImage(bmpImageToConvert, new Rectangle(0, 0, bmpNewImage.Width, bmpNewImage.Height), 0, 0, bmpImageToConvert.Width, bmpImageToConvert.Height, GraphicsUnit.Pixel);

                bmpNewImage.Save(image, ImageFormat.Png);
                bytes = image.ToArray();
            }
        }

        return bytes;
    }

    /// <summary>
    /// Get the instance of a MigraDoc.DocumentObjectModel.Shapes.Image from byte[]
    /// using XImage from PdfSharp to set the width and height automatically.
    /// </summary>
    /// <param name="img">byte array of the image data</param>
    /// <returns>instance of MigraDoc.DocumentObjectModel.Shapes.Image</returns>
    public static MigraDoc.DocumentObjectModel.Shapes.Image GetImageInstance(byte[] img)
    {
        MigraDoc.DocumentObjectModel.Shapes.Image image = null;

        using (MemoryStream stream = new MemoryStream(img))
        using (PdfSharp.Drawing.XImage imageAux = PdfSharp.Drawing.XImage.FromStream(stream))
        {
            image = new MigraDoc.DocumentObjectModel.Shapes.Image("base64:" + Convert.ToBase64String(img));
            image.Width  = imageAux.PointWidth;
            image.Height = imageAux.PointHeight;
        }

        return image;
    }