1. An image segmentation method comprising: displaying, through a display component, an image; receiving, through a user input component, a user command relative to an original designation region of the image; shrinking the original designation region according to first depth information corresponding to the image to generate a shrunk designation region of the image; generating a plurality of seeds according to the shrunk designation region and the user command; and segmenting the image according to the seeds to obtain at least one segmented region.