The disclosure is disclosed an apparatus of processing an image and a method thereof. According to the present invention, the method of transmitting a broadcast signal for 3-dimensional, 3D, service, may include encoding video data for a 3D service into a stream, generating first service information including a first descriptor including first information for specifying that a type of the stream is a video stream and second information for specifying a type of a component included in the video stream is a 3D video component and transmitting a broadcast signal including the encoded stream and the generated service information.