Abstract:
An image processing apparatus is provided. A density conversion component converts a density of a transparent color material so that a total amount of a plurality of color materials is smaller than a predetermined first amount when it is determined that the total amount of the plurality of color materials is larger than the predetermined first amount and when the transparent color material is included in the plurality of color materials. A density ratio calculation component calculates a ratio between a density before converting the density of the transparent color material and a density after converting the density of the transparent material. A reporting component reports that the ratio of the density is smaller than a predetermined second amount when determining that the ratio of the density is smaller than the predetermined second amount.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2010-066843 filed Mar. 23, 2010. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The invention relates to an image processing apparatus, an image forming apparatus, and a program. 
         [0004]    2. Related Art 
         [0005]    There exist an image processing apparatus for making a notification based on the amount of ink which is estimated from image data and an image processing method for producing a warning image with respect to an image to be warned. 
       SUMMARY 
       [0006]    According to an aspect of the present invention, an image processing apparatus is provided. The image processing apparatus includes: a color material total amount determination component that determines whether or not a total amount of a plurality of color materials is larger than a predetermined first amount when an image is formed using the plurality of color materials; a density conversion component that converts a density of a transparent color material so that the total amount of the plurality of color materials is smaller than the predetermined first amount when it is determined that the total amount of the plurality of color materials is larger than the predetermined first amount and when the transparent color material is included in the plurality of color materials; a density ratio calculation component that calculates a ratio between a density before the density conversion component converts the density of the transparent color material and a density after the density conversion component converts the density of the transparent material; a density ratio determination component that determines whether or not the ratio of the density calculated by the density ratio calculating component is smaller than a predetermined second amount; and a reporting component that reports that the ratio of the density is smaller than the predetermined second amount when the density ratio determination component determines that the ratio of the density calculated by the density ratio calculating component is smaller than the predetermined second amount. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    An exemplary embodiment of the invention will be described in detail based on the following figures, wherein: 
           [0008]      FIG. 1  is a block diagram illustrating an example of connection among a print server, printers, and client apparatuses; 
           [0009]      FIG. 2  is a block diagram illustrating one example of the configuration of the print server; 
           [0010]      FIG. 3  is a block diagram illustrating one example of the configuration of the printer; 
           [0011]      FIG. 4  is a view schematically showing the configuration of an image forming section; 
           [0012]      FIG. 5  is a diagram illustrating one example of a setting screen for setting the conditions of formation of a transparent image; 
           [0013]      FIG. 6  is a flowchart illustrating the flow of a processing routine to be executed by the print server; 
           [0014]      FIG. 7  is a flowchart illustrating the flow of a sub routine of raster data producing processing; 
           [0015]      FIG. 8  is a graph illustrating total amount restricting processing for inks of four colors CMYK; 
           [0016]      FIG. 9  is a diagram conceptually illustrating one example of the total amount restricting processing; 
           [0017]      FIG. 10  is a graph illustrating the total amount restricting processing which is performed with respect to a pixel inside of an image forming region; 
           [0018]      FIG. 11  is a flowchart illustrating the flow of a sub routine of clear warning determining processing; 
           [0019]      FIG. 12  is a diagram illustrating one example of a warning screen; 
           [0020]      FIG. 13  is a flowchart illustrating the flow of a sub routine of the clear warning determining processing; 
           [0021]      FIG. 14  is a diagram illustrating an example of connection between the printer and the client apparatuses; and 
           [0022]      FIG. 15  is a view schematically showing the configuration of the image forming section, in which a rotary developing device is installed. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    A detailed description will be given below of a preferred exemplary embodiment according to the invention with reference to the attached drawings. 
         [0024]    As illustrated in  FIG. 1 , plural client apparatuses  10  and a print server  12  are connected to each other via a communication component  16  in the present exemplary embodiment. The communication component  16  may be a public network, the INTernet, or a network such as a LAN (abbreviating a Local Area Network) or a WAN (abbreviating a Wide Area Network). Moreover, the communication component  16  may be a radio communication component or a cable communication component. To the print server  12  are connected printers  14  not via or via the communication component  16 . 
         [0025]    The client apparatus  10  produces image formation information for allowing the printer  14  to form an image so as to transmit the image formation information to the print server  12 . The image formation information is described in a page description language, and includes image information representing a colorful image. 
         [0026]    The print server  12  analyzes the image formation information received from the client apparatus  10 , and then, produces, per toner, image data (hereinafter referred to as raster data) on a density per pixel corresponding to the amount of an image forming material (hereinafter referred to as a toner) for use in forming an image in the printer  14  based on the image formation information (i.e., RIP, or raster image processing), so as to output the image data to the printer  14 . 
         [0027]    The printer  14  is adapted to form an image with a toner based on the raster data output from the print server  12 . 
         [0028]    In the present exemplary embodiment, the printer  14  forms a colorful image by using a Y (yellow) toner, an M (magenta) toner, a C (cyan) toner, and a K (black) toner. Here, these color toners are generically referred to as a colorful toner. As described later, the printer  14  is configured so as to form a transparent image in superimposition on a colorful image with a toner for forming the transparent image. Hereinafter, the toner for forming such a transparent image is referred to as a clear toner, and further, raster data for use in forming the image with the clear toner is referred to as clear raster data. Incidentally, the toner is simply referred to in the case where a description will be given without distinguishing the colorful toner from the clear toner. 
         [0029]      FIG. 2  is a block diagram illustrating one example of the configuration of the print server  12 . 
         [0030]    In the print server  12  in the present exemplary embodiment, a CPU (abbreviating a Central Processing Unit)  30 , a ROM (abbreviating a Read Only Memory)  31 , a RAM (abbreviating a Random Access Memory)  32 , a display unit  33 , an operating unit  34 , an HDD (abbreviating a Hard Disk Drive)  35 , a communication IF (abbreviating Interface)  36 , and an IF (abbreviating an Interface)  37  are connected to each other via a bus  38 . 
         [0031]    The CPU  30  is adapted to execute a program stored in the ROM  31  or the HDD  35 , to control the entire operation of the print server  12 . In the ROM  31  are stored the program to be executed by the CPU  30 , data required for the processing of the CPU  30 , and the like. The RAM  32  is used as a work memory. Moreover, the RAM  32  includes also a region serving as an image memory for storing therein the raster data which is produced by the RIP. 
         [0032]    The HDD  35  stores therein the program to be executed by the CPU  30  and various kinds of data. Moreover, the HDD  35  previously stores therein first and second total amount restriction values, described later. 
         [0033]    Incidentally, a storage medium for storing therein the program to be executed by the CPU  30  is not limited to the HDD  35  or the ROM  31 . For example, a flexible disk, a DVD disk, a magneto-optical disk, a USB memory (i.e., a universal serial bus memory), or the like may be used, or a storage device for another apparatus connected to the communication component  16  may be used. 
         [0034]    The display unit  33  is constituted of, for example, a liquid crystal display or the like, and the display unit  33  displays various kinds of images, a message, or the like under control of the CPU  30 . The operating unit  34  is constituted of, for example, a keyboard, a mouse, and the like. Various kinds of pieces of information are designated by operating the operating unit  34  by a user. 
         [0035]    The communication IF  36  is an interface for transmitting/receiving data to/from another apparatus via the communication component  16 . 
         [0036]    The IF  37  is an interface for connecting the print server  12  to the printer  14 . 
         [0037]    The above-described client apparatus  10  has the same configuration as that of the print server  12 . Here, programs to be executed by the CPU in the client apparatus  10  include various kinds of application software programs and programs for producing and transmitting the above-described image formation information. 
         [0038]      FIG. 3  is a block diagram illustrating one example of the configuration of the printer  14 . Here, a description will be given of one example of the configuration of the printer  14  connected to the print server  12  not via the communication component  16 . 
         [0039]    In the printer  14 , a CPU (abbreviating a Central Processing Unit)  80 , a ROM (abbreviating a Read Only Memory)  81 , a RAM (abbreviating a Random Access Memory)  82 , an image forming section  83 , an IF (abbreviating an Interface)  84 , and a UI (abbreviating a User Interface)  85  are connected to each other via a bus  86 . 
         [0040]    The CPU  80  executes programs stored in the ROM  81  (including, for example, a program for achieving reception of the raster data from the print server  12  and control of the image forming section  83  so as to form an image based on the received raster data), thereby controlling the operation of the printer  14  as a whole. The ROM  81  stores therein programs to be executed by the CPU  80  and data required for the processing by the CPU  80 , and the like. The RAM  82  is used as a work memory. 
         [0041]    A storage medium for storing therein the programs to be executed by the CPU  80  is not limited to the ROM  81 . For example, a flexible disk, a DVD disk, a magneto-optical disk, a USB memory, or the like may be used. 
         [0042]    The image forming section  83  is adapted to form an image based on the raster data received from the print server  12 . The configuration of the image forming section  83  will be described later. 
         [0043]    The IF  84  is an interface for connecting the printer  14  to the print server  12 . 
         [0044]    The UI  85  is constituted of, for example, a touch panel display including a touch panel placed on a display, an operating button, and the like. On the UI  85  are displayed various kinds of pieces of information. Furthermore, various pieces of information or setting are input into the UI  85  by operation by a user. 
         [0045]    Here, the printer  14  connected directly to the communication component  16  is provided with a communication IF for connecting the printer  14  to the communication component  16  in addition to the above-described configuration. 
         [0046]      FIG. 4  is a view schematically showing the configuration of the image forming section  83 . 
         [0047]    The image forming section  83  includes an intermediate transfer belt  42  which is rotated in a direction indicated by an arrow α in  FIG. 4 . Moreover, an L image forming unit  20 L that forms a transparent image, a Y image forming unit  20 Y that forms a yellow image, an M image forming unit  20 M that forms a magenta image, a C image forming unit  20 C that forms a cyan image, and a K image forming unit  20 K that forms a black image are arranged in a tandem manner from upstream to downstream along the rotational direction α (i.e., a process direction) of the intermediate transfer belt  42 . Here, the L image forming unit  20 L is adapted to form the transparent image with the clear toner. 
         [0048]    As shown in  FIG. 4 , the L image forming unit  20 L, the Y image forming unit  20 Y, the M image forming unit  20 M, the C image forming unit  20 C, and the K image forming unit  20 K in the image forming section  83  include, respectively, photosensitive members  22 L,  22 Y,  22 M,  22 C, and  22 K; chargers  24 L,  24 Y,  24 M,  24 C, and  24 K for electrically charging the surfaces of the photosensitive members  22 L,  22 Y,  22 M,  22 C, and  22 K, respectively; exposing devices  26 L,  26 Y,  26 M,  26 C, and  26 K for exposing the charged photosensitive members  22 L,  22 Y,  22 M,  22 C, and  22 K based on the respective raster data so as to form electrostatic latent images; developing devices  28 L,  28 Y,  28 M,  28 C, and  28 K for allowing a clear toner, a yellow toner, a magenta toner, a cyan toner, and a black toner to adhere onto the photosensitive members  22 L,  22 Y,  22 M,  22 C, and  22 K having the electrostatic latent images formed thereon, followed by developing; and cleaners  50 L,  50 Y,  50 M,  50 C, and  50 K for cleaning the surfaces of the photosensitive members  22 L,  22 Y,  22 M,  22 C, and  22 K after primary transferring so as to remove residual waste toners after the transferring. 
         [0049]    Furthermore, the image forming section  83  includes: a conveying roller  44  rotated in contact with the inner circumferential surface of the intermediate transfer belt  42  so as to allow the intermediate transfer belt  42  to travel in the direction indicated by the arrow α; a support roller  46  which tensely holds the intermediate transfer belt  42  in cooperation with the conveying roller  44  and constitutes a secondary transferring unit  6 ; auxiliary rollers  52  and  54  that are rotated following the rotation of the conveying roller  44  in contact with the inner circumferential surface of the intermediate transfer belt  42 ; a transfer roller  48 L which transfers the transparent image formed by the L image forming unit  20 L onto the peripheral surface of the intermediate transfer belt  42 ; a transfer roller  48 Y which transfers the yellow image formed by the Y image forming unit  20 Y onto the peripheral surface of the intermediate transfer belt  42 ; a transfer roller  48 M which transfers the magenta image formed by the M image forming unit  20 M onto the peripheral surface of the intermediate transfer belt  42 ; a transfer roller  48 C which transfers the cyan image formed by the C image forming unit  20 C onto the peripheral surface of the intermediate transfer belt  42 ; and a transfer roller  48 K which transfers the black image formed by the K image forming unit  20 K onto the peripheral surface of the intermediate transfer belt  42 . 
         [0050]    Each of the transfer rollers  48 L,  48 Y,  48 M,  48 C, and  48 K is adapted to be rotated in contact with the inner circumferential surface of the intermediate transfer belt  42 , so as to transfer the transparent image, the Y image, the M image, the C image, and the K image, all of which are developed, onto the intermediate transfer belt  42 , and arranged along the rotational direction α of the intermediate transfer belt  42  in the order of the transfer rollers  48 Y,  48 M,  48 C,  48 L, and  48 K. The transfer rollers  48 L,  48 Y,  48 M,  48 C, and  48 K are connected to primary transfer bias power sources, respectively, so as to receive a predetermined voltage. 
         [0051]    Additionally, there is provided a sheet container  70  containing therein recording sheets serving as recording media, onto which the images transferred onto the intermediate transfer belt  42  are transferred. An arrow P indicates a conveyance path for the recording sheet. 
         [0052]    The secondary transferring unit  6  is constituted of the support roller  46  and a secondary transfer roller  62 . The secondary transfer roller  62  is disposed opposite to the support roller  46  while holding the intermediate transfer belt  42  therebetween. The secondary transfer roller  62  is rotated while pressing the recording sheet onto the support roller  46  and the peripheral surface of the intermediate transfer belt  42 , and then, transfers the image transferred at the peripheral surface of the intermediate transfer belt  42  onto the recording sheet. The secondary transfer roller  62  is connected to a secondary transfer bias power source, so as to receive a predetermined voltage. 
         [0053]    A fixing device  64  is disposed downstream of the support roller  46 , and includes a heating roller  66  whose temperature becomes high and a supporting roller  68 . The recording sheet having the image transferred thereon in the secondary transfer unit  6  is held between the heating roller  66  and the supporting roller  68  in the fixing device  64 . At this time, the toners are melted and coagulated to be then fixed onto the recording sheet. The recording sheet after the fixing is discharged onto a discharge unit  71 . 
         [0054]    Although the description has been given of the image forming section using the intermediate transfer belt, the toner images may be transferred directly onto the recording sheet, not via the intermediate transfer belt. 
         [0055]    Next, explanation will be made on the flow of image formation in the present exemplary embodiment. 
         [0056]    An administrator, who operates the print server  12 , previously sets the validity (ON) or invalidity (OFF) of a warning function in the print server  12 . The warning function is a function of determining based on clear raster data after corrected by the total amount restricting processing, described later, whether or not a transparent image intended by a user, who has transmitted image formation information, is formed, and then, when it is determined that the intended transparent image is not formed, the client apparatus  10  on the transmission source of the image formation information is notified of a warning or the display unit  33  is notified of the warning. 
         [0057]    In the meantime, the user designates the formation of a colorful image to be formed on the side of the client apparatus  10 , and then, the designation is converted into image formation information in a page description language by a printer driver or the like, to be thus transmitted to the print server  12 . 
         [0058]    Formation conditions for forming the transparent image in superimposition on the image based on the received image formation information can be set in the print server  12 .  FIG. 5  is a diagram illustrating one example of a setting screen  90  for setting the formation conditions of the transparent image. In the case where no transparent image is superimposed on a colorful image, “No”  91  is designated. In contrast, in the case where a transparent image is superimposed on a colorful image, “Yes”  92  is designated. Moreover, when “Yes”  92  is designated (i.e., a transparent image is superimposed on a colorful image), a region in which the transparent image is superimposed is designated at  93 . Here, a region in which the transparent image is superimposed (i.e., a region in which a clear toner is actually placed) is designated by designating any of the following items.
       Entire Region   Color region   Non-color region   Photograph   Pattern   Spot color/RGB/CMYK   Substitute Designated Plate       
 
         [0066]    In the case where the transparent image is intended to be superimposed in the entire image formation region, “Entire Region” is designated. In the case where the transparent image is intended to be superimposed in a region other than a white region (i.e., a region in which any of CMYK toners are placed) in a colorful image, “Color region” is designated. In the case where the transparent image is intended to be superimposed in the white region (i.e., a region in which none of CMYK toners are placed) in a colorful image, “Non-color region” is designated. In the case where the transparent image is intended to be superimposed in a region having a photograph within a colorful image, “Photograph” is designated. 
         [0067]    In the case where the transparent image is intended to be superimposed according to a pattern previously registered within a colorful image, “Pattern” is designated. Here, the user depresses a set button  95  corresponding to “Pattern,” a list of registered patterns is displayed, and then, the pattern, according to which a transparent image is superimposed, is selected. 
         [0068]    In the case where the transparent image is intended to be superimposed in a region in which a spot color is placed within a colorful image, “Spot color/RGB/CMYK” is designated. Incidentally, the user depresses a setting button  96  corresponding to “Spot color/RGB/CMYK” to display a designation screen for designating the name of a spot color, the value of each of RGB colors, or the value of each of CMYK colors, thereby designating the spot color by designating the name of the spot color or the value of each of the colors. For example, in the case where the red (i.e., the R color) is designated, numerical values are designated in such a manner that R is 100%, G is 0%, and B is 0%. 
         [0069]    In the case where an image is intended to be formed by substituting image information used in forming an image of any of CMYK colors by transparent image information, “Substitute Designated Plate” is designated. In the case where the user designates “Substitute DesignatedPlate,” the user depresses a setting button  97  corresponding to “Substitute Designated Plate” to display a designation screen for designating a plate of any of the CMYK colors (i.e., raster data), so as to designate any of the CMYK colors. The raster data on the designated color is substituted as the raster data on the transparent image, and thus, achieving a region in which the clear toner is placed. 
         [0070]    In the present exemplary embodiment, in the case where the transparent image is superimposed on the colorful image, the density  94  of the transparent image to be superimposed also is designated. The density of the transparent image signifies, for example, the dot area ratio of the transparent image. Here, the density of the region in which the clear toner is actually placed is designated by selecting from 0% to 100%. Incidentally, the numerical value representing the density may be a gradation value. 
         [0071]    When an OK button  98  is selected after the designation of the formation conditions of the transparent image, as described above, the formation conditions are stored in a predetermined storage region, and then, are set there. In contrast, when a cancel button  99  is selected after the designation of the formation conditions of the transparent image, as described above, the designation is canceled. 
         [0072]    The printer driver in the client apparatus  10  produces image formation information including image information representing the designated colorful image, and then, transmits the information to the print server  12 . 
         [0073]    When the print server  12  receives the image formation information via the communication IF  36 , the CPU  30  in the print server  12  executes a predetermined program, so that the received image formation information is stored in the RAM  32  or the HDD  35 , and then, a processing routine illustrated in  FIG. 6  is executed. 
         [0074]    In step  100 , the image formation information is read in. 
         [0075]    In step  102 , a sub routine for raster data producing processing is invoked. 
         [0076]      FIG. 7  is a flowchart illustrating the flow of the sub routine for the raster data producing processing. 
         [0077]    In step  200 , color conversion processing is performed. Specifically, the raster data on each of the CMYK colors and the clear raster data are produced according to the resolution of the printer  14  based on the image formation information and the formation conditions of the transparent image. 
         [0078]    Next, in step  202 , the total amount restricting processing is performed with respect to the raster data on each of the CMYK colors. 
         [0079]    In the case where the total toner amount exceeds a predetermined threshold when an image is formed on a recording sheet in the printer  14 , a toner cannot be stably fixed onto the recording sheet, and therefore, when another recording sheet is discharged in the state in which it overlaps the recording sheet discharged in this state, the toner adheres onto the other recording sheet, thereby possibly inducing troubles such as color transfer or mutual adhesion between the recording sheets. In view of these, in the present exemplary embodiment, the total amount restricting processing for correcting the raster data before the image formation is performed in order to restrict the total amount of toner adhering onto the recording sheet. 
         [0080]    In the total amount restricting processing in step  202 , the density of each of the CMYK colors is corrected in such a manner as to be reduced in the same rate such that the total density, per pixel, of the raster data on each of the CMYK colors does not exceed a first predetermined upper value (hereinafter referred to as a first total amount restriction value). In the present exemplary embodiment, the first total amount restriction value with respect to the total density of the four CMYK colors is set to 235% (see also  FIG. 9 ). 
         [0081]    In the present exemplary embodiment, the first total amount restriction value is used as a boundary, and further, not only a pixel whose total density of the four CMYK colors exceeds the first total amount restriction value is corrected, but also when the total density of the four CMYK colors is a predetermined value or higher, as illustrated in  FIG. 8 , the density of the pixel of each of the CMYK colors is reduced to be corrected with respect to a pixel having the first total amount restriction value or lower, thereby preventing any abrupt change in hue. A pixel whose total density of the four CMYK colors is lower than the predetermined value is not corrected. 
         [0082]    Upon completion of the total amount restricting processing of the density of each of the CMYK colors, the total amount restricting processing of the clear raster data is performed in next step  204 . Here, in the case where the total value of each of the densities of the raster data on the CMYK colors after the total amount restricting processing in step  202  and the value of the density of the clear raster data (hereinafter referred to as a total value α) per pixel exceed a second predetermined upper value (hereinafter referred to as a second total amount restriction value), the density of the clear raster data is corrected (i.e., reduced) in such a manner that the total value α does not exceed the second total amount restriction value. In the present exemplary embodiment, the second total amount restriction value is set to 255% with respect to the total value α. Since the first total amount restriction value is 235%, the corrected density of the clear raster data becomes 20% or more at the minimum in the region designated as the region in which the clear toner is placed when the density of the clear raster data is 20% or more. 
         [0083]    Incidentally, the total amount restricting processing of the clear raster data is different from that of the CMYK raster data. The clear toner amount in excess of the boundary is reduced by using the second total amount restriction value as the boundary. Here, in the case where the total value α does not exceed the second total amount restriction value, the density of the clear toner is not corrected. 
         [0084]      FIG. 9  is a diagram conceptually illustrating one example of the total amount restricting processing performed in steps  202  and  204 . As illustrated in  FIG. 9 , in the case where the total value of the densities of the CMYK color toners before correction is 300% and the density of the clear toner is 100%, when the total value of the densities of the CMYK color toners is corrected to 235% by the total amount restricting processing in step  202 , the density of the clear toner is corrected to 20% by reducing (235+100)−255=80%. 
         [0085]    The total density of the CMYK and clear toners for each pixel of an image to be formed within an image formation region becomes 255% or less by the processing in steps  202  and  204 . 
         [0086]    As for each of the pieces of raster data, not only the raster data after the total amount restricting processing but also the raster data before the total amount restricting processing are not erased but stored in the HDD  35  or the like. Each of the pieces of raster data after the total amount restricting processing is set as output data to be output to the printer  14 . 
         [0087]    As illustrated in  FIG. 10 , each of the densities of the CMYK color toners (OrgCMYK[X,Y]) before the total amount restricting processing, each of the densities of the CMYK color toners (PrtCMYK[X,Y]) after the total amount restricting processing, the density OrgClear[X,Y] of the clear toner before the total amount restricting processing, and the density PrtClear[X,Y] of the clear toner after the total amount restricting processing are stored for each of the pixels located in the coordinates within the image formation region. 
         [0088]    The first and second total amount restriction values may be previously set and stored in each of the printers  14 , or a user may set the values at every image formation so as to transmit to the print server  12  together with the image formation information. 
         [0089]    It is determined in step  206  whether or not the warning function is ON. When it is determined that the warning function is OFF in step  206 , the sub routine is ended, and then, the control returns to the main routine illustrated in  FIG. 6 . In contrast, when it is determined in step  206  that the warning function is ON, a clear warning determination processing is performed in step  208 . 
         [0090]      FIG. 11  is a flowchart illustrating the flow of the sub routine of the clear warning determining processing. 
         [0091]    Each of OrgTotal, PrtTotal, X, and Y is set to 0 in step  300 . Here, OrgTotal is a variable for accumulating the densities of each of the pixels represented by the clear raster data before the total amount restricting processing; PrtTotal is a variable for accumulating the densities of each of the pixels represented by the clear raster data after the total amount restricting processing; and X and Y represent the coordinates of each of the pixels in the image formation region. 
         [0092]    In step  302 , the density OrgClear[X,Y] of the clear toner before the total amount restricting processing of the pixel located in the coordinates (X,Y) is added to OrgTotal, to be set to OrgTotal. In addition, the density PrtClear[X,Y] of the clear toner after the total amount restricting processing of the pixel located in the coordinates (X,Y) is added to PrtTotal, to be set to PrtTotal. Moreover, 1 is added to X. 
         [0093]    It is determined in step  304  whether or not X exceeds a maximum value X_MAX. When it is determined that X does not exceed the maximum value X_MAX, the control returns to step  302 , and then, the above-described processing is repeated. In contrast, when it is determined in step  304  that X exceeds the maximum value X_MAX, X is set to 0 in step  306 , and then, 1 is added to Y. The control proceeds to step  308 , in which it is determined whether or not Y exceeds a maximum value Y_MAX. When it is determined in step  308  that Y does not exceed the maximum value Y_MAX, the control returns to step  302 , and then, the above-described processing is repeated. In contrast, when it is determined in step  308  that Y exceeds the maximum value Y_MAX, the control proceeds to step  310 . 
         [0094]    In other words, the total density of each of the pixels of the clear raster data before the total amount restricting processing and the total density of each of the pixels of the clear raster data after the total amount restricting processing are obtained by the processing from step  302  to step  308 . 
         [0095]    The ratio (PrtTotal/OrgTOtal) of the total density of each of the pixels of the clear raster data after the total amount restricting processing with respect to the total density of each of the pixels of the clear raster data before the total amount restricting processing is calculated in step  310 . Thereafter, it is determined whether or not the calculated ratio is smaller than a predetermined threshold AmountLimit. 
         [0096]    When the determination in step  310  is affirmative, it is determined that a transparent image intended by a user is not formed. And then, TRUE is set in a flag ClearWarning indicating a warning in step  312 . The control returns from this sub routine to the sub routine illustrated in  FIG. 7 . In contrast, when the determination in step  310  is negative, it is determined that a transparent image intended by a user is formed. And then, FALSE is set in the flag ClearWarning indicating the warning in step  314 . The control returns from this sub routine to the sub routine illustrated in  FIG. 7 . 
         [0097]    Thereafter, it is determined with reference to the flag ClearWarning indicating the warning in step  210  in  FIG. 7  whether or not there is a warning. Here, when the flag ClearWarning indicating the warning is TRUE, it is determined that there is a warning. In contrast, when the flag ClearWarning indicating the warning is FALSE, it is determined that there is no warning. 
         [0098]    When it is determined in step  210  that there is a warning, the warning screen is displayed on the display unit  33  in the print server  12  in step  212 . 
         [0099]      FIG. 12  is a diagram illustrating one example of the warning screen. Reference numeral  501  designates a message indicating that a transparent image intended by the user is not formed. Moreover, reference numeral  502  denotes a value PrtTotal/OrgTOtal compared with the threshold in step  310 . 
         [0100]    The user designates with reference to the warnings  501  and  502  whether the image formation is stopped or executed by using the operating unit  34 . When the stoppage of the image formation is designated, “stop image formation” denoted by reference numeral  503  is selected on the warning screen. In contrast, when the execution of the image formation is designated, “execute image formation” denoted by reference numeral  504  is selected on the warning screen. 
         [0101]    When the user selects “execute image formation” denoted by reference numeral  504 , it is further determined whether only a CMYK colorful image is formed without forming any transparent image or a transparent image is formed in superimposition on a colorful image. In the case where only the CMYK colorful image is formed without forming any transparent image, the user designates “image formation except clear toner” denoted by reference numeral  505 . In contrast, when a transparent image is formed in superimposition on a colorful image, the user does not designate “image formation except clear toner” denoted by reference numeral  505 . 
         [0102]    In the case where “image formation except clear toner” denoted by reference numeral  505  is designated, it is further determined whether or not overprinting is performed. Here, the overprinting signifies formation of the transparent image in superimposition by, for example, taking the recording sheet after the image formation from the discharge unit  71  in the image forming section  83  and setting the recording sheet in the sheet container  70  again. In the case where the overprinting is performed, “designate overprinting” denoted by reference numeral  506  is selected. In contrast, in the case where the overprinting is not performed, “designate overprinting” denoted by reference numeral  506  is not selected. In the case of the overprinting, the clear raster data before the total amount restricting processing is used. 
         [0103]    When the user ends the designation to select a closure button  507 , the designation information indicating the contents designated by  503  to  506  is stored in the HDD  35  of the print server  12 . 
         [0104]    Upon completion of the designation of the designation information, the print server  12  determines based on the designation information in step  214  in  FIG. 7  whether or not the image formation is executed. When the determination in step  214  is negative, the above-produced raster data before and after the total amount restricting processing are deleted in step  216 , and then, the control returns from this sub routine to the main processing routine illustrated in  FIG. 6 . 
         [0105]    In contrast, when the determination in step  214  is affirmative, the control proceeds to step  218 . Referring to the received designation information in step  218 , it is determined whether or not the clear toner is removed, that is, the transparent image is not superimposed on the colorful image. When the determination is affirmative in step  218 , the clear raster data after the total amount restricting processing is deleted from the above-described output data in step  220 . 
         [0106]    When the determination is negative in step  218 , the user wants to form the transparent image in superimposition on the colorful image by using each of the raster data after the total amount restricting processing, and therefore, the control returns from the sub routine to the main processing routine illustrated in  FIG. 6  while the output data is kept to be set. 
         [0107]    After step  220 , it is determined in step  222  whether or not the overprinting is designated. When the determination is affirmative in step  222 , the clear raster data before the total amount restricting processing is set as data for the overprinting in step  224 , and then, the control returns from the sub routine to the main processing routine illustrated in  FIG. 6 . In contrast, when the determination is negative in step  222 , the control returns from the sub routine to the main processing routine illustrated in  FIG. 6  as it is. 
         [0108]    Thereafter, it is determined in step  104  illustrated in  FIG. 6  whether or not the image formation is stopped. At this time, after the affirmative determination in step  210  illustrated in  FIG. 7 , it is determined whether or not the image is formed based on the information designated by the user. When the determination in step  210  is negative, the negative determination is made in step  104 . 
         [0109]    When the determination in step  104  is affirmative, the processing routine is ended without outputting the raster data to the printer  14 . Therefore, the image formation is not performed. In contrast, when the determination in step  104  is negative, the raster data set as the output data is output to the printer  14  in step  106 , and then, an image is formed by the printer  14 . 
         [0110]    Next, it is determined in step  108  whether or not the overprinting is designated. After the affirmative determination in step  210  illustrated in  FIG. 7 , it is determined based on the information designated by the user whether or not the overprinting is designated. In the case of the negative determination in step  210 , the negative determination is made in step  108 . 
         [0111]    In the case of the affirmative determination in step  108 , the raster data set as the data for the overprinting is output to the printer  14  in step  110 , and then, the overprinting is performed. In contrast, in the case of the negative determination in step  108 , the control skips step  110 , and then, the processing routine is ended. 
         [0112]    Although it is determined whether or not PrtTotal/OrgTotal is smaller than the predetermined threshold AmountLimit in  FIG. 11 , it may be determined whether or not OrgTotal/PrtTotal is larger than a predetermined threshold AmountLimit_ 2 . 
         [0113]    Alternatively, a sub routine illustrated in  FIG. 13  may be executed in place of the sub routine of the clear warning determining processing illustrated in  FIG. 11 . 
         [0114]    In step  320 , the variables (ClearArea, FullArea, X, and Y) are set to 0. 
         [0115]    It is determined in step  322  whether or not the density OrgClear[X,Y] of the clear toner before the total amount restricting processing of the pixel located in the coordinates (X,Y) is larger than 0. When the determination is affirmative in step  322 , 1 is added to ClearArea in step  324 . 
         [0116]    It is determined in step  326  whether or not the density OrgClear[X,Y] of the clear toner before the total amount restricting processing of the pixel located in the coordinates (X,Y) is equal to the density PrtClear[X,Y] of the clear toner after the total amount restricting processing of the pixel located in the coordinates (X,Y). When the determination is affirmative in step  326 , 1 is added to FullArea in step  328 . 
         [0117]    When the determination is negative in step  322  and the processing in step  328  is ended, the control proceeds to step  330 . In step  330 , 1 is added to X. 
         [0118]    It is determined in step  332  whether or not X exceeds the maximum X_MAX. When the determination is negative, the control returns to the processing in step  322 , and then, the above-described processing is repeated. In contrast, when it is determined in step  332  that X exceeds the maximum X_MAX, 0 is set to X in step  334  whereas 1 is added to Y. And then, the control proceeds to step  336 , in which it is determined whether or not Y exceeds the maximum Y_MAX. When it is determined in step  336  that Y does not exceed the maximum Y_MAX, the control returns to step  332 , and then, the above-described processing is repeated. In contrast, when it is determined in step  336  that Y exceeds the maximum Y_MAX, the control proceeds to step  338 . 
         [0119]    In other words, the number (ClearArea) of pixels in the region of the transparent image formed based on the clear raster data before the total amount restricting processing (i.e., the region in which the density of the clear toner is larger than 0) and the number (FullArea) of pixels whose density is not corrected by the total amount restricting processing in the region of the transparent image formed based on the clear raster data before the total amount restricting processing (i.e., the region in which the density of the clear toner is larger than 0) are accumulated in the processing from step  322  to step  336 . In the present exemplary embodiment, the number of pixels is obtained as an area. 
         [0120]    In step  338 , it is determined whether or not FullArea/ClearArea is smaller than a predetermined threshold AreaLimit. 
         [0121]    In the case of the affirmative determination in step  338 , it is determined that the transparent image intended by the user is not formed. TRUE is set in a flag ClearWarning indicating a warning is set in step  340 , and then, the control is returned to the sub routine illustrated in  FIG. 7  from this sub routine. In contrast, in the case of the negative determination in step  338 , it is determined that the transparent image intended by the user is formed. FALSE is set in the flag ClearWarning indicating a warning is set in step  342 , and then, the control is returned to the sub routine illustrated in  FIG. 7  from this sub routine. 
         [0122]    Although it is determined in step  338  illustrated in  FIG. 13  whether or not FullArea/ClearArea is smaller than the predetermined threshold AreaLimit, it may be determined whether or not ClearArea/FullArea is larger than the predetermined threshold AreaLimit_ 2 . 
         [0123]    Moreover, although the determination uses the result obtained by counting the number of pixels whose density is not corrected by the total amount restricting processing in  FIG. 13 , it is not limited to this. For example, the determination may use a result obtained by counting the number of pixels in a region in which the density corrected by the total amount restricting processing becomes smaller than that before the correction. 
         [0124]    Specifically, a variable DecArea, for example, may be used in place of the variable FullArea. In the case of the negative determination in step  326 , DecArea is counted up. In contrast, in the case of the affirmative determination in step  326 , the processing in step  328  is not performed. It is determined in step  338  whether or not DecArea/ClearArea is larger than a predetermined threshold AreaLimit_ 3 . 
         [0125]    Additionally, although the description has been given of the present exemplary embodiment in which the density of the clear toner cannot become less than 20% even by the total amount restricting processing in the region designated as being the region in which the clear toner is placed, there may be no such setting, that is, the density may be 0% by the total amount restricting processing. In this case, the determination may use a result obtained by counting the number of pixels whose density becomes 0% by the total amount restricting processing, even though the density exceeds 0% before the total amount restricting processing. 
         [0126]    Specifically, a variable ZeroArea, for example, is used in place of the variable FullArea illustrated in  FIG. 13 , and further, the processing of determining whether or not PrtClear[X,Y] is equal to 0 is performed in place of the processing in step  326 . In the case of the affirmative determination herein, ZeroArea is counted up in place of the processing in step  328 . Moreover, it is determined in step  338  whether or not ZeroArea/ClearArea is larger than a predetermined threshold AreaLimit_ 4 . 
         [0127]    Although the description has been given of the example in which the print server  12  executes the processing routine or the like in the above-described exemplary embodiment, it is not limited to this. For example, no print server  12  is provided whereas the printer  14  is connected to the communication component  16  to be communicable with each of the client apparatuses  10 , as illustrated in  FIG. 14 . The printer  14  may be equipped with the function of the print server  12 , and further, the CPU  80  in the printer  14  may execute the programs of the above-described processing routine (wherein the programs may be stored in the ROM  81 ), so that the above-described processing routine may be executed. 
         [0128]    Moreover, the image forming section  83  is not limited to the above-described configuration of the tandem system. As shown in  FIG. 15 , an image forming section  400  including a rotary developing device  410  may be used, for example. 
         [0129]    A photosensitive member  401  is rotated in a direction indicated by an arrow A by a motor. Around the photosensitive member  401 , there are arranged a charging roll  408 , an exposing device  409 , the developing unit  410 , a primary transferring unit  402 , and a cleaning device  411 . 
         [0130]    The charging roll  408  is adapted to electrically charge the surface of the photosensitive member  401 . The exposing device  409  is designed to expose the charged surface of the photosensitive member  401  with a laser beam according to image data, thereby forming an electrostatic latent image. 
         [0131]    The developing unit  410  provided with developing devices  410 Y,  410 M,  410 C, and  410 K which use toners of Y, M, C, and K colors, and a developing device  410 L which uses a clear toner, arranged in a circumferential direction of the developing unit  410 . The developing devices  410 Y,  410 M,  410 C,  410 K, and  410 L develop the electrostatic latent image formed on the photosensitive member  401  with the Y, M, C, and K toners and the clear toner. In developing, the developing unit  410  is rotated in a direction indicated by an arrow R by the motor, and it is positioned in such a manner that the developing device concerned faces the electrostatic latent image formed on the photosensitive member  401 . 
         [0132]    The respective toner images developed on the photosensitive member  401  are transferred in sequence onto an intermediate transfer belt  403  by the primary transferring device  402 , to be then superimposed one on another. A belt cleaner  416  is disposed in the intermediate transfer belt  403 , and thus, the toners remaining on the intermediate transfer belt  403  are scraped off by a cleaning blade. 
         [0133]    A recording sheet drawn onto a transportation path by a drawing roll  419  or  420  from a recording sheet cassette  417  or  418  is transported to a transfer position in a secondary transferring device  404  by roll pairs  421 ,  422 , and  423 . The toner images formed on the intermediate transfer belt  403  are transferred onto the recording sheet at the transfer position, to be then thermally fixed by a fixing device  424 , and thus, is discharged onto a discharging device  425  or the top of a main apparatus. 
         [0134]    The above-described image forming apparatus  400  also may be used as an image forming apparatus for forming a transparent image onto a synthetic image, as described in the above-described exemplary embodiment. 
         [0135]    Although the software executes the processing for controlling the image formation according to the determination resulting from the raster data producing processing, the clear warning determining processing, and the clear warning determining processing in the above-described exemplary embodiment, hardware may execute the processing.