save-markers tool outputs the images of all the fiducial markers in a given type.
Each marker is surrounded by a white boarder, which is not considered part of the marker (it’s not counted when working out the marker’s size).
When –raw is passed, Markers are output as PNG files, at their smallest possible format. They can then be resized as necessary without losing quality.
Without –raw, images are saved 500px, plus a border with text identifying which marker is being used.