Abstract:
This invention provides an image conversion apparatus for converting a screen signal to display a converted screen signal on a monitor, with the screen signal comprising a plurality of first image signals. The image conversion apparatus comprises a format memory in which at least one data group is stored and a conversion matrix for conversion of the first image signals to a plurality of corresponding second image signals, a latch circuit electrically connected to the conversion matrix for latching the second image signals transmitted from the conversion matrix, and a control circuit electrically connected to the format memory and the latch circuit for controlling the latch circuit so that the latch circuit latches chosen second image signals, according to a lock signal in the data group transferred from the format memory.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a digital image conversion apparatus, and more specifically to a programmable digital image conversion apparatus.  
           [0003]    2. Description of the Prior Art  
           [0004]    Due to digital image systems such as digital still cameras (DSC) or digital video cameras having light volume and being capable for use in a computer system or on the internet directly, digital image systems have become the main stream products of the image system market.  
           [0005]    In general, a digital image system has a monitor to display digital signals recorded by the digital image system. Users may use the monitor as a viewfinder to help determine a proper position to take pictures, or review the pictures taken so as to edit or delete unsatisfactory pictures.  
           [0006]    Please refer to FIG.1. FIG. 1  is a functional block diagram of a prior art digital image system  100 . The digital image system  100  comprises a digital image forming apparatus  120  for generating a screen signal  140 . The screen signal  140  will be converted by an image conversion apparatus  160  and then a converted screen signal will be displayed on a monitor  180 . The digital image forming apparatus  120  always uses a charge-coupled device (CCD) as an image sensor. The monitor  180  always uses a liquid crystal display (LCD) as a display. However, data formats of the screen signal  140  generated by the digital image forming apparatus  120  are usually in a data format that is incompatible with the monitor  180 . At present, there is not any standard specification of the monitor  180 . Due to the lack of a standard, the digital image system  100  needs the installation of the image conversion apparatus  160  between the digital image forming apparatus  120  and the monitor  180  as a data format conversion interface. In this way, the monitor  180  is capable of properly displaying the digital signals recorded by the digital image forming apparatus  120 .  
           [0007]    The prior art image conversion apparatus  160  is a circuit that is designed for handling the screen signal  140 , and generates data formats that the particular monitor  180  can accept. Therefore, the image conversion apparatus  160  can be only used for the particular monitor  180 . If a manufacturer of the digital image system  100  wishes to use other types of monitors  180 , the manufacturer of the digital image system  100  must implement a new circuit in the image conversion apparatus  160  so the image conversion apparatus  160  can provide appropriate data formats to the new monitor  180 . For the manufacturer of the digital image system  100 , it is inconvenient to design different circuits in the image conversion apparatus  160  to match the different monitors. This is a drawback of the prior art image conversion apparatus  160 .  
         SUMMARY OF THE INVENTION  
         [0008]    It is therefore a primary objective of the claimed invention to provide a programmable digital image conversion apparatus for overcoming the drawbacks of the prior art digital image conversion apparatus.  
           [0009]    The claimed invention, briefly summarized, discloses a digital image conversion apparatus. The digital image conversion apparatus is provided for converting a screen signal to display a converted screen signal on a monitor. The screen signal comprises a plurality of first image signals. The image conversion apparatus comprises a format memory, a conversion matrix, a latch circuit, and a control circuit. There is at least one data group stored in the format memory. The conversion matrix is used to convert the first image signals to a plurality of corresponding second image signals. The latch circuit is electrically connected to the conversion matrix for latching the second image signals transmitted from the conversion matrix. The control circuit is electrically connected to the format memory and the latch circuit for controlling the latch circuit, so that the latch circuit latches chosen second image signals according to a lock signal in the data group transferred from the format memory.  
           [0010]    It is an advantage of the claimed invention that the image conversion apparatus of the digital image system employs the stored data of the data group in the format memory to control image conversion. For different monitors, a manufacturer needs only to change data within storage checks of the data group so as to be capable of performing image conversion. 
       
    
    
       [0011]    These and other objectives and advantages 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  
       [0012]    FIG. 1  is a functional block diagram of a prior art digital image system.  
         [0013]    FIG. 2  is a functional block diagram of a present invention digital image system.  
         [0014]    FIG. 3  is a diagram of data formats in data groups.  
         [0015]    FIG. 4  is a signal pulse diagram of the present invention digital image system when operating. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]    Please refer to FIG.2. FIG. 2  is a functional block diagram of a present invention digital image system  200 . The digital image system  200  comprises an image conversion apparatus  202  for converting a screen signal  260  for proper display on a monitor  280 . The screen signal  260  comprises a first image signal  262 , a vertical synchronizing signal  264 , a horizontal synchronizing signal  266 , and a pixel clock tick  268 . The first image signal  262  is generally a YUV signal, where the Y being a brightness component, U being a color difference signal corresponding to B-Y, and V being a color difference signal corresponding to R-Y. The image conversion apparatus  202  comprises a control circuit  210 , a format memory  300 , a wave formatter  250 , a conversion matrix  220 , a latch circuit  230  and a selector  240 . The latch circuit  230  may be implemented by D flip-flops.  
         [0017]    The format memory  300  has a data group  310  of odd scanning lines and a data group  310  of even scanning lines. Each data group  310  comprises a plurality of storage checks  311 . The conversion matrix  220  is used to convert the first image signals  262  to corresponding second image signals  225  which is a format that can be accepted by the monitor  280 . The second image signals  225  always are RGB (red, green and blue) signals. The three second image signals  225  shown in FIG. 2  respectively represent red signals, green signals and blue signals. The second image signals  225  are used to form a pixel on the monitor  280 . The wave formatter  250  is able to convert the horizontal synchronizing signals  266  and the vertical synchronizing signals  264  of the screen signal  260  to horizontal synchronizing signals and vertical synchronizing signals that accepted by the monitor  280 . Comparing the horizontal and vertical synchronizing signals contained in the screen signal  260 , the horizontal and vertical synchronizing signals that may be accepted by the monitors  280  generally have different polarization, pulse width, or time delay. Therefore a wave formatter  250  is used to convert these or other parameters of the vertical synchronizing signals  264  and the horizontal synchronizing signals  266  to match the specifications of the monitor  280 . The system clock tick  211  detonates the control circuit  210  so as to make the control circuit  210  control the operation of the image conversion apparatus  202 , and use the data contained in each storage check  311  of the format memory  300  to generate a first pixel clock tick  212  and a second pixel clock tick  214  that can be accepted by the monitor  280 . The control circuit  210  generates latch signals  216  and color signals  218  according to the data contained in the storage checks  311  of the data group  300 , so as to control the latch circuit  230  and the selector  240  and provide proper displaying signals  242  to the monitor  280 . The latch circuit  230  comprises DFlip-flops. The timing of the latch circuit  230  is also provided by the system clock tick  211 .  
         [0018]    The control circuit  210  of the present invention image conversion apparatus  202  utilizes data contained in each storage check  311  of the data group  310  to determine how to convert the screen signal  260  to data formats that the monitor  280  can accept. Therefore if the manufacture of the digital image system  200  desires to change the monitor  280  types, it does not need to redesign a new image conversion apparatus  202 , but only to replace the data contained in each storage checks  311  of the data group  310 . Manufactures of the digital image systems  200  can save considerable time and cost when changing monitor type in their products.  
         [0019]    Please refer to FIG.3. FIG. 3  is a diagram of data formats in each storage check  311  of the data groups  310 . The storage check  311  comprises a signal code  312  of a latch signal  216 , a signal code  316  of a first pixel clock tick  212 , a signal code  314  of a second pixel clock tick  214 , and a signal code  318  of a color signal  218 . The control circuit  210  generates the latch signal  216  to control the latch circuit  230  according to the signal code  312 . The control circuit  210  generates the color signal  218  to control the selector  240  according to the signal code  318 . The control circuit  210  generates the first pixel clock tick  212  according to the signal code  316 , and generates the second pixel clock tick  214  according to the signal code  314 . Each signal code  312 ,  314 ,  316  and  318  has two bits in the embodiment mentioned thereinafter, so that the storage check  311  has eight bits in total. The present invention image conversion apparatus  202  can generate not only the first pixel clock tick  212  and the second pixel clock tick  214 , but also modify the number of pixel clock ticks to meet practical needs. It should be noted that the number of the signal codes in the storage checks  311  must match the number of the pixel clock ticks  212 , so that changing the number of pixel clock ticks  212  would also change the size of the storage checks  311 .  
         [0020]    The operation principle of the present invention image conversion apparatus  202  can be described using the embodiment as follows: In the embodiment, there are  720  pixel clock ticks and image pixels between each two horizontal synchronizing signals  266 . However, each scanning line on the monitor  280  only has  640  pixel clock ticks and  320  image pixels, and each pixel can only display one color. In order to properly display images on the monitor  280 , the control circuit  210  must reduce the  720  pixel clock ticks to  640  pixel clock ticks, and reduce the  720  image pixels to  320  image pixels. Moreover, the proper color to be outputted has to be chosen. Therefore, the image is capable of displaying on the monitor  280 .  
         [0021]    Please refer to FIG.4. FIG. 4  is a signal pulse diagram of the present invention image conversion apparatus  202  when operating. Signals  710  are the pixel clock ticks  268  of the screen signals  260 , and each square wave of the signal  710  represents a period. The digital image system  200  performs a sampling of the second image signal  225  in each period, so each period is in line with a pixel datum of a pixel. As FIG. 4  shows, each square wave of the signal  710  is numbered (from  0  to  26 ). Each of the square waves numbered from  0  to  26  is in line with the pixel data of a corresponding pixel. In the operation process of the present invention image conversion apparatus  202 , each square wave corresponds to data stored in a corresponding storage check  311 . Each square wave is defined as a conversion period in the following description. A datum rank  912  shown in FIG. 4  arrays the signal codes  312 , which represents the latch signal  216  in the storage check  311 , into alignment in order to match each conversion period. As mentioned before, the signal code  312  has two bits in the storage check  311 . Therefore, the datum rank  912  shown in FIG. 4  has two checks  720  in each conversion period, and each check is represented as a bit. A filled check is represented as  1 , and a blank check is represented as  0 . This same arrangement is used in a datum rank  914  to represent the signal code  314 , which is used to generate the second pixel clock tick  214 . A similar arrangement in a datum rank  916  represents the signal code  316 , which is used to generate the first pixel clock tick  212 . The same arrangement in a datum rank  918  represents the signal code  318 , which is used to generate the color signals  218 . In the present embodiment, the signal code  318  represents blue (B) when the code is  11 , represents red (R) when the code is  00 , and represents green (G) when the code is  10 .  
         [0022]    A signal  216  shown in FIG. 4  is the latch signal  216  that the control circuit  210  uses to control the latch circuit  230  (please refer to FIG. 2  as well). Signals  232 ,  234  and  236  are monochrome signals transmitted from the latch circuit  230  to the selector  240 . A signal  218  is the color signal  218  that the control circuit  210  uses to control the selector  240 . A signal  212  is the first pixel clock tick  212 , which is output from the control circuit  210  to the monitor  280 . A signal  242  is the displaying signal  242 , which is output from the selector  240  to the monitor  280 .  
         [0023]    The operation of the present invention image conversion apparatus  202  can be described as follows (please refer to FIG. 2  as well) : The operating signal pulse of the image conversion apparatus  202  are controlled by the system clock ticks  211 , and the frequency of the system clock ticks  211  is double that of the pixel clock ticks  268 . When the system clock ticks  211  are enabled, the control circuit  210  can match the horizontal synchronizing signals  266  and the vertical synchronizing signals  264  of the screen signals  260  to synchronously read the data of one storage check  311  in each conversion period of the signal  710 . Please refer to the datum rank  912  shown in FIG. 4 , in the conversion period of a title  0 , the control circuit  210  reads the signal code from the storage checks  311  is  10 . The control circuit  210  generates a high-level latch signal  216  according to the signal code  312 , and the high-level latch signal  216  will enable the latch circuit  230  to latch the second image signal  225  in accordance with the conversion period of the title  0 . The second image signals  225  are the signals which are labeled R( 0 ), G( 0 ) and B( 0 )in the monochrome signals  232 ,  234  and  236 , respectively. The symbol  0  inside the bracket of the labels R( 0 ), G( 0 ) and B( 0 ) corresponds to the conversion period of the title  0 . Because the latch circuit  230  is implemented by D flip-flops, when the latch circuit  230  is enabled, there is a system clock tick period difference between the input and the output. Therefore, the signals  232 ,  234  and  236  shown in FIG. 4  have a time delay.  
         [0024]    Similarly, refer to the datum rank  916 . The signal code  316  of the first pixel clock ticks  212  in accordance with the conversion period labeled  0  is  01 . The control circuit  210  generates a high-to-low waveform in signal  1212  according to the periodic signal. (Please note that in each conversion period the lower bit will be read first, so the signals  1212  will be formed as illustrated in FIG. 4.) At last, according to the signal code  318  of the color signals  218  of the datum rank  918  in the conversion period labeled  0 , the control circuit  210  outputs the color signals  218  to the selector  240  in order to make the selector  240  choose the monochrome signal transmitted from the latch circuit  230 . The signal code  318  is  11  in the conversion period labeled  0 , so the selector  240  chooses the blue monochrome signal to output to the monitor  280 . In order to match a system clock tick period difference between the input and the output when the latch circuit  230  is enabled, the signal  212  and the signal  218 , which controls the selector  240 , will have a system clock tick delay comparing to the datum rank  918 . The system clock tick delay equals to half the period of the signal  710 .  
         [0025]    In a title  1  conversion period, the control circuit  210  is capable of reading data of the next storage check  311  in the data group  310 . According to the datum rank  912 ,  916  and  918 , the signal code  312 ,  316  and  318  of the latch signal  216 , the first pixel clock tick  212 , and the color signal  218  are separately numbered  00 ,  01  and  11 . Since the signal code  312  is numbered  00 , the control circuit  210  does not generate the latch signal  216  to enable the latch circuit  230 . Therefore, the monochrome signal latched by the latch circuit  230  remains R( 0 ), G( 0 ) and B( 0 ), as FIG. 4  shows for the signals  232 ,  234  and  236 . Since the signal code  316  is numbered  01 , the control circuit  210  will also generates the high-to-low waveform in the signal  1212 . The signal code  318  of the color signal  218  chooses B( 0 ) for an output of the selector  240 .  
         [0026]    In a title  2  conversion period, the signal code  318  of the color signal  218  is changed to a red code  00  so the output of the selector  240  is changed to R( 0 ).  
         [0027]    Responding to the system clock tick  211 , the control circuit  210  reads the signal codes  312 ,  314 ,  316  and  318  of the different storage checks  311  separately in follow-up conversion periods. In a title  6  conversion period, the signal code  312  is numbered  10  so the control circuit  210  enables the high-level latch signal  216  to the latch circuit  230 . The latch circuit  230  latches the second image signal  225 , and transmits the R( 6 ), G( 6 ) and B( 6 ) of the monochrome signals  232 ,  234  and  236  in the second image signal  225  to the selector  240 .  
         [0028]    In a title  7  conversion period, the signal code  316  of the first pixel clock tick  212  is numbered  11 , so the signal  1212  maintains a high-level, not the high-to-low waveform as shown in title  0  to title  6  conversion period. In a title  8  conversion period, the signal code  316  of the first pixel clock tick  212  is numbered  00 , so the signal  1212  maintains a low-level. By combining the corresponding signals of the signal  1212  in the numbered conversion period  7  and  8 , a complete new period formed in the signal  1212  can be obtained. The same situation happens in a title  16  and  17  conversion period, and a title  25  and  26  conversion period.  
         [0029]    There are other titles numbered starting from  0 ′ under the signal  1212  shown in FIG.4. These titles number all complete square waves in the signals  1212  (that means each period of the first pixel clock tick  212 ). Signal  1212  has  24  square waves numbered from  0 ′ to  23 ′ in accordance with  27  square waves of the signal  710  that numbered from  0  to  26 . As mentioned before, the purpose of the present embodiment is to reduce the image pixels and the pixel clock tick periods between two horizontal synchronizing signals  266  of the screen signals  260  so as to make the image properly displayed on the monitor  280 . In the signal pulse diagram shown in FIG. 4 , the  27  square waves numbered from  0  to  26  of the signal  710  are reduced to  24  square waves numbered from  0 ′ to  23 ′ of the signal  1212 . Therefore, the  720  pixel clock ticks between two horizontal synchronizing signals  266  can be reduced to  640  pixel clock ticks if the process of FIG. 4  is repeated. Moreover, the first image signals  262  of the screen signals  260  will be converted to the displaying signals  242  which the monitor  280  can accept by the conversion matrix  220 . The image pixels between two horizontal synchronizing signals  266  can be also reduced to  320 .  
         [0030]    The control circuit  210  separately generates the first pixel clock ticks  212  and a displaying signal  242  to the monitor  280  according to the signal  1212  and the color signal  218 . By way of the present invention image conversion apparatus  202 , the screen signal  260  is converted to the first pixel clock tick  212 , the second pixel clock tick  214 , the displaying signal  242  outputted from the selector  240 , and the horizontal synchronizing signals and the vertical synchronizing signals outputted from the wave formatter  250  in order to display the screen signals  260  properly on the monitor  280 . Please note that even though the second pixel clock tick  214  is not used in this embodiment, it can be used in other embodiments according to the present invention.  
         [0031]    In the process of reducing the numbers of the pixel clock ticks and the image pixels mentioned above, the image conversion apparatus  202  can finish the image conversion operation of each scanning line according to repeated use the data of the  27  storage checks  311  in each datum rank  310 . Data formats are different between the odd scanning lines and the even scanning lines for some monitors  280 . Therefore, the data groups  310  representing the odd scanning lines and the data groups  310  representing the even scanning lines can be used simultaneously in the present invention format memory  300 , so as to make the image conversion operation processes successful. If the data formats of the odd scanning lines of the monitor  280  are the same with the even scanning lines, then the data group  310  of the even scanning lines will not be used. However, if the data formats of the odd scanning lines of the monitor  280  are not the same with the even scanning lines, then the data group  310  of the even scanning lines will be used.  
         [0032]    In contrast to the prior art digital image system  100 , the image conversion apparatus  202  of the present invention digital image system  200  uses stored data in the storage checks  311  of the data group  310  to control image conversion. For different monitors, a manufacturer needs only to change data within the storage checks  311  of the data group  310 , so as to be capable of performing image conversion. Considerable time and cost can thus be saved.  
         [0033]    The above disclosure is not intended as limiting. Those skilled in the art will readily observe that numerous modifications and alterations of the device 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.