Extraire des images en utilisant iTextSharp

Question

J'ai utilisé ce code avec beaucoup de succès pour retirer la première image trouvée dans chaque page d'un PDF. Cependant, il ne fonctionne pas avec certains nouveaux fichiers PDF pour une raison inconnue. J'ai utilisé d'autres outils (Datalogics, etc) qui tirent bien les images avec ces nouveaux PDF. Cependant, je ne veux pas acheter Datalogics ou n'importe quel outil si je peux utiliser iTextSharp. Quelqu'un peut-il me dire pourquoi ce code ne trouve pas les images dans le PDF?

Connues: mes fichiers PDF ont seulement 1 image par page et rien d'autre.

using iTextSharp.text; 
using iTextSharp.text.pdf; 
... 
public static void ExtractImagesFromPDF(string sourcePdf, string outputPath) 
{ 
    // NOTE: This will only get the first image it finds per page. 
    PdfReader pdf = new PdfReader(sourcePdf); 
    RandomAccessFileOrArray raf = new iTextSharp.text.pdf.RandomAccessFileOrArray(sourcePdf); 

    try 
    { 
     for (int pageNumber = 1; pageNumber <= pdf.NumberOfPages; pageNumber++) 
     { 
      PdfDictionary pg = pdf.GetPageN(pageNumber); 
      PdfDictionary res = (PdfDictionary)PdfReader.GetPdfObject(pg.Get(PdfName.RESOURCES)); 

      PdfDictionary xobj = (PdfDictionary)PdfReader.GetPdfObject(res.Get(PdfName.XOBJECT)); 
      if (xobj != null) 
      { 
       foreach (PdfName name in xobj.Keys) 
       { 
        PdfObject obj = xobj.Get(name); 
        if (obj.IsIndirect()) 
        { 
         PdfDictionary tg = (PdfDictionary)PdfReader.GetPdfObject(obj); 
         PdfName type = (PdfName)PdfReader.GetPdfObject(tg.Get(PdfName.SUBTYPE)); 
         if (PdfName.IMAGE.Equals(type)) 
         { 
          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)) 
          { 
           using (System.IO.MemoryStream memStream = new System.IO.MemoryStream(bytes)) 
           { 
            memStream.Position = 0; 
            System.Drawing.Image img = System.Drawing.Image.FromStream(memStream); 
            // must save the file while stream is open. 
            if (!Directory.Exists(outputPath)) 
             Directory.CreateDirectory(outputPath); 

            string path = Path.Combine(outputPath, String.Format(@"{0}.jpg", pageNumber)); 
            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); 
            System.Drawing.Imaging.ImageCodecInfo jpegEncoder = Utilities.GetImageEncoder("JPEG"); 
            img.Save(path, jpegEncoder, parms); 
            break; 
           } 
          } 
         } 
        } 
       } 
      } 
     } 
    } 

    catch 
    { 
     throw; 
    } 
    finally 
    { 
     pdf.Close(); 
     raf.Close(); 
    } 
} 

Answer 1

J'ai trouvé que mon problème était que je ne cherchais pas récursivement à l'intérieur des formulaires et des groupes pour les images. Fondamentalement, le code original ne trouverait que les images qui ont été incorporées à la racine du document pdf. Voici la méthode révisée plus une nouvelle méthode (FindImageInPDFDictionary) qui recherche récursivement des images dans la page. REMARQUE: les défauts de prise en charge uniquement des images JPEG et non compressées s'appliquent toujours. Voir le code de R Ubben pour les options permettant de corriger ces failles. HTH quelqu'un.

public static void ExtractImagesFromPDF(string sourcePdf, string outputPath) 
    { 
     // NOTE: This will only get the first image it finds per page. 
     PdfReader pdf = new PdfReader(sourcePdf); 
     RandomAccessFileOrArray raf = new iTextSharp.text.pdf.RandomAccessFileOrArray(sourcePdf); 

     try 
     { 
      for (int pageNumber = 1; pageNumber <= pdf.NumberOfPages; pageNumber++) 
      { 
       PdfDictionary pg = pdf.GetPageN(pageNumber); 

       // recursively search pages, forms and groups for images. 
       PdfObject obj = FindImageInPDFDictionary(pg); 
       if (obj != null) 
       { 

        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)) 
        { 
         using (System.IO.MemoryStream memStream = new System.IO.MemoryStream(bytes)) 
         { 
          memStream.Position = 0; 
          System.Drawing.Image img = System.Drawing.Image.FromStream(memStream); 
          // must save the file while stream is open. 
          if (!Directory.Exists(outputPath)) 
           Directory.CreateDirectory(outputPath); 

          string path = Path.Combine(outputPath, String.Format(@"{0}.jpg", pageNumber)); 
          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); 
          System.Drawing.Imaging.ImageCodecInfo jpegEncoder = Utilities.GetImageEncoder("JPEG"); 
          img.Save(path, jpegEncoder, parms); 
         } 
        } 
       } 
      } 
     } 
     catch 
     { 
      throw; 
     } 
     finally 
     { 
      pdf.Close(); 
      raf.Close(); 
     } 


    } 

    private static PdfObject FindImageInPDFDictionary(PdfDictionary pg) 
    { 
     PdfDictionary res = 
      (PdfDictionary)PdfReader.GetPdfObject(pg.Get(PdfName.RESOURCES)); 


     PdfDictionary xobj = 
      (PdfDictionary)PdfReader.GetPdfObject(res.Get(PdfName.XOBJECT)); 
     if (xobj != null) 
     { 
      foreach (PdfName name in xobj.Keys) 
      { 

       PdfObject obj = xobj.Get(name); 
       if (obj.IsIndirect()) 
       { 
        PdfDictionary tg = (PdfDictionary)PdfReader.GetPdfObject(obj); 

        PdfName type = 
         (PdfName)PdfReader.GetPdfObject(tg.Get(PdfName.SUBTYPE)); 

        //image at the root of the pdf 
        if (PdfName.IMAGE.Equals(type)) 
        { 
         return obj; 
        }// image inside a form 
        else if (PdfName.FORM.Equals(type)) 
        { 
         return FindImageInPDFDictionary(tg); 
        } //image inside a group 
        else if (PdfName.GROUP.Equals(type)) 
        { 
         return FindImageInPDFDictionary(tg); 
        } 

       } 
      } 
     } 

     return null; 

    } 

Answer 2

Ce qui précède fonctionne uniquement avec les fichiers JPEG. En excluant les images en ligne et les fichiers incorporés, vous devez parcourir les objets du sous-type IMAGE, puis regarder le filtre et prendre les mesures appropriées. Voici un exemple, en supposant que nous avons un sous-type de PdfObject IMAGE:

  PdfReader pdf = new PdfReader("c:\\temp\\exp0.pdf"); 
     int xo=pdf.XrefSize; 
     for (int i=0;i<xo;i++) 
     { 
      PdfObject obj=pdf.GetPdfObject(i); 
      if (obj!=null && obj.IsStream()) 
      { 
       PdfDictionary pd=(PdfDictionary)obj; 
       if (pd.Contains(PdfName.SUBTYPE) && pd.Get(PdfName.SUBTYPE).ToString()=="/Image") 
       { 
        string filter=pd.Get(PdfName.FILTER).ToString(); 
        string width=pd.Get(PdfName.WIDTH).ToString(); 
        string height=pd.Get(PdfName.HEIGHT).ToString(); 
        string bpp=pd.Get(PdfName.BITSPERCOMPONENT).ToString(); 
        string extent="."; 
        byte [] img=null; 
        switch (filter) 
        { 
         case "/FlateDecode": 
          byte[] arr=PdfReader.FlateDecode(PdfReader.GetStreamBytesRaw((PRStream)obj),true); 
          Bitmap bmp=new Bitmap(Int32.Parse(width),Int32.Parse(height),PixelFormat.Format24bppRgb); 
          BitmapData bmd=bmp.LockBits(new Rectangle(0,0,Int32.Parse(width),Int32.Parse(height)),ImageLockMode.WriteOnly, 
           PixelFormat.Format24bppRgb); 
          Marshal.Copy(arr,0,bmd.Scan0,arr.Length); 
          bmp.UnlockBits(bmd); 
          bmp.Save("c:\\temp\\bmp1.png",ImageFormat.Png); 
          break; 
         default: 
          break; 
        } 
       } 
      } 
     } 

Ce gâchera la couleur à cause de Microsoft BGR, bien sûr, mais je voulais le garder court. Faire quelque chose de similaire pour "/ CCITTFaxDecode", etc.

Answer 3

Le code suivant intègre toutes les idées de Dave et R Ubben ci-dessus, plus il retourne une liste complète de toutes les images et traite également de multiples profondeurs de bits. Je devais le convertir en VB pour le projet, je travaille sur bien, désolé ...

Private Sub getAllImages(ByVal dict As pdf.PdfDictionary, ByVal images As List(Of Byte()), ByVal doc As pdf.PdfReader) 
    Dim res As pdf.PdfDictionary = CType(pdf.PdfReader.GetPdfObject(dict.Get(pdf.PdfName.RESOURCES)), pdf.PdfDictionary) 
    Dim xobj As pdf.PdfDictionary = CType(pdf.PdfReader.GetPdfObject(res.Get(pdf.PdfName.XOBJECT)), pdf.PdfDictionary) 

    If xobj IsNot Nothing Then 
     For Each name As pdf.PdfName In xobj.Keys 
      Dim obj As pdf.PdfObject = xobj.Get(name) 
      If (obj.IsIndirect) Then 
       Dim tg As pdf.PdfDictionary = CType(pdf.PdfReader.GetPdfObject(obj), pdf.PdfDictionary) 
       Dim subtype As pdf.PdfName = CType(pdf.PdfReader.GetPdfObject(tg.Get(pdf.PdfName.SUBTYPE)), pdf.PdfName) 
       If pdf.PdfName.IMAGE.Equals(subtype) Then 
        Dim xrefIdx As Integer = CType(obj, pdf.PRIndirectReference).Number 
        Dim pdfObj As pdf.PdfObject = doc.GetPdfObject(xrefIdx) 
        Dim str As pdf.PdfStream = CType(pdfObj, pdf.PdfStream) 
        Dim bytes As Byte() = pdf.PdfReader.GetStreamBytesRaw(CType(str, pdf.PRStream)) 

        Dim filter As String = tg.Get(pdf.PdfName.FILTER).ToString 
        Dim width As String = tg.Get(pdf.PdfName.WIDTH).ToString 
        Dim height As String = tg.Get(pdf.PdfName.HEIGHT).ToString 
        Dim bpp As String = tg.Get(pdf.PdfName.BITSPERCOMPONENT).ToString 

        If filter = "/FlateDecode" Then 
         bytes = pdf.PdfReader.FlateDecode(bytes, True) 
         Dim pixelFormat As System.Drawing.Imaging.PixelFormat 
         Select Case Integer.Parse(bpp) 
          Case 1 
           pixelFormat = Drawing.Imaging.PixelFormat.Format1bppIndexed 
          Case 24 
           pixelFormat = Drawing.Imaging.PixelFormat.Format24bppRgb 
          Case Else 
           Throw New Exception("Unknown pixel format " + bpp) 
         End Select 
         Dim bmp As New System.Drawing.Bitmap(Int32.Parse(width), Int32.Parse(height), pixelFormat) 
         Dim bmd As System.Drawing.Imaging.BitmapData = bmp.LockBits(New System.Drawing.Rectangle(0, 0, Int32.Parse(width), Int32.Parse(height)), System.Drawing.Imaging.ImageLockMode.WriteOnly, pixelFormat) 
         Marshal.Copy(bytes, 0, bmd.Scan0, bytes.Length) 
         bmp.UnlockBits(bmd) 
         Using ms As New MemoryStream 
          bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Png) 
          bytes = ms.GetBuffer 
         End Using 
        End If 
        images.Add(bytes) 
       ElseIf pdf.PdfName.FORM.Equals(subtype) Or pdf.PdfName.GROUP.Equals(subtype) Then 
        getAllImages(tg, images, doc) 
       End If 
      End If 
     Next 
    End If 
End Sub 

Answer 4

De C# Version:

private IList<System.Drawing.Image> GetImagesFromPdfDict(PdfDictionary dict, PdfReader doc){ 
     List<System.Drawing.Image> images = new List<System.Drawing.Image>(); 
     PdfDictionary res = (PdfDictionary)(PdfReader.GetPdfObject(dict.Get(PdfName.RESOURCES))); 
     PdfDictionary xobj = (PdfDictionary)(PdfReader.GetPdfObject(res.Get(PdfName.XOBJECT))); 

     if (xobj != null) 
     { 
      foreach (PdfName name in xobj.Keys) 
      { 
       PdfObject obj = xobj.Get(name); 
       if (obj.IsIndirect()) 
       { 
        PdfDictionary tg = (PdfDictionary)(PdfReader.GetPdfObject(obj)); 
        pdf.PdfName subtype = (pdf.PdfName)(pdf.PdfReader.GetPdfObject(tg.Get(pdf.PdfName.SUBTYPE))); 
        if (pdf.PdfName.IMAGE.Equals(subtype)) 
        { 
         int xrefIdx = ((pdf.PRIndirectReference)obj).Number; 
         pdf.PdfObject pdfObj = doc.GetPdfObject(xrefIdx); 
         pdf.PdfStream str = (pdf.PdfStream)(pdfObj); 
         byte[] bytes = pdf.PdfReader.GetStreamBytesRaw((pdf.PRStream)str); 

         string filter = tg.Get(pdf.PdfName.FILTER).ToString(); 
         string width = tg.Get(pdf.PdfName.WIDTH).ToString(); 
         string height = tg.Get(pdf.PdfName.HEIGHT).ToString(); 
         string bpp = tg.Get(pdf.PdfName.BITSPERCOMPONENT).ToString(); 

         if (filter == "/FlateDecode") 
         { 
          bytes = pdf.PdfReader.FlateDecode(bytes, true); 
          System.Drawing.Imaging.PixelFormat pixelFormat; 
          switch (int.Parse(bpp)) 
          { 
           case 1: 
            pixelFormat = System.Drawing.Imaging.PixelFormat.Format1bppIndexed; 
            break; 
           case 24: 
            pixelFormat = System.Drawing.Imaging.PixelFormat.Format24bppRgb; 
            break; 
           default: 
            throw new Exception("Unknown pixel format " + bpp); 
          } 
          var bmp = new System.Drawing.Bitmap(Int32.Parse(width), Int32.Parse(height), pixelFormat); 
          System.Drawing.Imaging.BitmapData bmd = bmp.LockBits(new System.Drawing.Rectangle(0, 0, Int32.Parse(width), 
           Int32.Parse(height)), System.Drawing.Imaging.ImageLockMode.WriteOnly, pixelFormat); 
          Marshal.Copy(bytes, 0, bmd.Scan0, bytes.Length); 
          bmp.UnlockBits(bmd); 
          using (var ms = new MemoryStream()) 
          { 
           bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Png); 
           bytes = ms.GetBuffer(); 
          } 
         } 
         images.Add(System.Drawing.Image.FromStream(new MemoryStream(bytes))); 
        } 
        else if (pdf.PdfName.FORM.Equals(subtype) || pdf.PdfName.GROUP.Equals(subtype)) 
        { 
         images.AddRange(GetImagesFromPdfDict(tg, doc)); 
        } 
       } 
      } 
     } 
     return images; 
    } 

Answer 5

Voici une solution plus simple:

iTextSharp.text.pdf.parser.PdfImageObject pdfImage = 
          new iTextSharp.text.pdf.parser.PdfImageObject(imgPRStream); 
         System.Drawing.Image img = pdfImage.GetDrawingImage(); 

Answer 6

Ceci est juste une autre réhash des idées des autres, mais celui qui a fonctionné pour moi. Ici, je l'utilise @ l'image de Malco saisissant extrait avec boucle de R Ubben:

private IList<System.Drawing.Image> GetImagesFromPdfDict(PdfDictionary dict, PdfReader doc) 
{ 
    List<System.Drawing.Image> images = new List<System.Drawing.Image>(); 
    PdfDictionary res = (PdfDictionary)(PdfReader.GetPdfObject(dict.Get(PdfName.RESOURCES))); 
    PdfDictionary xobj = (PdfDictionary)(PdfReader.GetPdfObject(res.Get(PdfName.XOBJECT))); 

    if (xobj != null) 
    { 
     foreach (PdfName name in xobj.Keys) 
     { 
      PdfObject obj = xobj.Get(name); 
      if (obj.IsIndirect()) 
      { 
       PdfDictionary tg = (PdfDictionary)(PdfReader.GetPdfObject(obj)); 
       PdfName subtype = (PdfName)(PdfReader.GetPdfObject(tg.Get(PdfName.SUBTYPE))); 
       if (PdfName.IMAGE.Equals(subtype)) 
       { 
        int xrefIdx = ((PRIndirectReference)obj).Number; 
        PdfObject pdfObj = doc.GetPdfObject(xrefIdx); 
        PdfStream str = (PdfStream)(pdfObj); 

        iTextSharp.text.pdf.parser.PdfImageObject pdfImage = 
         new iTextSharp.text.pdf.parser.PdfImageObject((PRStream)str); 
        System.Drawing.Image img = pdfImage.GetDrawingImage(); 

        images.Add(img); 
       } 
       else if (PdfName.FORM.Equals(subtype) || PdfName.GROUP.Equals(subtype)) 
       { 
        images.AddRange(GetImagesFromPdfDict(tg, doc)); 
       } 
      } 
     } 
    } 

    return images; 
}