A simple script to test whether there is a significant difference between two PDFs using ImageMagick and pdftocairo.
Project description
This script checks whether two PDFs are visually the same. So:
White text on a white background will be ignored.
Subtle changes in position, size, or color of text will be detected.
This program will ignore changes caused by a different version of the PDF generator, or by invisible changes in the source document.
This is in contrast to most other tools, which tend to extract the text stream out of a PDF, and then diff those texts. Such tools include:
pdf-diff by Joshua Tauberer
There seem to be some tools similar to the one you’re looking at now, although I have experience with none of these:
Václav Slavík seems to have an open source one
There might be more useful ones mentioned on this SuperUser thread
The strength of this script is that it’s simple to use on the command line, and it’s easy to reuse in scripts:
from diff_pdf_visually import pdfdiff
# Returns True or False
pdfdiff("a.pdf", "b.pdf")
Or use it from the command line:
$ pip3 install --user diff-pdf-visually
$ diff-pdf-visually a.pdf b.pdf
How it works
We use pdftocairo to convert both PDFs to a series of PNG images in a temporary directory. The number of pages and the dimensions of the page must be exactly the same. Then we call compare from ImageMagick to check how similar they are; if one of the pages compares different above a certain threshold, then the PDFs are reported as different, otherwise they are reported the same.
You must have ImageMagick and pdftocairo already installed.
Call diff-pdf-visually without parameters (or run python3 -m diff_pdf_visually) to see its command line arguments. Import it as diff_pdf_visually to use its functions from Python.
So what do you use this for?
Personally, I’ve used this a couple of times to refactor my LaTeX documents: I just simplify or remove some macro definitions, and if nothing changes, apparently it’s safe to make that change.
How to install this
pip3 install diff-pdf-visually
Status
At the moment, this program/module works best for finding whether two PDFs are visually different.
This project is licenced under the MIT licence.
Does it work on Python 2?
I don’t know! You tell me :D
Project details
Release history Release notifications | RSS feed
Download files
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.
Source Distribution
Built Distribution
Hashes for diff_pdf_visually-1.2.0-py3-none-any.whl
Algorithm | Hash digest | |
---|---|---|
SHA256 | b21e038f80f36a64891373faa5351d1d931efeda645ae79c8d2c412fc444dc69 |
|
MD5 | 0f1a27b358fc18e10f1ab0ce18d92f2d |
|
BLAKE2b-256 | 11ccae4944f72fd88aefc8c61b958b547e4df6cc454ea2038cf5d6410582786f |