A method of processing a 3 dimensional image, which is processed by a digital device containing a light-receiving unit including a first sensing unit to sense a visible light and a second sensing unit to sense an infrared light and a light-emitting unit to emit the infrared light, comprising the steps of: - receiving a 2 dimensional or a 3 dimensional image mode request signal; - if the image mode request signal corresponds to a 3 dimensional image mode request signal, checking by the control unit a resolution mode of the light-receiving unit; - switching by a control unit a resolution of the light-receiving unit from a first resolution to a second resolution which is lower than the first resolution, if the resolution of the light-receiving unit corresponds to the first resolution; - turning off operation of the light-emitting unit during a first time interval in order not to output an infrared light; - sensing by the light-receiving unit the visible light from a subject; - extracting by an image processing unit color image information from the visible light sensed by the first sensing unit of the light-receiving unit during a first time interval; - turning on operation of the light-emitting unit during a second time interval in order to output an infrared light to the subject; - sensing by the light-receiving unit the infrared light from the subject; - extracting by the image processing unit depth image information from the infrared light sensed by the second sensing unit of the light-receiving unit during the second time interval; - determining by the control unit whether extraction of both the color image information and the depth image information for the subject is completed; - if the extraction of both the color image information and the depth image information for the subject is completed, implementing by a 3D image implementing unit a 3D image of the subject based on the extracted color image information and the depth image information; characterized in - when the resolution of the light-receiving unit is switched from the first resolution to the second resolution which is lower than the first resolution, increasing a time interval between an color image frame and an depth image frame; and - controlling by the control unit the light-emitting unit, so that the time of turning on the infrared light is increased as much as the increased time interval between the color image frame and the depth image frame. - receiving a 2 dimensional or a 3 dimensional image mode request signal; - if the image mode request signal corresponds to a 3 dimensional image mode request signal, checking by the control unit a resolution mode of the light-receiving unit; - switching by a control unit a resolution of the light-receiving unit from a first resolution to a second resolution which is lower than the first resolution, if the resolution of the light-receiving unit corresponds to the first resolution; - turning off operation of the light-emitting unit during a first time interval in order not to output an infrared light; - sensing by the light-receiving unit the visible light from a subject; - extracting by an image processing unit color image information from the visible light sensed by the first sensing unit of the light-receiving unit during a first time interval; - turning on operation of the light-emitting unit during a second time interval in order to output an infrared light to the subject; - sensing by the light-receiving unit the infrared light from the subject; - extracting by the image processing unit depth image information from the infrared light sensed by the second sensing unit of the light-receiving unit during the second time interval; - determining by the control unit whether extraction of both the color image information and the depth image information for the subject is completed; - if the extraction of both the color image information and the depth image information for the subject is completed, implementing by a 3D image implementing unit a 3D image of the subject based on the extracted color image information and the depth image information; characterized in - when the resolution of the light-receiving unit is switched from the first resolution to the second resolution which is lower than the first resolution, increasing a time interval between an color image frame and an depth image frame; and - controlling by the control unit the light-emitting unit, so that the time of turning on the infrared light is increased as much as the increased time interval between the color image frame and the depth image frame.