Input: Identify the most salient words:

a large wall of stacked stones in different colors

Output: color
stone
wall

Input: Identify the most salient words:

detail from a banknote showing portrait

Output: banknote
detail
portrait

Input: Identify the most salient words:

Someone reaches up once more and this time someone grasps his hand tightly.

Output: grasp
hand
reach

Input: Identify the most salient words:

A group of zebras resting by a tree in a field.

Output:
rest
tree
zebra