我一直在成功使用此代碼來提取在PDF每頁中找到的第一張圖像。但是，由于某種未知的原因，它現在無法使用某些新的PDF。我使用了其他工具（Datalogics等），這些工具確實可以用這些新的PDF提取圖像。但是，如果可以使用iTextSharp，我不想購買Datalogics或任何工具。誰能告訴我為什么此代碼無法在PDF中找到圖像？已知：我的PDF每頁只有1張圖片，沒有其他內容。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))
{
}
}
}
}
}
}
}
3 回答
阿晨1998
TA貢獻2037條經驗 獲得超6個贊
這是一個更簡單的解決方案：
iTextSharp.text.pdf.parser.PdfImageObject pdfImage = new iTextSharp.text.pdf.parser.PdfImageObject(imgPRStream); System.Drawing.Image img = pdfImage.GetDrawingImage();
犯罪嫌疑人X
TA貢獻2080條經驗 獲得超4個贊
以下代碼合并了Dave和R Ubben的所有想法，并返回了所有圖像的完整列表，還處理了多個位深度。我不得不將其轉換為我正在從事的項目的VB，對此感到抱歉...
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 IfEnd Sub- 3 回答
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