internal static byte[] BildRendern(byte[] document, int targetWidth, int targetHeight)
{
	var doc = PdfDocument.Load(document);
	using (var page = doc.Pages[0])
	{
		using (MemoryStream bitmapStream = new MemoryStream())
		{
			using (var bitmap = new Bitmap(targetWidth, targetHeight))
			{
				using (var g = Graphics.FromImage(bitmap))
				{
					g.FillRectangle(new System.Drawing.SolidBrush(System.Drawing.Color.White), 0, 0, targetWidth, targetHeight);
					using (var pdfBitmap = new PdfBitmap(targetWidth, targetHeight, true))
					{
						page.Render(pdfBitmap, 0, 0, targetWidth, targetHeight, PageRotate.Normal, RenderFlags.FPDF_ANNOT | RenderFlags.FPDF_LCD_TEXT);
						g.DrawImageUnscaled(pdfBitmap.Image, 0, 0);
					}
				}

				bitmap.Save(bitmapStream, ImageFormat.Bmp);
				return bitmapStream.ToArray();
			}
		}
	}
}