Problem: What are the most important words?
corn on the cob with a knob of melting butter
Answer: cob, corn, knob

Problem: What are the most important words?
boats moored at the harbor against clear blue sky with peaceful sea in the foreground
Answer: harbor, sea, sky

Problem: What are the most important words?
bright ornament in a circle with dragonfly and flower
Answer:
circle, flower, ornament