1. A method of processing a depth image, the method comprising: receiving a high-resolution color image and a low-resolution depth image that corresponds to the high-resolution color image; generating a feature vector based on a depth distribution of the low-resolution depth image; selecting a filter to upsample the low-resolution depth image by classifying the generated feature vector according to a previously learnt classifier; upsampling the low-resolution depth image by using the selected filter; and outputting an upsampled high-resolution depth image.