So, you’ve scanned a bunch of documents and books via the DSLR camera photography method, developed the RAW, generated one JPEG image per page, and now you want to convert these to PDF files, one per logical book or document. Or, in other words, one PDF file per “print job.” Old fashioned conventional wisdom would state that you would use ImageMagick to convert from JPEG to PDF, but that introduces losses. Sure, the conversion process is simple enough for me to write my own tool, but surely someone else must have already written a tool, haven’t they?
First things first, for extracting images from PDF files. There is a
tool named pdfimages that is part of poppler, i.e. the Ghostscript
library. So, no need to keep using my hand-rolled tool.
20190407/DuckDuckGo linux embed literal jpeg inside pdf no lossy
conversion
20190407/https://unix.stackexchange.com/questions/11835/pdf-to-jpg-without-quality-loss-gscan2pdf
Second, that important information and distraction aside, we want to do the reverse. So, keep searching.
20190407/DuckDuckGo linux embed unmodified lossless jpeg into pdf
20190407/https://unix.stackexchange.com/questions/42856/how-can-i-convert-a-png-to-a-pdf-in-high-quality-so-its-not-blurry-or-fuzzy
Now let’s create a list of methods to convert independent images to PDF encapsulated format, and also methods for concatenating PDF files, in order of quality.
-
ImageMagick
convert, strongly discouraged due to mandatory raster re-encoding. -
Ghostscript, can sometimes result in re-encoding. Sometimes this is preferred if you want to reduce the resolution of embedded images.
-
pdflatex, JPEG images will be embedded literally, but other types of images will be re-encoded in an inefficient manner. -
qpdf, possibly a good PDF merger. -
PyMuPDF, a Python binding for MuPDF, for merging PDF files.
-
PDFMerger from Apache
pdfbox. -
pdfunite, part ofpopplerfor merging PDF files, but some have said it appears to break hyperlinks. Also, it does not work on encrypted files. -
pdfjoin, works with joining encrypted PDFs but breaks annotations and additional non-graphics items. -
tesseract, in addition to OCR it can also embed images in PDF files in a lossless manner. -
img2pdf, a modern Python program designed to losslessly embed an image file into a single-page PDF. -
pdftools, another modern Python program for simple, literal page concatenation of PDF documents.
I reckon that I wish such software has made its way into the libre world at an earlier time, but better late than never!
20190407/https://gitlab.mister-muffin.de/josch/img2pdf
20190407/https://en.wikipedia.org/wiki/PDFtk
20190407/DuckDuckGo linux concatenate pdf pages
20190407/https://stackoverflow.com/questions/2507766/merge-convert-multiple-pdf-files-into-one-pdf
20190407/https://github.com/stlehmann/pdftools