In previous macOS, when you used the Invert Colors feature (Preferences > Accessibility > Display > Invert Colors), all the colors on the screen would become inverted, including images, so a page like this one would look like this:
Note the image has blue tones and the rolling dice is black at the top
In recent macOS (I use Mojave), a feature called "Smart Invert" makes it now impossible to invert images on a webpage. The same page would now look like this:
Note how the dice and the image on the right have "normal" colors - and not the top left logo for some mysterious reason
How does one disable the so-called "Smart" part of the invert? It simply doesn't work for anyone trying to invert images, which a lot of people deal with very often, whether in the art world, historical research or any other photography-related fields. Besides, "Dark Mode" already does that.