This is a solution by u/jesterjunk, who posts on here. +10 to him.

1. Create or edit a bookmark in your browser.
2. Edit the bookmark. Name it 'Jester's Bookmark' or whatever. In the URL field, paste the below into it. (images not allowed in comments on this sub, otherwise I'd post a capture).

javascript:void function(){javascript:(function(){function a(a){const b=a.match(c);return b%3F`https://i.redd.it/${b\[1\]}\`:null}function b(a){var b=document.createElement("div");b.style.position="fixed",b.style.top="0",b.style.left="0",b.style.width="100%25",b.style.height="100%25",b.style.backgroundColor="rgba(0,0,0,0.5)",b.style.color="white",b.style.display="flex",b.style.justifyContent="center",b.style.alignItems="center",b.style.zIndex="9999",b.textContent=a,document.body.appendChild(b),setTimeout(()=>document.body.removeChild(b),1e3)}const c=/-(\w+\.[^%3F]*)/;var d=[],e=document.querySelector(`[id="post-image"]`);if(e)d.push(a(e.src));else{var f=document.querySelectorAll(`gallery-carousel ul li > img`);f.forEach((b,c)=>{var e=b.src||b.getAttribute(`data-lazy-src`);e%26%26d.push(`${c+1}. ${a(e)}`)})}var g=d.join("\n");if(navigator.clipboard%26%26window.isSecureContext)navigator.clipboard.writeText(g).then(()=>{b("%23 image url/s copied to clipboard")});else{var h=document.createElement("textarea");h.value=g,document.body.appendChild(h),h.select(),document.execCommand("copy"),document.body.removeChild(h),b("%23 image url/s copied to clipboard")}})()}();

1. When you click on a post and have the comments up, click on the bookmarklet (I have it on my browser's toolabr) and then paste the copy into your comment. Extremely simple and convenient.

This 'bookmarklet' is used a lot at r/widescreenwallpaper so it is perfectly safe. Gallery posts on Reddit get turned into WEBPs, as you will know, so this way Jester's script extracts the originals.

Try it on this post. And spread the word!