Okay, I got it, I was stuck because of that, I have to redact some signed .pdfs to finish a big report/roadmap regarding the citizenship of Spain https://tranio.com/spain/passport/ for my company, and I was worried about losing the integrity of the electronically signed documents.

Okay, that's good to know. I was thinking of experimenting with GdPicture on my Linux computer, but I'll use it on my Windows PC then, and will follow what happens on this forum to know if Linux support is implemented some day.

Good to know that the feature is coming in the future! It's so far the only issue I ever had with GdPicture, I'm entirely satisfied with everything else and adding it will make a lot of happy customers.

It sounds like it to me, at least.
And to be sure, is the .pdf in English? And is there a specific font that's used, or something unstandardised that could mess with the document's compatibility?

Well, the thread being from 2008, I guess some things have changed. To begin with, most people have laptops with integrated webcams... But for the record, it'd be interesting to know whether it's feasible with 2020 hardware, it can be useful for people with desktops computers, for example.