There is one picture of a man, named "Man."
There is one picture of a man and a woman, labeled "Couple."
There are six pictures of women, three named "Girl" and three called "Girl (first name)." You can choose to work with Lena, Elaine, or Tiffany*.
So not only are we directly juxtaposing the word girl with the word man while talking about adults, but the gender ratio is quite skewed. The people doing the image processing are mostly men, and the subjects of the images are mostly women.
It really does give the impression that for a woman, it's easier to make a name for yourself in image processing by posing for a picture than by writing an algorithm.
*Looking at the Tiffany image also makes me think that Lena is not the only centerfold used in image processing examples.