I spent precisely too long trying to do this, but I finally did it! here's how. thanks to jan Pensa and his programmer friend Robin for teaching me how to. sorry that this article is very lazy, it is mostly for me to not forget everything
first of all, download the PDF that you would like to extract the images from. outside of that, useful tools that you need include:
using pdfimages, open the command line and type this, substituting
image with the desired file paths. by the way, this is all on Windows so it might work differently for you, sorry
cd C:\Program Files\Xpdf\bin64 pdfimages.exe -j original_pdf.pdf image
and it will spit out a lot of images, but oh no they are all separated into the colour and alpha channels
so now using ImageMagick, try the command below for all the images, substituting
output with the desired names. quotes are important!!!
magick "image" "mask" -alpha off -compose copy-opacity -composite output.png
for this, just go read this page, it explains it way better than I could.