Had a look just to understand what HRPT stands for. I directly jumped to the section “1.2 What is HRPT” only to find a convoluted explanation already expecting a lot of knowledge. Calling that a beginner’s guide is a slap in the face for someone unfamiliar with the subject.

I then searched the internet and found https://usradioguy.com/hrpt-satellite-tracking-and-capture/. There it states right in the first sentence: “Weather satellite pictures are often broadcast as high-resolution picture transmissions (HRPTs)”. Aha, thanks, that is the tl;dr I was looking for.