This is a change on Google Image results. Perhaps you can get the old design back by clearing cache and cookies. That would be lucky. If that doesn't work, you can use an add-on to show the resolution.

Cache and Cookies

When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Clear Firefox's Cache

See: How to clear the Firefox cache

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, click the lock icon at the left end of the address bar. After a moment, a "Clear Cookies and Site Data" button should appear at the bottom. Go ahead and click that.

In the dialog that opens, you will see one or more matches to the current address so you can remove the site's cookies individually without affecting other sites.

Then try searching again. Does that help?

Style Rule Hack

You need two elements:

(1) Stylus extension

https://addons.mozilla.org/firefox/addon/styl-us/

(2) Rule for Google Image results

https://userstyles.org/styles/180867/google-images-width-x-height-dimensions

I wrote that user style, so let me know if it doesn't work for you.

You can also use a bookmarklet to get an easy and quick resolution display. A disadvantage is that this isn't automatic and you need to rerun the bookmarklet each time the page changes.

See this thread:

• /questions/1281440 How do I restore my cursor to show pixel image size when I move over google search result images?

You can create a new bookmark and paste the JavaScript code in its Location field.

javascript:(function(){var e=document.body.querySelectorAll('.isv-r[data-ow][data-oh]');for(i=0;E=e[i];i++){E.title=E.dataset['ow']+'x'+E.dataset['oh']}})()