Resizimg plugin
Basic usage
Images can be resized by dragging their bottom-right corner.
Read resizimg plugin documentationResize that image!

The code
nothing to do unless you want to change the default values of options, in which case you could:
$('#editor').trumbowyg({
plugins: {
resizimg : {
minSize: 64,
step: 16,
}
}
});
Setup
In head tag
At the end of body
Note the additional requirement: the jquery-resizable plugin must be loaded for Resizimg to work.
<!-- Import jQuery -->
<script src="//ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script>window.jQuery || document.write('<script src="js/vendor/jquery-3.2.1.min.js"><\/script>')</script>
<!-- Import dependency for Resizimg (note that the link below will only work for a limited number of requests, for a productive setup make a local copy from https://github.com/RickStrahl/jquery-resizable -->
<script src="https://rawgit.com/RickStrahl/jquery-resizable/master/dist/jquery-resizable.min.js"></script>