Abstract:
According to the present invention, document data containing both draw data and image data can properly and efficiently be converted into image data. There is provided a CMYK conversion unit  113  comprising an area unit converting section  1134  and a pixel unit converting section  1135 . The area unit converting section switches color conversion tables between LUT 134 and LUT 135 at every area, depending upon sort of draw object contained in the area, for an area except area containing both draw data and image data of RGB image data, thereby converting RGB image data into CMYK image data. The pixel unit converting section switches color conversion tables between LUT 134 and LUT 135 at every pixel, depending upon sort of draw object indicated by the pixel, for an area containing both draw data and image data of RGB image data, thereby converting RGB image data into CMYK image data.

Description:
This application claims a priority based on Japanese Patent Application No. 11-291493 filed on Oct. 13, 1999, the entire contents of which are incorporated herein by reference for all purposes. 
   BACKGROUND OF THE INVENTION 
   The present invention is directed to a technique capable of converting document data into image data constituted by a plurality of pixel data, in particular, CMYK image data corresponding to a format suitable for printing operation. The document data is constituted by containing a draw command used to designate a draw object of draw data such as a text and a figure, and of image data such as a photograph. 
   Conventionally, while using a printer driver constituted on a computer, a data conversion operation from document data into CMYK image data suitably formatted to a printing operation is carried out as follow. This document data is constituted by containing a draw command used to designate a draw object. 
   In this data converting operation, draw commands contained in document data sent from an application program are stored into a spooler formed on a memory in accordance with a drawing order. Next, the draw commands stored in the spooler are read out in the drawing order, and then draw objects specified by these read draw commands are image-expanded so as to obtain RGB image data. Thereafter, the RGB image data thus obtained is subjected to color-correction with reference to a color conversion table for storing thereinto color correction information and the like, so as to be converted into desirable CMYK image data. 
   On the other hand, normally, there is a difference between a color correction required when a draw object corresponds to draw data and another color correction required when this draw object corresponds to image data. Concretely speaking, in the case that a draw object designated by a draw command contained in document data corresponds to such draw data as a text and a figure, one color correction should be applied when RGB image data obtained from this document data is converted into CMYK image data. In the case that the above-described draw object corresponds to such image data as a photograph, another color correction should be applied when RGB image data obtained from this document data is converted into CMYK image data. In these color corrections, for instance, this image data is required to be color-matched with a monitor, whereas a saturation of the draw data constitutes a major important factor. 
   As a consequence, in a conventional image conversion system, two different sorts of color conversion tables are prepared for draw data and image data. Prior to a printing operation, a user is requested to select a sort of document data to be printed out (namely, user selects printing operation of draw data or image data). Then, RGB image data is converted into CMYK image data by employing a color conversion table in accordance with the selected data. 
   SUMMARY OF THE INVENTION 
   Very recently, various application programs have been widely popularized by which document data containing both draw commands for designating draw objects of draw data and draw commands for designating draw objects of image data can be formed. 
   The above-explained conventional printer driver owns such a problem that the document data formed by such an application program cannot be converted into CMYK image data in a proper manner. This document data contains both the draw command for designating the draw data, and also the draw command for designating the image data. 
   For example, in such a case that the user selects the draw data as the sort of this document data, such an image data portion of the RGB image data, which is image-expanded by the draw command for designating the image data would also be converted into the CMYK image data with reference to the color conversion table for the draw data. As a result, there is a problem that this image data portion could not be converted into the desirable CMYK image data in the proper manner. 
   The present invention has been made to solve the above-described problem, and therefore, has an object to provide such an image converting method/apparatus capable of converting document data which is constituted by containing plural sorts of draw objects into image data made of a plurality of pixel data in a proper manner and in a high efficiency. For example, such document data constituted by containing the draw command can be converted into the image data made of the plural pixel data, in particular, the CMYK image data corresponding to the format suitable for the printing operation in the proper manner and also in the higher efficiency. This draw command designates the draw object of the draw data (e.g., text and figure) or the image data (e.g., photograph). 
   To achieve the above-described object, there is provided an image converting apparatus, according to a first aspect of the present invention, for converting document data constituted by containing plural sorts of draw objects (for instance, draw object classified as draw data such as text and figure, and also draw object classified as image data such as photograph) into image data constituted by a plurality of pixel data, comprising:
         first conversion means for converting the document data into first image data (e.g., RGB image data);   second conversion means for converting the first image data into second image data (e.g., CMYK image data); and   a plurality of tables provided in correspondence with at least of plural sorts of draw objects and containing information (e.g., color correction information) to which the image converting apparatus refers when the first image data acquired by converting the sort of draw object corresponding thereto is converted into the second image data; wherein:   the second conversion means includes:   area unit conversion means, as to each of areas obtained by subdividing the first image data by plural number, for converting first image data of the area into second image data, while referring to the table corresponding to a sort of draw object contained in the area;   pixel unit conversion means, as to each of pixel data constituting the first image data, for converting the pixel data into second image data, while referring to the table corresponding to a sort of draw object indicated by the pixel data; and   conversion switching means for applying the pixel unit conversion means to such an area which contains at least two sorts of draw objects corresponding to the tables different from each other, and also for applying the area unit conversion means to such an area which contains at least one sort of draw object corresponding to the same table, within the first image data.       

   In this image converting apparatus, as to each of the areas obtained by subdividing the first image data by the plural number, in such a case that a draw object is not contained in the area, the area unit conversion means may convert first image data of the area into second predetermined image data without reference to the tables; and
         as to each of the pixel data constituting the first image data, in such a case that the pixel data does not indicate a draw object, the pixel unit conversion means may convert the pixel data into predetermined second image data without referring to the tables.       

   Also, the above-described area unit conversion means and the pixel unit conversion means may be switched by the conversion switching means in accordance with the below-mentioned manner: 
   That is, the image converting apparatus is further comprising first judging means operated, prior to the conversion of document data into first image data by the first conversion means, in such a manner that when the document data is converted into the first image data, as to each of first areas obtained by subdividing the first image data by plural number, the first judging means judges a draw object contained in the area;
         second judging means for judging as to whether or not plural sorts of draw objects (e.g., both draw object classified as draw data such as text and figure, and draw object classified as image data such as photograph) are contained, which corresponds to the tables different from each other, in each of plural second areas constituted by containing at least one first area, based upon the judgment result of the first judging means; and   third judging means operated in such a manner that while the document data is converted into the first image data by the first converting means, as to each of the pixel data contained in the second area which is judged by the second judging means in such a way that the plural sorts of draw objects corresponding to the tables different from each other are contained therein, the third judging means judges the draw object indicated by the pixel data.       

   The conversion switching means applies the area unit conversion means to such a second area which is not judged by the second judging means in such a way that the plural sorts of draw objects corresponding to the tables different from each other are contained. Further, the conversion switching means applies the pixel unit conversion means to such a second area which is so judged by the second judging means in such a way that the plural sorts of draw objects corresponding to the tables different from each other are contained. 
   In this case, the area unit conversion means may determine a table which should be referred to in the case that as to the second area application-instructed by the conversion switching means, first image data contained in this second area is converted based upon the judgment result of the first judging means. 
   Similarly, the pixel unit conversion means may determine the tables which should be referred to in the case that as to each of the pixel data contained in the second area application-instructed by the conversion switching means, the pixel data is converted based upon the judgment result of the third judging means. 
   In accordance with the present invention, with respect to the area which contains the plural sorts of draw objects (e.g. both draw object classified as draw data such as text and figure, and also draw object classified as image data such as photograph) corresponding to the tables different from each other among the first image data, as to each pixel data contained in the are, the table which should be referred to is determined in accordance with the sort of the draw object indicated by the pixel data concerned. While using the determined tables, the first image data is converted into the second image data. On the other hand, as to the area which does not contain the plural sorts of draw objects corresponding to the tables different from each other among the first image data, the table which should be referred to is determined in accordance with the sorts of the draw objects contained in the area. While using the determined tables, the first image data is converted into the second image data. As a consequence, the document data containing the plural sorts of draw objects can be properly converted into the second image data in the high efficiency. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the present invention, reference is made of a detailed description to be read in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a schematic block diagram for representing an entire arrangement of a print control apparatus  1  to which an embodiment mode of the present invention is applied; 
       FIG. 2  is an illustration for explaining a basic idea of processing operations executed in a first judging unit  1131  to a third judging unit  1133  employed in the print control apparatus  1  shown in  FIG. 1 ; 
       FIG. 3  is an illustration for explaining a basic idea of processing operations executed in an area unit converting section  1134 , a pixel unit converting section  1135 , and a conversion switching section  1136  employed in the print control apparatus  1  shown in  FIG. 1 ; and 
       FIG. 4  is a flow chart for describing print control operation of the print control apparatus  1  indicated in FIG.  1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to drawings, an embodiment of the present invention will be described in detail. 
     FIG. 1  schematically indicates an overall arrangement of a print control apparatus  1 , to which a preferred embodiment of the present invention is applied. 
   As shown in  FIG. 1 , a print control apparatus  1  of this embodiment may be constructed on a general-purpose computer. This general-purpose computer is provided with a CPU (central processing unit)  11 , a memory  12 , an external storage apparatus  13  such as a hard disk drive, a data reading apparatus  14  for reading data from a storage medium  15  having portability such as a CD-ROM (compact disk-read-only memory) and an FD (floppy disk). The computer is further provided with an input apparatus  16  such as a keyboard and a mouse, a display apparatus  17  such as a display unit, a printer connecting apparatus  18  such as either a serial interface or a parallel interface connected to a printer  2 , and also an interface  19  for inputting/outputting data among the above-explained structural elements. 
   In this computer system, the external storage apparatus  13  stores thereinto an OS (operating system) program  131 , an application program  132 , a printer driver program  133 , a draw data color conversion table  134 , and image data color conversion table  135 . The OS program  131  is loaded onto the memory  12  when the computer is initiated so as to totally control operations of this computer, and is executed by the CPU  11 . The application program  132  is used to form document data. This document data contains draw commands for designating a draw object of draw data such as a text and a figure (drawing), and also of image data such as a photograph. The printer driver program  133  is used to construct the print control apparatus  1  according to this embodiment on the computer. 
   In this case, the above-described printer driver program  133 , draw data color conversion table  134 , and image data color conversion table  135  may be read out from the portable storage medium  15  such as a CD-ROM and an FD by operating the reading apparatus  14 , and then, these read program and tables  133 ,  134 ,  135  may be installed in the external storage apparatus  13 . Furthermore, these printer driver program  133 , and color conversion tables  134 ,  135  may be down-loaded from a communication apparatus (not shown) via a network (not shown either) to the external storage apparatus  13 . 
   It should be understood that as the draw command used to designate the draw object in this computer system, the following commands may be utilized, for example, the command made of “Quick Draw Op-code” used in the operating system (OS) known as “Mac OS” (trade mark) and “Kanji Talk” (trade mark) marketed by Apple Computer, Inc. 
   The CPU  11  loads and executes the printer driver program  133  onto the memory  12  in response to an instruction issued from the application program  132  under execution. As a result, a SPOOL (Simultaneous Peripheral Operations OnLine) processing unit  111 , an RGB conversion processing unit  112 , a CMYK conversion processing unit  113 , a print control unit  114 , and a judging unit  115  are realized as a process. 
   The SPOOL processing unit  111  stores various draw commands contained in document data formed by the application program  132  into a SPOOL file  121  formed in either the memory  12  or the external storage apparatus  13  in the drawing order. 
   The RGB conversion processing unit  112  reads out the respective draw commands contained in the document data stored in the SPOOL file  121  in the drawing order, image-expands a draw object in accordance with the read draw command, whereby the document data is converted into the RGB image data. Thereafter, the RGB image data is stored into either the memory  12  or the external storage apparatus  13 . It should also be noted that when the above-explained “Quick Draw Op-code” is used as the draw command, the RGB conversion processing unit  112  can be realized by using the “rasterize engine” prepared by the operating system known as “Mac OS” and “Kanji Talk” (trade marks). 
   The CMYK conversion processing unit  113  converts the RGB image data formed by the RGB conversion processing unit  112  into CMYK image data having such a format suitable for printing operation by the printer  2 . Then, the CMYK conversion processing unit  113  stores the CMYK image data into either the memory  12  or the external storage apparatus  13 . The CMYK conversion processing unit  113  contains an area unit converting section  1134 , a pixel unit converting section  1135 , and also a conversion switching section  1136 . These converting and switching sections will be discussed later. 
   The print control unit  114  sends the CMYK image data produced by the CMYK conversion processing unit  113  via the printer connecting apparatus  18  to the printer  2  for printing out the image, while using a control command which can be interpreted by the printer  2 . 
   The judging unit  115  includes a first judging section  1131  to a third judging section  1133 . These judging sections  1131  to  1133  will be explained later. 
   In the case that a draw object designated by a draw command contained in document data corresponds to draw data such as a text and a figure (drawing), such color correction information is described in the draw data color conversion table  134 . That is, when RGB image data produced from this document data is converted into relevant CMYK image data, this color correction information should be applied. 
   In the case that a draw object designated by a draw command contained in document data corresponds to image data such as a photograph, such color correction information is described in the image data color conversion table  135 . That is, when RGB image data produced from this document data is converted into relevant CMYK image data, this color correction information should be applied. 
   As previously explained, the draw data color conversion table  134  and the image data color conversion table  135  are conventionally used when the RGB image data is converted into the CMYK image data. 
   Next, a description will now be made of the first judging unit  1131  to the third judging unit  1133  contained in the judging unit  115 . 
     FIG. 2  is a diagram for illustratively showing a basic idea of process operations executed in the first judging unit  1131  to the third judging unit  1133 . 
   While the SPOOL processing unit  111  stores the respective draw commands  31  to  34  contained in the document data  3  formed by the application program  132  into a SPOOL file  121 , the first judging unit  1131  checks a sort of a draw object (namely, draw data or image data) designated by each of the draw commands, and a draw position of this draw object. Then, the first judging unit  1131  registers the check results into a cell unit management table  122  formed on either the memory  12  or the external storage apparatus  13 . 
   As indicated in  FIG. 2 , the cell unit management table  122  is constituted by a plurality of cells. These plural cells correspond to the respective areas obtained by subdividing the RGB image data  4  into plural image areas in the case that the document data  3  is converted into the RGB image data  4 . The respective cells of this cell unit management table  122  are empty under initial condition. It should be noted that the size of the RGB image data  4  obtained by converting the document data  3  may be acquired from the size information contained in the document data  3 . First, the first judging unit  1131  produces such a cell unit management table  122 , the respective cells of which are empty, based on this size information. 
   Next, every time the SPOOL file  121  stores thereinto one draw command, the first judging unit  1131  checks a sort of a draw object and a draw position of this draw object, which are designated by this draw command, and then sets a flag indicative of this sort of the checked draw object to the cell corresponding to this designated draw position. In an example, shown in  FIG. 2 , when the draw object is the draw data, the first judging unit  1131  sets a flag “A”, whereas when the draw object is the image data, the first judging unit  1131  sets another flag “B.” As a consequence, as represented in  FIG. 2 , two different flags “A” and “B” are set to such a cell corresponding to an area where both draw data and image data are drawn. 
   After the process operation by the first judging unit  1131  has been accomplished, the second judging unit  1132  checks the contents of the cell unit management table  122  so as to detect such a row where two different flags “A” and “B” are set. In the example of  FIG. 2 , one row is constructed of 6 cells. In the cell unit management table  122  shown in  FIG. 2 , two rows, namely a 5th row and a 6th row are detected by the second judging unit  1131 . 
   In such a case that the RGB conversion processing unit  112  reads out the respective draw commands stored in the SPOOL file  121  in the draw order so as to image-expand a draw object and produce RGB image data  4 , as to each of the pixel data located in the area corresponding to the row of the cell unit management table  122 , which is detected by the second judging unit  1132 , the third judging unit  1133  checks a sort of a draw object indicated by this pixel data and then registers the checked result to the pixel unit management table  123  formed on either the memory  12  or the external storage apparatus  13 . 
   As represented in  FIG. 2 , each of the pixel unit management tables  123  is provided in correspondence with such an area corresponding to the row of the cell unit management table  122 , which is detected by the second judging unit  1132 , among the RGB image data  4  obtained by converting the document data  3 . In the respective pixel unit management tables  123 , the pixel management data corresponding to the respective pixel data contained in the above-explained area are stored. Under initial condition, each of these pixel management data constitutes a value for indicating that a draw object is not drawn. First, the third judging unit  1133  produces the pixel unit management table  123  in which the respective pixel management data constitute such values for indicating that no draw objects are drawn based upon the size information contained in the document data  3  and the row of the cell unit management table  122 , which is detected by the second judging unit  1132 . 
   Next, when the RGB conversion processing unit  112  commences the data conversion from the document data  3  into the RGB image data  4 , the third judging unit  1133  monitors this conversion condition. Then, when the drawing operation of the draw object located in the area of the RGB image data  4  corresponding to the pixel unit management table  123  is commenced, the third judging unit  1133  changes the value of each of the pixel management data stored in the pixel unit management table  123 , which corresponds to each of the pixel data of the RGB image data  4  in which the draw object concerned is drawn, into a value indicative of a sort of this draw object (namely, draw data, or image data) at the same time, while utilizing the draw command which designates this draw object. This process operation is repeatedly carried out with respect to all of the draw commands which designate the draw object located in the area of the RGB image data  4  corresponding to the pixel unit management table  123 , so that the pixel unit management table  123  is accomplished. It should also be noted that as shown in the RGB image data  4  of  FIG. 2 , such pixel management data is changed into a value indicative of a sort of a finally drawn draw object. This pixel management data corresponds to a portion in which a plurality of draw objects are drawn, while being overlapped with each other (namely, a portion where image data by draw command  33  is overlapped with draw data by draw command  34 ). 
   It should also be understood that when the above-described “Quick f 4  Draw Op-code” is used as the draw command, the third judging unit  1133  may be realized by using the above-described “rasterize engine” prepared by the operating system known as “Mac OS (trade mark)” and “Kanji Talk (trade mark).” In this case, as the values of the respective pixel management data for constituting the pixel unit management table  123 , for example, a data value indicative of “red” color may be allocated to such a value which indicates that the draw object is not drawn; a data value indicative of “green” color may be allocated to such a value which represents that the drawn draw object is the draw data; and also a data value indicative of “blue” color may be allocated to such a value which indicates that the drawn draw object is the image data. 
   Subsequently, a description will now be made of the area unit converting section  1134 , the pixel unit converting section  1135 , and the conversion switching section  1136 , which are contained in the CMYK conversion processing unit  113 . 
     FIG. 3  is an explanatory diagram for explaining basic process operations of the area unit converting section  1134 , the pixel unit converting section  1135 , and the conversion switching section  1136 . 
   In the case that as to each of the areas of the RGB image data  4  shown in  FIG. 2 , a draw object contained in this area corresponds to draw data, the area unit converting section  1134  converts RGB image data contained in this area into CMYK image data with reference to the draw data color conversion table  134 . When this draw object corresponds to image data, the area unit converting section  1134  converts RGB image data contained in this area into CMYK image data with reference to the image data color conversion table  135 . Then, in such a case that no draw object is contained in this area, the area unit converting section  1134  converts RGB image data contained in this area into predetermined CMYK image data (for instance, RGB image data is converted into such CMYK image data having data value “0” indicative of no drawing). 
   It should also be noted that the judgement of the draw object contained in each of the areas can be carried out with reference to the cell unit management table  122  produced by the above-explained first judging section. In other words, as indicated in  FIG. 3 , when a certain area of the RGB image data  4  is converted into CMYK image data, a check is made of a flag of a cell corresponding to this area of the cell unit management table  122 . In the case that this checked flag represents draw data (A), the area unit converting section  1134  converts RGB image data of this area into CMYK image data by using the draw data color conversion table  134 . In the case that this checked flag represents image data (B), the area unit converting section  1134  converts RGB image data of this area into CMYK image data by using the image data color conversion table  135 . In the case no flag is set, the area unit converting section  1134  converts RGB image data of this area into predetermined CMYK image data. 
   With respect to each of the pixel data which constitute the RGB image data  4  shown in  FIG. 2 , when the relevant pixel data represents draw data, the pixel unit converting unit  1135  converts this pixel data into CMYK image data with reference to the draw data color conversion table  134 . In the case that the relevant pixel data represents image data, the pixel unit converting section  1135  converts this pixel data into CMYK image data with reference to the image data color conversion table  135 . Then, in such a case that this relevant pixel data does not indicate a draw object, the pixel unit converting section  1135  converts this pixel data into predetermined CMYK image data. For instance, this pixel data is converted into CMYK image data of such a data value “0” indicative of no drawing. 
   It should also be noted that the judgement of the draw object indicated by each of the pixel data can be carried out with reference to the pixel unit management table  123  produced by the above-explained third judging section. In other words, as indicated in  FIG. 3 , when certain pixel data of the RGB image data  4  is converted into CMYK image data, a check is made of pixel management data corresponding to this pixel data of the pixel unit management table  123 . In the case that this checked pixel management data represents draw data, the pixel unit converting section  1135  converts the pixel data into CMYK image data by using the draw data color conversion table  134 . In the case that this pixel management data represents image data, the pixel unit converting section  1135  converts the pixel data into CMYK image data by using the image data color conversion table  135 . In the case that this pixel management data indicates such a fact that the draw object is not drawn, the pixel unit converting section  1135  converts the above-described pixel data into predetermined CMYK image data. 
   The conversion switching section  1136  converts the RGB image data produced by the RGB conversion processing unit  112  into CMYK image data by using both the area unit converting section  1134  and the pixel unit converting section  1135 . Concretely speaking, as to an area of the RGB image data  4  corresponding to the row of the cell unit management table  122 , which is detected by the second judging section  1132 , this conversion switching section  1136  applies the pixel unit converting section  1135  for converting the RGB image data into the CMYK image data. As to an area of the RGB image data  4  corresponding to the row of the cell unit management table  122 , other than such a row detected by the second judging unit  1132 , this conversion switching section  1136  applies the area unit converting section  1134  for converting the RGB image data into the CMYK image data. It should also be understood that in the example of  FIG. 3 , as to areas corresponding to the fifth row and the sixth row of the RGB image data  4 , the conversion switching section  1136  applies the pixel unit converting section  1135  for converting the RGB image data into the CMYK image data, whereas as to areas corresponding to rows other than the fifth and sixth rows of the RGB image data  4 , the conversion switching section  1136  applies the area unit converting section  1134  for converting the RGB image data into the CMYK image data. 
   Next, print control operation by the print control apparatus with employment of the above-descried arrangement will now be described. 
     FIG. 4  is a flow chart for describing the print control operation of the print control apparatus  1  to which this embodiment is applied. 
   At a first step S 1001 , the first judging section  1131  forms such a cell unit management table  122  in which the respective cells are empty (namely, cell unit management table  122  under initial condition) based upon the size information or the like of the document data produced by the application program  132 . 
   Next, the SPOOL processing unit  111  stores the respective draw commands contained in the document data produced by the application program  132  into the SPOOL file  121  in the drawing order. In connection with this command storage operation, the first judging section  1131  checks the sort of draw object and the draw position of this draw object designated by the draw command every time the SPOOL file  121  stores thereinto the draw command. Then, the first judging section  1131  sets the flag indicative of the sort of this draw object to such a cell of the cell unit management table  122  under initial condition formed at the previous step S 1001 . This cell corresponds to the above-described draw position. As a result, the cell unit management table  122  is accomplished (step S 1002 ). 
   Subsequently, the second judging section  1132  checks the completed cell unit management table  122  so as to detect such a row that two flags indicative of draw data and image data are set (step S 1003 ). 
   Next, based upon the size information contained in the document data and the row of the cell unit management table  122  detected at the step S 1003 , the third judging section  1133  forms such a pixel unit management table  123  (namely, pixel unit management table  123  under initial condition) with respect to an area of RGB image data corresponding to the above-described row. At this time, the values of the respective pixel management data stored in this pixel unit management table  123  are set to such values which indicate that no draw object is drawn (step S 1004 ). 
   Next, the RGB conversion processing unit  112  reads out the draw commands stored in the SPOOL file  121  in the drawing order and image-expands a draw object, so that the document data is converted into RGB image data. In this case, as to each of the pixel data positioned in the area of the RGB image corresponding to the row of the cell unit management table  122  detected at the step  51003 , the third judging section  1133  checks a sort of a draw object indicated by this pixel data. Then, the third judging section  1133  registers the checked result into the pixel unit management table  123  under initial condition formed at the step  51004 . As a result, a pixel unit management table  123  is completed (step S 1005 ). 
   Next, the conversion switching section  1136  converts the RGB image data produced at the step S 1005  into CMYK image data by utilizing both the area unit converting section  1134  and the pixel unit converting section  1135  (step S 1006 ). Concretely speaking, the conversion switching section  1136  applies the pixel unit converting section  1135  with respect to the area of the RGB image data corresponding to the row of the cell unit management table  122 , which is detected at the step  51003  for converting the RGB image data into the CMYK image data. The conversion switching section  1136  applies the area unit converting section  1134  to the areas of the RGB image data corresponding to the columns of the cell unit management table  122  other than the row detected at the step  51003  for converting the RGB image data into the CMYK image data. 
   Next, the print control unit  114  sends the CMYK image data produced at the step S 1006  via the printer connecting apparatus  18  to the printer  2  by using such a control command which can be interpreted by the printer  2  for printing out the desirable image (step S 1007 ). 
   The print control apparatus  1  according to one embodiment mode of the present invention has been described. 
   In accordance with this embodiment mode, since the above-described arrangement is adopted, in the RGB image data produced by the RGB conversion processing unit  112 , as to such a data portion where the draw data is drawn, the RGB image data is converted into the CMYK image data by referring to the draw data color conversion table  134 , whereas as to such a data portion where the image data is drawn, the RGB image data is converted into the CMYK image data by referring to the image data color conversion table  135 . As a consequence, the document data containing both the draw data and the image data can be converted into the CMYK image data in a proper manner. 
   Also, in accordance with this embodiment, the conversion switching unit  1135  utilizes the area unit converting section  1134  and the pixel unit converting section  1135  for converting the RGB image data produced by the RGB conversion processing unit  112  into the CMYK image data. In this case, as to the respective areas obtained by subdividing the RGB image data by the plural number, when the draw object contained in this area corresponds to the draw data, the area unit converting section  1134  converts the RGB image data contained in this area into the CMYK image data with reference to the draw data color conversion table  134 , whereas when the draw object contained in this area corresponds to the image data, the area unit converting section  1134  converts the RGB image data contained in this area into the CMYK image data with reference to the image data color conversion table  135 . On the other hand, as to the respective pixel data which constitute the RGB image data, when the relevant pixel data indicates the draw data, the pixel unit converting section  1135  converts this pixel data into the CMYK image data with reference to the draw data color conversion table  134 , whereas when the relevant pixel data indicates the image data, the pixel unit converting section  1135  converts this pixel data into the CMYK image data with reference to the image data color conversion table  135 . 
   Since the pixel unit converting section  1135  judges the sort of draw object every pixel to determine the color conversion table to which this converting section  135  should refer, the color correction which should be applied while the RGB image data is converted into the CMYK image data can be set in the unit of such a pixel. However, since the draw object indicated by the relevant pixel data must be managed every pixel in the pixel unit converting section  1135 , a heavy work load would be required. Furthermore, a memory capacity required to execute this management process operation would be increased. 
   As a consequence, in accordance with this embodiment mode, the cell unit management table  122  is formed. This cell unit management table  122  is used to manage the draw objects contained in each of the plural areas which are obtained by subdividing the RGB image data by the plural number. While using this cell unit management table  122 , such an area where both draw data and image data are drawn is detected. Only as to the detected area, such a pixel unit management table  123  is formed so as to manage the draw object indicated by the relevant pixel data every pixel. Then, only as to the above-explained detected area, the pixel unit converting section  1135  converts the RGB image data into the CMYK image data by using the pixel unit management table  123 , whereas as to other areas than this area, the area unit converting section  1134  converts the RGB image data into the CMYK image data by employing the cell unit management table  122 . 
   As a result, in accordance with this embodiment mode, the document data containing both the draw data and the image data can be converted into the CMYK image data in the high efficiency. 
   As previously described, in accordance with the above-explained embodiment, the second judging section  1132  detects the area where both the draw data and the image data are drawn with respect to each of the row of the cell unit management table  122  shown in FIG.  2 . However, the present invention is not limited thereto. 
   For instance, the second judging section  1132  may alternatively detect such an area that both the draw data and the image data are drawn every cell of the cell unit management table  122  shown in FIG.  2 . 
   Then, with respect to an area of RGB image data corresponding to a row containing such a cell where a flag is set and this flag indicates such a fact that both draw data and image data are drawn, the pixel unit management table  122  may be formed every pixel so as to manage draw objects indicated by this pixel data, and the data conversion into the CMYK image data by the pixel unit converting section  1135  may be applied. 
   Alternatively, with respect to an area of RGB image data corresponding to such a cell where a flag is set and this flag indicates such a fact that both draw data and image data are drawn, the pixel unit management table  122  may be formed every pixel so as to manage draw objects indicated by this pixel data, and the data conversion into the CMYK image data by the pixel unit converting section  1135  may be applied. 
   In these alternative cases, in the example shown in  FIG. 2 , only such an area of the RGB image data, which corresponds to either a sixth row of the cell unit management table  122  or an area of a fourth column from the left and the sixth row from the top of the cell unit management table  122 , is to be converted by the pixel unit converting section  1135 . As a consequence, the document data containing both the draw data and the image data may be converted into the CMYK image data in a higher efficiency. 
   Also, in the above-described embodiment mode, as the area of the RGB image data  4  corresponding to each of the cells of the cell unit table  122 , such a rectangular area is employed by subdividing the RGB image data  4  by M×N pieces. However, the present invention is not limited to this embodiment. For instance, the RGB image data  4  may be subdivided by M pieces along the horizontal direction to obtain M rows of areas, and/or may be subdivided by N pieces along the vertical direction to obtain N columns of areas. Wider area corresponding to the cell increases converting process efficiency in the area unit converting section  1134 . However, when the area is widened, since there is increased probability that both the image data and the draw data are involved in this area, it is conceivable that the application frequency of the pixel unit converting section  1135  would be increased. 
   It should also be understood that the RGB image data is converted into the CMYK image data in the above-described print control apparatus of the embodiment, though the present invention is not limited thereto. For instance, the RGB image data may be converted into such image data obtained by adding both light magenta (LM) and light yellow (LY) to CMYK image data. 
   Also, in the above-explained embodiment mode, the present invention has been applied to the print control apparatus. The inventive idea of the present invention may be widely applied to an image converting apparatus by which document data containing both draw data and image data is converted into first image data, and this first image data is further converted into second image data. 
   Furthermore, in the above-described embodiment, while the texts and the figures are defined as the draw data and the photographs are defined as the image data, the draw objects are classified by two sorts, the color conversion tables to be used are switched in correspondence with the sort of the relevant draw object. However, the present invention is not limited to the above-described embodiment. For example, alternatively, while a draw object is classified into more than 3 sorts of draw objects such as character data, figure data, and photograph data, color conversion tables are prepared with respect to these plural sort of draw objects, and these color conversion tables may be switched for use in accordance with a sort of a draw object under use. 
   As previously explained, in accordance with the present invention, the document data constituted by containing the plural sorts of draw objects can be converted into the image data constructed of the plural pixel data in the proper manner and in the higher efficiency. For example, such document data constituted by containing the draw command, which designates the draw object of such image data as the draw data (e.g., text and figure) and the image data (e.g., photograph), can be converted into the image data made of the plural pixel data, in particular, the CMYK image data corresponding to the format suitable for the printing operation in the proper manner and also in the higher efficiency.