forked from josch/img2pdf
312 lines
12 KiB
Markdown
312 lines
12 KiB
Markdown
[](https://app.travis-ci.com/josch/img2pdf)
|
|
[](https://ci.appveyor.com/project/josch/img2pdf/branch/main)
|
|
|
|
img2pdf
|
|
=======
|
|
|
|
Lossless conversion of raster images to PDF. You should use img2pdf if your
|
|
priorities are (in this order):
|
|
|
|
1. **always lossless**: the image embedded in the PDF will always have the
|
|
exact same color information for every pixel as the input
|
|
2. **small**: if possible, the difference in filesize between the input image
|
|
and the output PDF will only be the overhead of the PDF container itself
|
|
3. **fast**: if possible, the input image is just pasted into the PDF document
|
|
as-is without any CPU hungry re-encoding of the pixel data
|
|
|
|
Conventional conversion software (like ImageMagick) would either:
|
|
|
|
1. not be lossless because lossy re-encoding to JPEG
|
|
2. not be small because using wasteful flate encoding of raw pixel data
|
|
3. not be fast because input data gets re-encoded
|
|
|
|
Another advantage of not having to re-encode the input (in most common
|
|
situations) is, that img2pdf is able to handle much larger input than other
|
|
software, because the raw pixel data never has to be loaded into memory.
|
|
|
|
The following table shows how img2pdf handles different input depending on the
|
|
input file format and image color space.
|
|
|
|
| Format | Colorspace | Result |
|
|
| ------------------------------------- | ------------------------------ | ------------- |
|
|
| JPEG | any | direct |
|
|
| JPEG2000 | any | direct |
|
|
| PNG (non-interlaced, no transparency) | any | direct |
|
|
| TIFF (CCITT Group 4) | monochrome | direct |
|
|
| any | any except CMYK and monochrome | PNG Paeth |
|
|
| any | monochrome | CCITT Group 4 |
|
|
| any | CMYK | flate |
|
|
|
|
For JPEG, JPEG2000, non-interlaced PNG and TIFF images with CCITT Group 4
|
|
encoded data, img2pdf directly embeds the image data into the PDF without
|
|
re-encoding it. It thus treats the PDF format merely as a container format for
|
|
the image data. In these cases, img2pdf only increases the filesize by the size
|
|
of the PDF container (typically around 500 to 700 bytes). Since data is only
|
|
copied and not re-encoded, img2pdf is also typically faster than other
|
|
solutions for these input formats.
|
|
|
|
For all other input types, img2pdf first has to transform the pixel data to
|
|
make it compatible with PDF. In most cases, the PNG Paeth filter is applied to
|
|
the pixel data. For monochrome input, CCITT Group 4 is used instead. Only for
|
|
CMYK input no filter is applied before finally applying flate compression.
|
|
|
|
Usage
|
|
-----
|
|
|
|
The images must be provided as files because img2pdf needs to seek in the file
|
|
descriptor.
|
|
|
|
If no output file is specified with the `-o`/`--output` option, output will be
|
|
done to stdout. A typical invocation is:
|
|
|
|
$ img2pdf img1.png img2.jpg -o out.pdf
|
|
|
|
The detailed documentation can be accessed by running:
|
|
|
|
$ img2pdf --help
|
|
|
|
Bugs
|
|
----
|
|
|
|
- If you find a JPEG, JPEG2000, PNG or CCITT Group 4 encoded TIFF file that,
|
|
when embedded into the PDF cannot be read by the Adobe Acrobat Reader,
|
|
please contact me.
|
|
|
|
- An error is produced if the input image is broken. This commonly happens if
|
|
the input image has an invalid EXIF Orientation value of zero. Even though
|
|
only nine different values from 1 to 9 are permitted, Anroid phones and
|
|
Canon DSLR cameras produce JPEG images with the invalid value of zero.
|
|
Either fix your input images with `exiftool` or similar software before
|
|
passing the JPEG to `img2pdf` or run `img2pdf` with `--rotation=ifvalid`
|
|
(if you run img2pdf from the commandline) or by passing
|
|
`rotation=img2pdf.Rotation.ifvalid` as an argument to `convert()` when using
|
|
img2pdf as a library.
|
|
|
|
- img2pdf uses PIL (or Pillow) to obtain image meta data and to convert the
|
|
input if necessary. To prevent decompression bomb denial of service attacks,
|
|
Pillow limits the maximum number of pixels an input image is allowed to
|
|
have. If you are sure that you know what you are doing, then you can disable
|
|
this safeguard by passing the `--pillow-limit-break` option to img2pdf. This
|
|
allows one to process even very large input images.
|
|
|
|
Installation
|
|
------------
|
|
|
|
On a Debian- and Ubuntu-based systems, img2pdf can be installed from the
|
|
official repositories:
|
|
|
|
$ apt install img2pdf
|
|
|
|
If you want to install it using pip, you can run:
|
|
|
|
$ pip3 install img2pdf
|
|
|
|
If you prefer to install from source code use:
|
|
|
|
$ cd img2pdf/
|
|
$ pip3 install .
|
|
|
|
To test the console script without installing the package on your system,
|
|
use virtualenv:
|
|
|
|
$ cd img2pdf/
|
|
$ virtualenv ve
|
|
$ ve/bin/pip3 install .
|
|
|
|
You can then test the converter using:
|
|
|
|
$ ve/bin/img2pdf -o test.pdf src/tests/test.jpg
|
|
|
|
If you don't want to setup Python on Windows, then head to the
|
|
[releases](/josch/img2pdf/releases) section and download the latest
|
|
`img2pdf.exe`.
|
|
|
|
GUI
|
|
---
|
|
|
|
There exists an experimental GUI with all settings currently disabled. You can
|
|
directly convert images to PDF but you cannot set any options via the GUI yet.
|
|
If you are interested in adding more features to the PDF, please submit a merge
|
|
request. The GUI is based on tkinter and works on Linux, Windows and MacOS.
|
|
|
|
|
|
|
|
Library
|
|
-------
|
|
|
|
The package can also be used as a library:
|
|
|
|
import img2pdf
|
|
|
|
# opening from filename
|
|
with open("name.pdf","wb") as f:
|
|
f.write(img2pdf.convert('test.jpg'))
|
|
|
|
# opening from file handle
|
|
with open("name.pdf","wb") as f1, open("test.jpg") as f2:
|
|
f1.write(img2pdf.convert(f2))
|
|
|
|
# using in-memory image data
|
|
with open("name.pdf","wb") as f:
|
|
f.write(img2pdf.convert("\x89PNG...")
|
|
|
|
# multiple inputs (variant 1)
|
|
with open("name.pdf","wb") as f:
|
|
f.write(img2pdf.convert("test1.jpg", "test2.png"))
|
|
|
|
# multiple inputs (variant 2)
|
|
with open("name.pdf","wb") as f:
|
|
f.write(img2pdf.convert(["test1.jpg", "test2.png"]))
|
|
|
|
# convert all files ending in .jpg inside a directory
|
|
dirname = "/path/to/images"
|
|
imgs = []
|
|
for fname in os.listdir(dirname):
|
|
if not fname.endswith(".jpg"):
|
|
continue
|
|
path = os.path.join(dirname, fname)
|
|
if os.path.isdir(path):
|
|
continue
|
|
imgs.append(path)
|
|
with open("name.pdf","wb") as f:
|
|
f.write(img2pdf.convert(imgs))
|
|
|
|
# convert all files ending in .jpg in a directory and its subdirectories
|
|
dirname = "/path/to/images"
|
|
imgs = []
|
|
for r, _, f in os.walk(dirname):
|
|
for fname in f:
|
|
if not fname.endswith(".jpg"):
|
|
continue
|
|
imgs.append(os.path.join(r, fname))
|
|
with open("name.pdf","wb") as f:
|
|
f.write(img2pdf.convert(imgs))
|
|
|
|
|
|
# convert all files matching a glob
|
|
import glob
|
|
with open("name.pdf","wb") as f:
|
|
f.write(img2pdf.convert(glob.glob("/path/to/*.jpg")))
|
|
|
|
# ignore invalid rotation values in the input images
|
|
with open("name.pdf","wb") as f:
|
|
f.write(img2pdf.convert('test.jpg'), rotation=img2pdf.Rotation.ifvalid)
|
|
|
|
# writing to file descriptor
|
|
with open("name.pdf","wb") as f1, open("test.jpg") as f2:
|
|
img2pdf.convert(f2, outputstream=f1)
|
|
|
|
# specify paper size (A4)
|
|
a4inpt = (img2pdf.mm_to_pt(210),img2pdf.mm_to_pt(297))
|
|
layout_fun = img2pdf.get_layout_fun(a4inpt)
|
|
with open("name.pdf","wb") as f:
|
|
f.write(img2pdf.convert('test.jpg', layout_fun=layout_fun))
|
|
|
|
# use a fixed dpi of 300 instead of reading it from the image
|
|
dpix = dpiy = 300
|
|
layout_fun = img2pdf.get_fixed_dpi_layout_fun((dpix, dpiy))
|
|
with open("name.pdf","wb") as f:
|
|
f.write(img2pdf.convert('test.jpg', layout_fun=layout_fun))
|
|
|
|
# create a PDF/A-1b compliant document by passing an ICC profile
|
|
with open("name.pdf","wb") as f:
|
|
f.write(img2pdf.convert('test.jpg', pdfa="/usr/share/color/icc/sRGB.icc"))
|
|
|
|
Comparison to ImageMagick
|
|
-------------------------
|
|
|
|
Create a large test image:
|
|
|
|
$ convert logo: -resize 8000x original.jpg
|
|
|
|
Convert it into PDF using ImageMagick and img2pdf:
|
|
|
|
$ time img2pdf original.jpg -o img2pdf.pdf
|
|
$ time convert original.jpg imagemagick.pdf
|
|
|
|
Notice how ImageMagick took an order of magnitude longer to do the conversion
|
|
than img2pdf. It also used twice the memory.
|
|
|
|
Now extract the image data from both PDF documents and compare it to the
|
|
original:
|
|
|
|
$ pdfimages -all img2pdf.pdf tmp
|
|
$ compare -metric AE original.jpg tmp-000.jpg null:
|
|
0
|
|
$ pdfimages -all imagemagick.pdf tmp
|
|
$ compare -metric AE original.jpg tmp-000.jpg null:
|
|
118716
|
|
|
|
To get lossless output with ImageMagick we can use Zip compression but that
|
|
unnecessarily increases the size of the output:
|
|
|
|
$ convert original.jpg -compress Zip imagemagick.pdf
|
|
$ pdfimages -all imagemagick.pdf tmp
|
|
$ compare -metric AE original.jpg tmp-000.png null:
|
|
0
|
|
$ stat --format="%s %n" original.jpg img2pdf.pdf imagemagick.pdf
|
|
1535837 original.jpg
|
|
1536683 img2pdf.pdf
|
|
9397809 imagemagick.pdf
|
|
|
|
Comparison to pdfLaTeX
|
|
----------------------
|
|
|
|
pdfLaTeX performs a lossless conversion from included images to PDF by default.
|
|
If the input is a JPEG, then it simply embeds the JPEG into the PDF in the same
|
|
way as img2pdf does it. But for other image formats it uses flate compression
|
|
of the plain pixel data and thus needlessly increases the output file size:
|
|
|
|
$ convert logo: -resize 8000x original.png
|
|
$ cat << END > pdflatex.tex
|
|
\documentclass{article}
|
|
\usepackage{graphicx}
|
|
\begin{document}
|
|
\includegraphics{original.png}
|
|
\end{document}
|
|
END
|
|
$ pdflatex pdflatex.tex
|
|
$ stat --format="%s %n" original.png pdflatex.pdf
|
|
4500182 original.png
|
|
9318120 pdflatex.pdf
|
|
|
|
Comparison to podofoimg2pdf
|
|
---------------------------
|
|
|
|
Like pdfLaTeX, podofoimg2pdf is able to perform a lossless conversion from JPEG
|
|
to PDF by plainly embedding the JPEG data into the pdf container. But just like
|
|
pdfLaTeX it uses flate compression for all other file formats, thus sometimes
|
|
resulting in larger files than necessary.
|
|
|
|
$ convert logo: -resize 8000x original.png
|
|
$ podofoimg2pdf out.pdf original.png
|
|
stat --format="%s %n" original.png out.pdf
|
|
4500181 original.png
|
|
9335629 out.pdf
|
|
|
|
It also only supports JPEG, PNG and TIF as input and lacks many of the
|
|
convenience features of img2pdf like page sizes, borders, rotation and
|
|
metadata.
|
|
|
|
Comparison to Tesseract OCR
|
|
---------------------------
|
|
|
|
Tesseract OCR comes closest to the functionality img2pdf provides. It is able
|
|
to convert JPEG and PNG input to PDF without needlessly increasing the filesize
|
|
and is at the same time lossless. So if your input is JPEG and PNG images, then
|
|
you should safely be able to use Tesseract instead of img2pdf. For other input,
|
|
Tesseract might not do a lossless conversion. For example it converts CMYK
|
|
input to RGB and removes the alpha channel from images with transparency. For
|
|
multipage TIFF or animated GIF, it will only convert the first frame.
|
|
|
|
Comparison to econvert from ExactImage
|
|
--------------------------------------
|
|
|
|
Like pdflatex and podofoimg2pf, econvert is able to embed JPEG images into PDF
|
|
directly without re-encoding but when given other file formats, it stores them
|
|
just using flate compressen, which unnecessarily increases the filesize.
|
|
Furthermore, it throws an error with CMYK TIF input. It also doesn't store CMYK
|
|
jpeg files as CMYK but converts them to RGB, so it's not lossless. When trying
|
|
to feed it 16bit files, it errors out with Unhandled bps/spp combination. It
|
|
also seems to choose JPEG encoding when using it on some file types (like
|
|
palette images) making it again not lossless for that input as well.
|