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JPEG2000 support

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josch 2012-03-29 11:53:57 +02:00
parent 571266a513
commit 0bd841c530
2 changed files with 63 additions and 35 deletions
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53
README.md
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@ -1,17 +1,17 @@
img2pdf img2pdf
======= =======
Lossless conversion of images to PDF without unnecessarily re-encoding JPEG Lossless conversion of images to PDF without unnecessarily re-encoding JPEG and
files. Thus, no loss of quality and no unnecessary large output file. JPEG2000 files. Thus, no loss of quality and no unnecessary large output file.
background background
---------- ----------
PDF is able to embed JPEG images as they are without re-encoding them (and PDF is able to embed JPEG and JPEG2000 images as they are without re-encoding
hence loosing quality) but I was missing a tool to do this automatically, thus them (and hence loosing quality) but I was missing a tool to do this
I wrote this piece of python code. automatically, thus I wrote this piece of python code.
If you know how to embed JPEG images into a PDF container without If you know how to embed JPEG and JPEG2000 images into a PDF container without
recompression, using existing tools, please contact me so that I can put this recompression, using existing tools, please contact me so that I can put this
code into the garbage bin :D code into the garbage bin :D
@ -19,12 +19,12 @@ functionality
------------- -------------
The program will take image filenames from commandline arguments and output a The program will take image filenames from commandline arguments and output a
PDF file with them embedded into it. If the input image is a JPEG file, it will PDF file with them embedded into it. If the input image is a JPEG or JPEG2000
be included as-is without any processing. If it is in any other format, the file, it will be included as-is without any processing. If it is in any other
image will be included as zip-encoded RGB. As a result, this tool will be able format, the image will be included as zip-encoded RGB. As a result, this tool
to lossless wrap any image into a PDF container while performing better (in will be able to lossless wrap any image into a PDF container while performing
terms of quality/filesize ratio) than existing tools in case the input image is better (in terms of quality/filesize ratio) than existing tools in case the
a JPEG. input image is a JPEG or JPEG2000 file.
For the record, the imagemagick command to lossless convert any image to For the record, the imagemagick command to lossless convert any image to
PDF using zip-encoding, is: PDF using zip-encoding, is:
@ -32,24 +32,25 @@ PDF using zip-encoding, is:
convert input.jpg -compress Zip output.pdf convert input.jpg -compress Zip output.pdf
The downside is, that using imagemagick like this will make the resulting PDF The downside is, that using imagemagick like this will make the resulting PDF
files a few times bigger than the input JPEG and can also not output a files a few times bigger than the input JPEG or JPEG2000 file and can also not
multipage PDF. output a multipage PDF.
img2pdf is able to output a PDF with multiple pages if more than one input img2pdf is able to output a PDF with multiple pages if more than one input
image is given, losslessly embed JPEGs into a PDF container without adding more image is given, losslessly embed JPEG and JPEG2000 files into a PDF container
overhead than the PDF structure itself and will save all other graphics formats without adding more overhead than the PDF structure itself and will save all
using lossless zip-compression. other graphics formats using lossless zip-compression.
bugs bugs
---- ----
If you find a JPEG that, when embedded can not be read by the Adobe Acrobat If you find a JPEG or JPEG2000 file that, when embedded can not be read by the
Reader, please contact me. Adobe Acrobat Reader, please contact me.
For lossless conversion of other formats than JPEG, zip/flate encoding is used. For lossless conversion of other formats than JPEG or JPEG2000 files, zip/flate
This choice is based on a number of tests I did on images. I converted them encoding is used. This choice is based on a number of tests I did on images.
into PDF using imagemagick and all compressions it has to offer and then I converted them into PDF using imagemagick and all compressions it has to
compared the output size of the lossless variants. In all my tests, zip/flate offer and then compared the output size of the lossless variants. In all my
encoding performed best. You can verify my findings using the test_comp.sh tests, zip/flate encoding performed best. You can verify my findings using the
script with any input image given as a commandline argument. If you find an test_comp.sh script with any input image given as a commandline argument. If
input file that is outperformed by another lossless compression, contact me. you find an input file that is outperformed by another lossless compression,
contact me.

45
img2pdf.py
View file

@ -4,6 +4,7 @@ import Image
import sys import sys
import zlib import zlib
import argparse import argparse
import struct
from datetime import datetime from datetime import datetime
def parse(cont, indent=1): def parse(cont, indent=1):
@ -38,6 +39,8 @@ class obj():
def main(images, dpi, title=None, author=None, creator=None, producer=None, def main(images, dpi, title=None, author=None, creator=None, producer=None,
creationdate=None, moddate=None, subject=None, keywords=None): creationdate=None, moddate=None, subject=None, keywords=None):
version = 3 # default pdf version 1.3
now = datetime.now() now = datetime.now()
info = dict() info = dict()
@ -67,15 +70,32 @@ def main(images, dpi, title=None, author=None, creator=None, producer=None,
pagestuples = list() pagestuples = list()
for im in images: for im in images:
imgdata = Image.open(im) try:
width, height = imgdata.size imgdata = Image.open(im)
if dpi: except IOError:
dpi_x, dpi_y = dpi, dpi # test if it is a jpeg2000 image
im.seek(0)
if im.read(12) != "\x00\x00\x00\x0C\x6A\x50\x20\x20\x0D\x0A\x87\x0A":
print "cannot read input image"
exit(1)
# image is jpeg2000
imgformat = "JP2"
im.seek(48)
height, width = struct.unpack(">II", im.read(8))
color = "RGB" # TODO: read real colorspace
if dpi:
dpi_x, dpi_y = dpi, dpi
else:
dpi_x, dpi_y = (96, 96) # TODO: read real dpi
else: else:
dpi_x, dpi_y = imgdata.info.get("dpi", (96, 96)) width, height = imgdata.size
pdf_x, pdf_y = 72.0*width/dpi_x, 72.0*height/dpi_y # pdf units = 1/72 inch if dpi:
imgformat = imgdata.format dpi_x, dpi_y = dpi, dpi
color = imgdata.mode else:
dpi_x, dpi_y = imgdata.info.get("dpi", (96, 96))
imgformat = imgdata.format
color = imgdata.mode
if color == 'L': if color == 'L':
color = "/DeviceGray" color = "/DeviceGray"
elif color == 'RGB': elif color == 'RGB':
@ -84,11 +104,18 @@ def main(images, dpi, title=None, author=None, creator=None, producer=None,
print "unsupported color space:", color print "unsupported color space:", color
exit(1) exit(1)
pdf_x, pdf_y = 72.0*width/dpi_x, 72.0*height/dpi_y # pdf units = 1/72 inch
# either embed the whole jpeg or deflate the bitmap representation # either embed the whole jpeg or deflate the bitmap representation
if imgformat is "JPEG": if imgformat is "JPEG":
ofilter = [ "/DCTDecode" ] ofilter = [ "/DCTDecode" ]
im.seek(0) im.seek(0)
imgdata = im.read() imgdata = im.read()
elif imgformat is "JP2":
ofilter = [ "/JPXDecode" ]
im.seek(0)
imgdata = im.read()
version = 5 # jpeg2000 needs pdf 1.5
else: else:
ofilter = [ "/FlateDecode" ] ofilter = [ "/FlateDecode" ]
imgdata = zlib.compress(imgdata.tostring()) imgdata = zlib.compress(imgdata.tostring())
@ -147,7 +174,7 @@ def main(images, dpi, title=None, author=None, creator=None, producer=None,
xreftable = list() xreftable = list()
result = "%PDF-1.3\n" result = "%%PDF-1.%d\n"%version
xreftable.append("0000000000 65535 f \n") xreftable.append("0000000000 65535 f \n")
for o in objects: for o in objects: