You can search in online catalogs for terms associated with images in books.
For example, use the terms "portrait" (often port for portrait in book catalogs)
Other examples: use "ill" for "illustrations" or "col" (for color)
Older books may use terms like "plate"
You can also look in the Table of Contents at the front of a book for "List of Illustrations"
For searching in ebooks or journal databases such as JSTOR, use terms like "image"
The problem with Google images:
1) images may not be available for use and can be in copyright
2) images are very often NOT labeled correctly. For example, if you search for a person, many images associated, but not that person can appear.
3) Can use google images to find a wikipedia image, which has usually been vetted.