In JMIR, the copyright is not owned by the publisher, but retained by authors.
You do not need a permission from JMIR Publications (or the author) to use any part of an article published in JMIR journals, including figures, Multimedia Appendices, etc. unless the figure/Multimedia Appendix specifically states a different copyright holder than the authors, or a different license than the standard JMIR licence cc-by (see below and What is a "Creative Commons License"?).
All JMIR journals are open access. JMIR articles are published under a Creative Commons Attribution (cc-by) license (see copyright statement on each article), meaning that authors retain copyright and license it to anybody under the rules of the cc-by license, which means you can use it in whatever way (without written permission) you like as long as:
- you cite the original source (complete citation of the JMIR article with URL) and
- state that it was published (and can be reproduced) under the terms of Creative Commons Attribution 4.0 licence (or 2.0 prior to mid-May 2017).