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@ -2,19 +2,19 @@ img2pdf
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=======
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Losslessly convert raster images to PDF. The file size will not unnecessarily
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increase. One major application would be a number of scans made in JPEG format
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which should now become part of a single PDF document. Existing solutions
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would either re-encode the input JPEG files (leading to quality loss) or store
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them in the zip/flate format which results into the PDF becoming unnecessarily
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large in terms of its file size.
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increase. It can for example be used to create a PDF document from a number of
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scans that are only available in JPEG format. Existing solutions would either
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re-encode the input JPEG files (leading to quality loss) or store them in the
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zip/flate format which results into the PDF becoming unnecessarily large in
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terms of its file size.
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Background
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----------
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Quality loss can be avoided when converting JPEG and JPEG2000 images to PDF by
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embedding them without re-encoding. I wrote this piece of python code.
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because I was missing a tool to do this automatically. Img2pdf basically just
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wraps JPEG images into the PDF container as they are.
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embedding them into the PDF without re-encoding them. This is what img2pdf
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does. It thus treats the PDF format merely as a container format for storing
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one or more JPEGs without re-encoding the JPEG images themselves.
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If you know an existing tool which allows one to embed JPEG and JPEG2000 images
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into a PDF container without recompression, please contact me so that I can put
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@ -23,12 +23,18 @@ this code into the garbage bin.
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Functionality
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-------------
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This program will take a list of images and produce a PDF file with the images
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embedded in it. JPEG and JPEG2000 images will be included without
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recompression. Raster images in other formats will be included with zip/flate
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encoding which usually leads to an increase in the resulting size because
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formats like png compress better than PDF which just zip/flate compresses the
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RGB data. As a result, this tool is able to losslessly wrap images into a PDF
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This program will take a list of raster images and produce a PDF file with the
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images embedded in it. JPEG and JPEG2000 images will be included without
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recompression and the resulting PDF will only be slightly larger than the input
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images due to the overhead of the PDF container. Raster images in other
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formats (like png, gif or tif) will be included using the lossless zip/flate
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encoding which usually leads to a significant increase in the PDF size if the
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input was for example a png image. This is unfortunately unavoidable because
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there is no other way to store arbitrary RGB bitmaps in PDF in a lossless way
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other than zip/flate encoding. And zip/flate compresses bitmaps worse than png
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is able to compress them.
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As a result, this tool is able to losslessly wrap raster images into a PDF
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container with a quality to filesize ratio that is typically better (in case of
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JPEG and JPEG2000 images) or equal (in case of other formats) than that of
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existing tools.
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@ -67,7 +73,9 @@ The images must be provided as files because img2pdf needs to seek in the file
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descriptor.
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If no output file is specified with the `-o`/`--output` option, output will be
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done to stdout.
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done to stdout. A typical invocation is:
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img2pdf img1.png img2.jpg -o out.pdf
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The detailed documentation can be accessed by running:
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