The purpose of this plugin is for cropping and rotating an image.
When you run the plugin you get a second screen that you can click on to create a selection.
Once the plugin is started a second image will be created that you can click on.
The first two clicks obtain the front and back of the area to be cropped.
The third and fourth clicks determin the width of the area being cropped
The box shows the location of the crop.
Finally a version of the image is created on the fourth click. You can crop more than one section from an image.
Note the image of the yeast is used without permission from: Here