The present specification provides a method for transmitting video data by a source device, by using a high definition media interface (HDMI). In particular, the method comprises the steps of: receiving, from a sink device, capability information about whether reference display model (RDM)-based image processing of the sink device is supported; performing the RDM-based image processing on a plurality of pieces of video data, on the basis of the received capability information; and transmitting, to the sink device, (i) the plurality of pieces of video data on which the RDM-based image processing is performed and (ii) image processing information about a result of the RDM-based image processing, wherein the RDM-based image processing is (i) performed on the basis of a value of a feature of one piece of video data among the plurality of pieces of video data or (ii) performed on the basis of one feature value among feature values related to a separately set feature aside from values of features of the plurality of pieces of video data.