One way to extract the images from the .webarchive file is through the Terminal app. Here’s how.
1 – First, press Command and space on the keyboard to launch Spotlight, type in “Terminal” and hit Enter. That’ll open the Terminal app.
2 – Then type in this command without hitting Enter. Note there is a space at the end after “html”.
textutil -convert html
3 – Lastly, drag the .webarchive file into Terminal. Hit Enter and you’ll find all the extracted files in the same folder where the .webarchive file is located. How to Extract Images from Webarchive Files Using Terminal