Figures, diagrams, and drawings are considered to be “whole works”, and they are protected by copyright. Redrawing or adapting a figure will also require copyright permission. If you are using a figure from an academic source such as a journal or book, check to see if that title is covered by our copyright clearance license by going to www.copyright.com. Type in the name of the book/journal in the search box. If you see a green checkmark beside "Academic -- Digital/Print" then our license covers your use. However, you will need to ensure that the figure you are using was created by the author of the book/journal article and that the author did not get permission to use someone else's work--since that permission is not transferrable. In other words, if the author sought permission to use that image in their work, you will need to find the original source of that figure and seek permission from the original author.
If you can't find the original author/source, try contacting the publisher for copyright permission.
You may end up changing a figure significantly to suit your needs. This is considered an adaptation, and you must give a proper citation for adapted work. You must obtain copyright permission to use adapted figures, no matter how different they are from the original.
You should only adapt a figure if it is necessary to do so; redrawing a figure without adding your own ideas is not advised. It is often easier to obtain copyright permission to use an original figure rather than an adaptation.