Here is a comprehensive resource list with links to a huge number of open source online images and texts related to the study of Islamic art and architecture, put together by Richard McClary in the History of Art Department.
Islamic Art and Architectur... by on Scribd
York Digital Library (YODL) contains multimedia resources used in or created out of teaching, research and study at the University. The digital library is in a developmental stage but already holds a growing number of image collections to support the History of Art department. Some of the material is public, some of the collections can be accessed by members of the University only and some collections are restricted to students taking certain courses. All of the images which you are able to find in YODL are available for you to use within your essays and presentations. Remember to login so that you can see the full range of images available to you. The Digital Library also contains past exam papers, theses, archive material and rare books.
Images which have been made Creative Commons Zero, also known as CCO, are available to use by anyone, however they like. The images are in the Public Domain and can be reproduced, incorporated into other works, modified, and reused, without needing permission and in some cases without even needing to credit the author.
A number of image sites offer CCO works. They are in two broad categories - artworks, and stock photography. The latter may be useful for pepping up presentations or websites; examples of the former are listed below and may be directly useful as part of your degree.