1. A method of filtering depth noise, the method comprising: obtaining depth information of a region that constitutes a filtering target frame of a three-dimensional (3D) image; generating automatically a spatial filter for the region using the depth information; and performing depth noise filtering for the 3D image by applying the generated spatial filter to the depth information of the region, wherein the generating comprises determining at least one of a size of a spatial filter and a coefficient of the spatial filter to be applied to the region, based on the depth information, wherein the size of the spatial filter for a particular pixel is related to a depth value for the particular pixel in depth information, and wherein strength of the coefficient of the spatial filter for a particular pixel is related to the depth value for the particular pixel in depth information.