Image data format conversion apparatus

• US 6,256,068 B1
• Filed: 05/07/1997
• Issued: 07/03/2001
• Est. Priority Date: 05/08/1996
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Takada, Shuichi, Kajimura, Toshiyuki
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): DESIR, JEAN WICEL
• Application Number:
  US08/852,351
• Time in Patent Office: 1,518 Days
• Field of Search: H04/N.701, 348/441, 348/445, 348/447, 348/446, 348/454, 348/448, 348/458, 348/910, 348/555, 348/556, 386/131, 345/154, 345/153
• US Class Current: 348/441
• CPC Class Codes: G06T 3/4007 based on interpolation, e.g. bilinear interpolation image demosaicing G06T3/4015; edge-driven or edge-based scaling G06T3/403
• CPC Class Codes: G09G 2340/125 wherein one of the images is motion video
• CPC Class Codes: G09G 5/391 Resolution modifying circuits, e.g. variable screen formats
• CPC Class Codes: G09G 5/395 Arrangements specially adapted for transferring the contents of the bit-mapped memory to the screen G09G5/399 takes precedence
• CPC Class Codes: H04N 9/641 Multi-purpose receivers, e.g. for auxiliary information H04N9/642 takes precedence
• CPC Class Codes: Y10S 348/91 Flicker reduction

Abstract

An image data format conversion apparatus comprises: a memory storing image data; a data reading means reading image data from the memory to output it; a format converting means converting the image data output from the data reading means to a predetermined format to output it or making the image data pass through without converting it; a vertical filter vertically interpolating the image data output from the format converting means by filtering operation to output the data or making the image data pass through without interpolating it; a horizontal filter vertically interpolating the image data output from the vertical filter by filtering operation to output the data or making the image data pass through without interpolating it; an image synthesizing means performing logic operation for image data output from the filter, and synthesizing the image data to output it; and an image output means outputting the image data from the image synthesizing means to a designated display unit.

In this image data format conversion apparatus, as a memory for storing groups of image data with different formats (attributes) is provided, and after making uniform the format of the image data output from the memory, interpolating processing is performed using the vertical and horizontal filters to reduce flickers Furthermore, since image reducing/expanding processing is performed utilizing the interpolating processing to make pixel ratios uniform and then operations are performed for plural series of image data to synthesize plural series of images with a same ratio in the image synthesizing means, it is possible to implement filters and buffers necessary to make uniform formats when plural series of original images having different formats are superposed and displayed, making use of filters and buffers used for flicker reducing processing, and thus hardware cost can be minimized.

In addition, in the image data format conversion apparatus, the image data obtained by synthesization in the image synthesizing means is not output directly to the display, instead the data is once written into the memory to be synthesized with the other original image. Therefore, it is not necessary to consider a correspondence between a production rate of moving picture data and a display rate of the display unit, whereby system configuration is facilitated.

Claims

1. An image data format conversion apparatus comprising:

a memory storing image data having different image attributes;

a data reading means reading image data from the memory to output the data;

a format converting means for detecting whether a format of the image data output from the data reading means is a predetermined format and when an image data format is not the predetermined format, converting the image data to the predetermined format to output the data and when an image data format is the predetermined format, passing the image data through without converting the data; and

filter means for determining an attribute of the image data from said format converting means and vertically and horizontally interpolating the image data output from the format converting means by filtering operation to output the data or making the image data pass through without interpolating the data in accordance with an attribute of the image data.

2. An image data format conversion apparatus as defined in claim 1 further comprising:

an image synthesizing means performing logic operations for the image data output from the filter, synthesizing the image data to output the image data.

3. An image data format conversion apparatus as defined in claim 1 further comprising:

an image output means outputting the image data output from the image synthesizing means to a designated display unit.

4. An image format data conversion apparatus as defined in claim 1, wherein the predetermined format is an RGB format.

5. An image data format conversion apparatus as defined in claim 3 wherein the image output means writes the image data as an output thereof into the memory as well as the designated display.

6. An image data format conversion apparatus comprising:

a memory storing image data;

a data reading means reading image data from the memory to output the data;

a format converting means converting the image data output from the data reading means to a predetermined format to output the data or making the image data pass through without converting the data;

a filter vertically and horizontally interpolating the image data output from the format converting means by filtering operation to output the data or making the image data pass through without interpolating the data;

an image synthesizing means performing logic operations for the image data output from the filter, synthesizing the image data to output the image data; and

an image output means outputting the image data output from the image synthesizing means to a designated display unit

wherein the memory stores groups of image data having different formats separately;

the data reading means comprises an input buffer temporarily storing the groups of image data having different formats and an input control means reading image data in a designated format from the memory to write the data into the input buffer or reading image data in a designated format from the input buffer to output the data;

the filter comprises a vertical filter and a horizontal filter which vertically or horizontally interpolate the image data output from the format converting means, respectively, so that the data can be subjected to processing almost simultaneously, said vertical filter comprising a vertical filter buffer temporarily and separately storing groups of image data having different formats;

a vertical filter distributing means writing the image data output from the format converting means or the horizontal filter into the vertical filter buffer according to a designated format or reading image data from the vertical filter buffer according to a designated format to output the data; and

a vertical filter control means performing convolution operation for the image data output from the vertical filter distributing means and a vertical filter coefficient prepared according to a designated format to output the result, said horizontal filter comprising a horizontal filter buffer temporarily and separately storing groups of image data having different formats;

a horizontal filter distributing means writing image data output from the vertical filter or the format converting means into the horizontal filter buffer according to a designated format or reading image data from the horizontal filter buffer according to a designated format to output the data; and

a horizontal filter control means performing convolution operation for the image data output from the horizontal filter distributing means and a horizontal filter coefficient prepared according to a designated format;

the image synthesizing means comprises a synthesization buffer temporarily and separately storing groups of image data having different formats, a synthesization distributing means writing the image data output from the filter into the synthesization buffer according to a designated format or reading image data from the synthesization buffer according to a designated format to output the data, and a synthesization control means performing logical operation for the image data in a designated format output from the synthesization distributing means; and

the image output means comprises an output buffer temporarily storing groups of image data having different formats and an output control means writing the image data output from the image synthesizing means into the output buffer according to a designated format or reading image data from the output buffer according to a designated format to output the data.

7. An image data format conversion apparatus comprising:

a memory storing image data;

a data reading means reading image data from the memory to output the data;

a format converting means converting the image data output from the data reading means to a predetermined format to output the data or making the image data pass through without converting the data;

a filter vertically and horizontally interpolating the image data output from the format converting means by filtering operation to output the data or making the image data pass through without interpolating the data;

an image synthesizing means performing logic operations for the image data output from the filter, synthesizing the image data to output the image data; and

an image output means outputting the image data output from the image synthesizing means to a designated display unit;

wherein the memory stores groups of image data having different formats separately;

the data reading means comprises an input buffer temporarily storing the groups of image data having different formats and an input control means reading image data in a designated format from the memory to write the data into the input buffer or reading image data in a designated format from the input buffer to output the data;

the filter comprises a vertical filter and a horizontal filter which vertically or horizontally interpolate the image data output from the format converting means, respectively, so that the data can be subjected to processing almost simultaneously, said vertical filter comprising a vertical filter buffer temporarily and separately storing groups of image data having different formats;

a vertical filter distributing means writing the image data output from the format converting means or the horizontal filter into the vertical filter buffer according to a designated format or reading image data from the vertical filter buffer according to a designated format to output the data; and

a vertical filter control means performing convolution operation for the image data output from the vertical filter distributing means and a vertical filter coefficient prepared according to a designated format to output the result, said horizontal filter comprising a horizontal filter buffer temporarily and separately storing groups of image data having different formats;

a horizontal filter distributing means writing image data output from the vertical filter or the format converting means into the horizontal filter buffer according to a designated format or reading image data from the horizontal filter buffer according to a designated format to output the data; and

a horizontal filter control means performing convolution operation for the image data output from the horizontal filter distributing means and a horizontal filter coefficient prepared according to a designated format;

the image synthesizing means comprises a synthesization buffer temporarily and separately storing groups of image data having different formats, a synthesization distributing means writing the image data output from the filter into the synthesization buffer according to a designated format or reading image data from the synthesization buffer according to a designated format to output the data, and a synthesization control means performing logical operation for the image data in a designated format output from the synthesization distributing means; and

the image output means comprises an output buffer temporarily storing groups of image data having different formats and an output control means writing the image data output from the image synthesizing means into the output buffer according to a designated format or reading image data from the output buffer according to a designated format to output the data;

wherein the input control means reads image data from the memory for writing the data into the input buffer, the image data having a format corresponding to that of the image data having the smallest data storage unit number in one of groups of image data stored separately according to formats in the input buffer, or reading image data from the input buffer according to a designated format to output the data;

the format converting means requests image data in the data reading means according to a designated format or converts the image data output from the data reading means to a predetermined format according to a designated format;

the vertical filter distributing means requests image data in the format converting means or the horizontal filter, the image data having a format corresponding to that of the image data having the smallest data storage unit number in one of groups of image data stored separately according to formats in the vertical filter buffer or reads image data from the vertical filter buffer according to a designated format to output the data;

the horizontal filter distributing means requests image data in the vertical filter or the format converting means, the image data having a format corresponding to that of the image data having the smallest data storage unit number in one of groups of image data stored separately according to formats in the horizontal filter buffer or reads image data from the horizontal filter buffer according to a designated format to output the data;

the synthesization distributing means requests image data in the filter, the image data having a format corresponding to that of the image data having the smallest data storage unit number in one of groups of image data stored separately according to formats in the synthesization buffer or reads image data from the synthesization buffer according to a designated format to output the data; and

the output control means requests image data in the image synthesizing means, the image data having a format corresponding to that of the image data having the smallest data storage unit number in one of groups of image data stored separately according to formats in the output buffer or reads image data from the output buffer according to a designated format to output the data.

8. An image data format conversion apparatus comprising:

a memory storing image data;

a data reading means reading image data from the memory to output the data;

a format converting means converting the image data output from the data reading means to a predetermined format to output the data or making the image data pass through without converting the data;

a filter vertically and horizontally interpolating the image data output from the format converting means by filtering operation to output the data or making the image data pass through without interpolating the data;

an image synthesizing means performing logic operations for the image data output from the filter, synthesizing the image data to output the image data; and

an image output means outputting the image data output from the image synthesizing means to a designated display unit;

wherein the memory stores groups of image data having different formats separately;

the data reading means comprises an input buffer temporarily storing the groups of image data having different formats and an input control means reading image data in a designated format from the memory to write the data into the input buffer or reading image data in a designated format from the input buffer to output the data;

the filter comprises a vertical filter and a horizontal filter which vertically or horizontally interpolate the image data output from the format converting means, respectively, so that the data can be subjected to processing almost simultaneously, said vertical filter comprising a vertical filter buffer temporarily and separately storing groups of image data having different formats;

a vertical filter distributing means writing the image data output from the format converting means or the horizontal filter into the vertical filter buffer according to a designated format or reading image data from the vertical filter buffer according to a designated format to output the data; and

a vertical filter control means performing convolution operation for the image data output from the vertical filter distributing means and a vertical filter coefficient prepared according to a designated format to output the result, said horizontal filter comprising a horizontal filter buffer temporarily and separately storing groups of image data having different formats;

a horizontal filter distributing means writing image data output from the vertical filter or the format converting means into the horizontal filter buffer according to a designated format or reading image data from the horizontal filter buffer according to a designated format to output the data; and

a horizontal filter control means performing convolution operation for the image data output from the horizontal filter distributing means and a horizontal filter coefficient prepared according to a designated format;

the image synthesizing means comprises a synthesization buffer temporarily and separately storing groups of image data having different formats, a synthesization distributing means writing the image data output from the filter into the synthesization buffer according to a designated format or reading image data from the synthesization buffer according to a designated format to output the data, and a synthesization control means performing logical operation for the image data in a designated format output from the synthesization distributing means;

the image output means comprises an output buffer temporarily storing groups of image data having different formats and an output control means writing the image data output from the image synthesizing means into the output buffer according to a designated format or reading image data from the output buffer according to a designated format to output the data;

the vertical filter comprises a vertical filter coefficient calculating means comprising an input Y register for detecting a point by counting pixel by pixel from an original point in the vertical direction to store the point as an input Y coordinate and outputting a value thereof, the original point being designated to correspond to image data stored in the memory;

an output Y register for detecting a point by counting pixel by pixel from an original point in the vertical direction to store the point as an output Y coordinate and outputting a value thereof, the original point being designated to correspond to image data output from the image output means;

an Y coordinate ratio register for storing a predetermined ratio between the input Y coordinate and the output Y coordinate to output the ratio;

a vertical DDA means for obtaining a converted input Y coordinate to which a reducing/expanding ratio is added, using an output of the output Y coordinate ratio register and an output of the output Y register to output the coordinate; and

a vertical filter coefficient calculating means for obtaining a vertical filter coefficient which is to be input to the vertical filter control means using an output of the vertical DDA means and an output of the input Y register,

wherein the horizontal filter comprises;

an input X register detecting a point by counting pixel by pixel from an original point in the horizontal direction to store the point as an input X coordinate and outputting a value thereof, the original point being designated to correspond to image data stored in the memory;

an output X register for detecting a point by counting pixel by pixel from an original point in the horizontal direction to store the point as an output X coordinate and outputting a value thereof, the original point being designated to correspond to image data output from the image output means;

an X coordinate ratio register for storing a predetermined ratio between the input X coordinate and the output X coordinate to output the ratio;

a horizontal DDA means for obtaining a converted input X coordinate to which a reducing/expanding ratio is added, using an output of the X coordinate ratio register and an output of the output X register to output the coordinate; and

a horizontal filter coefficient calculating means for obtaining a horizontal filter coefficient which is to be input to the horizontal filter control means using an output of the horizontal DDA means and an output of the input X register.

9. An image data format conversion apparatus comprising:

a memory storing image data;

a data reading means reading image data from the memory to output the data;

a format converting means converting the image data output from the data reading means to a predetermined format to output the data or making the image data pass through without converting the data;

a filter vertically and horizontally interpolating the image data output from the format converting means by filtering operation to output the data or making the image data pass through without interpolating the data;

an image synthesizing means performing logic operations for the image data output from the filter, synthesizing the image data to output the image data; and

an image output means outputting the image data output from the image synthesizing means to a designated display unit;

wherein the memory stores groups of image data having different formats separately;

the data reading means comprises an input buffer temporarily storing the groups of image data having different formats and an input control means reading image data in a designated format from the memory to write the data into the input buffer or reading image data in a designated format from the input buffer to output the data;

the filter comprises a vertical filter and a horizontal filter which vertically or horizontally interpolate the image data output from the format converting means, respectively, so that the data can be subjected to processing almost simultaneously, said vertical filter comprising a vertical filter buffer temporarily and separately storing groups of image data having different formats;

a vertical filter distributing means writing the image data output from the format converting means or the horizontal filter into the vertical filter buffer according to a designated format or reading image data from the vertical filter buffer according to a designated format to output the data; and

a vertical filter control means performing convolution operation for the image data output from the vertical filter distributing means and a vertical filter coefficient prepared according to a designated format to output the result, said horizontal filter comprising a horizontal filter buffer temporarily and separately storing groups of image data having different formats;

a horizontal filter distributing means writing image data output from the vertical filter or the format converting means into the horizontal filter buffer according to a designated format or reading image data from the horizontal filter buffer according to a designated format to output the data; and

a horizontal filter control means performing convolution operation for the image data output from the horizontal filter distributing means and a horizontal filter coefficient prepared according to a designated format;

the image synthesizing means comprises a synthesization buffer temporarily and separately storing groups of image data having different formats, a synthesization distributing means writing the image data output from the filter into the synthesization buffer according to a designated format or reading image data from the synthesization buffer according to a designated format to output the data, and a synthesization control means performing logical operation for the image data in a designated format output from the synthesization distributing means;

the image output means comprises an output buffer temporarily storing groups of image data having different formats and an output control means writing the image data output from the image synthesizing means into the output buffer according to a designated format or reading image data from the output buffer according to a designated format to output the data wherein the vertical filter comprises a vertical filter coefficient calculating means comprising an input Y register for detecting a point by counting pixel by pixel from an original point in the vertical direction to store the point as an input Y coordinate and outputting a value thereof, the original point being designated to correspond to image data stored in the memory;

an output Y register for detecting a point by counting pixel by pixel from an original point in the vertical direction to store the point as an output Y coordinate and outputting a value thereof, the original point being designated to correspond to image data output from the image output means;

an Y coordinate ratio register for storing a predetermined ratio between the input Y coordinate and the output Y coordinate to output the ratio;

a vertical DDA means for obtaining a converted input Y coordinate to which a reducing/expanding ratio is added, using an output of the output Y coordinate ratio register and an output of the output Y register to output the coordinate; and

a vertical filter coefficient calculating means for obtaining a vertical filter coefficient which is to be input to the vertical filter control means using an output of the vertical DDA means and an output of the input Y register,

wherein the horizontal filter comprises;

an input X register detecting a point by counting pixel by pixel from an original point in the horizontal direction to store the point as an input X coordinate and outputting a value thereof, the original point being designated to correspond to image data stored in the memory;

an output X register for detecting a point by counting pixel by pixel from an original point in the horizontal direction to store the point as an output X coordinate and outputting a value thereof, the original point being designated to correspond to image data output from the image output means;

an X coordinate ratio register for storing a predetermined ratio between the input X coordinate and the output X coordinate to output the ratio;

a horizontal DDA means for obtaining a converted input X coordinate to which a reducing/expanding ratio is added, using an output of the X coordinate ratio register and an output of the output X register to output the coordinate; and

a horizontal filter coefficient calculating means for obtaining a horizontal filter coefficient which is to be input to the horizontal filter control means using an output of the horizontal DDA means and an output of the input X register wherein the vertical filter coefficient calculating means obtains a vertical filter coefficient with respect to image data output from the vertical distributing means using the converted input Y coordinate output from the vertical DDA means and an input integral Y coordinate which is an integral value in closest proximity to the converted input Y coordinate, the vertical filter coefficient being referred to with the input integral Y coordinate as a center thereof.

10. An image data format conversion apparatus comprising:

a memory storing image data;

a data reading means reading image data from the memory to output the data;

a format converting means converting the image data output from the data reading means to a predetermined format to output the data or making the image data pass through without converting the data;

a filter vertically and horizontally interpolating the image data output from the format converting means by filtering operation to output the data or making the image data pass through without interpolating the data;

an image synthesizing means performing logic operations for the image data output from the filter, synthesizing the image data to output the image data; and

an image output means outputting the image data output from the image synthesizing means to a designated display unit;

wherein the memory stores groups of image data having different formats separately;

the data reading means comprises an input buffer temporarily storing the groups of image data having different formats and an input control means reading image data in a designated format from the memory to write the data into the input buffer or reading image data in a designated format from the input buffer to output the data;

the filter comprises a vertical filter and a horizontal filter which vertically or horizontally interpolate the image data output from the format converting means, respectively, so that the data can be subjected to processing almost simultaneously, said vertical filter comprising a vertical filter buffer temporarily and separately storing groups of image data having different formats;

a vertical filter distributing means writing the image data output from the format converting means or the horizontal filter into the vertical filter buffer according to a designated format or reading image data from the vertical filter buffer according to a designated format to output the data; and

a vertical filter control means performing convolution operation for the image data output from the vertical filter distributing means and a vertical filter coefficient prepared according to a designated format to output the result, said horizontal filter comprising a horizontal filter buffer temporarily and separately storing groups of image data having different formats;

a horizontal filter distributing means writing image data output from the vertical filter or the format converting means into the horizontal filter buffer according to a designated format or reading image data from the horizontal filter buffer according to a designated format to output the data; and

a horizontal filter control means performing convolution operation for the image data output from the horizontal filter distributing means and a horizontal filter coefficient prepared according to a designated format;

the image synthesizing means comprises a synthesization buffer temporarily and separately storing groups of image data having different formats, a synthesization distributing means writing the image data output from the filter into the synthesization buffer according to a designated format or reading image data from the synthesization buffer according to a designated format to output the data, and a synthesization control means performing logical operation for the image data in a designated format output from the synthesization distributing means;

the image output means comprises an output buffer temporarily storing groups of image data having different formats and an output control means writing the image data output from the image synthesizing means into the output buffer according to a designated format or reading image data from the output buffer according to a designated format to output the data wherein the vertical filter comprises a vertical filter coefficient calculating means comprising an input Y register for detecting a point by counting pixel by pixel from an original point in the vertical direction to store the point as an input Y coordinate and outputting a value thereof, the original point being designated to correspond to image data stored in the memory;

an output Y register for detecting a point by counting pixel by pixel from an original point in the vertical direction to store the point as an output Y coordinate and outputting a value thereof, the original point being designated to correspond to image data output from the image output means;

an Y coordinate ratio register for storing a predetermined ratio between the input Y coordinate and the output Y coordinate to output the ratio;

a vertical DDA means for obtaining a converted input Y coordinate to which a reducing/expanding ratio is added, using an output of the output Y coordinate ratio register and an output of the output Y register to output the coordinate; and

a vertical filter coefficient calculating means for obtaining a vertical filter coefficient which is to be input to the vertical filter control means using an output of the vertical DDA means and an output of the input Y register;

wherein the horizontal filter comprises

can input X register detecting a point by counting pixel by pixel from an original point in the horizontal direction to store the point as an input X coordinate and outputting a value thereof, the original point being designated to correspond to image data stored in the memory;

an output X register for detecting a point by counting pixel by pixel from an original point in the horizontal direction to store the point as an output X coordinate and outputting a value thereof, the original point being designated to correspond to image data output from the image output means;

an X coordinate ratio register for storing a predetermined ratio between the input X coordinate and the output X coordinate to output the ratio;

a horizontal DDA means for obtaining a converted input X coordinate to which a reducing/expanding ratio is added, using an output of the X coordinate ratio register and an output of the output X register to output the coordinate; and

a horizontal filter coefficient calculating means for obtaining a horizontal filter coefficient which is to be input to the horizontal filter control means using an output of the horizontal DDA means and an output of the input X register wherein the vertical filter coefficient calculating means obtains a vertical filter coefficient with respect to image data output from the vertical distributing means using the converted input Y coordinate output from the vertical DDA means and an input integral Y coordinate which is an integral value in closest proximity to the converted input Y coordinate, the vertical filter coefficient being referred to with the input integral Y coordinate as a center thereof and wherein the vertical filter coefficient calculating means comprises a vertical interpolating means performing, using the input integral Y coordinate as an original point and a vertical filter coefficient of the coordinate as h (0<

h23

     1), interpolation with a straight line having an angle k when an input coordinate is located under the original point while performing interpolation with a straight line having an angle −

k when an input point is located above the original point, and outputting the interpolated result as 0 when the result as a negative value; and

a vertical filter tap means inputting coordinates corresponding to a tap number of a filter to the vertical interpolating means to obtain a vertical filter coefficient corresponding to the image data output from the vertical distributing means and output the coefficient, the filter being designated with a converted input Y coordinate output from the vertical DDA means as a center thereof.

11. An image data format conversion apparatus comprising:

a memory storing image data;

a data reading means reading image data from the memory to output the data;

a format converting means converting the image data output from the data reading means to a predetermined format to output the data or making the image data pass through without converting the data;

a filter vertically and horizontally interpolating the image data output from the format converting means by filtering operation to output the data or making the image data pass through without interpolating the data;

an image synthesizing means performing logic operations for the image data output from the filter, synthesizing the image data to output the image data; and

an image output means outputting the image data output from the image synthesizing means to a designated display unit;

wherein the memory stores groups of image data having different formats separately;

the data reading means comprises an input buffer temporarily storing the groups of image data having different formats and an input control means reading image data in a designated format from the memory to write the data into the input buffer or reading image data in a designated format from the input buffer to output the data;

the filter comprises a vertical filter and a horizontal filter which vertically or horizontally interpolate the image data output from the format converting means, respectively, so that the data can be subjected to processing almost simultaneously, said vertical filter comprising a vertical filter buffer temporarily and separately storing groups of image data having different formats;

a vertical filter distributing means writing the image data output from the format converting means or the horizontal filter into the vertical filter buffer according to a designated format or reading image data from the vertical filter buffer according to a designated format to output the data; and

a vertical filter control means performing convolution operation for the image data output from the vertical filter distributing means and a vertical filter coefficient prepared according to a designated format to output the result, said horizontal filter comprising a horizontal filter buffer temporarily and separately storing groups of image data having different formats;

a horizontal filter distributing means writing image data output from the vertical filter or the format converting means into the horizontal filter buffer according to a designated format or reading image data from the horizontal filter buffer according to a designated format to output the data; and

a horizontal filter control means performing convolution operation for the image data output from the horizontal filter distributing means and a horizontal filter coefficient prepared according to a designated format;

the image synthesizing means comprises a synthesization buffer temporarily and separately storing groups of image data having different formats, a synthesization distributing means writing the image data output from the filter into the synthesization buffer according to a designated format or reading image data from the synthesization buffer according to a designated format to output the data, and a synthesization control means performing logical operation for the image data in a designated format output from the synthesization distributing means;

the image output means comprises an output buffer temporarily storing groups of image data having different formats and an output control means writing the image data output from the image synthesizing means into the output buffer according to a designated format or reading image data from the output buffer according to a designated format to output the data wherein the vertical filter comprises a vertical filter coefficient calculating means comprising an input Y register for detecting a point by counting pixel by pixel from an original point in the vertical direction to store the point as an input Y coordinate and outputting a value thereof, the original point being designated to correspond to image data stored in the memory;

an output Y register for detecting a point by counting pixel by pixel from an original point in the vertical direction to store the point as an output Y coordinate and outputting a value thereof, the original point being designated to correspond to image data output from the image output means;

an Y coordinate ratio register for storing a predetermined ratio between the input Y coordinate and the output Y coordinate to output the ratio;

a vertical DDA means for obtaining a converted input Y coordinate to which a reducing/expanding ratio is added, using an output of the output Y coordinate ratio register and an output of the output Y register to output the coordinate; and

a vertical filter coefficient calculating means for obtaining a vertical filter coefficient which is to be input to the vertical filter control means using an output of the vertical DDA means and an output of the input Y register;

wherein the horizontal filter comprises;

an input X register detecting a point by counting pixel by pixel from an original point in the horizontal direction to store the point as an input X coordinate and outputting a value thereof, the original point being designated to correspond to image data stored in the memory;

an output X register for detecting a point by counting pixel by pixel from an original point in the horizontal direction to store the point as an output X coordinate and outputting a value thereof, the original point being designated to correspond to image data output from the image output means;

an X coordinate ratio register for storing a predetermined ratio between the input X coordinate and the output X coordinate to output the ratio;

a horizontal DDA means for obtaining a converted input X coordinate to which a reducing/expanding ratio is added, using an output of the X coordinate ratio register and an output of the output X register to output the coordinate; and

a horizontal filter coefficient calculating means for obtaining a horizontal filter coefficient which is to be input to the horizontal filter control means using an output of the horizontal DDA means and an output of the input X register wherein the horizontal filter coefficient calculating means obtains a horizontal filter coefficient for the image data output from the horizontal filter distributing means, from a converted input X coordinate output from the horizontal DDA means and an input integral X coordinate which is an integral value in closest proximity to the converted input X coordinate, the horizontal filter coefficient being referred to with the input integral X coordinate as a center thereof.

12. An image data format conversion apparatus comprising:

a memory storing image data;

a data reading means reading image data from the memory to output the data;

a format converting means converting the image data output from the data reading means to a predetermined format to output the data or making the image data pass through without converting the data;

a filter vertically and horizontally interpolating the image data output from the format converting means by filtering operation to output the data or making the image data pass through without interpolating the data;

an image synthesizing means performing logic operations for the image data output from the filter, synthesizing the image data to output the image data; and

an image output means outputting the image data output from the image synthesizing means to a designated display unit;

wherein the memory stores groups of image data having different formats separately;

the data reading means comprises an input buffer temporarily storing the groups of image data having different formats and an input control means reading image data in a designated format from the memory to write the data into the input buffer or reading image data in a designated format from the input buffer to output the data;

the filter comprises a vertical filter and a horizontal filter which vertically or horizontally interpolate the image data output from the format converting means, respectively, so that the data can be subjected to processing almost simultaneously, said vertical filter comprising a vertical filter buffer temporarily and separately storing groups of image data having different formats;

a vertical filter distributing means writing the image data output from the format converting means or the horizontal filter into the vertical filter buffer according to a designated format or reading image data from the vertical filter buffer according to a designated format to output the data; and

a vertical filter control means performing convolution operation for the image data output from the vertical filter distributing means and a vertical filter coefficient prepared according to a designated format to output the result, said horizontal filter comprising a horizontal filter buffer temporarily and separately storing groups of image data having different formats;

a horizontal filter distributing means writing image data output from the vertical filter or the format converting means into the horizontal filter buffer according to a designated format or reading image data from the horizontal filter buffer according to a designated format to output the data; and

a horizontal filter control means performing convolution operation for the image data output from the horizontal filter distributing means and a horizontal filter coefficient prepared according to a designated format;

the image synthesizing means comprises a synthesization buffer temporarily and separately storing groups of image data having different formats, a synthesization distributing means writing the image data output from the filter into the synthesization buffer according to a designated format or reading image data from the synthesization buffer according to a designated format to output the data, and a synthesization control means performing logical operation for the image data in a designated format output from the synthesization distributing means;

the image output means comprises an output buffer temporarily storing groups of image data having different formats and an output control means writing the image data output from the image synthesizing means into the output buffer according to a designated format or reading image data from the output buffer according to a designated format to output the data wherein the vertical filter comprises a vertical filter coefficient calculating means comprising an input Y register for detecting a point by counting pixel by pixel from an original point in the vertical direction to store the point as an input Y coordinate and outputting a value thereof, the original point being designated to correspond to image data stored in the memory;

an output Y register for detecting a point by counting pixel by pixel from an original point in the vertical direction to store the point as an output Y coordinate and outputting a value thereof, the original point being designated to correspond to image data output from the image output means;

an Y coordinate ratio register for storing a predetermined ratio between the input Y coordinate and the output Y coordinate to output the ratio;

a vertical DDA means for obtaining a converted input Y coordinate to which a reducing/expanding ratio is added, using an output of the output Y coordinate ratio register and an output of the output Y register to output the coordinate; and

a vertical filter coefficient calculating means for obtaining a vertical filter coefficient which is to be input to the vertical filter control means using an output of the vertical DDA means and an output of the input Y register;

wherein the horizontal filter comprises an input X register detecting a point by counting pixel by pixel from an original point in the horizontal direction to store the point as an input X coordinate and outputting a value thereof, the original point being designated to correspond to image data stored in the memory;

an output X register for detecting a point by counting pixel by pixel from an original point in the horizontal direction to store the point as an output X coordinate and outputting a value thereof, the original point being designated to correspond to image data output from the image output means;

an X coordinate ratio register for storing a predetermined ratio between the input X coordinate and the output X coordinate to output the ratio;

a horizontal DDA means for obtaining a converted input X coordinate to which a reducing/expanding ratio is added, using an output of the X coordinate ratio register and an output of the output X register to output the coordinate; and

a horizontal filter coefficient calculating means for obtaining a horizontal filter coefficient which is to be input to the horizontal filter control means using an output of the horizontal DDA means and an output of the input X register wherein the horizontal filter coefficient calculating means obtains a horizontal filter coefficient for the image data output from the horizontal filter distributing means, from a converted input X coordinate output from the horizontal DDA means and an input integral X coordinate which is an integral value in closest proximity to the converted input X coordinate, the horizontal filter coefficient being referred to with the input integral X coordinate as a center thereof wherein the horizontal filter coefficient calculating means comprises a horizontal interpolating means storing a horizontal filter coefficient having a sampling ratio an integer times higher than that of the image data stored in the memory and outputting an horizontal filter coefficient in closest proximity to an input coordinate with a horizontal filter coefficient obtained when the input integral X coordinate is an original point as a center of the horizontal filter coefficient; and

a horizontal filter tap means inputting coordinates corresponding to a tap number of a filter into the horizontal interpolating means, the filter being designated with a converted input X coordinate output from the horizontal DDA means as a center thereof, and obtaining a horizontal filter coefficient for the image data output from the horizontal filter distributing means to output the coefficient.