Compare the way you read the frame as a whole with the way you read one small area of it. Ask whether there is a section of the frame that changes your sense of the portrait when viewed on its own.

A portrait to view as a complete composition
A closer look at the portrait
A selected portrait in the image collection
A frame from the gallery
A gallery portrait organized around a person
Included in the photo gallery
A portrait included in the photo collection
A featured image for closer viewing