Abstract:
A mobile terminal including a display unit outputting an image, a communication unit transceiving data with an external mobile terminal, and a controller controlling the communication unit to receive a screen information of the mobile terminal and a 1 st  control information of the screen information from the mobile terminal and to transmit a 2 nd  control information of the screen information to the mobile terminal, the controller controlling the display unit to transform the 1 st  control information of the screen information and to output the transformed screen information to a user. The 1 st  control information includes an image size transformation information of the screen information and an image compression format information of the screen information. The 2 nd  control information includes a supportable compression format information.

Description:
[0001]    This application claims the benefit of the U.S. Provisional Patent Application No. 61/527,610, filed on Aug. 25, 2011, which is hereby incorporated by reference as if fully set forth herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a mobile terminal, image display device mounted on a vehicle and data processing method using the same. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for the mobile terminal and the image display device to share a screen with each other. 
         [0004]    2. Discussion of the Related Art 
         [0005]    Generally, an image display device is the device that displays image information using a screen. In particular, an image display device mounted on a vehicle provides a user with such a function as a vehicle information display function, a navigation system function, a TV output function and the like. The recent development of technology enables an image display device mounted on a vehicle to perform data communication with a mobile terminal carried by a user by being connected with the mobile terminal using wire/wireless network. 
         [0006]    Through the data communication between the image display device mounted on the vehicle and the mobile terminal, screen data of one device is transmitted to another device so as to share a screen between the two devices. However, in order to share a screen between the image display device and the mobile terminal, the demand for a data processing method for efficiently transmitting screen data between devices is rising. 
       SUMMARY OF THE INVENTION 
       [0007]    Accordingly, the present invention is directed to a mobile terminal, image display device mounted on a vehicle and data processing method using the same, which may substantially obviate one or more of the problems due to limitations and disadvantages of the related art. 
         [0008]    An object of the present invention is to provide a mobile terminal, image display device mounted on a vehicle and data processing method using the same, by which a transmission rate of screen data can be improved in a manner of adjusting a compression scheme for a transmission screen, a loss rate of the transmission screen and the like to be suitable for a screen situation in transmitting screen data of the mobile terminal to the image display device to enable the image display device and the mobile terminal to share a screen with each other. 
         [0009]    Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
         [0010]    To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, an image display device mounted on a vehicle according to one embodiment of the present invention may include a display unit configured to output an image, a communication unit configured to transceive data with an external mobile terminal, and a controller configured to control the communication unit to receive a screen information of the mobile terminal and a 1 st  control information of the screen information from the mobile terminal, the controller configured to control the communication unit to transmit a 2 nd  control information of the screen information to the mobile terminal, the controller configured to control the display unit to transform the 1 st  control information of the screen information, the controller configured to control the display unit to output the transformed screen information to a user, wherein the 1 st  control information comprises an image size transformation information of the screen information and an image compression format information of the screen information and wherein the 2 nd  control information comprises a supportable compression format information. 
         [0011]    Preferably, the 2 nd  control information may further include an information indicating whether the screen information is a transformed screen. 
         [0012]    Preferably, the 2 nd  control information may further include a supportable encoding type information. 
         [0013]    Preferably, the 2 nd  control information may further include an information of a 1 st  frame buffer included in the image display device mounted on the vehicle. 
         [0014]    Preferably, the image size transformation information may include a multiple information of an image size of the screen information. 
         [0015]    Preferably, the communication unit may receive the screen information using VNC (virtual networking computing). 
         [0016]    More preferably, the controller may receive the screen information generated from a 2 nd  frame buffer included in the mobile terminal. 
         [0017]    In this case, the 2 nd  control information may include an information for requesting the 2 nd  frame buffer to update the screen information. 
         [0018]    And, the 1 st  control information may include an information for notifying the 2 nd  frame buffer that the screen information has been updated and an information of the updated 2 nd  frame buffer. 
         [0019]    To further achieve these and other advantages and in accordance with the purpose of the present invention, a mobile terminal according to another embodiment of the present invention may include a communication unit configured to transceive data with an external image display device and a controller configured to control the communication unit to transmit a screen information of the mobile terminal and a 1 st  control information of the screen information to the image display device, the controller configured to control the communication unit to receive a 2 nd  control information of the screen information from the image display device, the controller configured to generate the screen information in accordance with the 1 st  control information, wherein the 1 st  control information comprises an image size transformation information of the screen information and an image compression format information of the screen information and wherein the 2 nd  control information comprises a supportable compression format information supportable by the image display device. 
         [0020]    Preferably, the 2 nd  control information may further include an information indicating whether the screen information is a transformed screen. 
         [0021]    Preferably, the 2 nd  control information may further include an encoding type information supportable by the image display device. 
         [0022]    Preferably, the 2 nd  control information may further include an information of a 1 st  frame buffer included in the image display device mounted on the vehicle. 
         [0023]    Preferably, the image size transformation information may include a multiple information of an image size of the screen information. 
         [0024]    Preferably, the communication unit may transmit the screen information using VNC (virtual networking computing). 
         [0025]    More preferably, the controller may generate the screen information from a 2 nd  frame buffer included in the mobile terminal. 
         [0026]    More preferably, the 2 nd  control information may include an information for requesting the 2 nd  frame buffer to update the screen information. 
         [0027]    More preferably, the 1 st  control information may include an information for notifying the 2 nd  frame buffer that the screen information has been updated and an information of the updated 2 nd  frame buffer. 
         [0028]    Accordingly, the present invention may improve a transmission rate of screen data in a manner of adjusting a compression scheme for a transmission screen, a loss rate of the transmission screen and the like to be suitable for a screen situation in transmitting screen data between a mobile terminal and an image display device. 
         [0029]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
           [0031]      FIG. 1  is a schematic diagram of a data processing system including an image display device and a mobile terminal according to an embodiment of the present invention; 
           [0032]      FIG. 2  is a block diagram of a mobile terminal according to an embodiment of the present invention; 
           [0033]      FIG. 3  is a block diagram of an image display device according to an embodiment of the present invention; 
           [0034]      FIG. 4  is a flowchart of a sequence for an application launch in an image display device and a mobile terminal according to an embodiment of the present invention; 
           [0035]      FIG. 5  is a table of a client profile according to an embodiment of the present invention; 
           [0036]      FIG. 6  is a table of an application list according to an embodiment of the present invention; 
           [0037]      FIG. 7  is a schematic diagram of a screen transmitting system of an image display device and a mobile terminal according to an embodiment of the present invention; 
           [0038]      FIG. 8  is a flowchart of VNC service according to an embodiment of the present invention; 
           [0039]      FIG. 9  is a table of a message of VNC service according to an embodiment of the present invention; 
           [0040]      FIG. 10  is a table of an extended message of VNC service according to an embodiment of the present invention; 
           [0041]      FIG. 11  is a diagram for a method of transmitting a screen between an image display device and a mobile terminal according to an embodiment of the present invention; 
           [0042]      FIG. 12  is a table of a resizing level according to an embodiment of the present invention; 
           [0043]      FIG. 13  is a table of a pixel format according to an embodiment of the present invention; 
           [0044]      FIG. 14  is a table of client display configuration according to an embodiment of the present invention; 
           [0045]      FIG. 15  is a table of a framebuffer update according to an embodiment of the present invention; and 
           [0046]      FIG. 16  is a diagram for one example of a framebuffer update message according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0047]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
         [0048]    ---Insert--- 
         [0049]      FIG. 4  is a flowchart of a sequence for an application launch in an image display device  200  and a mobile terminal  100  according to an embodiment of the present invention. 
         [0050]    Referring to  FIG. 4 , a case of connecting the aforementioned image display device  200  and the aforementioned mobile terminal  100  by UPnP (universal plug and play) is explained as follows, for example. 
         [0051]    First of all, UPnP is the technique of setting a connection between devices located in the same subnet. When a device is added to a local network, the UPnP enables the added device to be automatically connected to and interoperate with another device that supports UPnP. Primary functions of the UPnP include a device advertisement function of automatically searching a local network for a specific resource, a service action invocation function of activating a specific function of a specific device remotely or requesting information on the specific device, a data subscription function of exchanging events between devices and the like. 
         [0052]    A sequence for an application launch shown in the drawing is one example of the aforementioned service action invocation and is the sequence for the image display device  200  to launch an application installed at the mobile terminal  100 . In this case, the image display device  200  includes a UPnP client  201  as a module responsible for a UPnP function. And, the mobile terminal  100  includes a UPnP server  101  as a module responsible for a UPnP function. 
         [0053]    The UPnP client  201  transmits a command ‘SetClientProfile’ to the UPnP server  101  [S 101 ]. In this case, the SetClientProfile registers a client profile of the UPnP client  201  to the UPnP server  101 . In this case, the client profile is general information on the UPnP client  201  and may include network address information, transceivable data size information, icon information and the like. Details of the client profile shall be described with reference to  FIG. 5  later. 
         [0054]    Subsequently, the UPnP server  101  transmits an updated client profile to the UPnP client  201  [S 102 ]. In particular, the client profile of the UPnP client  100  registered to the UPnP server  200  is transmitted. 
         [0055]    The UPnP client  201  transmits a command ‘GetApplication’ to the UPnP server  101  [S 103 ]. The GetApplication makes a request for a list of applications, which can be launched in the UPnP client  201 , among applications installed at the UPnP server  101 . 
         [0056]    The UPnP server  101  then transmits the list (Application List) of applications, which can be launched in the UPnP client  201 , to the UPnP client  201  [S 104 ]. In this case, the application list may contain application information, display information, remoting information, audio information and the like. And, the application list shall be described in detail with reference to  FIG. 6  later. 
         [0057]    The UPnP client  201  transmits a launch application, which commands a launch of a specific application, to the UPnP server  101  [S 105 ]. In particular, a user may be able to command a launch of a specific application among the applications contained in the aforementioned application list. In doing so, the UPnP client  201  commands the UPnP server  101  to launch the specific application, which is selected by the user, using the launch application. 
         [0058]    Subsequently, the UPnP server  101  transits a remoting protocol info. to the UPnP  201  [S 106 ]. In this case, the remoting protocol info. contains information on a remoting protocol used between applications. 
         [0059]    The UPnP server  101  then transmits data, which is generated by the launch of the application, to the UPnP client  201  [Content transfer: S 107 ]. 
         [0060]    The UPnP client  201  transmits a command ‘GetApplicationStatus’ for requesting status information on the specific application to the UPnP server  101  [S 108 ]. The UPnP server  101  then transmits the requested application status information to the UPnP client  201  [Application status requested: S 109 ]. 
         [0061]    Finally, the UPnP client  201  transmits a command ‘TerminateApplication’ for terminating the specific application to the UPnP server  101  [S 110 ]. The UPnP server  101  terminates the launch of the specific application and then notifies the termination of the corresponding application to the UPnP client  201  [Termination result: S 111 ]. 
         [0062]    Therefore, in accordance with the aforementioned sequence for the application launch, the image display device  200  launches the specific application installed at the mobile terminal  100  and a launched screen of the corresponding application may be outputted to the image display device  200 . 
         [0063]      FIG. 5  is a table of a client profile according to an embodiment of the present invention. 
         [0064]    Referring to  FIG. 5 , a client file is general information on the UPnP client  201  and may contain connectivity information, RTP information and icon preference. 
         [0065]    The connectivity information is the communication connectivity information of the UPnP client  201  and may contain Bluetooth MAC address (Bdaddr), information (startConnection) indicating whether to use Bluetooth as a basic channel for audio data transmission and the like. 
         [0066]    The RTP information is the information on RTP (real time protocol) of the UPnP client  201  and may contain supportable RTP payload type information (payloadtype), minimum buffer size information (audioIPL) required for playing back audio data received by RTP, maximum buffer size information (audioMPL) for buffering audio data received by RTP and the like. 
         [0067]    The icon reference is the information on an icon used by the UPnP client  201  and may contain a type (mimetype) of an icon image, icon image size information (e.g., height, width, etc.) and the like. 
         [0068]    The UPnP client  201  registers the client profile of the UPnP client  201  to the UPnP server  101  through the aforementioned command ‘SetClientProfile’. The UPnP server  101  then communicates with the UPnP  201  using the registered client profile. 
         [0069]      FIG. 6  is a table of an application list according to an embodiment of the present invention. 
         [0070]    Referring to  FIG. 6 , an application list is a list of applications, which can be launched in the UPnP client  201 , among applications installed at the UPnP server  101  and may include such attribute information of a corresponding application as application information, display information, remoting information, audio information and the like. 
         [0071]    The application information includes information (appCategory) on a category of application launchable in the UPnP client  201  and information (trustLevel) on trust level of application. One example of the trust level (trustLevel) of application may include information indicating whether a corresponding application corresponds to an unknown application, a user configuration application, a self-registered application or a registered application. 
         [0072]    The display information may include information (contentCategory) on a content category provided by an application and information (contentRule) on a rule for determining whether to output a content. 
         [0073]    The remoting information may include information (protocolID) on a remoting protocol to be used between applications, information (format) on a content type transmitted by a remoting protocol and the like. 
         [0074]    And, the audio information may include type information (audioType) on an audio content, information (audioCategory) on a category of an audio content, information (trustLevel) on a trust level of a current audio content and the like. 
         [0075]    Therefore, the UPnP client  201  receives the ApplicationList via the aforementioned command ‘GetApplicationList’ and may be then able to recognize category and attribute information on an application launchable in the UPnP client  201 . 
         [0076]    According to the above description of the sequence for the application launch, a specific application installed at the mobile terminal  100  is launched in the image display device  200  and information on the launched application is outputted to the image display device  200 . 
         [0077]    In the following description, in order for the mobile terminal  100  and the image display device  200  to share a screen with each other, a screen transmitting system configured to transmit screen information of one of the mobile terminal  100  and the image display device  200  to the other is explained. 
         [0078]    In particular, in the screen transmitting system including the mobile terminal  100  and the image display device  200 , as screen information of one of the image display device  200  and the mobile terminal  100  connected to each other is transmitted to and outputted from the other, each of the two devices (i.e., the image display device  200  and the mobile terminal  100 ) may be able to provide a user with the same screen. 
         [0079]    In this specification, one example of transmitting screen information of the mobile terminal  100  to the image display device  200  is described as follows. 
         [0080]    And, the screen transmitting system according to the present invention may be able to transmit the screen information of the mobile terminal  100  to the image display device  200  using VNC (virtual networking computing). 
         [0081]    In particular, the VNC (virtual networking computing) is RFB (remote frame buffer) protocol for enabling devices located remotely to share a frame buffer with each other. According to the VNC, if a client makes a request for a current frame buffer content via network, a server delivers captures a frame buffer and then delivers the frame buffer in a client-understandable graphic format via the network. Hence, two devices may be able to share a screen with each other. 
         [0082]    In this specification, if screen information of a mobile terminal is transmitted to an image display device  200  using VNC (virtual networking computing), it can be named a VNC service and described as follows. 
         [0083]      FIG. 7  is a schematic diagram of a screen transmitting system of an image display device  200  and a mobile terminal  100  according to an embodiment of the present invention. 
         [0084]    Referring to  FIG. 7 , a mobile terminal  100  may include a VNC server  102  as a module in charge of the above-mentioned VNC service and an output unit  103  configured to output a transmitted screen to a user. An image display device  200  may include a VNC client  202  as a module in charge of the aforementioned VNC service and an output unit  203  configured to output a transmitted screen to a user. 
         [0085]    The VNC server  102  and the VNC client  202  of the present invention may be implemented by the controller  180  of the mobile terminal  100  and the controller  212  of the image display device  200 , respectively. Alternatively, the VNC  102  and the VNC client  202  may be implemented into independent software modules, respectively. 
         [0086]    The VNC server  102  and the VNC client  202  may perform the VNC service of transmitting screen information of the mobile terminal  100  or the image display device  200  using the VNC (virtual networking computing). 
         [0087]    As mentioned in the foregoing description, in order to perform the VNC service, each of the VNC server  102  and the VNC client  202  transmits screen information and display control information of one device to the other device using the RFB (remote frame buffer) protocol for enabling remotely-located devices to share a frame buffer with each other. In this case, the display control information of the present invention may include information related to a transmitted screen, information on a frame buffer of each device and the like. 
         [0088]    In the following description, the VNC service of the present invention is explained in detail with reference to the accompanying drawings. 
         [0089]      FIG. 8  is a flowchart of VNC service according to an embodiment of the present invention. 
         [0090]    Referring to  FIG. 8 , according to the VNC service of the present invention configured to transmit screen information of a mobile terminal  100  to an image display device  200 , the screen information of the mobile terminal  100 , which is saved in a frame buffer of the mobile terminal  100 , is transmitted to the image display device  200 . 
         [0091]    The aforementioned VNC service of the present invention can be performed by the steps shown in the drawing. The VNC service of the present invention is described in detail with reference to the accompanying drawing. 
         [0092]    First of all, a VNC client  202  sends a client init message containing a size, name, color support information and the like of a frame buffer of an image display device  200  to a VNC server  102  [S 201 ]. And, the VNC server  102  sends a server init message containing a size, name, color support information and the like of a frame buffer of a mobile terminal  100  to the VNC client  202  [S 201 ]. 
         [0093]    The VNC client  202  sends a set encodings message containing encoding type information on an encoding type supportable by the image display device  200  to the VNC server  102  [S 203 ]. Subsequently, the VNC server  102  encodes screen information of the mobile terminal  100  by an encoding type supportable by the image display device  200  and then transmits the encoded information. 
         [0094]    The VNC client  202  sends a set pixel format message containing compression scheme information supportable by the image display device  200  to the VNC server  102  [S 204 ]. Subsequently, the VNC server  102  compresses the screen information of the mobile terminal  100  by the compression scheme supportable by the image display device  200  and then transmits the compressed information. 
         [0095]    The VNC client  202  sends a framebuffer update request message containing information for requesting the frame buffer of the mobile terminal to update the screen information of the mobile terminal  100  to the VNC server  102  [S 205 ]. 
         [0096]    Having received the framebuffer update request message, the VNC client  202  updates the current screen information of the mobile terminal  100  in the frame buffer. 
         [0097]    The VNC server  102  sends a framebuffer update message containing information indicating that the screen information in the frame buffer of the mobile terminal  100  has been updated and the corresponding information in the updated frame buffer to the VNC client  202  [S 206 ]. 
         [0098]    Finally, the VNC client  202  brings the screen information of the mobile terminal  100  from the updated frame buffer of the mobile terminal  100  and then outputs the corresponding screen information to the image display device  200 . 
         [0099]    As mentioned in the foregoing description, in the VNC service of the present invention, the VNC server  102  and the VNC client  202  exchange various messages to perform the VNC service. In the following description, messages used by the VNC service of the present invention are explained. 
         [0100]      FIG. 9  is a table of a message of VNC service according to an embodiment of the present invention. And,  FIG. 10  is a table of an extended message of VNC service according to an embodiment of the present invention. 
         [0101]    Referring to  FIG. 9  and  FIG. 10 , a message of a VNC service of the present invention may include Set Pixel Format, Set Encodings, Framebuffer Update Request, Key Event, Pointer Event, Client Cut Text, Framebuffer Update, Set Color Map Entries, Bell, and ServerCutText. 
         [0102]    The Set Pixel Format may include information on a compression scheme (pixel format) supportable by the image display device  200 . 
         [0103]    The Set Encodings may include information on an encoding type supportable by the image display device  200 . 
         [0104]    The Framebuffer Update Request may include information for making an update of screen information of the mobile terminal  100  to the frame buffer of the mobile terminal  100 . 
         [0105]    The Key Event may include information on an event occurring by a hard key (e.g., a keyboard in case of PC) of the image display device  200 . 
         [0106]    The Pointer Event may include information on an event occurring by a pointer of the image display device  200 . 
         [0107]    The Client Cut Text may include information on clipboard event information of the image display device  200 . 
         [0108]    The Framebuffer Update may include information indicating that screen information has been updated in the frame buffer of the mobile terminal  100  and information on the updated frame buffer. The Framebuffer Update Message shall be described in detail with reference to  FIG. 15  and  FIG. 16  later. 
         [0109]    The Set Color Map Entries may include color map (palette) information of a screen saved in a frame buffer. 
         [0110]    The Bell may include information for generating a bell sound from the image display device  200 . 
         [0111]    The ServerCutText may include clipboard event information of the mobile terminal  100 . 
         [0112]    Meanwhile, the extended message of the VNC service of the present invention may include various messages shown in  FIG. 10  as various control informations for sharing a screen of the mobile terminal  100 . 
         [0113]    In the extended message, Display Configuration may include such information of a frame buffer as information on possibility of screen direction change, information on possibility of up/down scaling, information on possibility of Empty Framebuffer Update Message Handling, information on possibility of supporting Framebuffer Alternative Text, information on a supportable pixel format, information on a physical size of a device, information on a distance from a user and the like. The Client Display Configuration corresponding to the various informations of the frame buffer of the image display device  200  shall be described in detail with reference to  FIG. 14  later. 
         [0114]    The Event Configuration may include information on language setting of keyboard or UI, information on various hard keys (e.g., knob, ITU key, virtual keyboard, etc.) and event (e.g., input type such as single/multi touch, a count of total inputs of multi-touch, pressure, etc.) setting information. 
         [0115]    The Event Mapping may include information on a request and processing for an input function activation for a hard key event. 
         [0116]    The Device Status may include such device status information as possibility of key/touch input of device, lock/unlock, screen saver mode, night mode, audio input, presence or non-presence of disturbance caused to a vehicle driver, current horizontal/vertical angle of frame buffer and the like. 
         [0117]    The Framebuffer/Audio Blocking Notification may include message information indicating that a delivered frame buffer/audio is cut off. 
         [0118]    The Touch Event may include multi-touch input information. 
         [0119]    Meanwhile, the VNC service of the present invention provides frame transformation. According to the frame transformation of the present invention, screen information of a mobile terminal  100  is transmitted to an image display device  200  in a manner of being transformed. 
         [0120]    In particular, the mobile terminal  100  does not transmit whole pixel data of a screen of the mobile terminal  100  but transmits the screen of the mobile terminal  100  in a manner of reducing a size of the screen of the mobile terminal  100  or changing a pixel format of the screen of the mobile terminal  100  (e.g., decreasing a color depth). 
         [0121]    In the following description, a method of transmitting a screen between an image display device  200  and a mobile terminal  100  using frame transformation is explained. 
         [0122]      FIG. 11  is a diagram for a method of transmitting a screen between an image display device  200  and a mobile terminal  100  according to an embodiment of the present invention. 
         [0123]    Referring to  FIG. 11 , according to a method of transmitting a screen between an image display device  200  and a mobile terminal  100  using the frame transformation of the present invention, the mobile terminal  100  creates screen information of the mobile terminal  100 . For instance, the mobile terminal  100  may be able to create the screen information by capturing a current frame buffer of the mobile terminal  100 . 
         [0124]    Subsequently, the mobile terminal  100  transforms an image size of the created screen information, a pixel format of the created screen information or the like. For instance, the screen information of the mobile terminal  100  may be transformed in a manner of reducing a size of an image or changing a color depth of a pixel format into a low color depth. In this case, it may be able to reduce a data size of the screen information. The mobile terminal encodes the transformed screen information by an encoding type supportable by the image display device  200 . 
         [0125]    The above-transformed screen information of the mobile terminal  100  may be transmitted to the image display device  200  using the aforementioned VNC service. In particular, the mobile terminal  100  may transmit the transformed screen information of the mobile terminal  100  to the image display device  200  via such a message as Framebuffer Update and the like. 
         [0126]    Subsequently, the image display device  200  performs decoding and re-transformation on the received screen information of the mobile terminal  100 . In particular, the image display device  200  decodes the encoded screen information and then retransforms the reduced image size into the original size. The image display device  200  then outputs the retransformed screen information of the mobile terminal  100  to a user. 
         [0127]    According to a method of transmitting a screen between an image display device  200  and a mobile terminal  100  using the aforementioned frame transformation, since a data size of a transmitted screen information is reduced, it may be able to save encoding/decoding/data transmission time and the like and increase a frame rate of a transmitted screen. 
         [0128]    In a method of transmitting a screen between an image display device  200  and a mobile terminal  100 , it may be able to dynamically apply the aforementioned frame transformation in accordance with a status of a screen of a device or the mobile terminal  100 . In particular, in accordance with the status of the screen of the device or the mobile terminal  100 , whether to use the frame transformation may be set different or a screen transformation level may be set different. 
         [0129]    For instance, like a case that data processing performance of the mobile terminal  100  or the image display device  200  is low, a case that a screen changes, or a case that a screen is switched by an occurrence of a user input to a screen, in case that a screen of high definition is unnecessary, an image size may be further reduced or screen information may be changed into a pixel format having a low color depth. 
         [0130]    In particular, when a screen is switched by an occurrence of a user input to a screen, if an image size is further reduced or screen information is changed into a pixel format having a low color depth, a screen switching speed (i.e., screen response sped) may be increased. 
         [0131]    In this case, according to the present invention, a switched image size ad color depth may be determined in a manner of being selected from preset resizing levels and pixel formats. 
         [0132]      FIG. 12  is a table of a resizing level according to an embodiment of the present invention. And,  FIG. 13  is a table of a pixel format according to an embodiment of the present invention. 
         [0133]    Referring to  FIG. 12 , the present invention may determine a resizing factor in accordance with a resizing level. In particular, if a resizing level becomes higher, a resizing factor and a transformed image size may be set smaller. 
         [0134]    Referring to  FIG. 13 , the present invention may define a specific pixel format including such information as color depth, bits-per-pixel and the like. And, the present invention may use a conventional pixel format already known to the public. 
         [0135]    On the other hand, in case that data processing performance of the mobile terminal  100  or the image display device  200  is high, for such a still image as an SMS image, an email image and the like, frame transformation may not be used, a resizing level may be lowered (i.e., a resizing level may be increased), screen information may be changed into a pixel format having a high color depth. Hence, it may be bale to transmit and output screen information of high definition. 
         [0136]    In the following description, a data structure for implementing the above-described screen transmitting method between the mobile terminal  100  or the image display device  200  is explained with reference to the accompanying drawings. 
         [0137]      FIG. 14  is a table of client display configuration according to an embodiment of the present invention. 
         [0138]    Referring to  FIG. 14 , as mentioned in the foregoing description, a client display configuration according to an embodiment of the present invention may include information on a frame buffer of an image display device  200  and the like. 
         [0139]    The client display configuration according to the embodiment of the present invention may further include Frame Transformation Used and Pixel Format Support as well as the information on the frame buffer of the image display device  200 . 
         [0140]    The Frame Transformation Used may include information indicating whether to apply the aforementioned frame transformation in the screen transmission between the mobile terminal  100  and the image display device  200 . 
         [0141]    The Pixel Format Support may include pixel format information supportable by the image display device  200 . 
         [0142]    The VNC client  202  may send a client display configuration message to the VNC server  201 . And, the VNC server  201  and the VNC client  202  may perform the aforementioned screen transmitting method of the mobile terminal  100  and the image display device  200  in accordance with the client display configuration information. 
         [0143]      FIG. 15  is a table of a framebuffer update according to an embodiment of the present invention, and  FIG. 16  is a diagram for one example of a framebuffer update message according to an embodiment of the present invention. 
         [0144]    As mentioned in the foregoing description, Framebuffer Update of the present invention may include information indicating that screen information is updated in the frame buffer of the mobile terminal  100  and information related to a corresponding updated screen. 
         [0145]    The Framebuffer Update of the present invention may further include Resizing Level and Pixel Format, as shown in  FIG. 15 . 
         [0146]    The Resizing Level may include the aforementioned resizing factor information defined in  FIG. 12 . And, the Pixel Format may include the aforementioned pixel format information defined in  FIG. 13 . 
         [0147]    In the example of Framebuffer Update message, Resizing Level and Pixel Format are set to 2 and RGB565, respectively. 
         [0148]    According to this example, the screen information currently updated in the frame buffer of the mobile terminal indicates that an image size of an original screen is reduced by ¼ and that a pixel format of the original screen is changed into the pixel format ‘RGB565’. 
         [0149]    The image display device  200  enlarges the received screen information by 4×-size and then outputs the screen information of the mobile terminal  100  to a user by performing image processing in accordance with the pixel format ‘RGB565’. 
         [0150]    It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.