Looks interesting! Just a heads up as you seem to be a UK registered limited company :
>On business letters, order forms and websites, you must show:
>the company’s registered number
>its registered office address
>where the company is registered (England and Wales, Scotland or Northern Ireland)
>the fact that it’s a limited company (usually by spelling out the company’s full name including ‘Limited’ or ‘Ltd’)
PDFC compares not only graphical differences but also detects content, columns, etc. We originally created it for ourselves because we weren't happy with any of the PDF comparison tools that were out there.
The black and white mode doesn't look very useful. Check out how Autodesk is visualising changes. They use three colours: blue=only in first pdf, red=only in second pdf, black=in both pdfs.
At PlanGrid, we built a version of this into all of our native platforms as well as into our web app. Allowing people to see what changed between pdf revisions was a priceless tool, even for less sophisticated users in the field.
Rasterization is a must since pdfs otherwise are extremely inconsistent based on how they were generated and post-processed.
Suggestion: When highlighting text, you want to use "multiply" blend mode (a.k.a. subtractive color mixing) instead of opacity. Opacity makes black text lighter/greyish, which is not how physical text markers work, or colored sheets of transparent plastic.
Thanks for the suggestion. I plan on having user selectable blend modes. Currently, it's using the "difference" blend mode. This mode makes it easy to spot shifted images.
I’m going to check this out. Over the years in university, I accumulated different versions of PDFs with different annotations, because I tested various apps. It is very annoying to merge them manually.
This is likely lesspipe.sh used via LESSOPEN. Less itself certainly doesn’t understand PDF, but it allows automatic custom preprocessing of its input, which many Linux distributions have preconfigured as the system default.
https://www.qtrac.eu/diffpdf-foss.html
https://github.com/vslavik/diff-pdf https://vslavik.github.io/diff-pdf/