在带有用于CCITTFaxDecode过滤器的PyPDF2的Python中：

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 = '

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()