JP5233881B2 - Image data processing apparatus and liquid ejection apparatus - Google Patents

Description

  The present invention relates to an image data processing apparatus that processes image data, and a liquid ejection apparatus that records an image on a recording medium by ejecting liquid droplets from a plurality of ejection openings based on the image data.

  In the ink jet printer, if the next printed paper is stacked before the ink on the surface of the previously printed paper is dried, the next printing is performed by the ink on the surface of the previously completed paper. The back side of the completed paper may be soiled. In order to prevent this, it is necessary to adjust the timing for starting the printing of the next sheet in accordance with the drying time for drying the surface of the sheet on which printing has been completed. In continuous printing in which a plurality of sheets are continuously printed, it is preferable to accurately grasp the drying time. In this regard, the predetermined area with the highest dot density is extracted by inspecting the dot density in the predetermined area while moving the rectangular predetermined area (swath) arranged in the recording area of the paper, and the extracted predetermined area A technique for determining the drying time from the dot density is known (see Patent Document 1).

JP-A-8-230178

  Although the above-described technique can accurately detect a predetermined area having a high dot density, the recording area is inspected in a superimposed manner while moving the predetermined area, so that the processing time becomes long. Further, since the shape of the predetermined area is determined, it is impossible to extract an area corresponding to the density distribution of dots.

  An object of the present invention is to provide an image data processing apparatus and a liquid ejection apparatus capable of easily and quickly dividing a recording area into a plurality of areas having an arbitrary shape corresponding to the density distribution of an image.

  An image data processing apparatus according to the present invention includes an image data storage unit that stores image data corresponding to density values of a plurality of pixels arranged in a matrix in a recording area of a recording medium, and the plurality of pixels include one or a plurality of pixels. Block dividing means for dividing the block into a plurality of blocks, representative point arranging means for arranging a plurality of representative points in the recording area, and each of the plurality of blocks closest to each block among all the representative points. Cluster generation means for generating a plurality of clusters composed of a plurality of blocks associated with the same representative point by associating with the representative point, and a center of gravity regarding the image data in each cluster based on the image data A representative point for calculating the position and updating the representative point for each cluster to the center of gravity position for the cluster New means, and control means for repeating the update of the representative point by the representative point update means and the generation of the cluster related to the updated representative point by the cluster generation means until a predetermined condition is satisfied. .

  According to the present invention, pixels having high density values are densely moved by repeatedly moving the representative point to the center of gravity of the density distribution of pixels related to the cluster (in the case of an ink jet recording apparatus, the distribution of the ejection amount of the liquid in the cluster). A cluster is easily generated in the area, and a cluster having an arbitrary shape corresponding to the density distribution of pixels in the recording area is generated. Thereby, the recording area can be easily and quickly divided into a plurality of areas having an arbitrary shape corresponding to the density distribution of the pixels. Note that the image data corresponding to the density value of the pixel is in a form as long as it is a value related to the magnitude of the output when the image is output, such as the pixel value of the pixel itself or a value obtained by quantizing the pixel value. Does not matter.

  In the present invention, it is preferable that the predetermined condition is that a distance between the representative point before update and the representative point after update is not more than a predetermined value. According to this, it is possible to accurately generate a cluster corresponding to the density distribution of the pixels in the recording area to a necessary level.

  Alternatively, the predetermined condition may be that the representative point update by the representative point update unit and a new cluster generation by the cluster generation unit are repeated a predetermined number of times. According to this, a cluster corresponding to the density distribution of the pixels in the recording area can be generated more easily.

  In the present invention, it is preferable that the representative point arrangement means arranges the plurality of representative points so as to be arranged in a matrix in the recording area. According to this, since the density distribution of the pixels in the entire recording area can be searched efficiently, a cluster corresponding to the density distribution of the pixels can be surely generated. In addition, since arithmetic processing is reduced, a cluster corresponding to the density distribution of pixels can be generated quickly.

  A liquid ejection apparatus according to the present invention includes a conveyance mechanism that conveys a recording medium, a liquid ejection head that ejects liquid onto the recording medium that is conveyed by the conveyance mechanism, and a drying unit that dries the recording medium from which the liquid has been discharged; Among the above-described image data processing device and the average value of the image data in each finally generated cluster, as the maximum average value becomes larger, the drying time related to the drying means becomes longer. Drying control means for controlling the drying means.

  According to the present invention, the cluster having an arbitrary shape corresponding to the density distribution of the pixels in the recording area is generated by repeatedly moving the representative point to the center of gravity of the density distribution of the pixels related to the cluster. It can be easily and quickly divided into a plurality of regions having an arbitrary shape corresponding to the density distribution of the pixels. Thereby, the drying time corresponding to the density distribution of the pixels in the recording area can be determined, and the drying means can be driven efficiently.

  From another viewpoint, the liquid ejection apparatus according to the present invention includes a transport mechanism that transports a recording medium, a liquid ejection head that ejects liquid onto the recording medium transported by the transport mechanism, and a recording medium on which the liquid is ejected. Of the image data processing device described above, and the average value of the image data in each of the last generated clusters, the flattening unit increases as the maximum average value increases. And flattening control means for controlling the flattening means so as to lengthen the flattening time.

  According to the present invention, the cluster having an arbitrary shape corresponding to the density distribution of the pixels in the recording area is generated by repeatedly moving the representative point to the center of gravity of the density distribution of the pixels related to the cluster. It can be easily and quickly divided into a plurality of regions having an arbitrary shape corresponding to the density distribution of the pixels. Thereby, the flattening time corresponding to the density distribution of the pixels in the recording area can be determined, and the flattening means can be driven efficiently.

  In the present invention, it is preferable that the flattening means flatten the recording medium by electrostatic adsorption. According to this, the flattening means can be realized at low cost.

  According to the present invention, a cluster having an arbitrary shape corresponding to the density distribution of pixels in the recording area is generated by repeatedly moving the representative point to the center of gravity of the density distribution of pixels related to the cluster. Thereby, the recording area can be easily and quickly divided into a plurality of areas having an arbitrary shape corresponding to the density distribution of the pixels.

1 is a schematic plan view of an inkjet printer according to an embodiment of the present invention. It is a schematic side view of the inkjet printer shown in FIG. It is a functional block diagram of the control apparatus shown in FIG. It is a figure for demonstrating the function of the block division part shown in FIG. It is a figure for demonstrating the function of the representative point arrangement | positioning part shown in FIG. It is a figure for demonstrating the function of the representative point arrangement | positioning part shown in FIG. It is a figure for demonstrating the function of the cluster production | generation part shown in FIG. It is a figure for demonstrating the function of the representative point update part shown in FIG. It is a figure for demonstrating the function of the representative point update part shown in FIG. It is a figure for demonstrating the function of the density distribution area | region judgment part of the pixel shown in FIG. It is a figure for demonstrating the function of the representative point arrangement | positioning part shown in FIG. It is a figure for demonstrating the function of the density distribution area | region judgment part of the pixel shown in FIG. It is a figure for demonstrating the function of the density distribution area | region judgment part of the pixel shown in FIG. 4 is a flowchart illustrating an operation of the image processing apparatus illustrated in FIG. 3. It is a figure for demonstrating a modification.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the ink jet printer 101 includes a transport unit 20 that transports the paper P from the upper side to the lower side of FIG. 1, and inks of magenta, cyan, yellow, and black on the paper P transported by the transport unit 20. There are four inkjet heads 1 that respectively eject droplets, a drying device 30, a suction device 40, and a control device 16 that controls the entire inkjet printer 101. In the present embodiment, the sub-scanning direction is a direction parallel to the transport direction when the paper P is transported by the transport unit 20, and the main scanning direction is a direction orthogonal to the sub-scanning direction and along the horizontal plane. Direction.

  The transport unit 20 includes two belt rollers 6, 7, an endless transport belt 8 wound around the rollers 6, 7, and four inkjet heads 1 in a loop of the transport belt 8. And a platen 19 arranged to face each other. The belt roller 7 is a driving roller, and rotates when a driving force is applied from a conveyance motor (not shown). The belt roller 6 is a driven roller and rotates as the conveyor belt 8 travels due to the rotation of the belt roller 7. The paper P placed on the outer peripheral surface of the transport belt 8 is transported downward in FIG.

  The four inkjet heads 1 each extend along the main scanning direction and are arranged in parallel to each other in the sub-scanning direction. That is, the ink jet printer 101 is a line type color ink jet printer in which a plurality of ejection openings for ejecting ink droplets are arranged in the main scanning direction. The lower surface of each inkjet head 1 is an ejection surface on which a plurality of ejection ports from which ink droplets are ejected are arranged.

  The platen 19 is disposed so as to be in contact with the inner peripheral surface of the upper loop of the conveyor belt 8, and supports this from the inner peripheral side of the conveyor belt 8. As a result, the outer peripheral surface of the upper loop of the conveyor belt 8 and the ejection surface of the inkjet head 1 are parallel to each other, and a gap having a predetermined interval suitable for image formation is formed. When the paper P transported by the transport belt 8 passes immediately below the four ink jet heads 1, ink droplets of each color are sequentially ejected from the respective ink jet heads 1 toward the upper surface of the paper P, and are then onto the paper P. A desired color image is formed.

  The drying device 30 is disposed on the downstream side of the four inkjet heads 1 so as to face the outer peripheral surface of the conveyor belt 8. The drying device 30 dries the ink on the printing surface by blowing warm air onto the printing surface of the paper P that has passed under the four inkjet heads 1.

  The suction device 40 is disposed so as to contact the inner peripheral surface of the upper loop of the transport belt 8 and to face the drying device 30. A pair of comb-shaped electrodes (not shown) is disposed on the surface of the suction device 40 that contacts the inner peripheral surface of the transport belt 8. Each tooth electrode has a plurality of electrodes arranged in a row in the main scanning direction, and the electrodes in one and the electrodes in the other are alternately arranged in the main scanning direction. When a voltage is applied between the pair of comb electrodes, the sheet P is adsorbed via the conveyance belt 8. The suction device 40 sucks the paper P, thereby flattening the paper P and preventing the paper P dried by the drying device 30 from being bent.

  Next, the control device 16 will be described with reference to FIG. The control device 16 includes a CPU (Central Processing Unit), a program executed by the CPU, and an EEPROM (Electrically Erasable and Programmable Read Only Memory) that stores data used for these programs in a rewritable manner. It includes RAM (Random Access Memory) for temporary storage. Each functional unit constituting the control device 16 is constructed by cooperation of these hardware and software in the EEPROM. As illustrated in FIG. 3, the control device 16 includes a conveyance control unit 51, an image data processing unit 52, a head control unit 53, a drying control unit 54, and a suction control unit 55.

  The transport control unit 51 controls the transport motor of the transport unit 20 so that the paper P is transported along the transport direction.

  The image data processing unit 52 outputs image data relating to an image to be printed on the paper P to the head control unit 53, and displays the image related to the image data in eight regions corresponding to the density distribution of pixels (dot density in this embodiment). The result of the division is output to the drying control unit 54 and the adsorption control unit 55.

  The image data processing unit 52 will be described in detail. As shown in FIG. 3, the image data processing unit 52 includes an image data storage unit 61, a block division unit 62, a representative point arrangement unit 63, a cluster generation unit 64, a representative point update unit 65, and a density distribution region. And a determination unit 66.

  The image data storage unit 61 stores image data relating to an image to be printed on the paper P. In the image data, the ink discharge amount of each of the four types of ink (magenta, cyan, yellow, and black) discharged to each of a plurality of pixels arranged in a matrix in the main scanning direction and the sub-scanning direction in the printing region of the paper P. Show. As shown in FIG. 4, in the present embodiment, processing of image data relating to 768 pixels arranged in a 24 × 32 matrix will be described. In order to simplify the description, data originally represented by four types of ink ejection amounts is indicated by the presence or absence of dots for each pixel.

  As shown in FIGS. 4 and 5, the block dividing unit 62 converts 768 pixels arranged in a matrix in the print area 70 of the paper P into 48 pixels each including 16 pixels arranged in a 4 × 4 matrix. Divide into blocks 71. The print area 70 is a virtual plane developed on the memory space. 5 to 14, the ink ejection amount in each of the 48 blocks 71 divided by the block dividing unit 62 is shown by the number of dots.

  The representative point arrangement unit 63 arranges representative points 76 and 76a to 76n that serve as a reference when the print area 70 is divided. First, the representative point arrangement unit 63 calculates a centroid position related to the ink ejection amount in the print region 70 based on the image data, and arranges one representative point 76 at the calculated centroid position. Further, the representative point arrangement unit 63 repeatedly divides the representative points 76 and 76a to 76f by the density distribution region determination unit 66 described later (see FIGS. 6 and 11), and finally, the eight representative points 76g to 76n. (See FIG. 13). When the representative point placement unit 63 divides the representative points 76 and 76a to 76f, the representative points 76 and 76a to 76f are only randomly determined distances in mutually different directions based on the representative points 76 and 76a to 76f before the division. Two representative points 76a to 76n are arranged so as to be separated from the representative points 76a to 76f before the division. Note that at least one of the separation direction and the distance may be determined based on a predetermined value.

  The cluster generation unit 64 associates each of the 48 blocks 71 with the representative points 76a to 76n closest to each block 71 among all the representative points 76a to 76n, thereby associating with the same representative points 76a to 76n. Clusters 77a to 77n composed of a plurality of blocks 71 are generated (see FIGS. 7 to 13).

  Based on the image data, the representative point update unit 65 calculates the center-of-gravity position regarding the ink ejection amount in each of the clusters 77a to 77n, and the representative points 76a to 76n relate to the clusters 77a to 77n related to the representative points 76a to 76n. The positions of the representative points 76a to 76n are updated so as to be arranged at the position of the center of gravity (see FIGS. 8, 10, and 12).

  The density distribution region determination unit 66 arranges the representative points 76 and 76a to 76n by the representative point arrangement unit 63, generates the clusters 77a to 77n by the cluster generation unit 64, and sets the representative points 76a to 76n by the representative point update unit 65. The representative point arrangement unit 63, the cluster generation unit 64, and the representative point update unit 65 are controlled so that the update is repeated (detailed later). When the representative point update unit 65 updates the eight representative points 76g to 76n, the density distribution region determination unit 66 updates the representative points 76g to 76n before the update to the representative points 76g to 76n after the update. If all the distances are equal to or smaller than the predetermined value, the eight clusters 77g to 77n generated last are eight regions obtained by dividing the image related to the image data so as to correspond to the density distribution of the pixels. Judge. At this time, the density distribution region determination unit 66 outputs data indicating the eight clusters 77g to 77n to the drying control unit 54 and the adsorption control unit 55.

  The head control unit 53 drives the inkjet head 1 based on the image data stored in the image data storage unit 61 of the image data processing unit 52. Thus, ink droplets are ejected from the ejection ports so that an image is formed on the paper P.

When the density distribution region determination unit 66 of the image data processing unit 52 outputs data indicating the eight clusters 77g to 77n, the drying control unit 54 dries the paper P by the drying device 30 based on the following equation. t1 is calculated, and the drying device 30 is driven so that the paper P is dried by the drying device 30 during the calculated drying time t1.
t1 = V · αP · β / γN
V (maximum ink discharge amount): among eight clusters 77g to 77n, ink discharge amount P (congestion rate) relating to the largest cluster with the largest ink discharge amount: corresponding to the center and maximum cluster of each block 71 in the maximum cluster Sum N (proximity ratio) of values obtained by weighting the distances to the representative points 76g to 76n so as to increase as the distances to the representative points 76g to 76n become shorter: corresponding to the largest cluster Distance α between representative points 76g to 76n and other representative points 76g to 76n closest thereto (accumulation coefficient): coefficient β (shape factor) related to the density: cluster shape and paper quality of paper P (fineness of paper) ) (Proximity coefficient) determined by

  Note that the drying time t1 may be determined by other methods. For example, the drying time t1 may be determined only by the ink ejection amount related to the maximum cluster. Alternatively, it may be determined based on the maximum average value among the average values of the ink ejection amounts of the eight clusters 77g to 77n. At this time, the drying time t1 becomes longer as the ink discharge amount or the maximum average value related to the maximum cluster increases. Further, the drying time t1 may be determined by referring to a previously stored table, or may be calculated based on a predetermined formula. According to this, the drying time t1 can be easily determined.

  The suction control unit 55 drives the suction device 40 so that the paper P is flattened during the drying time t1 when the paper P is dried by the drying device 30.

  Hereinafter, the operation of the image data processing unit 52 will be described in detail with reference to FIGS. As shown in FIGS. 14 and 5, first, the representative point placement unit 63 places one representative point 76 as a reference (S101), and as shown in FIG. Dividing into points 76a and 76b (S102). As shown in FIG. 7, the cluster generation unit 64 generates clusters 77a and 77b for the divided representative points 76a and 76b (S103). Thereafter, as shown in FIG. 8, the representative point update unit 65 updates the positions of the representative points 76a and 76b to the barycentric positions related to the clusters 77a and 77b generated by the cluster generation unit 64 (S104). As shown in FIGS. 9 and 10, the density distribution region determination unit 66 determines whether or not all the distances between the representative points 76a and 76b before the update and the representative points 76a and 76b after the update are equal to or less than a predetermined value. (S105) When it is determined that the value is not less than the predetermined value (S105: NO), the cluster generation unit 64 generates the clusters 77a and 77b (S103), and the representative point update unit 65 updates the representative points 76a and 76b ( S104) is repeated.

  When the density distribution region determination unit 66 determines that all the distances between the representative points 76a and 76b before the update and the representative points 76a and 76b after the update are equal to or less than a predetermined value (S105: YES), FIG. 11 shows. As described above, the representative point arrangement unit 63 divides the representative point 76a into two representative points 76c and 76d, and divides the representative point 76b into two representative points 76e and 76f (S106). Then, as shown in FIG. 12, the cluster generation unit 64 generates clusters 77c to 77f for the representative points 76c to 76f (S107), and the representative point update unit 65 determines the positions of the representative points 76c to 76f. The cluster generation unit 64 updates the centroid positions related to the clusters 77c to 77f generated (S108). The density distribution region determination unit 66 determines whether all the distances between the representative points 76c to 76f before the update and the representative points 76c to 76f after the update are equal to or less than a predetermined value (S109), and determines that they are not equal to or less than the predetermined value. When this is done (S109: NO), the generation of clusters 77c to 77f by the cluster generation unit 64 (S107) and the update of the representative points 76c to 76f by the representative point update unit 65 (S108) are repeated.

  When the density distribution region determination unit 66 determines that all the distances between the representative points 76c to 76f before the update and the representative points 76c to 76f after the update are equal to or less than a predetermined value (S109: YES), FIG. 13 shows. As described above, the representative point arrangement unit 63 divides each of the representative points 76c to 76f into two, and arranges a total of eight representative points 76g to 76n in the printing area 70 (S110). The cluster generation unit 64 generates clusters 77g to 77n for the representative points 76g to 76n (S111), and the representative point update unit 65 generates the positions of the representative points 76g to 76n. The center of gravity regarding the clusters 77g to 77n is updated (S112). The density distribution region determination unit 66 determines whether or not all the distances between the representative points 76g to 76n before the update and the representative points 76g to 76n after the update are less than or equal to a predetermined value (S113), and determines that they are not less than the predetermined value. When this is done (S113: NO), the generation of clusters 77g to 77n by the cluster generation unit 64 (S111) and the update of the representative points 76g to 76n by the representative point update unit 65 are repeated (S112). When the density distribution region determination unit 66 determines that all the distances between the representative points 76g to 76n before the update and the representative points 76g to 76n after the update are equal to or less than a predetermined value (S113: YES), the last generated 8 It is determined that the eight clusters 77g to 77n are eight regions obtained by dividing the image related to the image data so as to correspond to the density distribution of the pixels. At this time, the density distribution region determination unit 66 outputs data indicating the eight clusters 77g to 77n to the drying control unit 54 and the adsorption control unit 55 (S114).

  The drying control unit 54 calculates the drying time t1 based on the data indicating the eight clusters 77g to 77n output from the density distribution region determination unit 66, and the paper P is loaded by the drying device 30 during the calculated drying time t1. The drying device 30 is driven so as to be dried. Further, the suction control unit 55 drives the suction device 40 so that the paper P is flattened during the drying time t1 when the paper P is dried by the drying device 30.

  As described above, according to the inkjet printer 101 of the present embodiment, the pixel density in the print region 70 of the paper P is obtained by repeatedly updating the representative points 76g to 76n to the center of gravity of the pixel density distribution related to the clusters 77g to 77n. Clusters 77g to 77n having an arbitrary shape corresponding to the distribution are generated. Thereby, the print area 70 can be easily and quickly divided into a plurality of areas having an arbitrary shape corresponding to the density distribution of the pixels.

  At this time, when all the distances between the representative points 76g to 76n before the update and the representative points 76g to 76n after the update are equal to or less than a predetermined value, the density distribution region determination unit 66 performs the eight clusters generated last. Since 77g to 77n are determined to be eight regions obtained by dividing the image related to the image data so as to correspond to the pixel density distribution, a cluster corresponding to the pixel density distribution in the print region 70 is required. It can be accurately generated to the extent.

  Further, the drying control unit 54 calculates a drying time t1 based on the eight clusters 77g to 77n generated last, and the paper P is dried by the drying device 30 during the calculated drying time t1. The drying device 30 is driven. For this reason, the drying time t1 corresponding to the density distribution of the pixels in the print region 70 is determined, and the drying device 30 can be driven efficiently.

  Further, the suction control unit 55 drives the suction device 40 so that the paper P is flattened during the drying time t1. For this reason, the drying apparatus 30 can be driven efficiently.

  Further, since the suction device 40 flattens the paper P by electrostatic suction, the suction device 40 can be realized at low cost.

<Modification>
In the present embodiment, the representative point arrangement unit 63 first determines one representative point 76, then divides the representative point 76 into two in order, and finally arranges eight representative points 76g to 76n. However, for example, as shown in FIG. 15, the representative point arrangement unit may first have eight representative points 76 g to 76 n arranged in a matrix in the print region 70. In this case, as in the above-described embodiment, the cluster generation unit 64 generates clusters 77g to 77n for the representative points 76g to 76n, and the representative point update unit 65 determines the positions of the representative points 76g to 76n as clusters. The generation unit 64 updates the barycentric positions related to the clusters 77g to 77n generated. The density distribution region determination unit 66 generates clusters 77g to 77n by the cluster generation unit 64 until all the distances between the representative points 76g to 76n before the update and the representative points 76g to 76n after the update are equal to or less than a predetermined value. And the update of each representative point 76g-76n by the representative point update part 65 should just be repeated.

  According to this, since the eight representative points 76g to 76n arranged in a matrix in the print area 70 are first determined, the eight representative points 76g to 76n are not partially dense and correspond to the pixel density distribution. Clusters 77g-77n thus produced can be generated reliably. In addition, since arithmetic processing is reduced, clusters 77g to 77n corresponding to the density distribution of pixels can be quickly generated.

  In the present modification, the eight representative points 76g to 76n may be arranged in another pattern such as a zigzag pattern as long as the eight representative points 76g to 76n are evenly arranged in the print region 70. . Moreover, the structure by which arbitrary numbers of 2-7 or 9 or more representative points are arrange | positioned initially may be sufficient.

  In the above-described embodiment, the final number of representative points is eight, but the final number of representative points is not fixed, and the ink ejection amount in a cluster belonging to a certain representative point is less than or equal to a predetermined value. In such a case, the division of the representative points may be completed. This predetermined value is, for example, 10% of the ink ejection amount in all clusters. In this case, the number of representative points is automatically determined, and the cluster can be set to a size suitable for the image data.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. In the above-described embodiment, the density distribution region determination unit 66 causes the cluster 77a by the cluster generation unit 64 until all the distances from the representative points 76a to 76f before the update to the representative points 76a to 76f after the update are equal to or less than a predetermined value. The representative points 76a to 76f are divided into two after the generation of .about.77f and the update of the representative points 76a to 76f by the representative point update unit 65 are repeated. The configuration is such that the representative points 76a to 76f are divided after the generation of the clusters 77a to 77f by the cluster generating unit 64 and the updating of the representative points 76a to 76f by the representative point updating unit 65 are repeated a predetermined number of times. May be.

  As for the division of the representative points 76 and 76a to 76f, the clusters 77a to 77f associated with the representative points 76 and 76a to 76f before the division have the largest ink discharge amount in the cluster to which the representative points before the division belong. Two representative points 76a to 76n may be arranged at the midpoint position between the upper two blocks and the representative point before division. In this case, when there are three or more upper two blocks having the largest ink ejection amount due to the presence of blocks having the same ink ejection amount, the block closer to the representative point before the division is selected.

  Further, in the above-described embodiment, the density distribution region determination unit 66 is generated when all the distances from the representative points 76g to 76n before the update to the representative points 76g to 76n after the update are equal to or less than a predetermined value. The eight clusters 77g to 77n are determined to be eight regions obtained by dividing the image related to the image data so as to correspond to the density distribution of the pixels. The eight clusters 77g to 77n after the generation of the clusters 77g to 77n by the unit 64 and the update of the representative points 76g to 76n by the representative point updating unit 65 are repeated a predetermined number of times, are related to the image data. A configuration may be adopted in which it is determined that the image is divided into eight regions corresponding to the pixel density distribution. According to this, it is possible to easily generate eight clusters 77g to 77n that are eight regions obtained by dividing an image related to image data so as to correspond to the density distribution of pixels.

  In addition, in the above-described embodiment, the representative point arrangement unit 63 is configured to divide each representative point 76, 76a to 76f into two representative points 76a to 76n, but is configured to divide into three or more representative points. It may be.

  Furthermore, in the above-described embodiment, the density distribution region determination unit 66 determines whether the eight clusters 77g to 77n generated last correspond to the image data image corresponding to the pixel density distribution. However, the configuration may be such that the density distribution region determination unit determines whether or not 2 to 7 or 9 or more clusters correspond to an image related to image data with a pixel density distribution.

  In addition, in the above-described embodiment, the 768 pixels arranged in a matrix in the print area 70 of the paper P are divided into 48 blocks 71 including 16 pixels arranged in a 4 × 4 square matrix. However, the print area 70 may be divided into blocks made up of a plurality of pixels arranged in a square matrix in an arbitrary number such as 2 × 2, 3 × 3, 5 × 5, or 2 × 3. It may be divided into blocks each composed of a plurality of pixels arranged in a matrix such as 4 × 5, or one pixel may be a single block.

  In the above-described embodiment, the image data processing unit 52 is configured to process the image data with the ink discharge amount of each pixel as the total value of the four types of ink, but the image data is processed for each type of ink. May be. At this time, the drying control unit calculates the drying time for each type of ink, and selects and uses the maximum drying time among the calculated drying times.

  Furthermore, in the above-described embodiment, the inkjet printer 101 is configured to include the drying device 30, but may be configured not to include the drying device 30. In this case, it is preferable that the drying time t1 is calculated as the time required for the paper P to be naturally dried, and the conveyance speed of the paper P is determined based on the calculated drying time t1.

  In addition, in the above-described embodiment, the ink jet printer 101 has the configuration having the electrostatic suction type suction device 40, but may have a configuration having another type of suction device such as an air suction type. A configuration without an adsorption device may be used.

  Further, in the above-described embodiment, the drying device 30 and the suction device 40 are disposed so as to face each other with the conveying belt 8 interposed therebetween. However, the drying device 30 and the suction device 40 include four inkjet heads 1. As long as it is on the downstream side in the transport direction, it may be disposed at an arbitrary location separated from the transport belt 8.

  The present invention is also applicable to a recording apparatus that ejects liquid other than ink. Further, the present invention is not limited to a printer, and can be applied to a facsimile, a copier, and the like.

  In the above-described embodiment, the example in which the present invention is applied to the ink jet printer 101 has been described. However, the present invention can also be applied to an image data processing apparatus having an independent image data processing unit.

DESCRIPTION OF SYMBOLS 1 Inkjet head 16 Control apparatus 19 Platen 20 Conveyance unit 30 Drying apparatus 40 Adsorption apparatus 51 Conveyance control part 52 Image data processing part 53 Head control part 54 Drying control part 55 Adsorption control part 61 Image data storage part 62 Block division part 63 Representative point Arrangement unit 64 Cluster generation unit 65 Representative point update unit 66 Density distribution region determination unit 71 Blocks 76, 76a to 76n Representative points 77a to 77n Cluster 101 Inkjet printer

Claims (7)

Image data storage means for storing image data corresponding to density values of a plurality of pixels arranged in a matrix in a recording area of the recording medium;
Block dividing means for dividing the plurality of pixels into a plurality of blocks composed of one or a plurality of pixels;
Representative point arrangement means for arranging a plurality of representative points in the recording area;
By associating each of the plurality of blocks with the representative point closest to each block among all the representative points, a plurality of clusters composed of the plurality of blocks associated with the same representative point are generated. Cluster generation means;
Based on the image data, a centroid position related to the image data in each cluster is calculated, and the representative point update means for updating the representative point related to each cluster to the centroid position related to the cluster,
Control means for repeating the update of the representative point by the representative point update means and the generation of the cluster for the representative point updated by the cluster generation means until a predetermined condition is satisfied. An image data processing apparatus.   The image data processing apparatus according to claim 1, wherein the predetermined condition is that a distance between the representative point before update and the representative point after update is equal to or less than a predetermined value.   The predetermined condition is that the update of the representative point by the representative point update unit and the generation of the new cluster by the cluster generation unit are repeated a predetermined number of times. Image data processing device.   The image data processing apparatus according to claim 1, wherein the representative point arrangement unit arranges the plurality of representative points so as to be arranged in a matrix in the recording area. A transport mechanism for transporting the recording medium;
A liquid ejection head that ejects liquid onto the recording medium conveyed by the conveyance mechanism;
Drying means for drying the recording medium on which the liquid has been discharged;
An image data processing device according to any one of claims 1 to 4,
The drying control means for controlling the drying means so that the drying time related to the drying means becomes longer as the maximum average value among the average values of the image data in the last generated clusters increases. A liquid ejection apparatus comprising: A transport mechanism for transporting the recording medium;
A liquid ejection head that ejects liquid onto the recording medium conveyed by the conveyance mechanism;
Flattening means for flattening the recording medium on which the liquid is discharged;
An image data processing device according to any one of claims 1 to 4,
The flattening unit is controlled so that the flattening time related to the flattening unit becomes longer as the maximum average value among the average values of the image data in each finally generated cluster increases. A liquid discharge apparatus comprising: a flattening control unit.   The liquid ejecting apparatus according to claim 6, wherein the flattening unit flattens the recording medium by electrostatic adsorption.

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