1. A depth value restoration method comprising: conducting image noise reduction with regard to a depth map and a corresponding color image to establish a candidate object region in each of the depth map and the corresponding color image, respectively, the candidate object region of the depth map including a foreground image from the depth map and the candidate object region of the corresponding color image including a foreground image from the corresponding color image; identifying an area of the candidate object region of the depth map associated with invalid depth values based on a determination that the area is associated with depth values that exceed a threshold range of valid depth values, the area being an invalid region of the depth map; determining whether an area ratio of the invalid region to the candidate object region of the depth map is greater than a particular threshold value; conducting region growing of the candidate object region of the depth map to generate a grown candidate object region of the depth map, based on determining whether at least one candidate growing point grows, wherein determining whether the at least one candidate growing point grows includes determining whether a depth value of the at least one candidate growing point is within a threshold range of valid depth values such that the depth value is valid; and if the depth value of the at least one candidate growing point is valid, calculating a depth value difference between the at least one candidate growing point and a seed point, and if the depth value difference is less than or equal to a predetermined depth similarity threshold value, adding the at least one candidate growing point into a growing region, or if the depth value of the at least one candidate growing point is invalid, calculating a color difference between the at least one candidate growing point and the seed point, and if the color difference is less than or equal to a predetermined color similarity threshold value, giving the depth value of the seed point to the at least one candidate growing point, and adding the at least one candidate growing point into the growing region, and determining that the area ratio is greater than the particular threshold value; and restoring depth values of one or more pixel points of the grown candidate object region of the depth map according to depth values of each pixel point located in a neighboring region of the depth map to generate a processed depth map.