img2pdf

Lossless conversion of raster images to PDF. You should use img2pdf if your priorities are (in this order):

always lossless: the image embedded in the PDF will always have the exact same color information for every pixel as the input
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
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:

not be lossless because lossy re-encoding to JPEG
not be small because using wasteful flate encoding of raw pixel data
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) | 1-bit monochrome | direct | | JBIG2 (single-page generic coding) | 1-bit monochrome | direct | | any | any except CMYK and 1-bit monochrome | PNG Paeth | | any | 1-bit monochrome | CCITT Group 4 | | any | CMYK | flate |

For JPEG, JPEG2000, non-interlaced PNG, TIFF images with CCITT Group 4 encoded data, and JBIG2 with single-page generic coding (e.g. using jbig2enc), 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 1-bit 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

With no command line arguments supplied, img2pdf will read a single image from standard input and write the resulting PDF to standard output. Here is an example for how to scan directly to PDF using scanimage(1) from SANE:

$ scanimage --mode=Color --resolution=300 | pnmtojpeg -quality 90 | img2pdf > scan.pdf

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 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))

# opening using pathlib
with open("name.pdf","wb") as f:
	f.write(img2pdf.convert(pathlib.Path('test.jpg')))

# 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")))

# convert all files matching a glob using pathlib.Path
from pathlib import Path
with open("name.pdf","wb") as f:
	f.write(img2pdf.convert(*Path("/path").glob("**/*.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

Compariso

Img2pdf

Install / Use

README