JP2008112384A - Controller, image formation apparatus, image formation system, image formation method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image formation system for making an image formation apparatus suitable for an image perform image formation. <P>SOLUTION: In accepting a print request from a user, a printer 10 selects a printer whose in-face uniformity is relatively high in an image region where specific image elements are arranged on the basis of the types of image elements included in image data and the in-face uniformity of each of a plurality of printers including its own equipment, and when its own equipment is selected, performs print processing on the basis of the image data received together with a print request, and when other printer is selected, transfers the image data to the selected printer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device, an image forming apparatus, an image forming system, an image forming method, and a program.

For example, in Patent Document 1, a gradation patch consisting of a uniform density signal is formed on the entire surface of a recording sheet corresponding to the print area of a photosensitive drum, and a plurality of sheets with different gradations are output and output. A plurality of gradation patches are read as luminance data for each pixel position, and the read luminance data for the entire surface are converted into reflection density values, and based on this, a two-dimensional γ correction LUT corresponding to the printing area is converted. A desired image processing apparatus is disclosed.
Further, in Patent Document 2, from the start to the end of printer calibration, the control state of this printer is set to a control state indicating that calibration is being performed, and jobs assigned to this printer are transferred to other printers. An image forming system to be assigned to is disclosed.
Further, Patent Document 3 discloses a method of dividing an output image into six or more regions and adjusting the dot area ratio for each region.
JP 2003-324608 A JP 2002-187331 A JP 2003-084432 A

  SUMMARY An advantage of some aspects of the invention is that it causes an image forming apparatus suitable for an image to form an image.

  In order to achieve the above object, the present invention according to claim 1 is directed to an image forming apparatus based on the types of image elements included in the image data and information on the uniformity of output density of each of the plurality of image forming apparatuses. And a transmission unit that transmits the image data to the image forming apparatus selected by the selection unit.

  Further, the present invention according to claim 2 further includes range specifying means for specifying a range in which a predetermined type of image element is arranged for the image data, and the selecting means is specified by the range specifying means. The image forming apparatus is selected based on the range thus formed and the uniformity in each area of the output image.

  Further, in the present invention according to claim 3, the range specifying means specifies at least a range where an image element of a photograph or a line image is arranged, and the selection means arranges an image element of a photograph or a line image. The image forming apparatus is selected based on the range that has been set and the uniformity in the range.

  According to a fourth aspect of the present invention, there is provided the correction information selecting means for selecting the correction information of the output density based on the range specified by the range specifying means, and the image formation in which the image data is transmitted by the transmitting means. The apparatus further includes correction instruction means for instructing the apparatus to perform density correction using the correction information selected by the correction information selection means.

  The present invention according to claim 5 further includes notification means for notifying a user of an image forming apparatus to which image data is transmitted by the transmission means.

  Further, in the present invention according to claim 6, the transmission means transmits the image data to an image forming apparatus having the fastest image forming processing speed among the image forming apparatuses selected by the selecting means. .

  Further, the present invention according to claim 7 is based on a range specifying unit that specifies a range in which a predetermined type of image element is arranged for image data, and a plurality of ranges based on the range specified by the range specifying unit. A selection unit that selects an image forming apparatus from among the image forming apparatuses, and a transmission unit that transmits the image data to the image forming apparatus selected by the selection unit.

  Further, the present invention according to claim 8 is based on image forming means, types of image elements included in the image data, and information on uniformity of output density by each of a plurality of image forming apparatuses including the own apparatus. A selecting unit that selects an image forming apparatus; and a control unit that causes the image forming unit to execute an image forming process based on the image data when the image forming apparatus is selected by the selecting unit.

  Further, the present invention according to claim 9 further includes a transmission unit that transmits the image data to the selected image forming apparatus when an image forming apparatus other than the image forming apparatus is selected by the selection unit. .

  According to a tenth aspect of the present invention, on the basis of a plurality of image forming apparatuses, types of image elements included in the image data, and information on uniformity of output density by each of the image forming apparatuses, A control device that selects an image forming apparatus and transmits the image data to the selected image forming apparatus.

  According to an eleventh aspect of the present invention, an image forming apparatus is selected and selected based on the types of image elements included in the image data and information on uniformity of output density by each of the plurality of image forming apparatuses. The image forming apparatus forms an image based on the image data.

  According to a twelfth aspect of the present invention, the step of selecting an image forming apparatus based on the type of image element included in the image data and the information on the uniformity of the output density by each of the plurality of image forming apparatuses; Instructing the selected image forming apparatus to perform an image forming process based on the image data.

According to the first aspect of the present invention, there is an effect that it is possible to preferentially suppress the occurrence of density unevenness with respect to a specific type of image element.
According to the second aspect of the invention, there is an effect that an image forming apparatus having stable output characteristics can be selectively used in a region where a specific image element is arranged.
According to the third aspect of the invention, there is an effect that it is possible to preferentially suppress the occurrence of density unevenness with respect to an image area where a photograph or a line image is arranged.
According to the fourth aspect of the present invention, there is an effect that the reproducibility of gradation can be preferentially enhanced with respect to a specific type of image element.
According to the fifth aspect of the invention, it is possible to notify the user of the image forming apparatus that performs the image forming process.
According to the sixth aspect of the invention, the image forming apparatus can be selected in consideration of the processing speed of each image forming apparatus.
According to the seventh aspect of the invention, there is an effect that an image forming apparatus suitable for the image layout can be selected.
According to the eighth aspect of the invention, there is an effect that the image forming process can be performed by the own device when the output characteristic of the own device is suitable for the image data.
According to the ninth aspect of the present invention, when the output characteristics of another image forming apparatus are more suitable for the image data than the image forming apparatus, this image data can be processed by the other image forming apparatus. .
According to the tenth aspect of the present invention, it is possible to suppress the occurrence of density unevenness preferentially for a specific type of image element.
According to the eleventh aspect of the invention, there is an effect that it is possible to preferentially suppress the occurrence of density unevenness with respect to a specific type of image element.
According to the twelfth aspect of the present invention, it is possible to preferentially suppress the occurrence of density unevenness with respect to a specific type of image element.

First, the overall configuration of the image forming system 1 will be described.
FIG. 1 is a diagram illustrating the overall configuration of the image forming system 1.
As illustrated in FIG. 1, the image forming system 1 includes a plurality of printers 10, a scanner 20, and a computer terminal 30.
The plurality of printers 10, the scanner 20, and the computer terminal 30 are connected to each other via a network.
The printer 10 prints an image in response to a print request from the computer terminal 30.
The scanner 20 reads a test chart printed by the printer 10. The test chart is an image formed based on a predetermined density value, and is used for detecting a change in output density.
The computer terminal 30 is a general-purpose computer operated by a user. In this example, the user operates the computer terminal 30 to cause the printer 10 to print desired image data.

Next, the configuration of the printer 10 will be described.
FIG. 2 is a diagram illustrating the configuration of the tandem printer 10.
As shown in FIG. 2, the printer 10 includes a control device 12, a communication device 13, an image forming unit 14, an intermediate transfer belt 16, a paper tray 17, a paper conveyance path 18, and a fixing device 19.
The printer 10 of this example has only a printer function for printing image data received from the computer terminal 30, but is not limited to this. The function as a scanner, the function as a copier, and the facsimile are not limited thereto. The function may be further provided.

First, the outline of the printer 10 will be described. A control device 12 and a communication device 13 are arranged on the upper portion of the printer 10. The control device 12 is a controller provided with an arithmetic device, a memory, an ASIC, and the like, and controls other configurations of the printer 10. The communication device 13 communicates with the scanner 20 (FIG. 1) or the computer terminal 30 (FIG. 1) via a network.
Below the control device 12, a plurality of image forming units 14 are arranged corresponding to the colors constituting the color image. In this example, the first image forming unit 14K, the second image forming unit 14Y, and the third image forming corresponding to each color of black (K), yellow (Y), magenta (M), and cyan (C). The unit 14M and the fourth image forming unit 14C are arranged horizontally along the intermediate transfer belt 16 with a certain interval. The intermediate transfer belt 16 rotates as an intermediate transfer member in the direction of the arrow A in the figure, and these four image forming units 14K, 14Y, 14M, and 14C have different colors based on the image data input from the control device 12. Toner images are sequentially formed, and transferred (primary transfer) to the intermediate transfer belt 16 at a timing at which the plurality of toner images are superimposed on each other. The order of the colors of the image forming units 14K, 14Y, 14M, and 14C is not limited to the order of black (K), yellow (Y), magenta (M), and cyan (C). ), Magenta (M), cyan (C), black (K), and the like.

  The sheet conveyance path 18 is disposed below the intermediate transfer belt 16. The recording paper supplied from the paper tray 17 is transported on the paper transport path 18, and the toner images of each color transferred onto the intermediate transfer belt 16 are collectively transferred (secondary transfer). The toner image thus fixed is fixed by the fixing device 19 and discharged to the outside along the arrow B.

Next, each configuration of the printer 10 will be described in more detail.
As illustrated in FIG. 2, when the control device 12 receives image data from the computer terminal 30 via the communication device 13, the control device 12 performs a color conversion process, a density correction process, and the like on the received image data to generate an image. Output to forming unit 14.

The first image forming unit 14K, the second image forming unit 14Y, the third image forming unit 14M, and the fourth image forming unit 14C are arranged and formed in parallel at a certain interval in the horizontal direction. The configuration is almost the same except that the color of the image is different. Accordingly, the first image forming unit 14K will be described below. The configuration of each image forming unit 14 is distinguished by adding K, Y, M, or C.
The image forming unit 14K includes an optical scanning device 140K that scans laser light in accordance with image data input from the control device 12, and an image in which an electrostatic latent image is formed by the laser light scanned by the optical scanning device 140K. And a forming apparatus 150K.

The optical scanning device 140K modulates the semiconductor laser 142K according to the black (K) image data, and emits the laser light LB (K) from the semiconductor laser 142K according to the image data. The laser beam LB (K) emitted from the semiconductor laser 142K is applied to the rotary polygon mirror 146K via the first reflection mirror 143K and the second reflection mirror 144K, and is deflected and scanned by the rotation polygon mirror 146K. The light is irradiated onto the photosensitive drum 152K of the image forming apparatus 150K through the second reflecting mirror 144K, the third reflecting mirror 148K, and the fourth reflecting mirror 149K.
The image forming apparatus 150K includes a photosensitive drum 152K as an image carrier that rotates at a predetermined rotational speed in the direction of arrow A, and primary charging as a charging unit that uniformly charges the surface of the photosensitive drum 152K. And a developing device 156K for developing the electrostatic latent image formed on the photosensitive drum 152K, and a cleaning device 158K. The photosensitive drum 152K is uniformly charged by the scorotron 154K, and an electrostatic latent image is formed by the laser beam LB (K) irradiated by the optical scanning device 140K. The electrostatic latent image formed on the photosensitive drum 152K is developed with black (K) toner by the developing device 156K and transferred to the intermediate transfer belt 16. Residual toner, paper dust, and the like adhering to the photosensitive drum 152K after the toner image transfer process are removed by the cleaning device 158K.
The other image forming units 14Y, 14M, and 14C also form yellow (Y), magenta (M), and cyan (C) toner images in the same manner as described above, and intermediately transfer the formed toner images of the respective colors. Transfer to belt 16.

The intermediate transfer belt 16 has a constant tension between the drive roll 164, the first idle roll 165, the steering roll 166, the second idle roll 167, the backup roll 168, and the third idle roll 169. The drive roll 164 is rotationally driven by a drive motor (not shown), and is circulated at a predetermined speed in the direction of arrow A. The intermediate transfer belt 16 is formed into an endless belt by, for example, forming a flexible synthetic resin film such as polyimide in a belt shape and connecting both ends of the synthetic resin film formed in a belt shape by welding or the like. It has been done.
Further, the intermediate transfer belt 16 includes a first primary transfer roll 162K, a second primary transfer roll 162Y, a third primary transfer roll 162M, and a position facing the image forming units 14K, 14Y, 14M, and 14C, respectively. A fourth primary transfer roll 162C is provided, and the toner images of the respective colors formed on the photosensitive drums 152K, 152Y, 152M, and 152C are transferred onto the intermediate transfer belt 16 in a multiple manner by these primary transfer rolls 162. The The residual toner adhering to the intermediate transfer belt 16 is removed by a cleaning blade or brush of a belt cleaning device 189 provided downstream of the secondary transfer position.

In the paper transport path 18, a paper feed roller 181 for taking out the recording paper from the paper tray 17, a first roller pair 182 and a second roller pair 183 for paper transport, and a secondary transfer of the recording paper at a predetermined timing. A resist roll 184 that is transported to a position is disposed.
In addition, a secondary transfer roll 185 that is in pressure contact with the backup roll 168 is disposed at the secondary transfer position on the paper transport path 18, and each color toner image transferred onto the intermediate transfer belt 16 is Secondary transfer is performed on the recording paper by the pressing force and electrostatic force of the secondary transfer roll 185. The recording paper on which the toner images of the respective colors are transferred is conveyed to the fixing device 19 by the first conveying belt 186 and the second conveying belt 187.
The fixing device 19 melts and fixes the toner to the recording paper by performing heat treatment and pressure treatment on the recording paper on which the toner images of the respective colors are transferred.

Next, the print control program 5 installed in the control device 12 will be described. In this example, a mode in which the print control program 5 is installed in all the printers 10 included in the image forming system 1 will be described.
FIG. 3 is a diagram illustrating a functional configuration of the print control program 5 executed by the control device 12 (FIG. 2).
As illustrated in FIG. 3, the print control program 5 includes a range specifying unit 510, a user interface unit (UI unit) 520, a printer selection unit 530, a correction information selection unit 540, a correction instruction unit 550, a transmission unit 560, and image correction. A printing unit 580 and a printing unit 580.
The print control program 5 may be recorded on a recording medium such as a CD-ROM and installed in the control device 12 via the recording medium, or may be distributed in the form of a data signal and installed in the control device 12. May be. In this example, the entire functional configuration of the print control program 5 is installed in the control device 12 as software. However, the present invention is not limited to this. For example, a part of the print control program 5 is a hardware such as an ASIC. The print control program 5 may be partly installed in the computer terminal 30 or the scanner 20, and the other part may be installed in the control device 12.

In the print control program 5, the range specifying unit 510 specifies a range in which a predetermined type of image element is arranged among the image elements included in the image data. Here, the image element is a part of an image, and is, for example, an optically read photographic image, a line image (computer graphics), a character image generated according to a text code, or the like.
For example, the range specifying unit 510 specifies a range where photographic images and computer graphics are arranged.
The range specifying unit 510 of this example specifies the range of a photographic image, computer graphics, and character image for the image data requested to be printed, and specifies the specified range and type (that is, photographic image, computer graphics, or character). Image) to the printer selection unit 530.

The UI unit 520 controls the computer terminal 30 (display device) and the like to display information for specifying the printer 10 to which image data is transmitted. The information for specifying the printer is, for example, a printer name.
The UI unit 520 of this example causes the printer driver of the computer terminal 30 to display the name of a printer to which image data is transmitted (that is, a printer that prints image data).

The printer selection unit 530 selects the printer 10 based on the type of the image element included in the image data and the information regarding the uniformity of the output density by each printer 10.
For example, when the image data includes photographic images or computer graphics (hereinafter collectively referred to as image elements) of a predetermined size or more in the image data, the printer selection unit 530 selects the printer with priority on the uniformity of the output density. If these image elements are not included, the printer is selected giving priority to the printing speed. Further, the printer selection unit 530 determines the size of these image elements in the main scanning direction or the sub-scanning direction based on the range of predetermined types of image elements (for example, image elements) specified by the range specifying unit 510. When it is determined that the value exceeds the default value, the printer is selected with priority on uniformity of output density, and when the size of these image elements is determined to be equal to or less than the default value in the main scanning direction and the sub-scanning direction. Select the printer with priority on the printing speed.
The printer selection unit 530 of this example specifies the range of image elements based on the range and type of image elements input from the range specification unit 510, and the range in which these image elements are arranged and the uniformity DB 610. Compare with the recorded uniformity information of each printer, select the printer so that the uniformity of the area where the image elements are arranged, and correct the selected printer name and the uniformity information of that printer The information is output to the information selection unit 540, and the selected printer name and image data are output to the transmission unit 560.

The correction information selection unit 540 selects output density correction information based on the range specified by the range specifying unit 510. Here, the correction information is information for the printer to correct the output density, for example, a look-up table for performing γ correction.
In this example, the correction coefficient DB 620 records at least one correction information (lookup table) for each printer 10 in association with the image quality priority area. The correction information selection unit 540 Based on the range and type of the input image element, the range in which the image element is arranged is specified, and the image quality of the specified range is given priority, and from the look-up table recorded in the correction coefficient DB 620, The lookup table of the selected printer is selected, and the selected lookup table is output to the correction instruction unit 550.

The correction instruction unit 550 instructs the printer to which image data is transmitted by the transmission unit 560 to perform density correction using the correction information selected by the correction information selection unit 540.
The correction instruction unit 550 of this example outputs the correction information (lookup table) selected by the correction information selection unit 540 to the image correction unit 570 when the printer selection unit 530 selects its own device, and selects the printer. When another printer is selected by the unit 530, the correction information (lookup table) selected by the correction information selection unit 540 is output to the transmission unit 560, and the selected printer is corrected via the transmission unit 560. Send information.

The transmission unit 560 controls the communication device 13 (FIG. 2) to transmit the input image data to the printer selected by the printer selection unit 530.
The transmission unit 560 of the present example outputs the input image data to the image correction unit 570 when the printer is selected by the printer selection unit 530, and when another printer is selected by the printer selection unit 530. The input image data and the correction information (lookup table) input from the correction instruction unit 550 are transmitted to the selected printer 10.

The image correction unit 570 performs correction processing on the input image data, and outputs the corrected image data to the printing unit 580.
The image correction unit 570 of this example corrects the image data input from the transmission unit 560 using the correction information (lookup table) input from the correction instruction unit 550, and prints the corrected image data into the printing unit 580. Output to.
The image data and the correction information transferred from the other printer 10 are directly input to the image correction unit 570 and are subjected to correction processing.

  The printing unit 580 controls the image forming unit 14 (FIG. 2) and the like, and executes an image forming process based on the image data input from the image correcting unit 570.

4 and 5 are diagrams illustrating the layout of input image data.
As illustrated in FIG. 4, when the input image data includes a font image (text) and a photographic image (natural image), the range specifying unit 510 (FIG. 3) displays the font image. The range and the range of the photographic image are specified. In this example, since the range of the photographic image is wider in the sub-scanning direction than in the main scanning direction, the printer selection unit 530 preferentially selects a printer with high output density uniformity in the sub-scanning direction. Further, the correction information selection unit 540 selects the correction information by giving priority to the image quality on the right side of the paper on which the photographic image is arranged. That is, a look-up table that enhances the tone reproducibility on the right side of the page is selected.

  As illustrated in FIG. 5, when a font image (text) and computer graphics (graphic) are included, the range specifying unit 510 (FIG. 3) displays the range of the font image and the computer. Identify the range of graphics. In this example, since the range of computer graphics is wider in the main scanning direction than in the sub-scanning direction, the printer selection unit 530 preferentially selects a printer with high output density uniformity in the main scanning direction. Further, the correction information selection unit 540 selects the correction information by giving priority to the image quality on the upper side of the paper on which the computer graphics is arranged. That is, a look-up table that enhances the gradation reproducibility on the upper side of the page is selected.

FIG. 6 is a diagram illustrating the output density characteristics of the printer 10.
As illustrated in FIG. 6A, some printers have output density that varies in the main scanning direction. In other words, it can be said that this printer has higher uniformity in the sub-scanning direction than in the main scanning direction. Accordingly, in the printer having the characteristics shown in FIG. 6A, when image data is printed as illustrated in FIG. 5, density fluctuations occur in computer graphics, and image quality deterioration is easily noticeable. When the image data exemplified in (1) is printed, the density fluctuation hardly occurs in the photographic image, and the image quality deterioration is less noticeable.
In addition, as illustrated in FIG. 6B, there is a printer in which the output density varies in the sub-scanning direction. In other words, this printer has higher uniformity in the main scanning direction than in the sub-scanning direction. Therefore, a printer having the characteristics shown in FIG. 6B has a high possibility of density fluctuation in a photographic image when image data is printed as illustrated in FIG. 4, but is illustrated in FIG. When image data is printed, it is unlikely that density fluctuations will occur in computer graphics, and it is expected that image quality deterioration will be less noticeable.

FIG. 7 is a diagram illustrating a test chart for determining the uniformity of the output density of the printer.
As illustrated in FIG. 7A, on the test chart, a patch in which toners of a plurality of colors are mixed is formed in each region divided in the main scanning direction and the sub-scanning direction. In this example, a patch in which toners of C color, M color, and Y color are mixed is formed. This patch is printed by a printer with input data (C value, M value, and Y value) that is scheduled to become a predetermined density of gray (achromatic color). Therefore, when this patch becomes a chromatic color, the output density of one of the colors fluctuates.
In this example, two patches are formed in each region, and these patches are formed based on input data having different densities.

  Further, as illustrated in FIG. 7B, in each area of the test chart, a single color patch (C color, M color, Y color, and K single color) and a mixed color patch (C color, M color) And a mixed color of Y color).

FIG. 8 is a diagram for explaining the relationship between the output density characteristics of the printer and the correction information. In this figure, the horizontal axis indicates the density value (0 to 255) input to the printer, and the vertical axis indicates the density value (0 to 255) output by the printer.
As illustrated in FIG. 8, the γ characteristic varies depending on the region of the image. Therefore, the optimum γ correction curve differs for each region. Therefore, it is difficult to correct the γ characteristic of the entire image to an optimal state with a single γ correction curve.
In the present embodiment, the amount of variation in the γ characteristic due to the image area is referred to as output density non-uniformity.
Therefore, as illustrated in FIG. 9, the correction coefficient DB 620 of the present embodiment records a lookup table (corresponding to a γ correction curve) that preferentially corrects the γ characteristic of each region in association with the printer and the region. The correction information selection unit 540 reads from the correction coefficient DB 620 a correction curve (lookup table) associated with the printer name selected by the printer selection unit 530 and the area where the image elements are arranged.

Next, the operation of the print control program 5 will be described.
FIG. 10 is a flowchart for explaining the overall operation (S10) of the image forming system 1 (printing control program 5).
As shown in FIG. 10, in step 100 (S100), when the control device 12 (FIG. 2) of the printer 10 receives a print request including image data and printing conditions from the computer terminal 30 (FIG. 1), Based on the received printing condition, it is determined whether the user has designated the image quality priority mode or the printing speed priority mode.
The control device 12 proceeds to the process of S105 when the image quality priority mode is designated, and proceeds to the process of S140 when the print speed priority mode is designated.

In step 105 (S105), the control device 12 activates the print control program 5.
The range specifying unit 510 of the print control program 5 analyzes the layout of the input image data, specifies the range of the image element (photographic image or computer graphics), and inputs the specified range of the image element. The image data is output to the printer selection unit 530.

In step 110 (S110), the printer selection unit 530 determines whether there is an image element having a size equal to or larger than a predetermined size based on the range of the image element input from the range specifying unit 510.
The print control program 5 proceeds to the process of S20 when the input image includes an image element of a predetermined size or larger, and proceeds to the process of S135 when neither a photographic image nor a graphic of the predetermined size or larger exists. To do. The predetermined size in this case is, for example, a size that does not cause a problem due to fluctuations in output density.

  In step 20 (S20), the printer selection unit 530 determines the printer registered in advance based on the range of image elements input from the range specifying unit 510 and the uniformity information recorded in the uniformity DB 610. Search for output printer candidates.

  In step 115 (S115), the print control program 5 proceeds to the process of S120 when an output printer candidate is found, and proceeds to the process of S135 when an output printer candidate is not found.

  In step 120 (S120), the printer selection unit 530 selects the printer with the fastest printing speed from the output printer candidates, notifies the UI unit 520 of the selected printer name, and selects the selected printer name and The image element range is output to the correction information selection unit 540, and the selected printer name and image data are output to the transmission unit 560.

  In step 125 (S125), the UI unit 520 causes the printer driver of the computer terminal 30 to display the selected printer name.

In step 130 (S130), the correction information selection unit 540, based on the printer name and image element range input from the printer selection unit 530, looks up the lookup table (corresponding to the γ correction curve) recorded in the correction coefficient DB 620. ) To select one lookup table and output the selected lookup table and printer name to the correction instruction unit 550.
The correction instruction unit 550 outputs the lookup table input from the correction information selection unit 540 to the image correction unit 570 and outputs the correction information selection unit 570 when the printer name input from the correction information selection unit 540 is its own device. When the printer name input from 540 is another printer, the lookup table input from the correction information selection unit 540 is output to the transmission unit 560.

  In step 135 (S135), the printer selection unit 530 selects a printer with the fastest printing speed from the registered printers, and sends the selected printer name and input image data to the transmission unit 560. Output.

In step 140 (S140), the transmission unit 560 selects the input image data and the lookup table selected by the correction information selection unit 540 when another printer is selected by the printer selection unit 530. When the printer is selected by the printer selection unit 530, the input image data is output to the image correction unit 570.
The image correction unit 570 (of the own apparatus or another printer) corrects the input image data using the lookup table selected by the correction information selection unit 540, and the corrected image data is output to the printing unit 580. Output to.

  In step 145 (S145), the printing unit 580 controls the image forming unit 14 (FIG. 2) based on the image data corrected by the image correcting unit 570 to print an image on the recording paper.

FIG. 11 is a flowchart for explaining the candidate search process (S20) of FIG. 10 in more detail.
As shown in FIG. 11, in step 200 (S200), the printer selection unit 530 sequentially selects one printer from the registered printers.
In step 205 (S205), the printer selection unit 530 determines the range of the image element specified by the range specification unit 510, the in-plane uniformity of the selected printer (uniformity information recorded in the uniformity DB 610), and the like. Compare Here, the in-plane uniformity is an example of information relating to output density uniformity, and is, for example, the amount of change in γ characteristics between image regions in the main scanning direction and the sub-scanning direction.

  In step 210 (S210), the printer selection unit 530 calculates a change amount of the γ characteristic in the range of the image element, and when the calculated change amount is equal to or less than a predetermined reference value, the process proceeds to S215. When the calculated amount of change exceeds this reference value, the process proceeds to S220.

  In step 215 (S215), the printer selection unit 530 adds the selected printer to the output printer candidates.

  In step 220 (S220), the printer selection unit 530 determines whether or not the amount of change in the γ characteristic in the range of the image element can be made equal to or less than the reference value by the correction in the selected printer, and can make it equal to or less than the reference value. In this case, the process shifts to the process of S215, and if the value cannot be equal to or less than the reference value, the process shifts to the process of S225.

  In step 225 (S225), the printer selection unit 530 determines whether or not there is an unselected printer. If there is an unselected printer, the process returns to S200 to select the next printer. If no unselected printer exists, the candidate search process (S20) is terminated.

Next, a method for determining in-plane uniformity will be described.
In this example, each printer 10 determines the in-plane uniformity of its own device in cooperation with the scanner 20, and registers the determination result in the uniformity DB 610. However, the present invention is not limited to this form. For example, the scanner 20 may be configured to determine the in-plane uniformity of each printer 10 alone and register the determination result in the uniformity DB 610.

FIG. 12 is a flowchart of the in-plane uniformity determination process (S30).
As shown in FIG. 12, in step 300 (S300), each printer 10 (FIG. 1) prints the test chart illustrated in FIG. 7A on a recording sheet.
The scanner 20 (FIG. 1) reads a test chart printed by each printer 10 and transmits image data of the read test chart to the printer 10.

In step 305 (S305), the printer 10 extracts RGB values of patches (CMY mixed colors) of each image area from the image data of the test chart received from the scanner 20.
In step 310 (S310), the printer 10 converts the RGB value of each extracted image region into a Lab value.

In step 315 (S315), the printer 10 determines, for each image area, a γ correction curve such that the converted Lab value becomes an achromatic color, and a lookup table (each density corresponding to the determined γ correction curve). The correction amount in the area is stored).
In step 320 (S320), the printer 10 evaluates the in-plane uniformity based on the Lab value of each image area. In this example, the printer 10 calculates the absolute value of the difference between Lab values between adjacent image regions for two patches, adds the two calculated absolute values, and uses the combined value as the in-plane uniformity. The evaluation value of

  In step 325 (S325), the printer 10 associates the evaluation value of in-plane uniformity and the model information of the printer (for example, the number of printed sheets per unit time) with the printer name in correspondence with the uniformity DB 610 (FIG. 3). ) And the lookup table created for each image area is registered in the correction coefficient DB 620 (FIG. 3) in association with the printer name and the image area.

[Modification]
Next, a modification of the above embodiment will be described.
In the above embodiment, the print control program 5 is installed in each printer 10, and the printer 10 that has received a print request selects an optimal printer and transfers image data to another printer or the like. It is not limited to.
Therefore, as a modification of the above-described embodiment, the print control server 40 receives a print request from the computer terminal 30, selects an optimal printer 10 according to the print request, and sends image data and correction information to the selected printer 10. A mode of transferring (lookup table) will be described.

FIG. 13 is a diagram illustrating a configuration of the second image forming system 11.
As illustrated in FIG. 13, the second image forming system 11 has a configuration in which a print control server 40 is added to the image forming system 1 in FIG. 1.
The print control server 40 has a function as a print server. Upon receiving a print request from the computer terminal 30, the print control server 40 selects the optimum printer 10 for the print request, and requests the selected printer 10 to perform print processing. .
More specifically, the print control server 40 has a functional configuration other than the image correction unit 570 and the printing unit 580 among the functional configurations shown in FIG. 3, and the layout of the image data requested for printing. The optimum printer 10 is selected based on the in-plane uniformity of each printer, and the image data is transferred to the selected printer 10 to execute the printing process. The print control server 40 reads correction information (lookup table) of the selected printer 10 from the correction coefficient DB 620 according to the layout (image element range) of the image data requested to be printed, and selects the selected printer. Forward to 10.
Note that the printer 10 according to the present modification does not need to have a functional configuration other than the image correction unit 570 and the printing unit 580 shown in FIG.

Next, a modified example regarding the in-plane uniformity determination method will be described.
FIG. 14 is a flowchart illustrating a second in-plane uniformity determination method. It should be noted that among the processes shown in this figure, the same reference numerals are assigned to the processes that are substantially the same as those shown in FIG.
As shown in FIG. 14, in S300, each printer 10 (FIG. 13) prints the test chart illustrated in FIG. 7A on a recording sheet, and the scanner 20 (FIG. 13) is printed by each printer 10. The read test chart is read, and the image data of the read test chart is transmitted to the printer 10.
In step S <b> 305, the printer 10 extracts the RGB value of the patch of each image area from the test chart image data received from the scanner 20. In S310, the printer 10 converts the extracted RGB values of each image region into Lab values.

In step 330 (S330), the printer 10 calculates a color difference between the image areas.
In step 335 (S335), the printer 10 calculates the sum of the color differences with respect to the other image regions around each image region, and sets the image region where the sum of the color differences is minimum as the reference region.
In step 340 (S340), the printer 10 compares the color difference between each image area and the reference area with a default value, and compares all the image areas with a group of image areas whose color difference with the reference area is equal to or greater than the default value. Classification is made into (color difference large group) and image area groups (color difference small group) in which the color difference from the reference area is less than a predetermined value.

In step 345 (S345), the printer 10 calculates the average value of Lab based on the Lab value of the image area of the color difference small group.
In step 350 (S350), the printer 10 determines a γ correction curve so that the calculated average value of Lab becomes an achromatic color, and creates a lookup table corresponding to the γ correction curve.

  In step 355 (S355), the printer 10 determines, for each image area in the large color difference group, a γ correction curve such that the Lab of each area is achromatic, and creates a lookup table corresponding to this γ correction curve. To do.

  In S325, the printer 10 registers the color difference between adjacent image areas in the uniformity DB 610 of the print control server 40 as an evaluation value of in-plane uniformity, and uses the lookup table created for the small color difference group as the small color difference group. The lookup table created for each image area of the large color difference group is registered in the correction coefficient DB 620 of the print control server 40 in association with these image areas.

  In the above embodiment, a relatively gradual change in density is detected by forming a patch in each image area. However, as illustrated in FIG. 15, it is uniformly in the main scanning direction or the sub-scanning direction. A relatively local density change (streak) may be detected by forming a solid streak detection patch. In this case, the printer selection unit 530 (FIG. 3) excludes printers that may cause streak in the range of image elements (photographic images or computer graphics) from the selection targets.

1 is a diagram illustrating an overall configuration of an image forming system 1. FIG. 1 is a diagram illustrating a configuration of a tandem type printer 10. FIG. It is a figure which illustrates the function structure of the printing control program 5 performed by the control apparatus 12 (FIG. 2). It is a figure which illustrates the image in which the photograph image and the font image are arrange | positioned. It is a figure which illustrates the image by which the computer graphics and the font image are arrange | positioned. 3 is a diagram illustrating characteristics of output density of the printer 10. FIG. It is a figure which illustrates a test chart. It is a figure explaining the relationship between (gamma) characteristic of a printer, and (gamma) correction curve. It is a figure which illustrates the information recorded on correction coefficient database. 6 is a flowchart illustrating an overall operation (S10) of the image forming system 1 (printing control program 5). It is a flowchart explaining the candidate search process (S20) of FIG. 10 in detail. It is a flowchart of the determination process (S30) of in-plane uniformity. It is a figure which illustrates the structure of the image forming system 11 in a modification. It is a flowchart explaining the determination method of the 2nd in-plane uniformity. It is a figure which illustrates the test chart provided with the patch for a nonuniformity detection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 ... Image forming system 10 ... Printer 12 ... Control apparatus 20 ... Scanner 30 ... Computer terminal 40 ... Print control server 5 ... Print control program 510 ... Range Identification unit 520 ... User interface unit 530 ... Printer selection unit 540 ... Correction information selection unit 550 ... Correction instruction unit 560 ... Transmission unit 570 ... Image correction unit 580 ... Printing unit

Claims (12)

Selection means for selecting an image forming apparatus based on the types of image elements included in the image data and information on uniformity of output density by each of the plurality of image forming apparatuses;
A control unit comprising: a transmission unit configured to transmit the image data to the image forming apparatus selected by the selection unit. The image data further includes a range specifying means for specifying a range in which a predetermined type of image element is arranged,
The control device according to claim 1, wherein the selection unit selects an image forming apparatus based on a range specified by the range specifying unit and uniformity in each region of the output image. The range specifying means specifies at least a range in which image elements of photographs or line images are arranged,
The control device according to claim 1, wherein the selection unit selects an image forming apparatus based on a range in which image elements of a photograph or a line image are arranged and the uniformity in the range. Correction information selecting means for selecting output density correction information based on the range specified by the range specifying means;
The correction instruction means for instructing an image forming apparatus to which image data is transmitted by the transmission means to perform density correction using the correction information selected by the correction information selection means. Control device. The control device according to claim 1, further comprising notification means for notifying a user of an image forming apparatus to which image data is transmitted by the transmission means. The control device according to claim 1, wherein the transmission unit transmits the image data to an image forming device having the fastest image forming process among the image forming devices selected by the selecting unit. For image data, range specifying means for specifying a range in which a predetermined type of image element is arranged,
Selection means for selecting an image forming apparatus from a plurality of image forming apparatuses based on the range specified by the range specifying means;
A control unit comprising: a transmission unit configured to transmit the image data to the image forming apparatus selected by the selection unit. An image forming means;
Selection means for selecting an image forming apparatus based on the types of image elements included in the image data and information on uniformity of output density by each of a plurality of image forming apparatuses including the image data;
An image forming apparatus comprising: a control unit that causes the image forming unit to execute an image forming process based on the image data when the own unit is selected by the selection unit. The image forming apparatus according to claim 8, further comprising: a transmitting unit that transmits the image data to the selected image forming apparatus when an image forming apparatus other than the image forming apparatus is selected by the selecting unit. A plurality of image forming apparatuses;
Based on the type of image element included in the image data and the information on the uniformity of output density by each of the image forming apparatuses, select any one of the image forming apparatuses, and the selected image forming apparatus An image forming system comprising: a control device that transmits image data. Based on the type of image element included in the image data and information on the uniformity of output density by each of the plurality of image forming apparatuses, the image forming apparatus is selected,
An image forming method in which the selected image forming apparatus forms an image based on the image data. Selecting an image forming apparatus based on the types of image elements included in the image data and information on uniformity of output density by each of the plurality of image forming apparatuses;
Instructing the selected image forming apparatus to perform an image forming process based on the image data.

Images