JPEG2000 support
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2 changed files with 63 additions and 35 deletions
53
README.md
53
README.md
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@ -1,17 +1,17 @@
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img2pdf
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=======
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Lossless conversion of images to PDF without unnecessarily re-encoding JPEG
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files. Thus, no loss of quality and no unnecessary large output file.
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Lossless conversion of images to PDF without unnecessarily re-encoding JPEG and
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JPEG2000 files. Thus, no loss of quality and no unnecessary large output file.
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background
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----------
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PDF is able to embed JPEG images as they are without re-encoding them (and
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hence loosing quality) but I was missing a tool to do this automatically, thus
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I wrote this piece of python code.
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PDF is able to embed JPEG and JPEG2000 images as they are without re-encoding
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them (and hence loosing quality) but I was missing a tool to do this
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automatically, thus I wrote this piece of python code.
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If you know how to embed JPEG images into a PDF container without
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If you know how to embed JPEG and JPEG2000 images into a PDF container without
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recompression, using existing tools, please contact me so that I can put this
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code into the garbage bin :D
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@ -19,12 +19,12 @@ functionality
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-------------
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The program will take image filenames from commandline arguments and output a
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PDF file with them embedded into it. If the input image is a JPEG file, it will
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be included as-is without any processing. If it is in any other format, the
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image will be included as zip-encoded RGB. As a result, this tool will be able
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to lossless wrap any image into a PDF container while performing better (in
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terms of quality/filesize ratio) than existing tools in case the input image is
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a JPEG.
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PDF file with them embedded into it. If the input image is a JPEG or JPEG2000
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file, it will be included as-is without any processing. If it is in any other
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format, the image will be included as zip-encoded RGB. As a result, this tool
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will be able to lossless wrap any image into a PDF container while performing
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better (in terms of quality/filesize ratio) than existing tools in case the
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input image is a JPEG or JPEG2000 file.
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For the record, the imagemagick command to lossless convert any image to
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PDF using zip-encoding, is:
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@ -32,24 +32,25 @@ PDF using zip-encoding, is:
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convert input.jpg -compress Zip output.pdf
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The downside is, that using imagemagick like this will make the resulting PDF
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files a few times bigger than the input JPEG and can also not output a
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multipage PDF.
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files a few times bigger than the input JPEG or JPEG2000 file and can also not
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output a multipage PDF.
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img2pdf is able to output a PDF with multiple pages if more than one input
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image is given, losslessly embed JPEGs into a PDF container without adding more
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overhead than the PDF structure itself and will save all other graphics formats
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using lossless zip-compression.
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image is given, losslessly embed JPEG and JPEG2000 files into a PDF container
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without adding more overhead than the PDF structure itself and will save all
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other graphics formats using lossless zip-compression.
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bugs
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----
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If you find a JPEG that, when embedded can not be read by the Adobe Acrobat
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Reader, please contact me.
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If you find a JPEG or JPEG2000 file that, when embedded can not be read by the
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Adobe Acrobat Reader, please contact me.
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For lossless conversion of other formats than JPEG, zip/flate encoding is used.
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This choice is based on a number of tests I did on images. I converted them
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into PDF using imagemagick and all compressions it has to offer and then
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compared the output size of the lossless variants. In all my tests, zip/flate
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encoding performed best. You can verify my findings using the test_comp.sh
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script with any input image given as a commandline argument. If you find an
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input file that is outperformed by another lossless compression, contact me.
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For lossless conversion of other formats than JPEG or JPEG2000 files, zip/flate
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encoding is used. This choice is based on a number of tests I did on images.
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I converted them into PDF using imagemagick and all compressions it has to
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offer and then compared the output size of the lossless variants. In all my
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tests, zip/flate encoding performed best. You can verify my findings using the
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test_comp.sh script with any input image given as a commandline argument. If
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you find an input file that is outperformed by another lossless compression,
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contact me.
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45
img2pdf.py
45
img2pdf.py
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@ -4,6 +4,7 @@ import Image
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import sys
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import zlib
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import argparse
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import struct
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from datetime import datetime
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def parse(cont, indent=1):
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@ -38,6 +39,8 @@ class obj():
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def main(images, dpi, title=None, author=None, creator=None, producer=None,
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creationdate=None, moddate=None, subject=None, keywords=None):
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version = 3 # default pdf version 1.3
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now = datetime.now()
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info = dict()
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@ -67,15 +70,32 @@ def main(images, dpi, title=None, author=None, creator=None, producer=None,
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pagestuples = list()
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for im in images:
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imgdata = Image.open(im)
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width, height = imgdata.size
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if dpi:
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dpi_x, dpi_y = dpi, dpi
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try:
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imgdata = Image.open(im)
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except IOError:
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# test if it is a jpeg2000 image
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im.seek(0)
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if im.read(12) != "\x00\x00\x00\x0C\x6A\x50\x20\x20\x0D\x0A\x87\x0A":
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print "cannot read input image"
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exit(1)
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# image is jpeg2000
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imgformat = "JP2"
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im.seek(48)
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height, width = struct.unpack(">II", im.read(8))
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color = "RGB" # TODO: read real colorspace
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if dpi:
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dpi_x, dpi_y = dpi, dpi
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else:
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dpi_x, dpi_y = (96, 96) # TODO: read real dpi
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else:
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dpi_x, dpi_y = imgdata.info.get("dpi", (96, 96))
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pdf_x, pdf_y = 72.0*width/dpi_x, 72.0*height/dpi_y # pdf units = 1/72 inch
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imgformat = imgdata.format
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color = imgdata.mode
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width, height = imgdata.size
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if dpi:
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dpi_x, dpi_y = dpi, dpi
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else:
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dpi_x, dpi_y = imgdata.info.get("dpi", (96, 96))
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imgformat = imgdata.format
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color = imgdata.mode
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if color == 'L':
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color = "/DeviceGray"
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elif color == 'RGB':
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@ -84,11 +104,18 @@ def main(images, dpi, title=None, author=None, creator=None, producer=None,
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print "unsupported color space:", color
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exit(1)
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pdf_x, pdf_y = 72.0*width/dpi_x, 72.0*height/dpi_y # pdf units = 1/72 inch
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# either embed the whole jpeg or deflate the bitmap representation
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if imgformat is "JPEG":
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ofilter = [ "/DCTDecode" ]
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im.seek(0)
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imgdata = im.read()
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elif imgformat is "JP2":
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ofilter = [ "/JPXDecode" ]
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im.seek(0)
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imgdata = im.read()
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version = 5 # jpeg2000 needs pdf 1.5
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else:
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ofilter = [ "/FlateDecode" ]
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imgdata = zlib.compress(imgdata.tostring())
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@ -147,7 +174,7 @@ def main(images, dpi, title=None, author=None, creator=None, producer=None,
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xreftable = list()
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result = "%PDF-1.3\n"
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result = "%%PDF-1.%d\n"%version
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xreftable.append("0000000000 65535 f \n")
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for o in objects:
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