Note: I'm using the word "character" in the general sense.
Let's say I want to find images that focus on a cephalopod character. Stuff like this:
However, while the majority of results do have a cephalopod in them, they aren't the focal point:
Another example would be regarding ray-finned fish (a.k.a. fish that aren't sharks etc.). Stuff like this:
Unfortunately, the No Cartoon Fish trope comes into full effect; Most of the resulting images feature fish as background objects, food, etc. not actually presented as any sort of character.
So yeah, what the thread title says. I'm not sure if it would be something that fits within the scope of tagging (it might need to be separate functionality?).
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