Abstract:
A scaling device and a scaling method that employs a pre-filter. Using a pre-filter instead of a post-filter and a data storage unit as in a conventional device, scaling quality of the device is improved and production cost of the device is reduced. The scaling device includes a pre-filter for receiving data columns and carrying out chromatic adjustment and a scaling process for receiving the adjusted data and producing scaled data.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    This application claims the priority benefit of Taiwan application serial no. 90110252, filed Apr. 30, 2001.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of Invention  
           [0003]    The present invention relates to an apparatus and method of using a scaling device. More particularly, the present invention relates to an apparatus and method of using the scaling device of a pre-filter.  
           [0004]    2. Description of Related Art  
           [0005]    In computer graphics, scaling is a process of enlarging or reducing an image (such as a pattern or a text). After a scaling, size of the image is changed but the original shape is retained. Scaling is a useful method for enhancing or shrinking image patterns, video signals, voice signals, digital signals and processing any changes in the resolution of multimedia. In particular, for a fixed resolution digital display device, image format from different source must be scaled before the image can be shown in an appropriate resolution that matches a given display device.  
           [0006]    [0006]FIG. 1 is a schematic block diagram showing a conventional scaling system that employs a post-filter. The scaling device in FIG. 1 includes a scaling engine  102 , a data storage unit  200  and a post-filter  104  all interconnected together. For a post-filter  104  capable of processing N data columns with each column having M data points, filtering can only be conducted after a plurality of batches of scaled data is input. Hence, the subsidiary data storage unit  200  for data storage is essential. With the data storage unit  200  in place, the post-filter  104  can concurrently receive multiple batches of data for initiating a filtering operation. However, a major drawback is the high cost for providing the data storage unit  200 .  
         SUMMARY OF THE INVENTION  
         [0007]    Accordingly, one object of the present invention is to provide a scaling device that uses a pre-filter instead of a post-filter while still using a data storage unit as in a conventional device. Ultimately, scaling quality of the device is improved and production cost of the device is reduced.  
           [0008]    To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a scaling device that uses a pre-filter. The pre-filter receives N data columns. After chromatic adjustment, the pre-filter outputs P data columns to the scaling processor for scaling. The scaling processor later output scaled data. Each of the N data columns includes M factors, where 1&lt;P≦N and M, N and P are positive integers. The pre-filter includes a first operational amplifier, a second operational amplifier, a third operational amplifier and a fourth operational amplifier. The first operational amplifier receives the N data columns and generates data K, where data K=[D 1M/2 ; D 2M/2 , D 3M/2 , . . . D PM/2 ; and data D PM/2  is the M/2 th  data of the P th  data column.  
           [0009]    The second operational amplifier receives the N data columns and generates a weighed function W and a coefficient factor C, where the weighed function is W=[W 1 ; W 2 ; W 3 ; . . . W P ;] and the coefficient factor is C=[C 11 , C 12 C 13  . . . C 1M ; C 21 , C 22 , C 23  . . . C 2M ; . . . ; C N1 , C N2 , C N3 , . . . C NM ;]. The weighed function W, is the weighed function of the P th  data column and the coefficient factor C NM  is the coefficient of the M th  data in the N th  data column, where W can be any value.  
           [0010]    The third operational amplifier is coupled to the second operational amplifier for receiving the N data column and generating data D and data FLT, wherein the data D=[D 11 , D 12 D 13  . . . D 1M ; D 21 , D 22 , D 23  . . . D 2M ; . . . ; D N1 , D N2 , D N3 , . . . D NM ; and the data FLT= n=1 . . . N,m=1 . . . M Σ(C nm ×D nm ). The data D NM  is the M th  data in the N th  data column, the coefficient C nm  is the coefficient of the m th  data in the n th  data column and the data D nm  is the m th  data in the n th  data column.  
           [0011]    The fourth operational amplifier is coupled to the first operational amplifier, the second operational amplifier, the third operational amplifier and the scaling processor. The fourth operational amplifier receives data from the first, the second and the third operational amplifier and generates a data column FO, where the data column FO=[FO 1 ; FO 2 ; FO 3 ; . . . FO p ;] and FO n=1 p =W n ×FLT+(1−W n )×K n , and FO p  represents the output data of the p th  column.  
           [0012]    This invention also provides a method of using the pre-filter. The N data columns are chromatically adjusted by the pre-filter to generate P reduced or enhanced data columns. The scaled data is passed to the scaling processor to produce scaled data. Each of the N data columns includes M factors, where 1&lt;P≦N and P, M and N are positive integers.  
           [0013]    It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings,  
         [0015]    [0015]FIG. 1 is a schematic block diagram showing a conventional scaling system that employs a post-filter;  
         [0016]    [0016]FIG. 2 is a schematic block diagram showing a scaling device with a pre-filter according to one preferred embodiment of this invention;  
         [0017]    [0017]FIG. 3 is a detailed block diagram of the pre-filter shown in FIG. 2; and  
         [0018]    [0018]FIG. 4 is a block diagram showing the type of data generated by various operational amplifiers shown in FIG. 3. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.  
         [0020]    [0020]FIG. 2 is a schematic block diagram showing a scaling device with a pre-filter according to one preferred embodiment of this invention. In this embodiment, a pre-filter  202  receives three data columns and each data column includes three pieces of data. As shown in FIG. 4, the first data column includes data D 11 , data D 12  and data D 13 , the second data column includes data D 21 , data D 22  and data D 23  and the third data column includes data D 31 , data D 32  and data D 33 . The pre-filter  202  receives these three data columns and performs a chromatic adjustment of the data. The adjusted data is output to a scaling processor  204  for scaling treatment.  
         [0021]    [0021]FIG. 3 is a detailed block diagram of the pre-filter shown in FIG. 2. As shown in FIG. 3, a first operational amplifier  302  receives the three data columns and generates data K, where data K=[D 12 , D 22 , D 32 ]. A second operational amplifier  304  receives the three data columns and generates a weighed function and a coefficient C, where W=[W 1 , W 2 , W 3 ] and C=[C 11 , C 12 , C 13 ; C 21 , C 22 , C 23 ; C 31 , C 32 , C 33 ]. A third operational amplifier  306  receives the three data columns and generates data D and data FLT, where FLT=[C 11 D 11 +C 12 D 12 +C 13 D 13 +C 21 D 21 +C 22 D 22 +C 23 D 23 +C 31 D 31 +C 32 D 32 +C 33 D 33 ]. A fourth operational amplifier  308  is coupled to the first operational amplifier  302 , the second operational amplifier and the third operational amplifier  306  and the scaling processor. The fourth operational amplifier  308  receives data from the first operational amplifier  302 , the second operational amplifier  304 , the third operational amplifier  306  and generates data FO, where FO=[FO 1 ; FO 2 ; FO 3 ].  
         [0022]    [0022]FIG. 4 is a block diagram showing the type of data generated by various operational amplifiers shown in FIG. 3. As shown in FIG. 4, the first operational amplifier in the pre-amplifier generates data K, where K=[D 12 , D 22 , D 32 ]. Thereafter, the second operational amplifier generates a weighed function W and a coefficient C, where W=[W 1 , W 2 , W 3 ] and C=[C 11 , C 12 , C 13 ; C 21 , C 22 , C 23 ; C 31 , C 32 , C 33 ] Next, the third operational amplifier generates data FLT, where FLT=[C 11 D 11 +C 12 D 12 +C 13 D 13 +C 21 D 21 +C 22 D 22 +C 23 D 23 +C 31 D 31 +C 32 D 32 +C 33 D 33 ]. Finally, the fourth operational amplifier receives data from the first, the second, the third operational amplifier and generates data FO=[FO 1 ; FO 2 ; FO 3 ], where FO 1 =W 1 ×FLT+(1−W 1 )×K 1 , K 1 =[D 12 ], W 1 is any number; FO 2 =W 2 ×FLT+(1−W 2 )×K 2 , K 2 =[D 22 ], W 2 is any number; and FO 3 =W 3 ×FLT+(1−W 3 )×K 3 , K 3 =[D 32 ], W 3 is any number. Finally, the pre-filter outputs data columns FO 1 , FO 2  and FO 3  to the scaling processor to produce scaled data.  
         [0023]    In summary, this invention uses a scaling device having a pre-filter instead of a post-filter and a data storage unit as in a conventional device. Hence, scaling quality of the device is improved and production cost of the device is reduced.  
         [0024]    It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.