C#将PDF转为多种图像文件格式的方法（Png/Bmp/Emf/Tiff）

using Spire.Pdf;
using System.Drawing;
namespace PDFtoImage1
{
  class Program
  {
    static void Main(string[] args)
    {
      //初始化一个PdfDocument类实例,并加载PDF文档
      PdfDocument doc = new PdfDocument();
      doc.LoadFromFile(@"C:\Users\Administrator\Desktop\sample.pdf");
      //遍历PDF每一页
      for (int i = 0; i < doc.Pages.Count; i++)
      {
        //将PDF页转换成Bitmap图形
        System.Drawing.Image bmp = doc.SaveAsImage(i);
        //将Bitmap图形保存为Png格式的图片
        string fileName = string.Format("Page-{0}.png", i + 1);
        bmp.Save(fileName, System.Drawing.Imaging.ImageFormat.Png);
      }
    }
  }
}

using System;
using System.Drawing;
using System.Drawing.Imaging;
using Spire.Pdf;
namespace SavePdfAsTiff
{
  class Program
  {
    static void Main(string[] args)
    {
      //创建一个PdfDocument类对象，并加载PDF文档
      PdfDocument document = new PdfDocument();
      document.LoadFromFile(@"C:\Users\Administrator\Desktop\sample.pdf");
      //调用方法SaveAsImage()将PDF文档保存为tiff格式
      JoinTiffImages(SaveAsImage(document), "result.tiff", EncoderValue.CompressionLZW);
      System.Diagnostics.Process.Start("result.tiff");
    }
    //自定义方法SaveAsImage()将PDF文档保存图像文件
    private static Image[] SaveAsImage(PdfDocument document)
    {
      Image[] images = new Image[document.Pages.Count];
      for (int i = 0; i < document.Pages.Count; i++)
      {
        images[i] = document.SaveAsImage(i);
      }
      return images;
    }
    private static ImageCodecInfo GetEncoderInfo(string mimeType)
    {
      ImageCodecInfo[] encoders = ImageCodecInfo.GetImageEncoders();
      for (int j = 0; j < encoders.Length; j++)
      {
        if (encoders[j].MimeType == mimeType)
          return encoders[j];
      }
      throw new Exception(mimeType + " mime type not found in ImageCodecInfo");
    }
    //自定义JoinTiffImages()方法，使用指定编码器和图像编码器参数将图像从pdf页面保存到tiff图像类型，。
    public static void JoinTiffImages(Image[] images, string outFile, EncoderValue compressEncoder)
    {
      Encoder enc = Encoder.SaveFlag;
      EncoderParameters ep = new EncoderParameters(2);
      ep.Param[0] = new EncoderParameter(enc, (long)EncoderValue.MultiFrame);
      ep.Param[1] = new EncoderParameter(Encoder.Compression, (long)compressEncoder);
      Image pages = images[0];
      int frame = 0;
      ImageCodecInfo info = GetEncoderInfo("image/tiff");
      foreach (Image img in images)
      {
        if (frame == 0)
        {
          pages = img;
          pages.Save(outFile, info, ep);
        }
        else
        {
          ep.Param[0] = new EncoderParameter(enc, (long)EncoderValue.FrameDimensionPage);
          pages.SaveAdd(img, ep);
        }
        if (frame == images.Length - 1)
        {
          ep.Param[0] = new EncoderParameter(enc, (long)EncoderValue.Flush);
          pages.SaveAdd(ep);
        }
        frame++;
      }
    }
  }
}

using Spire.Pdf;
using System.Drawing;
using System.Drawing.Imaging;
namespace PDFtoImage
{
  class Program
  {
    static void Main(string[] args)
    {
      //实例化一个PdfDocument类对象，并加载PDF文档
      PdfDocument doc = new PdfDocument();
      doc.LoadFromFile(@"C:\Users\Administrator\Desktop\sample.pdf");
      //调用方法SaveAsImage()将PDF第二页保存为Bmp格式
      Image bmp = doc.SaveAsImage(1);
      //调用另一个SaveAsImage()方法，并将指定页面保存保存为Emf、Png   
      Image emf = doc.SaveAsImage(0, Spire.Pdf.Graphics.PdfImageType.Metafile);
      Image zoomImg = new Bitmap((int)(emf.Size.Width * 2), (int)(emf.Size.Height * 2));
      using (Graphics g = Graphics.FromImage(zoomImg))
      {
        g.ScaleTransform(2.0f, 2.0f);
        g.DrawImage(emf, new Rectangle(new Point(0, 0), emf.Size), new Rectangle(new Point(0, 0), emf.Size), GraphicsUnit.Pixel);
      }
      //命名保存的文件并打开
      bmp.Save("convertToBmp.bmp", ImageFormat.Bmp);
      System.Diagnostics.Process.Start("convertToBmp.bmp");
      emf.Save("convertToEmf.emf", ImageFormat.Emf);
      System.Diagnostics.Process.Start("convertToEmf.emf");
      zoomImg.Save("convertToZoom.png", ImageFormat.Png);
      System.Diagnostics.Process.Start("convertToZoom.png");
    }
  }
}