This functions allows marking objects of interest/path/trajectory on an image, returning the marked image. The functionality is similar to usage of plot with a background image, but here plot command is not used. The resulting image can thus be used- saved as image file, added to a video, processed etc.. To achieve connection between trajectory points (plot style) calculate dense trajectory without holed. mask2poly does this for mask borders.
Similar functionality is available as part of the Computer Vision Toolbox.