Patent Publication Number: US-11030963-B2

Title: Motion blur effect adjustment method and display system capable of adjusting a motion blur effect

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention illustrates a motion blur effect adjustment method and a display system capable of adjusting a motion blur effect, and more particularly, a motion blur effect adjustment method and a display system capable of dynamically adjusting the motion blur effect according to position information of eyes tracking. 
     2. Description of the Prior Art 
     With the developments of technologies, various advanced displays or screens are widely used in our daily life, such as professional displays for E-sports players or professional displays for home theater systems. Since the requirements of providing high visual quality for users are important design issues, a moving picture response time (MPRT) function is introduced to these professional displays. The MPRT function can reduce an image sticking effect caused by rapidly shifting objects of the image. 
     Details of reducing the image sticking effect by using the MPRT function are illustrated below. Liquid crystal molecules of the display are operated under a transient state when the image is refreshed. The transient liquid crystal molecules easily trigger a dynamic image sticking effect. When the dynamic image sticking effect occurs, the motion blur of the object of the image is visible, leading to severely reducing quality of the visual experience. In order to reduce the dynamic image sticking effect, a time interval of turning on a backlight device and a time interval of refreshing the liquid crystal molecules (i.e., the transient state) are non-overlapped. In other words, the time interval of turning on the backlight device is within a blank interval of a vertical synchronization signal. However, when the blank interval is narrow, the backlight device can only be turned on for a very short time, resulting in insufficient brightness of the displayed image. 
     Another method for reducing the image sticking effect is to partition a display panel into a “good” area (i.e., the motion blur is absent) and a “bad” area (i.e., the motion blur is present). A position of the bad area can be set to a vertical edge area of the display panel. The time interval of turning on the backlight device falls within the blank interval of the vertical synchronization signal and a pixel active interval of scanning the bad area. The bad area can account for 20% of a range of the display panel. The good area can account for 80% of the range of the display panel. In other words, the time interval of turning on the backlight device and the time interval of refreshing the liquid crystal molecules (i.e., the transient state) are partially overlapped. However, although the time interval of turning on the backlight device is increased for enhancing the brightness of the displayed image, the motion blur effect of the bad area is severe. Therefore, when a user&#39;s visual range moves to the bad area, it results in bad visual experience. 
     SUMMARY OF THE INVENTION 
     In an embodiment of the present invention, a motion blur effect adjustment method is disclosed. The motion blur effect adjustment method comprises partitioning a display panel into at least two regions, tracking positions of eyes for generating position information of eyes tracking by using an image capturing device, acquiring a first region corresponding to a visual range of the positions of eyes from the at least two regions according to the position information of eyes tracking, reducing a first motion blur effect of the first region, and adjusting a second motion blur effect of a second region outside the first region. 
     In another embodiment of the present invention, a display system capable of adjusting a motion blur effect is disclosed. The display comprises a display panel, an image capturing device, a control device, a processor, a backlight device, and a motion blur control unit. The display panel is configured to display an image. The image capturing device is configured to track positions of eyes for generating position information of eyes tracking. The control device is coupled to the image capturing device and configured to partitioning the display panel into at least two regions and receive the position information of eyes tracking. The processor is coupled to the control device and configured to acquire a first region corresponding to a visual range of the positions of eyes from the at least two regions according to the position information of eyes tracking. The backlight device is configured to generate a backlight signal according to a backlight driving current. The motion blur control unit is coupled to the processor and the display panel and configured to generate the backlight driving current for controlling the backlight device, and configured to perform an anti-motion-blur function. The processor controls the motion blur control unit to reduce a first motion blur effect of the first region and adjust a second motion blur effect of a second region outside the first region. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a display system capable of adjusting a motion blur effect according to an embodiment of the present invention. 
         FIG. 2  is an illustration of partitioning a display panel into a plurality of regions of the display system in  FIG. 1 . 
         FIG. 3  is an illustration of a first correlation between a vertical synchronization signal and a backlight driving current when a first region covered by a visual range is located on a lower region of the display panel of the display system in  FIG. 1 . 
         FIG. 4  is an illustration of a second correlation between the vertical synchronization signal and the backlight driving current when the visual range covers the first region of the display panel of the display system in  FIG. 1 . 
         FIG. 5  is an illustration of a third correlation between the vertical synchronization signal and the backlight driving current when the visual range covers the first region of the display panel of the display system in  FIG. 1 . 
         FIG. 6  is an illustration of the first region covered by the visual range located on a center region of the display panel of the display system in  FIG. 1 . 
         FIG. 7  is an illustration of a fourth correlation between the vertical synchronization signal and the backlight driving current when the first region covered by the visual range is located on the center region of the display panel of the display system in  FIG. 1 . 
         FIG. 8  is an illustration of shifting the visual range from the first region to a third region. 
         FIG. 9  is an illustration of correlations of time intervals corresponding to the visual range and image frames of the synchronization signal when the visual range is shifted from the first region to the third region of the display system in  FIG. 1 . 
         FIG. 10  is an illustration of shifting a waveform of a high current portion of the backlight driving current when the visual range is shifted from the first region to the third region of the display system in  FIG. 1 . 
         FIG. 11  is a flow chart of a motion blur effect adjustment method performed by the display system in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a block diagram of a display system  100  capable of adjusting a motion blur effect according to an embodiment of the present invention. The display system  100  includes a display panel  10 , an image capturing device  11 , a control device  12 , a processor  13 , a backlight device  14 , and a motion blur control unit  15 . The display panel  10  is used for displaying an image. The display panel  10  can be any type of display panel, such as a Liquid-Crystal Display (LCD) panel, an Organic Light-Emitting Diode (OLED) display panel, or an Active-Matrix Organic Light-Emitting Diode (AMOLED) display panel. The image capturing device  11  is used for tracking positions of eyes for generating position information of eyes tracking. The image capturing device  11  can be a camera or a video recorder capable of tracking one eye or two eyes of a human. For example, the image capturing device  11  can continuously generate vertical-axis coordinates, longitudinal-axis coordinates, and lateral-axis coordinates of the positions of eyes according to pupil positions of the human eyes. The control device  12  is coupled to the image capturing device  11  for partitioning the display panel  10  into at least two regions and receiving the position information of eyes tracking. Here, the control device  12  can uniformly and virtually partition the display panel  10  into the at least two regions along a vertical axis. For example, the control device  12  can virtually partition the display panel  10  into three regions with the same widths. 
     However, a size of each partitioned region is not limited in the display system  100 . The size of each partitioned region can be user-defined. The processor  13  is coupled to the control device  12  for acquiring a first region corresponding to a visual range of the positions of eyes from the at least two regions according to the position information of eyes tracking. The processor  13  can be any type of processing device, such as a microprocessor, a scaler, or a central processing unit (CPU). Particularly, since the visual range of the human eyes is limited, a hot zone or a focused area of the visual range cannot cover a full-screen image. In other words, according to a result of positions of eyes detected by the image capturing device  11 , the processor  13  can estimate the focused area of the human eyes currently on the display panel  10  for enhancing image quality of the focused area. The backlight device  14  is used for generating a backlight signal according to a backlight driving current. The backlight device  14  can be any type of light-emitting element, such as an incandescent light bulb, a light-emitting diode (LED), or a cold cathode fluorescent lamp (CCFL). The backlight signal generated by the backlight device  14  can be transmitted to the human eyes through the display panel  10 . Therefore, the human eyes can see the image with high brightness displayed on the display panel  10 . The motion blur control unit  15  is coupled to the processor  13  and the display panel  10  for generating the backlight driving current to control the backlight device  14 . The motion blur control unit  15  can be used for performing an anti-motion-blur function, such as a moving picture response time (MPRT) function in order to reduce the image sticking effect of the display panel  10 . Further, the processor  13  can control the motion blur control unit  15  to reduce a first motion blur effect of the first region and adjust a second motion blur effect of a second region outside the first region. In other words, the display system  100  can dynamically enhance an image quality of the user&#39;s focused area (i.e., the first area) on the display panel  10  by reducing the motion blur effect. Further, the motion blur effect can be appropriately adjusted on a non-focused area (i.e., the second area). Thus, the average image brightness of the display panel  10  can satisfy a requirement of user configurations. In other words, the display system  100  can display the image with low motion blur effect and sufficient brightness. Details of a motion blur effect adjustment method performed by the display system  100  are illustrated later. 
       FIG. 2  is an illustration of partitioning the display panel  10  into a plurality of regions of the display system  100 . For simplicity, three regions  10   a  to  10   c  are introduced for partitioning the display panel  10 . In  FIG. 2 , the processor  13  can virtually partition the display panel  10  into an upper region  10   a , a center region  10   b , and a lower region  10   c . The number of vertical pixels of the upper region  10   a  is X. The number of vertical pixels of the center region  10   b  is Y. The number of vertical pixels of the lower region  10   c  is Z. Here, X, Y, and Z can be three identical or different positive integers. For example, a resolution of the display panel  10  is 2560×1440 pixels. The total number of vertical pixels of the display panel  10  is 1440. The number of vertical pixels X corresponding to the upper region  10   a  can be 480. Therefore, an index Xi of 480 vertical pixels corresponding to the upper region  10   a  is within a range of 0≤Xi&lt;480. The number of vertical pixels Y corresponding to the center region  10   b  can be 480. Therefore, an index Yi of 480 vertical pixels corresponding to the center region  10   b  is within a range of 480≤Yi&lt;960. The number of vertical pixels Z corresponding to the lower region  10   c  can be 480. Therefore, an index Zi of 480 vertical pixels corresponding to the lower region  10   c  is within a range of 960≤Zi&lt;1440. The first region R 1  corresponds to the visual range of human eyes. Here, the first region R 1  can be set to cover the lower region  10   c . However, a size of the first region R 1  can also be adjusted according to user&#39;s configurations. For example, a user with a wide visual range (i.e., such as an E-sports player) can increase the size of the first region R 1 . Therefore, the first region R 1  can cover the center region  10   b  and the lower region  10   c . The second region R 2  can be defined as a part of region outside the first region R 1 . For example, in  FIG. 2 , when the first region R 1  covers the lower region  10   c , the second region R 2  can be set to cover the upper region  10   a . Therefore, the second region R 2  can be regarded as a non-focused area of human eyes. 
       FIG. 3  is an illustration of a first correlation between a vertical synchronization signal Vsync and a backlight driving current BL when the first region R 1  covered by the visual range is located on the lower region  10   c  of the display panel  10  of the display system  100 . The first region R 1  of the display panel  10  corresponds to a first time interval T 1  during a pixel active interval ACT of the vertical synchronization signal Vsync. The second region R 2  of the display panel  10  corresponds to a second time interval T 2  during the pixel active interval ACT of the vertical synchronization signal Vsync. 
     The first time interval T 1  and the second time interval T 2  are non-overlapped. Here, the vertical synchronization signal Vsync can be a periodic signal. A period of the vertical synchronization signal Vsync includes the pixel active interval ACT and a blank interval BLK. The blank interval BLK can include a front porch interval FP and a back porch interval BP. An image frame period F can be formed by introducing the front porch interval FP, the pixel active interval ACT, and the back porch interval BP. In other words, the pixel active interval ACT and the blank interval BLK of the vertical synchronization signal Vsync form the image frame period F. When the first region R 1  covered by the visual range is located on the lower region  10   c , the processor  13  can control the motion blur control unit  15  for setting the backlight driving current BL to a low current during the first time interval T 1  of the vertical synchronization signal Vsync in order to temporarily suspend the backlight device  14 . Since the backlight device  14  is turned off during the first time interval T 1 , the transient state of refreshing pixels of the first region R 1  covered by the visual range is invisible. In other words, the motion blur effect of the first region R 1  covered by the visual range located on the lower region  10   c  can be reduced. The quality of the first region R 1  of the displayed image can be increased. Further, the processor  13  can control the motion blur control unit  15  for setting the backlight driving current BL to a high current during the second time interval T 2  and a part of the blank interval BLK of the vertical synchronization signal Vsync. As shown in  FIG. 3 , the backlight driving current BL can be set to the high current during an enabling time interval E 1 . Specifically, the enabling time interval E 1  and a part of the pixel active interval ACT are overlapped. However, an overlapped interval (i.e., the second time interval T 2 ) corresponds to a non-focused area of human eyes (i.e., the second region R 2 ). Therefore, for the user, although the transient state of refreshing pixels is visible on the non-focused area, the quality of visual experience can be maintained. Further, when the enabling time interval E 1  for enabling the backlight device  14  is long, it implies that the average brightness of the displayed image supported by the display panel  10  can be increased. In other words, the display system  100  can provide satisfactory visual experience and sufficient image brightness required by the user. 
       FIG. 4  is an illustration of a second correlation between the vertical synchronization signal Sync and the backlight driving current BL when the visual range covers the first region R 1  of the display panel  10  of the display system  100 . As previously mentioned, the processor  13  can control the motion blur control unit  15  for setting the backlight driving current BL to the low current during the first time interval T 1  of the vertical synchronization signal Vsync in order to temporarily suspend the backlight device  14 . Further, the processor  13  can control the motion blur control unit  15  for setting the backlight driving current BL to the high current during a part of the blank interval BLK and a part of the second time interval T 2  of the vertical synchronization signal Vsync after the visual range of the positions of eyes covers the first region R 1 . In other words, in  FIG. 4 , the backlight device  14  is turned on during an enabling time interval E 2 . A difference between  FIG. 4  and  FIG. 3  is illustrated below. In  FIG. 4 , an overlapped interval between the enabling time interval E 2  and the pixel active interval ACT of the vertical synchronization signal Vsync is not equal to the second time interval T 2  (i.e., corresponding to the second region R 2  located in the upper region  10   a ). Generally, the overlapped interval between the enabling time interval E 2  and the pixel active interval ACT of the vertical synchronization signal Vsync can be smaller than, equal to, or greater than the second time interval T 2 . In other words, any reasonable technology for turning off the backlight device  14  (i.e., setting the backlight driving current BL to the low current) during the first time interval T 1  and adjusting the backlight device  14  outside the first time interval T 1  falls into the scope of the present invention. 
       FIG. 5  is an illustration of a third correlation between the vertical synchronization signal Sync and the backlight driving current BL when the visual range covers the first region R 1  of the display panel  10  of the display system  100 . Here, the processor  13  can control the motion blur control unit  15  for merely setting the backlight driving current BL to the high current during the blank interval BLK when the visual range of the positions of eyes covers the first region R 1  or the second region R 2 . In other words, in  FIG. 5 , the backlight device  14  is turned on during an enabling time interval E 3 . Particularly, since the enabling time interval E 3  for turning on the backlight device  14  is within the blank interval of the vertical synchronization signal Vsync, the motion blur effect during any period of time of the pixel active interval ACT can be reduced. In other words, when the backlight device  14  is merely turned on during the blank interval BLK of the vertical synchronization signal Vsync, regardless of a position of the visual range (i.e., covering the first region R 1 , moving from the first region R 1  to the second region R 2 , covering the second region R 2 , or locating on any region of the display panel  10 ), the motion blur effect can be reduced. However, a length of the enabling time interval E 3  for turning on the backlight device  14  is limited by a maximum length of the blank interval BLK, thereby providing low image brightness (i.e., a dark mode). 
       FIG. 6  is an illustration of the first region R 1  covered by the visual range located on the center region  10   b  of the display panel  10  of the display system  100 . In  FIG. 6 , when the first region R 1  covered by the visual range is located on the center region  10   b , the second region R 2  can correspond to the upper region  10   a  or the lower region  10   c . The second region R 2  can correspond to any region outside the first region R 1 . However, the second region R 2  can be set to the upper region  10   a  preferably. The first region R 1  can be regarded as the focused area of human eyes. The second region R 2  can be regarded as the non-focused area of human eyes. Details of setting and adjusting the backlight driving current BL for the first region R 1  located on the center region  10   b  are illustrated later. 
       FIG. 7  is an illustration of a fourth correlation between the vertical synchronization signal Vsync and the backlight driving current BL when the first region R 1  covered by the visual range is located on the center region  10   b  of the display panel  10  of the display system  100 . The first region R 1  of the display panel  10  corresponds to the first time interval T 1  during the pixel active interval ACT of the vertical synchronization signal Vsync. The second region R 2  of the display panel  10  corresponds to a second time interval T 2  during the pixel active interval ACT of the vertical synchronization signal Vsync. The first time interval T 1  and the second time interval T 2  are non-overlapped. Specifically, a rising edge of the vertical synchronization signal Vsync during the pixel active interval ACT corresponds to a first refreshing time FT 1  of rotating pixels of the display panel  10  from a steady state to a transient state. A falling edge of the vertical synchronization signal Vsync during the pixel active interval ACT corresponds to a second refreshing time FT 2  of rotating pixels of the display panel from the transient state to the steady state. In other words, the pixels are not completely stable during the first refreshing time FT 1  and the second refreshing time FT 2 . The second refreshing time FT 2  is greater than the first refreshing time FT 1 . The processor  13  can control the motion blur control unit  15  for setting the backlight driving current BL to the high current during a time interval overlapping with the first refreshing time FT 1  of the rising edge of the vertical synchronization signal Vsync when the first region R 1  corresponding to the visual range approaches the center region  10   b  of the display panel  10  in a vertical axis. For example, the backlight driving current BL can be set to the high current during an enabling time interval E 4 . Therefore, the backlight device  14  is turned on during the enabling time interval E 4 . Further, the enabling time interval E 4  overlaps with a part of the blank interval BLK and a part of the pixel active interval ACT corresponding to the rising edge of the vertical synchronization signal Vsync. In  FIG. 7 , since the second refreshing time FT 2  is greater than the first refreshing time FT 1 , setting the enabling time interval E 4  overlapping with the first refreshing time FT 1  is superior to setting the enabling time interval E 4  overlapping with the second refreshing time FT 2 . A reason is illustrated below. When the backlight device  14  is turned on during the enabling time interval E 4 , since a visible time interval of displaying unstable pixels is short, the motion blur on the edges of the image displayed on the display panel  10  can be mitigated for a person having a wide visual range. 
       FIG. 8  is an illustration of shifting the visual range from the first region R 1  to a third region R 3 . The first region R 1  corresponds to the lower region  10   c  of the display panel  10 . The third region R 3  corresponds to the upper region  10   a  of the display panel  10 . The visual range of human eyes may move over time. For example, after the processor  13  acquires the first region R 1  corresponding to the visual range of the positions of eyes from the at least two regions for a period of time through the image capturing device  11  and the control device  12 , the processor  13  can continuously acquire the third region R 3  corresponding to the visual range of positions of eyes (i.e., the position of the visual range is moved from the first region R 1  to the third region R 3 ). As previously mentioned, the image capturing device  11  is used for tracking positions of eyes. Therefore, the image capturing device  11  can continuously detect a movement path of the visual range. In order to optimize the visual experience, in  FIG. 8 , when the position of the visual range is moved (or say, shifted) from the first region R 1  to the third region R 3 , the processor  13  can reduce the first motion blur effect from the first region R 1  to the third region R 3 . Further, the first region R 1  and the third region R 3  are different. Details of reducing the motion blur effect shifted from a position (range) to another position (range) are illustrated below. 
       FIG. 9  is an illustration of correlations of time intervals corresponding to the visual range and image frames F 1  to FN of the synchronization signal Vsync when the visual range is shifted from the first region R 1  to the third region R 3  of the display system  100 . As previously mentioned, the visual range of human eyes may move over time. Therefore, when the display panel  10  displays different image frames, positions of the visual range may be different. For simplicity, a movement of the visual range is can be regarded as a linear movement, as illustrated below. In  FIG. 9 , the visual range is located on the first region R 1  (the lower region  10   c ) during a period of a first image frame F 1  of the synchronization signal Vsync. When the period of the first image frame F 1  elapses, the visual range is gradually shifted from the first region R 1  to the third region R 3 . The visual range is located on the second region R 3  (the upper region  10   a ) during a period of an N-th image frame FN of the synchronization signal Vsync. In other words, during a time interval of N image frames, the position of the visual range is shifted from the first region R 1  to the third region R 3 . N is a positive integer. 
       FIG. 10  is an illustration of shifting a waveform of a high current portion of the backlight driving current BL when the visual range is shifted from the first region R 1  to the third region R 3  of the display system  100 . Since the display system  100  can reduce the motion blur effect within the visual range, the backlight driving current BL can be adjusted according to the movement of the visual range. In  FIG. 10 , initially, the processor  13  can control the motion blur control unit  15  for setting the backlight driving current BL 1  to the high current during a fourth time interval T 4 . As previously mentioned, the fourth time interval T 4  of the high current is non-overlapped with the first time interval T 1  corresponding to the first region R 1  covered by the visual range. However, since the position of the visual range is gradually shifted from the first region R 1  to the third region R 3 , the processor  13  can control the motion blur control unit  15  for shifting a waveform of the high current from the fourth time interval T 4  to a fifth time interval T 5 . The fourth time interval T 4  and the first time interval T 1  corresponding to the first region R 1  are non-overlapped. The fifth time interval T 5  and the third time interval T 3  corresponding to the third region R 3  are non-overlapped. For example, the waveform of the high current can be gradually shifted by using M offsets from the fourth time interval T 4  to the fifth time interval T 5  (i.e., as shown in the backlight driving current BL 1  to BL in  FIG. 10 ), as illustrated below. A beginning time point of the waveform of the high current during the fourth time interval T 4  is denoted as Xa. A beginning time point of the waveform of the high current during the fifth time interval T 5  is denoted as Xb. M is a positive integer. Therefore, a single offset D of the waveform of the high current can be derived as:
 
 D =( Xb−Xa )/ M  
 
     Therefore, a total offset of the waveform of the high current in a first shifting process is equal to D. A total offset of the waveform of the high current in a second shifting process is equal to 2×D, and so on. A total offset of the waveform of the high current in an M-th shifting process is equal to M×D. By performing M shifting processes, the beginning time point of the waveform of the high current can be derived as:
 
 Xa +( M×D )= Xa+M ×( Xb−Xa )/ M=Xb  
 
     In other words, the processor  13  can control the motion blur control unit  15  for gradually shifting the waveform of the high current from the fourth time interval T 4  to the fifth time interval T 5  by using a linear offset equation. Since the time interval of turning on the backlight device  14  can be gradually shifted, the brightness of the image displayed on the display panel  10  can be adjusted gently. By doing so, an unpleasant flickering effect of the image can be avoided. 
     Further, a method for shifting the waveform of the high current of the backlight driving current is not limited by using aforementioned parameters. For example, when the waveform of the high current is shifted from the time point Xa to a time point Xc, the processor  13  can perform M′ shifting processes with a single offset D′ for satisfying a linear offset equation of Xc=Xa+(M′×D′). Further, the M′ shifting processes and the single offset D′ can be adjusted according to an actual situation. 
       FIG. 11  is a flow chart of a motion blur effect adjustment method performed by the display system  100 . The motion blur effect adjustment method includes step S 111  to step S 115 . Any reasonable technology modification falls into the scope of the present invention. Step S 111  to step S 115  are illustrated below.
     step S 111 : partitioning the display panel  10  into at least two regions;   step S 112 : tracking the positions of eyes for generating the position information of eyes tracking by using the image capturing device  11 ;   step S 113 : acquiring the first region R 1  corresponding to the visual range of the positions of eyes from the at least two regions according to the position information of eyes tracking;   step S 114 : reducing the first motion blur effect of the first region R 1 ;   step S 115 : adjusting the second motion blur effect of the second region R 2  outside the first region R 1 .   

     Details of step S 111  to step S 115  are previously illustrated. Thus, they are omitted here. In the display system  100 , the backlight driving current can be dynamically adjusted for driving the backlight device  14 . After the processor  13  controls the control device  12  for virtually partitioning the display panel  10  into the at least two regions, the motion blur effect within the visual range of human eyes (i.e., especially in the focused area) can be reduced. The display system  100  can continuously detect the positions of eyes for dynamically reducing the motion blur within the visual range of the display panel  10 . Therefore, the quality of visual experience can be increased. 
     To sum up, the present invention discloses a motion blur effect adjustment method and a display system capable of adjusting the motion blur effect. The display system can acquire a visual range according to position information of eyes tracking by using an image capturing device. Then, the display system can adjust a backlight driving current for reducing the motion blur effect within the visual range. Further, the display system can continuously detect and track the positions of human eyes for updating the visual range. By doing so, the motion blur can be reduced within the visual range in real time. Therefore, when the user&#39;s visual range arbitrarily moves to any position of the display panel, the user can see the displayed image with high quality. Therefore, the display system of the present invention can increase the quality of visual experience for the user. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.