从PDF中的特定页面提取图像
我想从PDF文件中提取图像。 我尝试使用以下代码，它从PDF中完美地提取了一个jpeg图像。 问题是如何从特定页面（例如第1页）或其他页面中提取图像。 我不想阅读整个PDF来搜索图像。
有什么建议？
提取图像的代码：
private void List ExtractImages(String PDFSourcePath) { List ImgList = new List(); iTextSharp.text.pdf.RandomAccessFileOrArray RAFObj = null; iTextSharp.text.pdf.PdfReader PDFReaderObj = null; iTextSharp.text.pdf.PdfObject PDFObj = null; iTextSharp.text.pdf.PdfStream PDFStremObj = null; try { RAFObj = new iTextSharp.text.pdf.RandomAccessFileOrArray(PDFSourcePath); PDFReaderObj = new iTextSharp.text.pdf.PdfReader(RAFObj, null); for (int i = 0; i <= PDFReaderObj.XrefSize - 1; i++) { PDFObj = PDFReaderObj.GetPdfObject(i); if ((PDFObj != null) && PDFObj.IsStream()) { PDFStremObj = (iTextSharp.text.pdf.PdfStream)PDFObj; iTextSharp.text.pdf.PdfObject subtype = PDFStremObj.Get(iTextSharp.text.pdf.PdfName.SUBTYPE); if ((subtype != null) && subtype.ToString() == iTextSharp.text.pdf.PdfName.IMAGE.ToString()) { byte[] bytes = iTextSharp.text.pdf.PdfReader.GetStreamBytesRaw((iTextSharp.text.pdf.PRStream)PDFStremObj); if ((bytes != null)) { try { System.IO.MemoryStream MS = new System.IO.MemoryStream(bytes); MS.Position = 0; System.Drawing.Image ImgPDF = System.Drawing.Image.FromStream(MS); pictureBox1.Image = ImgPDF; MS.Close(); MS.Flush(); } catch (Exception) { } } } } } PDFReaderObj.Close(); } catch (Exception ex) { throw new Exception(ex.Message); } } 我目前没有iTextSharp 4.0可用，因此这段代码的目标是5.2，但它对老版本也应该可以正常工作。 此代码几乎直接来自此post ，所以请查看该post以及进一步问题的回复。 正如我在上面的评论中所说，您的代码正在查看文档透视图中的所有图像，而我链接的代码逐页进行。
请阅读另一篇文章中的所有评论，特别是这篇文章解释说这只适用于JPG图像。 PDF支持很多不同类型的图像，除非你知道你只处理JPG，否则你需要添加更多的代码。 有关提示，请参阅此帖和此帖 。
string testFile = System.IO.Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Doc1.pdf"); string outputPath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop); int pageNum = 1; PdfReader pdf = new PdfReader(testFile); PdfDictionary pg = pdf.GetPageN(pageNum); PdfDictionary res = (PdfDictionary)PdfReader.GetPdfObject(pg.Get(PdfName.RESOURCES)); PdfDictionary xobj = (PdfDictionary)PdfReader.GetPdfObject(res.Get(PdfName.XOBJECT)); if (xobj == null) { return; } foreach (PdfName name in xobj.Keys) { PdfObject obj = xobj.Get(name); if (!obj.IsIndirect()) { continue; } PdfDictionary tg = (PdfDictionary)PdfReader.GetPdfObject(obj); PdfName type = (PdfName)PdfReader.GetPdfObject(tg.Get(PdfName.SUBTYPE)); if (!type.Equals(PdfName.IMAGE)) { continue; } int XrefIndex = Convert.ToInt32(((PRIndirectReference)obj).Number.ToString(System.Globalization.CultureInfo.InvariantCulture)); PdfObject pdfObj = pdf.GetPdfObject(XrefIndex); PdfStream pdfStrem = (PdfStream)pdfObj; byte[] bytes = PdfReader.GetStreamBytesRaw((PRStream)pdfStrem); if (bytes == null) { continue; } using (System.IO.MemoryStream memStream = new System.IO.MemoryStream(bytes)) { memStream.Position = 0; System.Drawing.Image img = System.Drawing.Image.FromStream(memStream); if (!Directory.Exists(outputPath)) Directory.CreateDirectory(outputPath); string path = Path.Combine(outputPath, String.Format(@"{0}.jpg", pageNum)); System.Drawing.Imaging.EncoderParameters parms = new System.Drawing.Imaging.EncoderParameters(1); parms.Param[0] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Compression, 0); var jpegEncoder = ImageCodecInfo.GetImageEncoders().ToList().Find(x => x.FormatID == ImageFormat.Jpeg.Guid); img.Save(path, jpegEncoder, parms); } }
以下是我用于从PDF中提取图像的代码。 它对我来说完全没问题。
// Required: iTextSharp.dll using System.Drawing; using System.Drawing.Imaging; using System.IO; using iTextSharp.text.pdf.parser; using Dotnet = System.Drawing.Image; using iTextSharp.text.pdf; namespace PDF_Parsing { partial class ExtractPdfImage { string imgPath = @"c:\extractedImg.png"; private void ExtractImage(string pdfFile) { const int pageNumber = 1; PdfReader pdf = new PdfReader(pdfFile); PdfDictionary pg = pdf.GetPageN(pageNumber); PdfDictionary res = (PdfDictionary)PdfReader.GetPdfObject(pg.Get(PdfName.RESOURCES)); PdfDictionary xobj = (PdfDictionary)PdfReader.GetPdfObject(res.Get(PdfName.XOBJECT)); foreach (PdfName name in xobj.Keys) { PdfObject obj = xobj.Get(name); if (obj.IsIndirect()) { PdfDictionary tg = (PdfDictionary)PdfReader.GetPdfObject(obj); string width = tg.Get(PdfName.WIDTH).ToString(); string height = tg.Get(PdfName.HEIGHT).ToString(); ImageRenderInfo imgRI = ImageRenderInfo.CreateForXObject(new Matrix(float.Parse(width), float.Parse(height)), (PRIndirectReference)obj, tg); RenderImage(imgRI); } } } private void RenderImage(ImageRenderInfo renderInfo) { PdfImageObject image = renderInfo.GetImage(); using (Dotnet dotnetImg = image.GetDrawingImage()) { if (dotnetImg != null) { using (MemoryStream ms = new MemoryStream()) { dotnetImg.Save(ms, ImageFormat.Tiff); Bitmap d = new Bitmap(dotnetImg); d.Save(imgPath); } } } } } }
以下代码可以从特定页面中提取图像。
using System.Drawing; using System.Drawing.Imaging; using System.IO; using iTextSharp.text.pdf.parser; using Dotnet = System.Drawing.Image; using iTextSharp.text.pdf; namespace PDF_Parsing { partial class PDF_ImgExtraction { string imgPath; private void ExtractImage(string pdfFile) { const int pageNumber = 1;//Page number to extract the image from PdfReader pdf = new PdfReader(pdfFile); PdfDictionary pg = pdf.GetPageN(pageNumber); PdfDictionary res = (PdfDictionary)PdfReader.GetPdfObject(pg.Get(PdfName.RESOURCES)); PdfDictionary xobj = (PdfDictionary)PdfReader.GetPdfObject(res.Get(PdfName.XOBJECT)); foreach (PdfName name in xobj.Keys) { PdfObject obj = xobj.Get(name); if (obj.IsIndirect()) { PdfDictionary tg = (PdfDictionary)PdfReader.GetPdfObject(obj); string width = tg.Get(PdfName.WIDTH).ToString(); string height = tg.Get(PdfName.HEIGHT).ToString(); ImageRenderInfo imgRI = ImageRenderInfo.CreateForXObject(new Matrix(float.Parse(width), float.Parse(height)), (PRIndirectReference)obj, tg); RenderImage(imgRI); } } } private void RenderImage(ImageRenderInfo renderInfo) { PdfImageObject image = renderInfo.GetImage(); using (Dotnet dotnetImg = image.GetDrawingImage()) { if (dotnetImg != null) { using (MemoryStream ms = new MemoryStream()) { dotnetImg.Save(ms, ImageFormat.Tiff); Bitmap d = new Bitmap(dotnetImg); d.Save(imgPath); } } } } } }