images reversed in dark mode in safari

The text is black, white or something else depending on how the web page is configured.

It seems that you are using "Invert Colors" from System Preferences->Accessibility->Display.

I had not used this before, and I would have expected it to invert everything - including images.

Indeed that is what I see.

I would not rely on this accessibility feature.

Anyway, how a webpage displays is strongly dependent on how it is coded.

If the colors of the text are hard coded in the CSS code for that website, there is nothing one can do, short of cooking up a (probably very complex) Safari extension, and that would probably mess other things up.

I do not know enough about CSS, but I guess for this to work it would have to be coded in the page somehow.

What are those images?

Anything that is not part of the application user interface but is content from a website that you are viewing in Safari should display exactly the same way regardless of Dar Mode settings.

Can you post a screenshot illustrating the issue?