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pdf_images.py
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/
pdf_images.py
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# -*- coding: utf-8 -*-
"""
The Python PDF Toolkit
Copyright ©2016 Ronan Paixão
Licensed under the terms of the MIT License.
See LICENSE.txt for details.
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
@author: Ronan Paixão, with some code from
http://stackoverflow.com/questions/2693820/extract-images-from-pdf-without-resampling-in-python
"""
import struct
import base64
from PIL import Image
try:
from cStringIO import StringIO as BytesIO
except ModuleNotFoundError: # Py3
from io import BytesIO
from reportlab.pdfgen import canvas
from reportlab.lib.utils import ImageReader
from io import BytesIO
import PyPDF2 as pdf
img_modes = {'/DeviceRGB': 'RGB', '/DefaultRGB': 'RGB',
'/DeviceCMYK': 'CMYK', '/DefaultCMYK': 'CMYK',
'/DeviceGray': 'L', '/DefaultGray': 'L',
'/Indexed': 'P'}
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
)
def extract_images(page, filename_prefix="IMG_", start_index=0):
if '/XObject' not in page['/Resources']:
return start_index
xObject = page['/Resources']['/XObject'].getObject()
i = start_index
for obj in xObject:
if xObject[obj]['/Subtype'] == '/Image':
filt = xObject[obj].get('/Filter', 'raw')
print("extracting {} {} to {}{:04}.xxx".format(obj, filt, filename_prefix, i))
size = (xObject[obj]['/Width'], xObject[obj]['/Height'])
color_space = xObject[obj]['/ColorSpace']
if isinstance(color_space, pdf.generic.ArrayObject) and color_space[0] == '/Indexed':
color_space, base, hival, lookup = [v.getObject() for v in color_space] # pg 262
if isinstance(color_space, pdf.generic.ArrayObject) and color_space[0] == '/ICCBased':
color_space, components = [v.getObject() for v in color_space] # pg 274
if color_space == '/ICCBased':
mode = {1: 'P', 3: 'RGB', '4': 'CMYK'}.get(components['/N'])
else:
mode = img_modes[color_space]
# xObject[obj].getData() does not work for DCTDecode, JPXDecode and
# CCITTFaxDecode
if '/FlateDecode' in filt:
data = xObject[obj].getData()
else:
data = xObject[obj]._data # # for /FlateDecode only?
if data.endswith(b'~>'):
data = base64.a85decode(data, adobe=True)
if isinstance(filt, list):
while len(filt) > 1:
first_filter = filt.pop(0)
if first_filter == '/ASCII85Decode':
continue
else:
print("Unsupported filter:", first_filter)
return i
filt = filt[0]
if filt == '/FlateDecode':
img = Image.frombytes(mode, size, data)
fmt = 'jpg' if mode == 'CMYK' else 'png'
if color_space == '/Indexed':
rawmode = img_modes[base]
if rawmode == 'RGB':
img.putpalette(lookup.getData(), rawmode)
img = img.convert('RGB')
else: # Pillow's ImagePalette only supports RGB
if rawmode in {'RGBA', 'CMYK'}:
n = 4
else:
n = 3
palette = lookup.getData()
palette = [palette[i:i + n] for i in range(0, len(palette), n)]
data2 = b''.join([palette[b] for b in data])
img = Image.frombytes(rawmode, size, data2)
fmt = 'jpg'
img_fname = "{}{:04}.{}".format(filename_prefix, i, fmt)
img.save(img_fname)
elif filt == '/DCTDecode':
img_fname = "{}{:04}.jpg".format(filename_prefix, i)
img = open(img_fname, "wb")
img.write(data)
img.close()
elif filt == '/JPXDecode':
img_fname = "{}{:04}.jp2".format(filename_prefix, i)
img = open(img_fname, "wb")
img.write(data)
img.close()
# 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)
elif filt == '/CCITTFaxDecode':
if xObject[obj]['/DecodeParms']['/K'] == -1:
CCITT_group = 4
else:
CCITT_group = 3
width = xObject[obj]['/Width']
height = xObject[obj]['/Height']
img_size = len(data)
tiff_header = tiff_header_for_CCITT(width, height, img_size, CCITT_group)
img_fname = "{}{:04}.tiff".format(filename_prefix, i)
with open(img_fname, 'wb') as img_file:
img_file.write(tiff_header + data)
elif filt == 'raw':
img = Image.frombytes('CMYK', size, data)
img_fname = "{}{:04}.jpg".format(filename_prefix, i)
img.save(img_fname)
# Try to insert ICC profile
if color_space == '/ICCBased':
img = Image.open(img_fname)
img.save(img_fname, icc_profile=components.getData())
# Grabbing image mask and applying it to another image
# TODO: support the /Mask property (pg 341, 351)
# wish I had a test file
if '/SMask' in xObject[obj]: # Soft mask (pg 341)
# Simplified image loading. Masks should only be black & white
# or grayscale
msize = (xObject[obj]['/SMask']['/Width'],
xObject[obj]['/SMask']['/Height'])
mcolor_space = xObject[obj]['/SMask']['/ColorSpace']
mmode = img_modes[mcolor_space]
mdata = data = xObject[obj]['/SMask'].getData()
mask = Image.frombytes(mmode, msize, mdata)
img = Image.open(img_fname)
if img.mode not in {'RGB', 'RGBA'}:
img = img.convert('RGBA')
img.putalpha(mask)
img.save("{}{:04}_masked.png".format(filename_prefix, i))
i += 1
return i
def image_to_pdf(image_filename, page_size_cm):
tmp = BytesIO()
image_reader = ImageReader(image_filename)
size_pdf = [s/2.54*72 for s in page_size_cm] # cm->in->1/72" (PDF unit)
output_pdf = canvas.Canvas(tmp, pagesize=size_pdf)
output_pdf.drawImage(image_reader, 0, 0, *size_pdf, mask='auto')
output_pdf.showPage()
output_pdf.save()
tmp.seek(0)
return tmp