By their very nature, most pictures are "of" something; that is, they depict an identifiable person, place, or thing. The most obvious exceptions are abstract works of art which depict different things in the eyes of different viewers. In addition, pictorial works are sometimes "about" something; that is, there is an underlying intent or theme expressed in addition to the concrete elements depicted. This is often true of works of art and cartoons; it is frequently harder to discern with documentary works.
Subject cataloging must take into account both of these aspects if it is to satisfy as many search queries as possible. Indexers should examine images, their captions, and accompanying documentation carefully to determine both the most salient concrete aspects (what the picture is "of") and any apparent themes or authorial intents (what the picture is "about"), taking care not to read into the images any subjective aspects which are open to interpretation by the viewer.
Example: A political cartoon depicting a basketball game in which the players are dribbling a globe is "of" Basketball and "about" International relations.
Example: Dorothea Lange's photograph known as "Migrant Mother," which depicts a Dust Bowl migrant worker and her children, is "of" Mothers & children and Migrant laborers. In this case, it would be overly subjective to assign terms for "aboutness," since the caption fails to tell us whether the photographer's focus was poverty, despair, hardship, survival, or other abstract concepts.
If determining what an image is intended to be about poses challenges, determining what an image is of--what its focus is for indexing purposes--can often be no less challenging. This is particularly true when an image shows aspects of a subject that are commonly depicted together. In cases where the focus of an image is not readily apparent, P&P catalogers consider the questions listed in Section II.A., using two additional questions to try out the terms towards which they are leaning: "Is this image informative regarding [possible term]?" "If I were a researcher interested in [possible term], would I appreciate being brought to this image?"
Example: A photograph showing a bowling alley with people at several lanes engaged in the game. The indexer may decide that Bowling alleys and Bowling are both warranted, because the image provides plenty of detail about both the site and the activity, but Bowlers may be unnecessary, since the image does not show very clearly the types of people playing the game, what they wore, etc.