This is a common and interesting question. First of all – I am assuming that the photographs were of modern art and not art that would be considered in the public domain. The holder of copyright in art (typically the artist or his heirs unless it has been assigned to a rights management agency) has the exclusive right of reproduction, which is what a photograph would be. However, exceptions under the law, such as fair use, still apply. Photographs of art can be used for a variety of purposes under fair use – for research, education, study. I would argue that inclusion of the photographs in your book chapter could even be fair use under the four factor analysis (it isn’t as though someone is going to make a marketable and equal quality reproduction of the art from your photograph!) However, the publisher likely believes otherwise and that is who you have to appease. They will likely require a letter of permission from the copyright holder – which would be the artist.
An excellent resource on this topic from the WIPO is http://www.wipo.int/sme/en/documents/ip_photography.htm.
