>>5001105well its a bit of pre-workd. first you need to get all then picture links.
i did it with the firefox addon copy urls expert. but its not fore ff quantum. so you need to download another version of firefox (e.g. ff 52 esr) or another form of firefox, e.g. palemoon or waterfox.
go to each thread with faces, mark all face images and copy "urls in selection" (using copy urls expert addon).
fortunately, nijicollage leads directly to "view only image" link through the linked pictures.
the paste the copied linkts to notepad (i recommend notepad++).
if you have all links, put them into a download manager, e-g- downthemall (also legacy and not for ff quantum) or jdownloader2.
it will download all pics then.
