1. An apparatus for processing a digital image, the apparatus comprising: an input unit configured to receive the digital image; an extraction unit configured to extract a recovery feature from the received digital image using quad-tree decomposition, wherein the recovery feature is binary data that represents unique characteristics of the received digital image; an embedding unit configured to embed the extracted recovery feature into the received digital image; and an output unit configured to output the digital image embedded with the recovery feature as a feature hidden image.