The woman and girl dressed in white sleeveless dresses echo the statues in drapery and pose with bent elbows and stand out from the rest of the people who are all dressed in dark clothes more suitable for fall or winter. At/ you can see a picture of the artist painting this work.
By the way, the people working at this museum are the friendliest of all art museum staff I've encountered so far, and pictures without flash are allowed unless otherwise noted. Some museums, like the Frick Collection, do not allow any photography, even for sculptures around the fountain. The intent is to protect copyright rather than the artwork. You may be surprised how many art works are copyright protected.
It was explained in a New York Times article about Cameron's switch of paintings from the first to the second release of Titanic.
Artists’ copyright is frequently misunderstood. Even if a painting (or drawing or photograph) has been sold to a collector or a museum, in general, the artist or his heirs retain control of the original image for 70 years after the artist’s death.
Think of a novel. You may own a book, but you don’t own the writer’s words; they remain the intellectual property of the author for a time.
So while MoMA owns the actual canvas of “Les Demoiselles,” the family of Picasso, who died in 1973, still owns the image. And under existing law, the estate will continue to own the copyright until 2043.If someone wants to reproduce the painting — on a Web site, a calendar, a T-shirt, or in a film — it is the estate that must give its permission, not the museum. That is why, despite the expansion, Google Art Project still does not contain a single Picasso.