If you are in the U.S.A.: If the people you shot were on public property, or visible from public property (without you going to lengths to make them visible from public property, such as putting a ladder on the sidewalk so you can shoot over their gate, and/or using a long lens), or if they were on private property where there is no "reasonable expectation of privacy" (such as in a shopping mall), you are fine. You cannot sell the images as stock images, but you can sell them as art. Commercial = not fine. Editorial = fine. Art = fine. Editorial and art can both be sold for money, as in this case, but they are still not "commercial" in the legal sense of the word as it applies to photography. In other words, you can use their images to sell the pictures as pictures, but you can't use their images to sell a product or brand.
As mentioned, it would be courteous to ask permission, but they could not stop you from publishing or get any money out of you if you do publish and make a profit.
