1. An image capturing apparatus, comprising: a time of fly (TOF) image capturer configured for executing an image capturing action and outputting a TOF image; a TOF controller coupled to the TOF image capturer and calculating a TOF depth map according to the TOF image, defining an effective region and an un-effective region according to the TOF depth map, and capturing a first depth information set corresponding to the effective region from the TOF image; a main image capturer configured for executing an image capturing action and obtaining a first image; a sub image capturer configured for executing an image capturing action and obtaining a second image; and a controller coupled to the TOF image capturer and the main image capturer, and configured for: obtaining a second depth information set corresponding to the un-effective region by comparing the first image and an image of the second image in the un-effective region; and generating an overall depth map by combining the first depth information set and the second depth information set.