Abstract:
The present invention relates to an image enlarging method and a TV wall using the same. The image enlarging method is used for enlarging a first image into a second image in a non-integer multiple. In order to supply the lacking pixels, the method utilizes Digital Differential Analysis (DDA) algorithm-based process or equally dividing intervals. As a result, the distortion is improved, and the black area resulted from the lacking pixels in the conventional method will not occur.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the invention  
         [0002]     The present invention relates to an image enlarging method and a TV wall using the same, particularly to a method for enlarging an image in non-integer multiple and a TV wall using the same.  
         [0003]     2. Description of the Related Art  
         [0004]     The TV wall is constituted by plural display devices for displaying an enlarged image, which is usually applied as an advertising billboard. The image adopted in conventional TV wall is an analog image, which has the shortcomings of analog decay, color shift and low resolution (usually under 1024*768). Therefore, in order to raise the resolution of the displayed image and make the colors in the display devices more even, there is a trend of using digital enlarging system.  
         [0005]      FIGS. 1   a  and  1   b  show a conventional method for enlarging a digital image, wherein  FIG. 1   a  shows a source image  10  to be enlarged, and  FIG. 1   b  shows an enlarged image  20  that is derived from enlarging the source image  10  in four (2*2) multiple and displayed in the TV wall constituted by four display devices  21 ,  22 ,  23 ,  24 . In the following example, the resolutions of the source image  10  and single display device of the TV wall are both 1024*768. The resolution of 1024*768 means that one image has 1024 pixels in the horizontal direction (i.e. 1024 columns of pixels) and 768 pixels in the vertical direction (i.e. 768 rows of pixels). First, the source image  10  is divided into four partitions  11 ,  12 ,  13 ,  14 , wherein the partition  11  corresponds to the display device  21 , the partition  12  corresponds to the display device  22 , the partition  13  corresponds to the display device  23  and the partition  14  corresponds to the display device  24 .  
         [0006]      FIG. 2  shows the definition of the coordinate of an image in the specification. As shown in  FIG. 2 , a first image  31  is captured from a source image  30  and is then enlarged. There are two ways for defining the parameters of capture: the first way is defining the first image  31  from initial point A (X 0 , Y 0 ) on the upper-left corner to end point B (X f , Y f ) on the lower-right corner; the second way is defining the first image  31  by the initial point A (X 0 , Y 0 ), a horizontal length X 1  and a vertical length Y 1 , wherein X 1 =X f −X 0  and Y 1 =Y f −Y 0 .  
         [0007]     Referring to  FIGS. 1   a  and  1   b  again, in the source image  10 , if the upper-left corner is the origin ( 0 ,  0 ) of the coordinate, the partition  11  is from ( 0 ,  0 ) to ( 511 ,  383 ), the partition  12  is from ( 512 ,  0 ) to ( 1023 ,  383 ), the partition  13  is from ( 0 ,  384 ) to ( 511 ,  767 ), and the partition  14  is from ( 512 ,  384 ) to ( 1023 ,  767 ), wherein the resolution of each partition is 512*384. In order to display the image of each partition (the resolution is 512*384) on the corresponding display device (the resolution is 1024*768), the resolution must be supplemented to 1024*768. Therefore, along the horizontal direction, each pixel is repeated once so that 1024 pixels are carried out by 512 pixels; along the vertical direction, each row of pixels is repeated once so that 768 rows of pixels are carried out by 384 rows of pixels. Finally, the transformed images of the partitions are displayed on the corresponding display devices of the TV wall so as to combine the enlarged image  20 .  
         [0008]      FIG. 3  shows an actual displayed image of the conventional method for enlarging a digital image. The enlarged image  20  displayed on the above  FIG. 1   b  is an ideal situation. Since the display devices  21 ,  22 ,  23 ,  24  have frame  25 , the actual displayed image on the TV wall will have distortion, as shown in  FIG. 3 .  
         [0009]     To improve the distortion on full-size image derived from the conventional enlarging method, the frame  25  on the TW wall should be taken as frame of window, and some pixels of the source image  10  should be discarded. Taking  FIG. 3  for example, if the frame  25  covers 10 columns of pixels and 10 rows of pixels in the enlarged image, the coordinate values of capturing the partitions  11 ,  12 ,  13 ,  14  should be changed. That is, the partition  11  should be changed from ( 0 ,  0 ) to ( 506 ,  378 ), the partition  12  should be changed from ( 517 ,  0 ) to ( 1023 ,  378 ), the partition  13  should be changed from ( 0 ,  389 ) to ( 506 ,  767 ), and the partition  14  should be changed from ( 517 ,  389 ) to ( 1023 ,  767 ). However, Taking the partition  11  for example, when it is displayed on the display device  21  (the resolution is 1024*768), it lacks 10 columns of pixels along the horizontal direction and 10 rows of pixels along the vertical direction if it is enlarged in a multiple of 2 along the horizontal direction and the vertical direction since the resolution of the enlarged partition  11  is 1014*758.  
         [0010]     The conventional method for improving the above-mentioned shortcoming is to dispose the lacking pixels on the sides of the enlarged image. Taking partition  11  for example, when it is displayed on the display device  21 , the lacking 10 columns of pixels along the horizontal direction are disposed on the left side without any output signal and displayed in black color. Similarly, the lacking 10 rows of pixels along the vertical direction are disposed on the topside without any output signal and are displayed in black color. Although such method can improve the distortion of image, the black areas on the sides are not desired.  
         [0011]     Consequently, there is an existing need for a novel and improved image enlarging method and a TV wall using the same to solve the above-mentioned problem.  
       SUMMARY OF THE INVENTION  
       [0012]     One objective of the present invention is to provide an image enlarging method for enlarging a first image into a second image in a non-integer multiple. In order to supply the lacking pixels, the method utilizes Digital Differential Analysis (DDA) algorithm-based process or equally dividing intervals. As a result, the distortion is improved, and the black area resulted from the lacking pixels in the conventional method will not occur.  
         [0013]     Another objective of the present invention is to provide a method for forming an enlarged image on a TV wall having a plurality of display devices. The method comprises the following steps:  
         [0014]     (a) capturing a source image;  
         [0015]     (b) dividing the source image into a plurality of first images according to the amount and disposition of the display devices and the discard of the frame between the display devices, and determining a non-integer multiple;  
         [0016]     (c) enlarging the first images into a plurality of second images in a non-integer multiple; and  
         [0017]     (d) displaying the second images on the corresponding display devices respectively.  
         [0018]     Still another objective of the present invention is to provide a TV wall system comprising: a plurality of display devices, an image generating device and an image dividing and enlarging device. The display devices are arranged arrayed. The image generating device is used for providing a source image. The image dividing and enlarging device is used for dividing the source image into a plurality of first images according to the amount and disposition of the display devices and the discard of the frame between the display devices, and enlarging the first images into a plurality of second images in a non-integer multiple. The image dividing and enlarging device is connected to the display devices so as to display the second images on the corresponding display devices respectively.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIGS. 1   a  and  1   b  show a conventional method for enlarging a digital image;  
         [0020]      FIG. 2  shows the definition of the coordinate of an image in the specification;  
         [0021]      FIG. 3  shows an actual displayed image of the conventional method for enlarging a digital image;  
         [0022]      FIG. 4  shows an image enlarging method according to a first embodiment of the present invention;  
         [0023]      FIG. 5  shows the image enlarging method according to example 1 of the present invention;  
         [0024]      FIG. 6  shows an image enlarging method according to a second embodiment of the present invention;  
         [0025]      FIG. 7  shows the image enlarging method according to example 2 of the present invention;  
         [0026]      FIG. 8  shows an image enlarging method according to a third embodiment of the present invention;  
         [0027]      FIG. 9  shows the image enlarging method according to example 3 of the present invention;  
         [0028]      FIG. 10  shows a preferred embodiment of a TV wall system according to the present invention;  
         [0029]      FIG. 11  shows a source image applied for the embodiment of  FIG. 10 ; and  
         [0030]      FIG. 12  shows an enlarged image applied for the embodiment of  FIG. 10 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]      FIG. 4  shows an image enlarging method according to a first embodiment of the present invention. The image enlarging method of the embodiment is used for enlarging a first image  32  into a second image  34  in a non-integer multiple. The first image  32  is constituted by a plurality of arrayed first pixels, wherein the first image  32  has plural column first pixels arranged in X 1  columns along a first coordinate axis direction (for example, horizontal direction). That is, the first image  32  has X 1  columns of the first pixels. The first image  32  has plural row first pixels arranged in Y 1 . rows along a second coordinate axis direction (for example, vertical direction). That is, The first image  32  has Y 1 . rows of the first pixels. The second image  34  is constituted by a plurality of arrayed second pixels, wherein the second image  34  has plural column second pixels arranged in X 2  columns along the first coordinate axis direction (for example, horizontal direction). That is, the second image  34  has X 2  columns of the second pixels. The second image  34  has plural row second pixels arranged in Y 2  rows along the second coordinate axis direction (for example, vertical direction). That is, the second image  34  has Y 2  rows of the second pixels. The method comprises the following steps:  
         [0032]     (a) capturing the first pixels of the first image  32 ;  
         [0033]     (b) determining the X 2  columns of the second pixels of the second image  34  according to the X 1  columns of the first pixels of the first image  33  along the first coordinate axis direction by utilizing a Digital Differential Analysis (DDA) algorithm-based process so as to form a temporary image  33 . The temporary image  33  has plural column temporary pixels arranged in X 2  columns along the first coordinate axis direction. That is, the temporary image  33  has X 2  columns of temporary pixels. The temporary image  33  has plural row temporary pixels arranged in Y 1 , rows along the second coordinate axis direction. That is, the temporary image  33  has Y 1 , rows of temporary pixels; and  
         [0034]     (c) determining the rows of the second pixels of the second image according to the rows of the temporary pixels along the second coordinate axis direction by utilizing a DDA algorithm-based process so as to form the second image.  
         [0035]     In the embodiment, DDA algorithm-based process is used in steps (b) and (c), is carried out by accumulation and subtraction, and shows the next data when the carry situation happens. Taking step (b) for example, the carry condition is X 2 , the temporary value is P x  (x=1,2,3, . . . ), the last temporary value is P x−1 , and each DDA cycle executes P x =P x−1 +X 1  once. After execution, if P x &lt;X 2 , the output data is equal to the last data; otherwise, the output data is the next data and P x  is set to be P x =P x −X 2 .  
         [0036]     Therefore, the step (b) comprises the following steps:  
         [0037]     (b1) equalizing a predetermined column (for example, the first column  331   a ) of the temporary pixels of the temporary image  33  to a corresponding column (for example, the first column  321   a ) of the first pixels of the first image  32 ;  
         [0038]     (b2) accumulating the X 1  value and a first temporary value to form a second temporary value;  
         [0039]     (b3) determining whether or not the second temporary value is smaller than the X 2  value in order to determine a column (for example, the second column  332   a ) of the temporary pixels next to the predetermined column  331   a  of the temporary pixels of the temporary image  33 ;  
         [0040]     (b4) if the second temporary value is smaller than the X 2  value, which is defined as a non-carry situation, the column  332   a  of the temporary pixels next to the predetermined column  331   a  of the temporary pixels of the temporary image  33  is equal to the predetermined column  331   a  of the temporary pixels of the temporary image  33 , and the first temporary value is changed to the second temporary value;  
         [0041]     (b5) if the second temporary value is larger than or equal to the X 2  value, which is defined as a carry situation, the column  332   a  of the temporary pixels next to the predetermined column  331   a  of the temporary pixels of the temporary image  33  is equal to the column  322   a  of the first pixels next to the corresponding column  321   a  of the first pixels of the first image  32 , then the X 2  value is subtracted from the second temporary value to form a third temporary value, and the first temporary value is changed to the third temporary value; and  
         [0042]     (b6) repeating the steps (b3) to (b5).  
         [0043]     Similarly, the step (c) comprises the following steps:  
         [0044]     (c1) equalizing a predetermined row (for example, the first row  341   b ) of the second pixels of the second image  34  to a corresponding row (for example, the first row  331   b ) of the temporary pixels of the temporary image  33 ;  
         [0045]     (c2) accumulating the Y 1 , value and a fourth temporary value to form a fifth temporary value;  
         [0046]     (c3) determining whether or not the fifth temporary value is smaller than the Y 2  value in order to determine a row (for example, the second row  342   b ) of the second pixels next to the predetermined row  341   b  of the second pixels of the second image  34 ;  
         [0047]     (c4) if the fifth temporary value is smaller than the Y 2  value, which is defined as a non-carry situation, the row  342   b  of the second pixels next to the predetermined row  341   b  of the second pixels of the second image  34  is equal to the predetermined row  341   b  of the second pixels of the second image  34 , and the fourth temporary value is changed to the fifth temporary value;  
         [0048]     (c5) if the fifth temporary value is larger than or equal to the Y 2  value, which is defined as a carry situation, the row  342   b  of the second pixels next to the predetermined row  341   b  of the second pixels of the second image  34  is equal to the row (for example, the second row  332   b ) of the temporary pixels next to the corresponding row  331   b  of the temporary pixels of the temporary image  33 , then the Y 2  value is subtracted from the fifth temporary value to form a sixth temporary value, and the fourth temporary value is changed to the sixth temporary value; and  
         [0049]     (c6) repeating the steps (c3) to (c5).  
       EXAMPLE 1  
       [0050]      FIG. 5  shows the image enlarging method according to example 1 of the present invention. The image enlarging method of example 1 is used for enlarging a first image  35  into a second image  37  in a non-integer multiple. The first image  35  is constituted by a plurality of arrayed first pixels, wherein the first image  35  has 5 columns of the first pixels along the horizontal direction, and the first image  35  has 5 rows of the first pixels along the vertical direction. The second image  37  is constituted by a plurality of arrayed second pixels, wherein the second image  37  has 8 columns of the second pixels along the horizontal direction, and the second image  37  has 8 rows of the second pixels along the vertical direction.  
         [0051]     The method comprises the following steps. First, the first image  35  is captured from a source image (not shown). Then, a DDA algorithm-based process is utilized to fill the total length (8 columns) along the horizontal direction of the second image  37  with the 5 columns of the first pixels of the first image  35  so as to form a temporary image  36 . The execution of the DDA algorithm-based process is as follows.  
         [0052]     First, the first column of the temporary pixels  361   a  of the first column of the temporary image  36  is equal to the first column of the first pixels  351   a  of the first image  35 . That is, the temporary pixels  361   a  of the first column of the temporary image  36  are same with the first pixels  351   a  of the first column of the first image  35  respectively. Then, the DDA algorithm-based process is executed to obtain the results as shown in table 1 so as to determine the pixels after the first column.  
                                 TABLE 1                           the result of the execution of the DDA algorithm-based process            DDA cycle (x)   Length of image   Temporary value   carry               1   5   5 + 0 = 5   0       2   5   5 + 5 − 8 = 2   1       3   5   5 + 2 = 7   0       4   5   5 + 7 − 8 = 4   1       5   5   5 + 4 − 8 = 1   1       6   5   5 + 1 = 6   0       7   5   5 + 6 − 8 = 3   1                  
 
         [0053]     The result of table 1 is obtained by the following steps. The temporary pixels  362   a  of the second column are illustrated, and they correspond to the first cycle (x=1) of the DDA. First, a first temporary value P x =0 is provided. Then, a second temporary value (5) is obtained by accumulating the X 1  value (X 1 =5) and the first temporary value P x  (P x =0). Since the second temporary value (5) is smaller than the carry condition X 2  (X 2 =8), it is defined as non-carry situation (0). Therefore, the temporary pixels  362   a  of the second column of the temporary image  36  are equal to the temporary pixels  361   a  of the first column of the temporary image  36 , and the first temporary value P x  is changed to 5.  
         [0054]     Then, the second cycle (x=2) of the DDA are proceeded. A second temporary value (10) is obtained by accumulating the X 1  value (X 1 =5) and the first temporary value P x  (P x =5). Since the second temporary value (10) is larger than the carry condition X 2  (X 2 =8), it is defined as carry situation (1). Therefore, the temporary pixels  363   a  of the third column of the temporary image  36  are equal to the first pixels of the next column of the first image  35 , i.e., the first pixels  352   a  of the second column. Then the X 2  value (X 2 =8) is subtracted from the second temporary value (10) to obtain a third temporary value (2), and the first temporary value P x  is changed to 2.  
         [0055]     Then, the third cycle (x=3) of the DDA is proceeded. A second temporary value (7) is obtained by accumulating the X 1  value (X 1 =5) and the first temporary value P x  (P x =2). Since the third temporary value (7) is smaller than the carry condition X 2  (X 2 =8), it is defined as non-carry situation (0). Therefore, the temporary pixels  364   a  of the fourth column of the temporary image  36  are equal to the temporary pixels  363   a  of the third column of the temporary image  36 , and the first temporary value P x  is changed to 7.  
         [0056]     Similarly, the other cycles of the DDA are proceeded so as to fill 8 columns of pixels with 5 columns of the first image  35 , and the temporary image  36  is obtained. The temporary image  36  has 8 columns of temporary pixels along the vertical direction, and the temporary image  33  has 5 rows of temporary pixels along the horizontal direction.  
         [0057]     Then, the DDA algorithm-based process is executed again to fill the total length (8 rows) along the vertical direction of the second image  37  with the 5 columns of the temporary pixels of the temporary image  36  so as to form the second image  37 . The method is as follows.  
         [0058]     First, the first row of the second pixels  371   b  of the second image  37  is equal to the first row of the temporary pixels  361   b  of temporary image  36 . That is, the second pixels  371   b  of the first row of the second image  37  are the same as the temporary pixels  361   b  of the first row of the temporary image  36 . Then, the DDA algorithm-based process is executed according the above-mentioned way to determine the pixels after the first row so as to form the second image  37 . Finally, the second image  37  is displayed.  
         [0059]      FIG. 6  shows an image enlarging method according to a second embodiment of the present invention. The image enlarging method of the embodiment is used for enlarging a first image  38  into a second image  39  in a non-integer multiple. The first image  38  is constituted by a plurality of arrayed first pixels, wherein the first image  38  has X 1  first pixels along a first coordinate axis direction (for example, horizontal direction), and the first image  38  has Y 1 . first pixels along a second coordinate axis direction (for example, vertical direction). The second image  39  is constituted by a plurality of arrayed second pixels, wherein the second image  39  has X 2  second pixels along the first coordinate axis direction (for example, horizontal direction), and the second image  39  has Y 2  second pixels along the second coordinate axis direction (for example, vertical direction). The method comprises the following steps:  
         [0060]     (a) capturing the first pixels of the first image  38 , each first pixel is defined as a first coordinate value (for example, a 1 ), a second coordinate value (for example, b 1 ) and a first pixel value (for example, the RGB information), wherein the first coordinate value (for example, a 1 ) corresponds to the first coordinate axis direction, and the second coordinate value (for example, b 1 ) corresponds to the second coordinate axis direction. For example, the coordinate value of the first first pixel  381  is (11), that is, a 1 =1, b 1 =1. The coordinate values of other first pixels are increased in sequence;  
         [0061]     (b) determining the first coordinate values (for example, a 2 ) of the second pixels of the second image  39  according to the first coordinate values (for example, a 1 ) of the first pixels by utilizing a DDA algorithm-based process;  
         [0062]     (c) determining the second coordinate values (for example, b 2 ) of the second pixels of the second image  39  according to the second coordinate values (for example, b 1 ) of the first pixels by utilizing a DDA algorithm-based process; and  
         [0063]     (d) specifying the second pixel values of the second pixels according to the first coordinate values (for example, a 2 ) and the second coordinate values (for example, b 2 ) of the second pixels, wherein the second pixel values of the second pixels are the same as the first pixel values of the first pixels having the same first coordinate values (for example, a 1 ) and the second coordinate values (for example, b 1 ) with the second pixels.  
         [0064]     In the embodiment, the DDA algorithm-based process utilized in the steps (b) and (c) is same as that in the first embodiment. The difference between the embodiment and the first embodiment is that the second pixels in the second image  39  are designated with a first coordinate values and a second coordinate values, and the second pixels show the same information as the first pixels which have same coordinate values as the second pixels.  
         [0065]     The step (b) of the embodiment comprises the following steps:  
         [0066]     (b1) equalizing a first coordinate value a 2  of a predetermined second pixel (for example, the first second pixel  391 ) of the second image  39  to a first coordinate value a 1 , of a corresponding first pixel (for example, the first first pixel  381 ) of the first image  38 ;  
         [0067]     (b2) accumulating the X 1  value and a first temporary value to form a second temporary value;  
         [0068]     (b3) determining whether or not the second temporary value is smaller than the X 2  value in order to determine a first coordinate value a 2 ′ of a second pixel next to the predetermined second pixel;  
         [0069]     (b4) if the second temporary value is smaller than the X 2  value, which is defined as non-carry situation, the first coordinate value a 2 ′ of the second pixel next to the predetermined second pixel is equal to the first coordinate value a 2  of the predetermined second pixel, and the first temporary value is changed to the second temporary value;  
         [0070]     (b5) if the second temporary value is larger than or equal to the X 2  value, which is defined as carry situation, the first coordinate value a 2 ′ of the second pixel next to the predetermined second pixel is equal to the first coordinate value a 2  of the predetermined second pixel with an increment of 1, then the X 2  value is subtracted from the second temporary value to form a third temporary value, and the first temporary value is changed to the third temporary value; and  
         [0071]     (b6) repeating the steps (b3) to (b5).  
         [0072]     Similarly, the step (c) comprises the following steps:  
         [0073]     (c1) equalizing a second coordinate value b 2  of a predetermined second pixel (for example, the first second pixel  391 ) of the second image  39  to a second coordinate value b 1 , of a corresponding first pixel (for example, the first first pixel  381 ) of the first image  38 ;  
         [0074]     (c2) accumulating the Y 1 . value and a fourth temporary value to form a fifth temporary value;  
         [0075]     (c3) determining whether or not the fifth temporary value is smaller than the Y 2  value in order to determine a second coordinate value b 2 ′ of a second pixel next to the predetermined second pixel;  
         [0076]     (c4) if the fifth temporary value is smaller than the Y 2  value, which is defined as non-carry situation, the second coordinate value b 2 ′ of the second pixel next to the predetermined second pixel is equal to. the second coordinate value b 2  of the predetermined second pixel, and the fourth temporary value is changed to the fifth temporary value;  
         [0077]     (c5) if the fifth temporary value is larger than or equal to the Y 2  value, which is defined as carry situation, the second coordinate value b 2 ′ of the second pixel next to the predetermined second pixel is equal to the second coordinate value b 2  of the predetermined second pixel with an increment of  1 , and then the Y 2  value is subtracted from the fifth temporary value to form a sixth temporary value, and the fourth temporary value is changed to the sixth temporary value; and  
         [0078]     (c6) repeating the steps (c3) to (c5).  
       EXAMPLE 2  
       [0079]      FIG. 7  shows the image enlarging method according to example 2 of the present invention. The image enlarging method of example 2 is used for enlarging a first image  40  into a second image  41  in a non-integer multiple. The first image  40  is constituted by a plurality of arrayed first pixels, wherein the first image  40  has 5 first pixels along the horizontal direction, and the first image  40  has 5 first pixels along the vertical direction. The second image  41  is constituted by a plurality of arrayed second pixels, wherein the second image  41  has 8 second pixels along the horizontal direction, and the second image  41  has 8 second pixels along the vertical direction.  
         [0080]     The method comprises the following steps. First, capturing the first pixels of the first image  40 . Then, each first pixel is defined as a first coordinate value a 1 , and a second coordinate value b 1 . Taking the first column for example, the pixels from top to bottom are:  11 ,  12 ,  13 ,  14 ,  15  respectively. Taking the first row for example, the pixels from left to right are:  11 ,  21 ,  31 ,  41 ,  51  respectively.  
         [0081]     Then, the DDA algorithm-based process is executed to determine the coordinate values of the second pixels of the first row  411   b  of the second image  41  by utilizing the relationship between 5 and 8. The method is as follows.  
         [0082]     First, equalizing the first coordinate value and the second coordinate value of the first second pixel  411  of the second image  41  to the first coordinate value and the second coordinate value of a corresponding first first pixel of the first image  40 . That is, the first second pixel  411  of the second image  41  is defined as (11), the first coordinate values of the second pixels of the first column of the second image  41  are 1, and the second coordinate values of the second pixels of the first row of the second image  41  are 1.  
         [0083]     In the first row  411   b  of the second image  41 , the coordinate value of the first second pixel  411  is (11). Then, the DDA algorithm-based process is executed to obtain the results as shown in table 1 so as to determine the first coordinate values of the pixels after the first second pixel  411  in the same row.  
         [0084]     The second second pixel  412  of the first row  411   b  is illustrated, and it corresponds to the first cycle (x=1) of the DDA. First, a first temporary value P x =0 is provided. Then, a second temporary value (5) is obtained by accumulating the X 1  value (X 1 =5) and the first temporary value P x  (P x =0). Since the second temporary value (5) is smaller than the carry condition X 2  (X 2 =8), it is defined as non-carry situation (0). Therefore, the first coordinate value of the second second pixel  412  maintains the first coordinate value (1) of the last second pixel (i.e., the first second pixel  411 ), and the first temporary value P x  is changed to 5. Accordingly, the coordinate value of the second second pixel  412  is (11).  
         [0085]     Then, determining the third second pixel  413  which corresponds the second cycle (x=2) of the DDA. A second temporary value (10) is obtained by accumulating the X 1  value (X 1 =5) and the first temporary value P x  (P x =5). Since the second temporary value (10) is larger than the carry condition X 2  (X 2 =8), it is defined as carry situation (1). Therefore, the first coordinate value of the third second pixel  413  is equal to that of the second second pixel  412  with an increment of 1. Accordingly, the coordinate value of the third second pixel  413  is (21). Then the X 2  value (X 2 =8) is subtracted from the second temporary value (10) to obtain a third temporary value (2), and the first temporary value P x  is changed to 2.  
         [0086]     Similarly, from the table 1, the third cycle (x=3) of the DDA is defined as non-carry situation (0). Therefore, the coordinate value of the fourth second pixel  414  is (21). Then, in the fourth cycle (x=4) of the DDA, carry situation happens. Therefore, the coordinate value of the fifth second pixel  415  is (31). The other cycles of the DDA are repeated in the same way until the coordinate values of the second pixels of the first row  411   b  are determined.  
         [0087]     Then, the DDA algorithm-based process is executed to determine the coordinate values of the second pixels of the second row  412   b  of the second image  41  by utilizing the relationship between 5 and 8. The method is as follows. From table 1, the second row  412   b  of the second pixels of the second image  41  correspond to the first cycle (x=1) of the DDA, which is defined as non-carry situation. Therefore, the coordinate values of the second pixels of the second row  412   b  are equal to that of the first row  411   b.    
         [0088]     From table 1, the third row  413   b  of the second pixels of the second image  41  corresponds to the second cycle (x=2) of the DDA, which is defined as a carry situation. Therefore, the second coordinate values of the second pixels of the third row  413   b  are equal to those of the second row  412   b  with an increment of 1. Then, the fourth row  414   b  of the second pixels of the second image  41  corresponds to the third cycle (x=3) of the DDA, which is defined as non-carry situation. Therefore, the coordinate values of the second pixels of the fourth row  414   b  are equal to those of the third row  411   b.    
         [0089]     Finally, the second pixel values of the second pixels according to the first coordinate values a 2  and the second coordinate values b 2  of the second pixels are specified, wherein the second pixel values of the second pixels are the same as the first pixel values of the first pixels having the same first coordinate values a 1 , and the second coordinate values b 1 , with the second pixels. For example, the second pixel values of the second pixels (totally 4 second pixels) with a coordinate value of (11) in the second image  41  are equal to the first pixel value of the first pixel (totally 1 first pixel) with a coordinate value of (11) in the first image  40 . The second pixel values of the second pixels (totally 2 second pixels) with a coordinate value of (31) in the second image  41  are equal to the first pixel values of the first pixel (totally 1 first pixel) with a coordinate value of (31) in the first image  40 .  
         [0090]      FIG. 8  shows an image enlarging method according to a third embodiment of the present invention. The image enlarging method of the embodiment is used for enlarging a first image  42  into a second image  44  in a non-integer multiple. The first image  42  is constituted by a plurality of arrayed first pixels, wherein the first image  42  has X 1  columns of the first pixels along a first coordinate axis direction (for example, horizontal direction), and the first image  42  has Y 1 , rows of the first pixels along a second coordinate axis direction (for example, vertical direction). The second image  44  is constituted by a plurality of arrayed second pixels, wherein the second image  44  has X 2  columns of the second pixels along the first coordinate axis direction (for example, horizontal direction), and the second image  44  has Y 2  rows of the second pixels along the second coordinate axis direction (for example, vertical direction). The method comprises the following steps:  
         [0091]     (a) capturing the first pixels of the first image  42 ;  
         [0092]     (b) determining a difference value of column and a difference value of row, wherein the difference value of column is derived from subtracting the number of the columns of the first image  42  enlarged in an integer multiple from the number of the columns (X 2 ) of the second image  44 . The difference value of row is derived from subtracting the number of the rows of the first image  42  enlarged in the integer multiple from the number of the rows (Y 2 ) of the second image  44 , wherein the integer multiple is smaller than the non-integer multiple and is closest to the non-integer multiple. For example, the first image  42  is enlarged into a temporary image  43  that is smaller than and is closest to the second image  44  in an  
         [0093]     integer multiple n, wherein the difference value of column between the temporary image  43  and the second image  44  is X 3 , and the difference value of row between the temporary image  43  and the second image  44  is Y 3 ;  
         [0094]     (c) determining at least one repeatedly display column  421  according to the difference value of column. For example, the X 3  columns of the difference columns are distributed equally among the X 1  columns of the first image  42 , wherein d=X 1 /X 3 , d is an integer, and the (d−1)th, (2d−1)th, (3d−1)th, . . . , (nd−1)th columns are repeatedly displayed columns  421 ;  
         [0095]     (d) determining at least one repeatedly displayed row  422  according to the difference value of row. For example, the Y 3  rows of the difference rows are distributed equally among the Y 1 , columns of the first image  42  to determine the repeatedly displayed columns  421 ; and  
         [0096]     (e) repeating the repeatedly displayed column  421  and repeatedly displayed row  422  of the first image  42  in a multiple of the integer multiple with an increment of 1, and repeating the other columns and rows of the first image  42  in the integer multiple to form the second image  44 . That is, the repeatedly displayed columns  421  and repeatedly displayed rows  422  are enlarged in n+1 multiple, and other columns and rows are enlarged in n multiple.  
       EXAMPLE 3  
       [0097]      FIG. 9  shows the image enlarging method according to example 3 of the present invention. The image enlarging method of example 3 is used for enlarging a first image  45  into a second image  46  in a non-integer multiple. The first image  45  is constituted by a plurality of arrayed first pixels, and has a resolution of 507*379, that is, the first image  45  has 507 columns of first pixels and 379 rows of first pixels. The second image  46  is constituted by a plurality of arrayed second pixels, and has a resolution of 1024*768, that is, the second image  46  has 1024 columns of second pixels and 768 rows of second pixels.  
         [0098]     After the first image  45  is enlarged in a multiple of 2 along the horizontal direction and the vertical direction, its resolution is only 1014*758. The difference value of column is 10 in the horizontal direction, and the difference value of row is 10 in the vertical direction.  
         [0099]     Then, the 10 columns of the difference columns are distributed equally among the columns of the first image  42  to determine repeatedly displayed column  451 . First, the interval d 1  between two repeatedlyed display columns  451  is determined by 507/10=50.7, but d 1  must be an integer. Therefore, d 1  is 50. Accordingly, the  49   th  column (50-1),  99   th  column (2*50-1),  149   th  column (3*50-1),  199   th  column (4*50-1),  249   th  column (5*50-1),  299   th  column (6*50-1),  349   th  column (7*50-1),  399   th  column (8*50-1),  449   th  column (9*50-1), and  499   th  column (10*50-1) are repeatedly displayed columns  451 .  
         [0100]     Then, the 10 rows of the difference rows are distributed equally among the columns of the first image  42  to determine repeatedly displayed rows  452 . First, the interval d 2  between two repeatedly displayed rows  451  is determined by 379/10=37.9, but d 2  must be an integer. Therefore, d 2  is 37. Accordingly, the  36   th  row (37-1), 73rd row (2*37-1),  110   th  row (3*37-1),  147   th  row (4*37-1),  184   th  row (5*37-1),  221   st  row (6*37-1),  258   th  row (7*37-1),  295   th  row (8*37-1),  332   nd  row (9*37-1), and  369   th  row (10*37-1) are repeatedly displayed rows  452 .  
         [0101]     Finally, the second image  46  is displayed, wherein the repeatedly displayed columns  451  and repeatedly displayed rows  452  of the first image  42  are enlarged in a multiple of 3. That is, the repeatedly display columns  451  and repeatedly display rows  452  are displayed repeatedly 3 times, i.e., the integer multiple 2 adds 1. The other columns and rows are enlarged in a multiple of 2. That is, the other columns and rows are displayed repeatedly 2 times, i.e., the integer multiple 2.  
         [0102]     The present invention also relates to an image enlarging device for enlarging a first image into a second image in a non-integer multiple. The first image is constituted by a plurality of arrayed first pixels, wherein the first image has a plurality of columns of the first pixels along a first coordinate axis direction, and the first image has a plurality of rows of the first pixels along a second coordinate axis direction. The second image is constituted by a plurality of arrayed second pixels, wherein the second image has a plurality of columns of the second pixels along the first coordinate axis direction, and the second image has a plurality of rows of the second pixels along the second coordinate axis direction. The image enlarging device comprises: a capture device, a DDA device and a display device. The capture device is used for capturing the first pixels of the first image. The DDA device is used for executing a DDA algorithm-based process so as to determine the display information of the second pixels of the second image according to the first pixels of the first image. The display device is used for displaying the second image.  
         [0103]      FIG. 10  shows a preferred embodiment of a TV wall system according to the present invention. The TV wall system  50  comprises: a plurality of arrayed display devices  53 ,  54 ,  55 ,  56 , an image generating device  51  and an image dividing and enlarging device  52 . The image generating device  51  is used for providing a source image  60  ( FIG. 11 ) that is to be enlarged into an enlarged image  70  ( FIG. 12 ) that is displayed on the TV wall system  50 . The image generating device  51  may be any kind of players that can generate images, including but not limited to DVD player, VCD player, computer or demodulator.  
         [0104]      FIGS. 11 and 12  show a source image  60  and an enlarged image  70  applied for the embodiment of  FIG. 10 , respectively. The source image  60  is enlarged into the enlarged image  70  in a multiple of 4 (2*2) and displayed on the display devices  53 ,  54 ,  55 ,  56  of the TV wall. In the embodiment, the resolutions of the source image  60  and single display device are both 1024*768.  
         [0105]     The image dividing and enlarging device  52  is used for processing the source image  60  and transmitting to the display devices  53 ,  54 ,  55 ,  56  to display the enlarged image  70 . The process is as follows.  
         [0106]     First, the source image  60  is stored in a memory device (not shown). The memory device may be in the image dividing and enlarging device  52  or an independent device. The memory device can store the full-size image or partition image, which depends on the set up of the parameters. In the embodiment, the full-size source image  60  is stored and is divided into four partitions  61 ,  62 ,  63 ,  64 , wherein the partition  61  corresponds to the display device  53 , the partition  62  corresponds to the display device  54 , the partition  63  corresponds to the display device  55  and the partition  64  corresponds to the display device  56 .  
         [0107]     Then, the images stored in the memory device are captured out. There are two ways, as shown in  FIG. 2 , for defining the parameters of capture: the first way is defining the image from an initial point on the upper-left corner to an end point on the lower-right corner; the second way is defining the image by the initial point, a horizontal length and a vertical length. In the present invention, when capturing the image, the amount and disposition of the display devices  53 ,  54 ,  55 ,  56  and the discard of the frame between the display devices  53 ,  54 ,  55 ,  56  must be considered.  
         [0108]     In the embodiment, the frame  57  of the enlarged image  70  covers 10 columns of pixels and 10 rows of pixels. The partition  61  is captured from ( 0 ,  0 ) to ( 506 ,  378 ), the partition  62  is captured from ( 517 ,  0 ) to ( 1023 ,  378 ), the partition  63  is captured from ( 0 ,  389 ) to ( 506 ,  767 ), and the partition  64  is captured from ( 517 ,  389 ) to ( 1023 ,  767 ). However, taking the partition  61  for example, when it is displayed on the display device  53 , it lacks 10 columns of pixels along the horizontal direction and 10 rows of pixels along the vertical direction if it is enlarged in a multiple of 2 along the horizontal direction and the vertical direction since the resolution of the enlarged partition  61  is 1014*758.  
         [0109]     Then, the images of the partitions  61 ,  62 ,  63 ,  64  are enlarged into plural second images in a non-integer multiple respectively. The image enlarging method is the same as the above-mentioned first to third embodiments.  
         [0110]     Finally, the second images are displayed on the display devices  53 ,  54 ,  55 ,  56  which are connected to the image dividing and enlarging device  52  so as to combine an enlarged image  70 . Each of the display devices  53 ,  54 ,  55 ,  56  receives and displays one single image, and does not need to have the function of enlarging or dividing image.  
         [0111]     Comparing  FIG. 12  with  FIG. 3 , the enlarged image  70  formed by the present invention has no distortion that occurrs in the enlarged image formed by the conventional method, and enlarged image  70  has no black area on the sides thereof.  
         [0112]     While several embodiments of the present invention have been illustrated and described, various modifications and improvements can be made by those skilled in the art. The embodiments of the present invention are therefore described in an illustrative but not restrictive sense. It is intended that the present invention may not be limited to the particular forms as illustrated, and that all modifications which maintain the spirit and scope of the present invention are within the scope as defined in the appended claims.