Abstract:
To increase support a screen having a different aspect ratio or a large screen by use of existing graphics adapters, thus improving performance and flexibility of the whole system.  
     Disclosed is a monitor system comprising a liquid crystal display having a liquid crystal panel which displays an image and has a display area virtually divided into a plurality of divided area, and a plurality of graphics adapters to for developing image data for the divided areas of the liquid crystal display, wherein the divided areas of a screen in the liquid crystal display are obtained by further dividing an area in which the graphics adapters to create images, and a reconstruction circuit for reading out image data developed in the graphics adapters in turn to reconstruct the image data is provided.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Technical Field  
           [0002]    The present invention relates generally to a display system using a plurality of graphics adapters and, more particularly to an image display device adopting an image dividing method which demonstrates excellent performance and great flexibility.  
           [0003]    2. Description of the Related Art  
           [0004]    A high resolution display which showed a slow progress with respect to a CRT display has been making rapid progress with introductions of new technologies such as liquid crystal liquid. To be more specific, the liquid crystal display (LCD) can achieve a high resolution more easily compared to the CRT display by microfabricating it. With respect to this LCD, high definition (ultra-high resolution) displays with a very high resolution such as QXGA (Quad Extended Graphics Array) (2048×1536 dots), QSXGA (Quad Super Extended Graphics Array) (2560×2048 dots), and QUXGA (Quad Ultra Extended Graphics Array) (3200×2400 dots) have been put to practical use by making a panel itself into a high definition one.  
           [0005]    On the other hand, a device called a graphics adapter for performing image creation and the like to display an image on a display is provided in a personal computer (PC). A memory for writing and storing the image to be displayed on the display is provided in the graphics adapter, and this memory is called a frame buffer.  
           [0006]    As a technique for performing a high resolution display, there has been one to divide a screen to display an image using a plurality of graphics adapters. Specifically, this technique has a feature in that instead of developing a special graphics adapter having a large frame buffer, using an ordinary graphic adapters, a screen is divided into two to four sections, one graphics adapter is assigned to the corresponding section, and a corresponding image is displayed. These techniques are generally called ‘Partitioning Method’ or ‘Tiling Method.’ FIG. 8 is a diagram for explaining a conventional screen dividing method. As for implementation, it is constructed that Four graphics adapters  201  to  204  are installed at an adapter slot of PC or a work station (WS), and each of the graphics adapter  201  to  204  is assigned to corresponding one of sub-screens that are divided areas of the screen  205 ,  205   a  to  205   d . To be more specific, each of the graphics adapters  201  to  204  is allowed to be assigned symmetrically to the corresponding one of the divided areas having the same shape, and the screen  205  is divided crosswise. The sub-screens  205   a  to  205   d , each of which is the divided area, are driven so as to create an image by the corresponding graphics adapters  201  to  204 .  205   a  to  205   d , the divided areas of the screen  205 , have a size, which is a proper scale for the graphics adapters  201  to  204  to create an image.  
           [0007]    With respect to a size of the whole screen of the foregoing ultra-high resolution display, the ones having aspect ratios, that is, ratios of the length of the screen to the width thereof 4:3 or 5:4, such as QXGA (2048×1536 dots) and QSXGA (2560×2048 dots), have been the main stream. However, with the diffusion of high definition televisions (HDTV) (and the like), displays and graphics adapters, which have a new aspect ratio such as an aspect ratio in which  1920  dots in the horizontal direction and  1200  dots in the vertical direction are arranged, come to appear. When this display for use in the HDTV is displayed using a plurality of graphics adapters for a high resolution by the screen dividing method, it is impossible to effectively use a frame buffer in each graphics adapter, because a size of whole screen is not equal to an integral multiple of a size of the sub-screen, which is a proper scale for one graphics adapter to create an image.  
           [0008]    [0008]FIG. 9 is a diagram for explaining the case where a size of the sub-screen, which is a proper scale for one graphics adapter to create an image, is not equal to an integral multiple of a size of the whole screen. In FIG. 9, illustrated is a case where four graphics adapters, each of which includes 1280 dots horizontally and  1024  dots vertically, are used, and an image is displayed on a display (portion indicated by slanted lines) including 1920 dots horizontally and 1200 dots vertically. In this case, since the size of the display is larger than that of one graphics adapter, in other words, since one graphics adapter is narrower than the display (portions indicated by slated lines) both by length and by width, four graphics adapters are necessary as shown in FIG. 9. For this reason, as can be understood from FIG. 9, a useless memory area other than the portion indicated by slanted lines is very large, and hence it was impossible to effectively use the system.  
           [0009]    Work stations comprising only one extension slot showing a fast transfer rate and a large bus width in addition to a standard slot can be recently found. In these work stations, for example, one high speed graphics adapter using AGP (Accelerated Graphics Port) and graphics adapters using a PCI bus (Peripheral Component Interconnect bus) bus are allowed to be mixedly present. When it is intended to use a plurality of graphics adapters, the graphics adapters using the PCI bus are used in many cases for the reason that as to the AGP, only one port can be used for the system. However, though it is tried to increase a processing speed by inserting one graphics adapter among the four graphics adapters in the extension slot, the processing speed cannot be increased because the processing speed is ruled by other three graphics adapters. Accordingly, it is impossible to improve performance of the whole of the system.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention is invented to solve the above-described technical problems. The object of the present invention is to provide a monitor system adopting an excellent screen dividing method from a viewpoint of performance and flexibility in a display system using a plural of graphics adapters.  
           [0011]    Another object of the present invention is to effectively use a frame buffer of a graphics adapter by reducing a useless memory area, even when an aspect ratio of the graphics adapter and an aspect ratio of a display differ from each other.  
           [0012]    To achieve the foregoing object, in the monitor system of the present invention, when screens having different aspect ratios are supported by an existing graphics adapter or when a large screen is supported by a plurality of graphics adapters, an area for which each of graphics adapters can create an image (develop) is divided furthermore into a plurality of divided areas, image data divided by each graphics adapter in accordance with a specified assignment is developed, and the developed image data is reconstructed on a display side. Thus, loads are distributed to each graphics adapter. Therefore, the monitor system to which the present invention is applied comprises a display device having a screen for displaying an image, in which its display area is virtually divided into a plurality of divided areas; and a plurality of graphics adapters, each of which develops image data for corresponding one of the divided areas, wherein each divided area of the screen in the display device is obtained by further dividing an area for which one graphics adapter can create an image.  
           [0013]    In such construction, the area for which each graphics adapter can create an image can be characterized by making it smaller than an area that can be displayed by the screen. The display device reconstructs a screen from the image data output from the graphics based on assignment information for the respective divided areas. With such construction, a correct picture can be displayed from divided image data assigned based on characteristics of an application and performance of the system and the graphics adapter.  
           [0014]    Furthermore, in the monitor system of the present invention, a high performance graphics adapter is assigned to a divided area having a heavy load on the screen. Thus, it is preferable that performance of the whole of the system can be improved. For example, when the monitor system is constructed so that a graphics adapter using a high performance AGP takes charge of image creation in a central portion of the screen, an image creation speed can be increased even when an application in which loads concentrate in the central portion like a system of, for example, CAD is executed.  
           [0015]    The plurality of graphics adapters are assigned to the respective divided areas scattered on the screen to create images on the respective divided areas. Even when the plurality of graphics adapters having the same performance are used, it is possible by the distribution of the loads to cope with a problem in which the image creation speed is slowed down by a graphics adapter having the heaviest load.  
           [0016]    When the present invention is comprehended from another point of view, a monitor system comprises: a display device including a screen for displaying an image with a resolution of a first aspect ratio; and a plurality of graphics adapters, each having an area with a resolution of a second aspect ratio which is different from the first aspect ratio, for which image creation can be performed and each supplying, to the display device, image data corresponding to a resolution lower than that of the first aspect ratio of the screen, wherein the image data supplied from each of the graphics adapters divides the area with the resolution of the second aspect ratio, for which an image creation can be performed, into areas having a predetermined size, and undergoes a clipping processing; and the display device reconstructs the image data supplied from the plurality of graphics adapters, outputs the image data to the screen with the resolution of the first aspect ratio. The aspect ration can be defined generally as a ratio of a lengthwise length to a crosswise length of an image.  
           [0017]    The image data supplied from the graphics adapters is formed based on image creation assignment for divided areas obtained by virtually dividing the screen. The display device reads out the image data of the divided areas supplied from the plurality of graphics adapters in turn based on information of the image creation assignment, the image data being subjected to the clipping processing, and reconstructs the image data. This clipping processing is generally defined as an operation to cut off image data corresponding to portions of a screen other than those taken charge of by one of the graphics adapters. The image creation assignment is the one for determining which graphics adapter takes charge of the image creation for a certain area of the screen.  
           [0018]    When the present invention is comprehended from the display device side, in the present invention, a reconstruction section is provided in the display device, and the image data, which has a size obtained by further dividing an area for which the graphics adapter can display an image, is read out in turn so that a correct picture is formed. This makes it possible to display an image on the ultra-high resolution display and the image on a display having a different aspect ratio. Specifically, a display device to which the present invention is applied comprises: a frame buffer for storing divided image data received from a plurality of graphics adapters capable of creating an image with a low resolution; a reconstruction section for reading out the divided image data stored in the frame buffer in turn based on a predetermined assignment, and forming display data; and a high resolution screen for displaying an image based on the display data formed by the reconstruction section, wherein the divided image data stored in said frame buffer is formed by further dividing the data of an area having a proper size which is a proper scale for a plurality of adapters to create an image. Here, the high resolution screen is used as a display area an aspect ratio different from that of an area having a proper size which is a proper scale for a plurality of graphics adapters to create an image.  
           [0019]    The present invention is directed to a method of displaying an image on a large screen by use of a plurality of graphics adapters, which comprises the steps of: forming divided image data from the image data to be displayed having a size obtained by further dividing an area which said graphics adapters can develop; reading out the divided image data developed into the graphics adapters in a predetermined order and reconstructing the image data; and displaying an image on the screen based on the image data reconstructed.  
           [0020]    Assignments of the divided image data to the graphics adapters are performed based on assignment information indicating which portion of the screen is taken charge of by a specific graphics adapter among the graphics adapters. The assignment information complies with assignment used when the divided image data is assigned to a plurality of graphics adapters to be developed in them. The present invention may be constructed so that the assignment information is transmitted to the display device along with the image data. Moreover, the present invention can be constructed so that the assignment information is determined by circuits previously fixed. Specifically, a reconstruction of the image data is read out in a predetermined order based on the assignment information. This makes it possible to display the image data as a correct picture even when the image data is randomly divided in accordance with characteristics of the application. With respect to the divided image data, an area which can be developed by the graphics adapter is divided into different sizes or an even size.  
           [0021]    On the other hand, when the present invention is comprehended from another point of view, an image display method to display an image on a high resolution screen of a first aspect ratio, by use of a plurality of low resolution graphics adapters, each being capable of displaying an image having a second aspect ratio different from the first aspect ratio, which comprises the steps of: dividing image data to be displayed to form divided image data in a size obtained by dividing the image displayed by each graphics adapter into a plurality of areas; assigning the divided image data formed to each of the low resolution graphics adapters; reading out the divided image data assigned to each of said low resolution graphics adapters in an order to create a correct image on the high resolution screen, thus reconstructing the image data; and displaying the image data reconstructed on the high resolution screen. The reconstruction of the image data is to read out the divided image data in order based on assignment information to the low resolution graphics adapters. The assignments of the divided image data are determined in consideration of a degree of a load required for displaying the image data. This makes it possible to apply difference of capabilities among the graphics adapters to an unevenness of loads of the image data, and to improve the image creation performance by distributing the loads, thus improving performance of the whole of the system. 
       
    
    
       [0022]    These and other aspects, features and advantages of the present invention will be described or become apparent from the following detailed description of the preferred embodiments, which is to be read in connection with the accompanying drawings.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    [0023]FIG. 1 is a block diagram for explaining a display monitor system to which this embodiment is applied.  
         [0024]    [0024]FIG. 2 is a diagram showing an example of a screen division method adopted in this embodiment.  
         [0025]    [0025]FIG. 3 is a diagram explaining a processing flow of the division method in this embodiment.  
         [0026]    [0026]FIG. 4 is a flowchart showing a processing flow in this embodiment.  
         [0027]    [0027]FIG. 5 is a flowchart for explaining a processing to remove a special function from a construction in changing the construction of end points.  
         [0028]    [0028]FIG. 6 is a diagram for explaining an example of a screen division method when aspect ratios are different.  
         [0029]    FIGS.  7 ( a ),  7 ( b ) and  7 ( c ) are diagrams for explaining another example when an image display is performed using graphics adapters having different aspect ratios from that of a screen area.  
         [0030]    [0030]FIG. 8 is an explanatory view for explaining a conventional screen division method.  
         [0031]    [0031]FIG. 9 is a diagram for explaining a case in which a screen size is not equal to an integral multiple of a size which is a proper scale for one graphics adapter to create an image. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]    The present invention will be described based on embodiments shown in attached drawings below.  
         [0033]    [0033]FIG. 1 is a block diagram for explaining a display monitor system to which an embodiment is applied. The monitor system comprises a personal computer (PC)  10  or a work station (WS)  10  for generating image data to be displayed; and a liquid crystal display  30  as a display device for displaying an image based on the image data supplied thereto. The PC (WS)  10  comprises a microprocessor  11  for executing a dividing processing in this embodiment; and a bus controller  12  for controlling an AGP bus port and a PCI bus port. Furthermore, the PC(WS) 10  comprises four graphics adapters  13  to  16  corresponding to a resolution of, for example, 1280×1024 dots. The graphics adapters  13  to  16  have frame buffers  17  to  20  for storing image data, and image creation function, respectively. The graphics adapters  13  to  16  perform a clipping processing, respectively. The clipping processing is an operation to cut off image data corresponding to portions of a screen other than those taken charge of respective graphics adapters,  13  to  16 . The clipping processing is sometimes performed by the microprocessor  11  by means of software. If the graphics adapters  13  to  16  are supported by hardware, the monitor system can be constructed so that the clipping processing is performed by each of the graphics adapters  13  to  16 . Furthermore, in this embodiment, one graphics adapter  13  is constructed as a high performance AGP adapter, and other three graphics adapters  14  to  16  are PCI adapter.  
         [0034]    On the other hand, the liquid crystal display  30  comprises a frame buffer  31  (on the monitor side) for temporarily storing image data supplied from the graphics adapters  13  to  16 , and a reconstruction circuit  32  for performing a screen division and reconstructing the image data for a display screen, which has been subjected to the clipping processing. The reconstructing circuit  32  is incorporated in the liquid crystal display  30 . In the liquid crystal display  30 , the reconstruction circuit  32  is constructed in the form of logical hardware in accordance with a screen division style on the PC (WS)  10  side. Furthermore, the liquid display  30  further comprises a liquid crystal panel  33  as the screen for displaying an image, which is composed of, for example, a TFT array; a panel interface LSI  34  for generating timing pulses for driving the liquid crystal panel  33 ; a source driver  35  for outputting a voltage to be applied to each of source electrodes of TFTs in the liquid crystal panel  33 ; and a gate driver  36  for outputting a voltage to each of gate electrodes of the TFTs. Note that in this embodiment, a high resolution display such as QSXGA (2560×2048 dots) is used as the liquid crystal panel  33 .  
         [0035]    [0035]FIG. 2 is a diagram showing an example of the screen division method applied to this embodiment. Numbers  1  to  4  shown in FIG. 2 show states where they are assigned to the respective graphics adapters  13  to  16 . The number  1  corresponds to the graphics adapter  13 ; the number  2 , the graphics adapter  14 ; the number  4 , and so on. Generally, in an applying operation using the high resolution display, a rate of image creation in the central portion of the screen becomes high. This trend is particularly conspicuous in CADs that is one of users of ultra high resolution displays. In the CADs, applications for displaying menus in the peripheral portions (for example, upper and lower portions) of the screen and for displaying CAD figures with a large quantity of information in the central portion thereof are used in many cases. At this time, when the screen is simply divided into four equally as shown in FIG. 8 which is used for describing the prior art, the central portion of the screen where image creation is performed most frequently is sectioned crosswise. Accordingly, the clipping processing occurs many times. General graphics adapters require interventions of a CPU for the clipping processing. When the clipping processing occurs many times, deterioration in performance is brought about. To solve such problems, in this embodiment, image creation is performed by the graphics adapter  13  for the central portion of the screen collected as the area  1 , as shown in FIG. 2, and the other three graphics adapters  14  to  16  perform image creation for the respective periphery portions around the central portion. Thus, the screen  11  is formed. With such construction, the clipping processing for the central portion can be lessened, and hence it is possible to improve performance of the monitor system.  
         [0036]    Furthermore, when the screen division is performed as shown in FIG. 2, marked effects are particularly brought about with use of the high speed graphics adapter  13  using the AGP and the graphics adapters  14  to  16  using the PCI bus. Generally, when the plurality of graphics adapters  13  to  16  are used, for the reason that as to the AGP only one port can be used for the system, the graphics adapters using the PCI bus are used for other ports in many cases. However, when the area  1  is assigned to the central portion shown in FIG. 2 and the graphics adapter  13  using the AGP is assigned to the area  1 , it is possible to use the unevenness of the loads well, and performance of the monitor system can be improved. To be more specific, one graphics adapter  13  is previously designed so as to be assigned to a large part of the image creation, and then the graphics adapter  13  is mounted to an extension slot showing a large transfer rate and a large bus width. A difference of the loads between the graphics adapter  13  and the graphics adapters  14  to  16  is absorbed, and hence performance of the whole of the system can be improved.  
         [0037]    [0037]FIG. 3 is a diagram for explaining processing of the division method in this embodiment. Image data  60  supplied from the PC(WS)  10  on the host side is input to the respective graphics adapters  13  to  16 . In the graphics adapters  13  to  16 , the image data  60  is developed to the data  61  for the area  1 , the data  62  for the area  2 , the data  63  for the area  3  and the data  64  for the area  4 , respectively, and the screen division and the clipping are performed. Here, since the division method shown in FIG. 2 is adopted, with regard to the area  1  the clipping processing performed so as not to write the protrusion areas is performed only for the peripheral portion around the place where the four divided areas collected together. Thereafter, the data  61  to  64  from the four graphics adapters  13  to  16  is collected and the screen is reconstructed, and the display screen is displayed on the liquid crystal panel  33 . At this time, though the clipping processing is most frequently performed for the data  64  of the area  4 , this area is considered that in general, a quantity of images is less and hence a load is less.  
         [0038]    [0038]FIG. 4 shows a flowchart of a processing flow in this embodiment. Either the image data  60  to displayed on the large screen or the image data  60  to be displayed on the screen showing a different aspect ratio is read out (step  101 ). The microprocessor  11  is divided the image data  60  by means of software under a previously decided screen division method (step  102 ). This previously decided screen division method determines which portion of the screen the graphics adapters  13  to  16  takes charge of. The way how to divide the screen is determined based on characteristics of the application and performance of the system and the graphics adapters  13  to  16 . Thereafter, the divided image data  61  to  64  is transferred to the corresponding graphics adapters  13  to  16  (step  103 ). In FIG. 1, though the description for the case where the four graphics adapters  13  to  16  are provided was made, the number of the graphics adapters is discretionary in accordance with the system or the performance.  
         [0039]    The graphics adapters  13  to  16  to which the image data  61  to  64  is transferred perform image creation for the image data  61  to  64  in the corresponding frame buffers  17  to  20 , and perform the clipping processing (step  104 ). At this time, the images created in the frame buffers  17  to  20  cannot be displayed on the screen when the pictures are not subjected to any processing as shown in FIG. 3. The clipping processing is an operation to cut off image data corresponding to portions of the screen other than those taken charge of respective graphics adapters  13  to  16 . The clipping processing is sometimes executed by means of software, or the clipping processing can be executed by the graphics adapters  13  to  16  if the graphics adapters  13  to  16  are supported by hardware like this embodiment.  
         [0040]    Thereafter, the graphics adapters  13  to  16  transfer the image data  61  to  64  created in the frame buffers  17  to  20  to the frame buffer  31  of the liquid crystal display  31  (step  105 ). Then, the reconstruction circuit  32  of the liquid crystal display  30  reads out the contents of the frame buffer  31 , based on assignment information, in the order that a correct image is created on the screen, and transmits the contents read out to the liquid crystal panel  33  side (step  106 ). This assignment information is an information making the screen division method clear. The assignment information may be constructed, for example, so as to be transmitted from the PC (WS)  10  side to the liquid crystal display  30  in some way. Moreover, like this embodiment, the assignment information is previously determined when the system is designed, and a construction of the reconstruction circuit  32  may be fixedly provided.  
         [0041]    [0041]FIG. 5 is a diagram for explaining another screen division method. In FIG. 2, the division method suitable for the case where the application of concentrating the loads at the central portion of the CAD and the like was used was described. It can be said that FIG. 5 shows a screen division method suitable for the load distribution. In FIG. 5, the divided areas  1  to  4  are arranged so as to be scattered on the entire of the screen, and the respective loads are distributed. This screen division method is particularly effective when a graphics adapter is used, which has a function to perform a hardware geometric computing processing and a low speed image creation though it performs the clipping processing with a sufficiently high speed. In such case, the loads are distributed whichever portion of the screen is concentrically used, it is possible to prevent an extreme deterioration of the performance of the whole system.  
         [0042]    Next, descriptions will be made for a case where the aspect ratio of the graphics adapter and the aspect ratio of the display (liquid crystal panel  33 ) differ from each other.  
         [0043]    [0043]FIG. 6 is a diagram for explaining an example of the screen division method in the case where the aspect ratios of the graphics adapter and the display differ. FIG. 6 shows a case where the area (1280×1024 dots) of the graphics adapter is divided equally to eight and the display (portion indicated by slanted lines) of 1920×1200 dots is displayed. In this example, the second graphics adapter covers an area of the display protruding from the area covered by the first graphics adapter. If the division method shown in FIG. 6 is adopted, the image data can be displayed on the rectangular display with more width than length by use of the two graphics adapters, and hence the useless memory area shown in FIG. 9 which was described in the prior art can be eliminated.  
         [0044]    FIGS.  7 ( a ),  7 ( b ) and  7 ( c ) are diagrams for explaining another example in the case wwhere an image display is performed using graphics adapters having a different aspect ratio from that of a screen area. FIGS.  7 ( a ) and  7 ( b ) show developing states by the graphics adapters A and B having an area of 1280×1024 dots, and FIG. 7( c ) shows an area of a display having a display area of 2048×1280 dots. In this example, using a screen division method in which A 1  and B 1  are used as the divided area of 1024×1024 dots and A 2  to A 5  and B 2  to B 5  are used as the divided area of 256×256 dots, it is made to be possible to display an image on the display having a different aspect ratio. As shown in FIG. 7(a), in the graphics adapter A, thick lines are drawn for the divided areas A 1 , A 2  and A 3 , and undergo the clipping processing to be stored in the frame buffer. In this example, in the graphics adapter B shown in FIG. 7( b ), no image data to be created exists. Describing the reference numerals of FIG. 1, the image data from the graphics adapters A and B is stored in the frame buffer  31  of the liquid crystal display  30 . Based on the assignment information, the image data is read out from the frame buffer  31  in turn by the reconstruction circuit  32 , and sent out to the liquid crystal panel  33 . As a result, the image as shown in FIG. 7( c ) is displayed on the liquid crystal panel  33 . From the fact that the divided areas A 1 , A 2  and A 3  in which the thick lines are drawn are read out as shown in FIG. 7( c ), it can be understood that a straight line formed of the thick line is displayed continuously. Unlike the example of FIG. 6, also by allowing the sizes of the divided areas to be different from each other, an image can be displayed on the display having a different aspect ratio.  
         [0045]    As described above, generally, the loads among the graphics adapters differ in many cases, and a speed of the image creation with respect to the whole screen is decided in the form that the whole system is ruled by a graphics adapter taking charge of the heaviest load. According to this embodiment, even when an image is displayed on the high resolution liquid crystal panel  33  using the conventional graphics adapters  13  to  16  with a low resolution, it is possible to distribute the loads for the graphics adapters  13  to  16 , and the performance of the whole system can be improved. Moreover, according to this embodiment, even when an image is displayed on a screen size which is not equal to an integral multiple of a size of the conventional graphics adapter, specifically, even when an image is displayed on a high resolution display having a different aspect ratio, the frame buffer  31  in the graphics adapters  13  to  16  can be effectively used. As described above, the four graphics adapters  13  to  16  are not always necessary, and the graphics adapters of the random number composed of two or more graphics adapters may be provided according to the size of a screen or an application.  
         [0046]    As described in detail, according to the present invention, it is possible to support a screen having a different aspect ratio or a large screen by use of, for example, existing graphics adapters, and performance and flexibility of the whole system can be increased.  
         [0047]    Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by persons ordinarily skilled in the art without departing from the scope or spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as defined by the appended claims.