A display device, comprising: a source unit; and a sink unit operatively connected with the source unit via an embedded display port (eDP) interface to provide signal transmission between the source unit and the sink unit and to enable a panel self refresh mode for reducing power consumption, wherein, if an input image is a still image, the source unit is arranged to apply operating power to a frame buffer of the sink unit and to transmit data of the still image to the sink unit, characterized in that, the sink unit is arranged to perform compression of the data of the still image based on a predetermined lossless compression algorithm, the sink unit being further arranged, if the size of data compressed by the compression algorithm is equal to or less than the size of the frame buffer, to determine that the data of the still image can be losslessly compressed and stored in the frame buffer and to output a first control signal, the sink unit being further arranged, if the size of data compressed by the compression algorithm exceeds the size of the frame buffer, to determine that the data of the still image cannot be losslessly compressed and stored in the frame buffer and to output a second control signal, and the source unit is arranged to activate the panel self refresh mode in response to the first control signal, and to deactivate the panel self refresh mode in response to the second control signal, wherein, if the panel self refresh mode is activated, the operating power of the source unit is arranged to be turned off, and the sink unit is arranged to store the compressed data of the still image in the frame buffer, to recover the compressed data stored in the frame buffer and to apply the same to a display portion for image display when the operating power of the source unit is off, wherein, if the panel self refresh mode is deactivated, the sink unit is arranged to turn off the operating power for elements (220,240,250) that perform the panel self refresh, to apply the data of the still image input from the source unit to the display portion for image display without the compression, storage, and recovery processes. a source unit; and a sink unit operatively connected with the source unit via an embedded display port (eDP) interface to provide signal transmission between the source unit and the sink unit and to enable a panel self refresh mode for reducing power consumption, wherein, if an input image is a still image, the source unit is arranged to apply operating power to a frame buffer of the sink unit and to transmit data of the still image to the sink unit, characterized in that, the sink unit is arranged to perform compression of the data of the still image based on a predetermined lossless compression algorithm, the sink unit being further arranged, if the size of data compressed by the compression algorithm is equal to or less than the size of the frame buffer, to determine that the data of the still image can be losslessly compressed and stored in the frame buffer and to output a first control signal, the sink unit being further arranged, if the size of data compressed by the compression algorithm exceeds the size of the frame buffer, to determine that the data of the still image cannot be losslessly compressed and stored in the frame buffer and to output a second control signal, and the source unit is arranged to activate the panel self refresh mode in response to the first control signal, and to deactivate the panel self refresh mode in response to the second control signal, wherein, if the panel self refresh mode is activated, the operating power of the source unit is arranged to be turned off, and the sink unit is arranged to store the compressed data of the still image in the frame buffer, to recover the compressed data stored in the frame buffer and to apply the same to a display portion for image display when the operating power of the source unit is off, wherein, if the panel self refresh mode is deactivated, the sink unit is arranged to turn off the operating power for elements (220,240,250) that perform the panel self refresh, to apply the data of the still image input from the source unit to the display portion for image display without the compression, storage, and recovery processes.