[maqr]

You can tell your browser to not download images: https://support.mozilla.org/en-US/questions/981640

This would disable all images, but that's what you want, because you can never tell if a site you're going to has been compromised and what content they're going to serve up until you've already downloaded it.

This doesn't completely solve the problem though, you'd also need to make sure you don't have Flash or Java, and disable SVG and CSS now that I think about it... plus an encoded text of an illegal image is still probably illegal, even if it's text-encoded, so, uhh... I don't know, it depends how paranoid you want to be.

If someone wanted to force you to have illegal data on your machine, there's almost certainly a way to make it happen if you're connected to the internet in any way. Hell, even gmail shows embedded images by default... and even if you didn't open the email containing the illegal content, you still have it in your inbox, so there's that...

[patcheudor]

This advice tends to be akin to the advise to disable JavaScript. Basically at this point why are you even on the Internet? Also, as you mentioned Flash, Java, and especially SVG. The only real mitigation here is full drive encryption with a long passphrase which you'll never give up. Of course in the eyes of the courts and public that's a serious double-edged sword because you are assumed guilty at that point.

[abyd]

This is a good argument for Full disk encryption with a vpn and dns leak protection. You're right about people using encryption too. They have a whole playbook dedicated to targeting encryption(physical access is page one).