Generally, if you want to republish a figure or a table that has already been published in a journal, you must obtain written permission from the copyright holder. For published articles, the authors are very rarely the copyright holders. Most of time, the authors have transferred their copyright to the publisher.
Obtaining permission to reuse previously published material is absolutely necessary to avoid claims of copyright infringement, but not everyone seems to know that.
Some authors think that if they acknowledge the source of the material, they have satisfied copyright requirements. They’re wrong.
Some authors think that if they add the statement “used with permission” to a figure legend or table title, they have satisfied copyright requirements. They’re wrong.
You have to do three things: (1) obtain written permission from the copyright holder, (2) cite the source of the material, and (3) acknowledge that the material is being republished with permission.
Obtaining written permission for republication often involves fees, and in the case of the big biomedical publishers, those fees can be quite steep.
The Copyright Clearance Center and RightsLink were developed to automate permissions and reprint requests. The sites are easy to use and quickly calculate the fees, but you have to answer a series of questions about the intended use. The answers factor into the cost of the licensing fee. For-profit or nonprofit? Educational or commercial use? You can guess which answers trigger the higher fees.
The big exception to the written permission rule is material that is published under a Creative Commons license. If an article is published with CC BY license, you have the right to distribute, republish, adapt, and build upon the work, even commercially, as long as you credit the original source. No written permission is required. Other Creative Commons licenses are more restrictive, but many allow republication with only a citation. Read more about Creative Commons licenses here..