Extracting image from PDF with /CCITTFaxDecode filter

Question

I have a pdf that was generated from scanning software. The pdf has 1 TIFF image per page. I want to extract the TIFF image from each page.

I am using iTextSharp and I have successfully found the images and can get back the raw bytes from the PdfReader.GetStreamBytesRaw method. The problem is, as many before me have discovered, iTextSharp does not contain a PdfReader.CCITTFaxDecode method.

What else do I know? Even without iTextSharp I can open the pdf in notepad and find the streams with /Filter /CCITTFaxDecode and I know from the /DecodeParams that it is using CCITTFaxDecode group 4.

Does anyone out there know how I can get the CCITTFaxDecode filter images out of my pdf?

Answer 1

Actually, vbcrlfuser's answer did help me, but the code was not quite correct for the current version of BitMiracle.LibTiff.NET, as I could download it. In the current version, equivalent code looks like this:

using iTextSharp.text.pdf;
using BitMiracle.LibTiff.Classic;

...
      Tiff tiff = Tiff.Open("C:\\test.tif", "w");
      tiff.SetField(TiffTag.IMAGEWIDTH, UInt32.Parse(pd.Get(PdfName.WIDTH).ToString()));
      tiff.SetField(TiffTag.IMAGELENGTH, UInt32.Parse(pd.Get(PdfName.HEIGHT).ToString()));
      tiff.SetField(TiffTag.COMPRESSION, Compression.CCITTFAX4);
      tiff.SetField(TiffTag.BITSPERSAMPLE, UInt32.Parse(pd.Get(PdfName.BITSPERCOMPONENT).ToString()));
      tiff.SetField(TiffTag.SAMPLESPERPIXEL, 1);
      tiff.WriteRawStrip(0, raw, raw.Length);
      tiff.Close();

Using the above code, I finally got a valid Tiff file in C:\test.tif. Thank you, vbcrlfuser!

Answer 2

This library... http://www.bitmiracle.com/libtiff/ and this example below should get you 99% of the way there

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();

switch (filter)
{
   case "/CCITTFaxDecode":

      byte[] data = PdfReader.GetStreamBytesRaw((PRStream)pdfStream);
      int tiff = TIFFOpen("example.tif", "w");
      TIFFSetField(tiff, (uint)BitMiracle.LibTiff.Classic.TiffTag.IMAGEWIDTH,(uint)Int32.Parse(width));
      TIFFSetField(tiff, (uint)BitMiracle.LibTiff.Classic.TiffTag.IMAGEHEIGHT, (uint)Int32.Parse(height));
      TIFFSetField(tiff, (uint)BitMiarcle.LibTiff.Classic.TiffTag.COMPRESSION, (uint)BitMiracle.Libtiff.Classic.Compression.CCITTFAX4);
      TIFFSetField(tiff, (uint)BitMiracle.LibTiff.Classic.TiffTag.BITSPERSAMPLE, (uint)Int32.Parse(bpp));
      TIFFSetField(tiff, (uint)BitMiarcle.Libtiff.Classic.TiffTag.SAMPLESPERPIXEL,1 );

      IntPtr pointer = Marshal.AllocHGlobal(data.length);
      Marshal.copy(data, 0, pointer, data.length);
      TIFFWriteRawStrip(tiff, 0, pointer, data.length);
      TIFFClose(tiff);

      break;




      break;

}

Answer 3

Here is python implementation:

import PyPDF2
import struct

"""
Links:
PDF format: http://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/pdf_reference_1-7.pdf
CCITT Group 4: https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-T.6-198811-I!!PDF-E&type=items
Extract images from pdf: http://stackoverflow.com/questions/2693820/extract-images-from-pdf-without-resampling-in-python
Extract images coded with CCITTFaxDecode in .net: http://stackoverflow.com/questions/2641770/extracting-image-from-pdf-with-ccittfaxdecode-filter
TIFF format and tags: http://www.awaresystems.be/imaging/tiff/faq.html
"""


def tiff_header_for_CCITT(width, height, img_size, CCITT_group=4):
    tiff_header_struct = '<' + '2s' + 'h' + 'l' + 'h' + 'hhll' * 8 + 'h'
    return struct.pack(tiff_header_struct,
                       b'II',  # Byte order indication: Little indian
                       42,  # Version number (always 42)
                       8,  # Offset to first IFD
                       8,  # Number of tags in IFD
                       256, 4, 1, width,  # ImageWidth, LONG, 1, width
                       257, 4, 1, height,  # ImageLength, LONG, 1, lenght
                       258, 3, 1, 1,  # BitsPerSample, SHORT, 1, 1
                       259, 3, 1, CCITT_group,  # Compression, SHORT, 1, 4 = CCITT Group 4 fax encoding
                       262, 3, 1, 0,  # Threshholding, SHORT, 1, 0 = WhiteIsZero
                       273, 4, 1, struct.calcsize(tiff_header_struct),  # StripOffsets, LONG, 1, len of header
                       278, 4, 1, height,  # RowsPerStrip, LONG, 1, lenght
                       279, 4, 1, img_size,  # StripByteCounts, LONG, 1, size of image
                       0  # last IFD
                       )

pdf_filename = 'scan.pdf'
pdf_file = open(pdf_filename, 'rb')
cond_scan_reader = PyPDF2.PdfFileReader(pdf_file)
for i in range(0, cond_scan_reader.getNumPages()):
    page = cond_scan_reader.getPage(i)
    xObject = page['/Resources']['/XObject'].getObject()
    for obj in xObject:
        if xObject[obj]['/Subtype'] == '/Image':
            """
            The  CCITTFaxDecode filter decodes image data that has been encoded using
            either Group 3 or Group 4 CCITT facsimile (fax) encoding. CCITT encoding is
            designed to achieve efficient compression of monochrome (1 bit per pixel) image
            data at relatively low resolutions, and so is useful only for bitmap image data, not
            for color images, grayscale images, or general data.

            K < 0 --- Pure two-dimensional encoding (Group 4)
            K = 0 --- Pure one-dimensional encoding (Group 3, 1-D)
            K > 0 --- Mixed one- and two-dimensional encoding (Group 3, 2-D)
            """
            if xObject[obj]['/Filter'] == '/CCITTFaxDecode':
                if xObject[obj]['/DecodeParms']['/K'] == -1:
                    CCITT_group = 4
                else:
                    CCITT_group = 3
                width = xObject[obj]['/Width']
                height = xObject[obj]['/Height']
                data = xObject[obj]._data  # sorry, getData() does not work for CCITTFaxDecode
                img_size = len(data)
                tiff_header = tiff_header_for_CCITT(width, height, img_size, CCITT_group)
                img_name = obj[1:] + '.tiff'
                with open(img_name, 'wb') as img_file:
                    img_file.write(tiff_header + data)
                #
                # import io
                # from PIL import Image
                # im = Image.open(io.BytesIO(tiff_header + data))
pdf_file.close()

Answer 4

It has been written extension for this (c#).

PdfDictionary item;
if (item.IsImage()) {
  Image image = item.ToImage();
}