JP2018065302A - Image processing device, printing system, image processing method, and program - Google Patents

Abstract

An image processing apparatus capable of more appropriately correcting uneven printing due to a pitch shift of dots constituting a print image. An image processing apparatus includes: a print data generation unit that generates print data for causing a printer to print a print image formed by a plurality of dots based on the image data; and a dot size. A correction unit 202 that corrects dot data indicating the image data. The correction unit 202 corresponds to an image density of a predetermined print area SA of a print image printed by the printer 100 and a corrected print area RA including the predetermined print area SA. The dot data is corrected based on the area correction information RD that designates the correction content of each dot data to be corrected. [Selection] Figure 11

Description

  The present invention relates to an image processing apparatus, a printing system including the image processing apparatus, an image processing method, and a program for executing the image processing method.

  In a printing apparatus such as an ink jet printer, various techniques for suppressing a decrease in print quality due to a positional deviation of dots (landing droplets formed by ink droplets) forming a printed image are being studied. For example, in Patent Document 1, when the pitch of adjacent landing droplets is deviated from a predetermined pitch, an instruction is output to the inkjet recording apparatus so that the size of the area of the formed landing droplets is different from the predetermined size. An ink jet recording apparatus control apparatus (image processing apparatus) including a discharge instruction means is described. According to this inkjet recording apparatus control apparatus, it is possible to form a high-quality image.

JP 2006-51617 A

  However, the control device for an ink jet recording apparatus described in Patent Document 1 has a problem that the image quality may be deteriorated by warping. That is, the image quality is reduced by forming landing droplets (dots) having a size different from the predetermined size, rather than the degree of image quality deterioration caused by the difference between adjacent landing droplets (dots) with respect to the predetermined pitch. The problem is that the degree may become larger. Specifically, for example, in an image having a low image density (landing droplet (dot) density), when the pitch of adjacent landing droplets (dots) is larger than a predetermined pitch, a predetermined amount corresponding to that is set. When larger landing droplets (dots) with respect to the size are formed, the density unevenness that is visually recognized may become more conspicuous.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following application examples or forms.

  Application Example 1 An image processing apparatus according to this application example includes a print data generation unit that generates, based on image data, print data for causing the printing apparatus to print a print image formed by a plurality of dots. A correction unit that corrects dot data indicating the size of the dots, and the correction unit includes an image density of a predetermined print area of the print image printed by the printing apparatus and a correction including the predetermined print area. The dot data is corrected based on area correction information for designating correction contents for each dot of the dot data corresponding to a print area.

  According to this application example, the correction unit specifies the image density of the predetermined print area of the print image printed by the printing apparatus and the correction content for each dot of the dot data corresponding to the correction print area including the predetermined print area. The dot data is corrected based on the correction information. Since dot data is corrected based on the image density of a predetermined print area of a print image printed by the printing apparatus, more appropriate correction can be performed on the density of the print image. In addition, since dot data is corrected based on area correction information that specifies correction contents for each dot of dot data corresponding to a correction print area including a predetermined print area of a print image printed by the printing apparatus, the correction print area unit is corrected. Correction can be performed based on more appropriately set information.

  Application Example 2 In the image processing apparatus according to the application example, when the image density corresponding to the predetermined print area obtained from the print data exceeds a predetermined value, the correction unit performs the correction. Features.

  According to this application example, when the image density corresponding to the predetermined print area obtained from the print data exceeds a predetermined value, the correction unit performs correction. That is, when the image density obtained from the print data is equal to or lower than a predetermined value, no correction is performed. Therefore, depending on the image density, it is possible to prevent the correction from being performed when the effect of performing the correction cannot be obtained or when the reverse effect is assumed.

  Application Example 3 In the image processing apparatus according to the application example described above, the area correction information includes a correction priority dot table in which a correction priority for each dot of the dot data corresponding to the correction print area is determined. It is characterized by being.

  According to this application example, the area correction information for specifying the correction content for each dot of the dot data corresponding to the correction print area including the predetermined print area is the correction priority for each dot of the dot data corresponding to the correction print area. A predetermined correction priority dot table is included. That is, based on the image density of a predetermined print area of a print image printed by the printing apparatus, correction can be performed for each corrected print area, and stepwise according to the correction priority set for each dot in the area. Correction can be performed.

  Application Example 4 In the image processing apparatus according to the application example described above, when n and m are integers of 4 or more, the correction priority dot table has n × m corresponding to the dot arrangement in the correction print area. It is a matrix table.

  According to this application example, since the correction priority dot table in which the correction priority for each dot is determined is a matrix table having a size of 4 × 4 or more corresponding to the dot arrangement of the correction print area, 4 × 4. It is possible to perform correction set more appropriately in the wider area.

  Application Example 5 In the image processing apparatus according to the application example described above, when the image density of the predetermined print area is lower than a predetermined density, the correction unit is set in the correction priority dot table based on the degree. The dot data corresponding to the corrected print area is corrected in order of the correction priority so that the size of the dot is increased.

  According to this application example, when the image density of the predetermined print area is lower than the predetermined density, the correction unit supports the correction print areas in the order of the correction priorities set in the correction priority dot table based on the degree. The dot data to be corrected is corrected so that the dot size becomes large. That is, when the image density is lower than the predetermined density, correction can be performed to a more appropriate image density by correcting the dot size to be larger. In addition, since dot size correction is performed in the order of correction priorities set in advance in the correction priority dot table, more appropriate correction can be performed.

  Application Example 6 In the image processing apparatus according to the application example described above, when the image density of the predetermined print area is higher than a predetermined density, the correction unit is determined in the correction priority dot table based on the degree. The dot data corresponding to the corrected print area is corrected in order of the correction priority so that the size of the dot is reduced.

  According to this application example, when the image density of the predetermined print area is higher than the predetermined density, the correction unit corresponds to the correction print areas in the order of the correction priorities set in the correction priority dot table based on the degree. The dot data to be corrected is corrected so that the dot size becomes small. That is, when the image density is higher than the predetermined density, correction can be performed to a more appropriate image density by correcting the dot size to be small. In addition, since dot size correction is performed in the order of correction priorities set in advance in the correction priority dot table, more appropriate correction can be performed.

  Application Example 7 In the image processing apparatus according to the application example, the area correction information includes a dot correction table that specifies a correction level for each dot of the dot data corresponding to the corrected print area. It is characterized by that.

  According to this application example, the area correction information for specifying the correction content for each dot of the dot data corresponding to the correction print area including the predetermined print area specifies the correction level for each dot of the dot data corresponding to the correction print area. And a dot correction table to be configured. That is, based on the image density of a predetermined print area of a print image printed by the printing apparatus, correction can be performed in units of corrected print areas, and more appropriate according to the correction level specified for each dot in the area. Correction can be performed.

  Application Example 8 In the image processing apparatus according to the application example, when n and m are integers of 4 or more, the dot correction table is an n × m matrix corresponding to the dot arrangement in the correction print area. It is a table.

  According to this application example, the dot correction table for designating the correction level for each dot of the dot data corresponding to the correction print area is a matrix table having a size of 4 × 4 or more corresponding to the dot arrangement of the correction print area. Therefore, it is possible to perform correction set more appropriately in a wider area of 4 × 4 or more.

  Application Example 9 In the image processing apparatus according to the application example described above, the correction unit may select the difference from a plurality of dot correction tables corresponding to the degree of difference between the image density of the predetermined print area and the predetermined density. The dot correction table is selected according to the degree, and the correction is performed.

  According to this application example, there are a plurality of dot correction tables that specify the correction level for each dot of the dot data corresponding to the correction print area, corresponding to the degree of difference between the image density of the predetermined print area and the predetermined density, The correction unit performs correction by selecting a dot correction table corresponding to the degree of difference from the plurality of dot correction tables. Therefore, it is possible to perform correction more appropriately according to the degree of difference between the image density of the predetermined print area and the predetermined density.

  Application Example 10 A printing system according to this application example includes the image processing apparatus according to the application example, and a printing apparatus that performs printing based on print data generated by the image processing apparatus. To do.

  According to this application example, since the printing system includes the image processing apparatus described in the application example, it is possible to obtain a print image corrected more appropriately.

  Application Example 11 An image processing method according to this application example includes a print data generation step of generating print data for causing a printing apparatus to print a print image formed by a plurality of dots based on the image data; A correction step of correcting dot data indicating the size of the dot included in the print data, and the correction step includes an image density of a predetermined print area of the print image printed by the printing apparatus, and It is a step of correcting the dot data based on area correction information that specifies the correction content for each dot of the dot data corresponding to the corrected print area including the predetermined print area.

  According to this application example, the image processing method includes: a print data generation step for generating print data for causing the printing apparatus to print a print image formed by a plurality of dots based on the image data; And a correction step of correcting dot data indicating the size of the dots. In addition, the correction process includes an image density of a predetermined print area of a print image printed by the printing apparatus, and area correction information that specifies correction contents for each dot of dot data corresponding to the corrected print area including the predetermined print area. This is a step of correcting dot data based on the above. Since dot data is corrected based on the image density of a predetermined print area of a print image printed by the printing apparatus, more appropriate correction can be performed on the density of the print image. In addition, since dot data is corrected based on area correction information that specifies correction contents for each dot of dot data corresponding to a correction print area including a predetermined print area of a print image printed by the printing apparatus, the correction print area unit is corrected. Correction can be performed based on more appropriately set information.

  Application Example 12 A program according to this application example causes an image processing apparatus to function including the image processing method described in the application example.

  According to this application example, the program causes the image processing apparatus to function including the image processing method described in the above application example, so that the print image corrected more appropriately with respect to the printing apparatus including the image processing apparatus. Can be printed.

1 is a front view illustrating a configuration of a printing system according to a first embodiment. 1 is a block diagram illustrating a configuration of a printing system according to a first embodiment. Illustration of basic functions of printer driver in the prior art Plan view showing the configuration of the print head Conceptual image imagining the size of small dots, medium dots, and large dots Conceptual diagram showing an example of streaks Conceptual diagram showing another example of streaks Conceptual diagram showing correction to reduce unevenness in density due to dot gaps Conceptual diagram showing correction to reduce unevenness in density due to overlapping dots Conceptual diagram showing an example of a predetermined area Conceptual diagram showing the configuration of the functions of the printer driver provided in the image processing apparatus Conceptual diagram showing an example of a correction priority dot table Flowchart explaining a series of correction processing Conceptual diagram for explaining relationships such as predetermined density, predetermined threshold, and degree of difference Conceptual diagram for explaining an example of a dot correction table Conceptual diagram showing an example of a dot correction table for correcting black lines Conceptual diagram showing an example of a dot correction table for correcting black lines Conceptual diagram showing an example of a dot correction table for correcting black lines Conceptual diagram showing an example of a dot correction table for correcting black lines

  DESCRIPTION OF EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention. In the following drawings, the scale may be different from the actual scale for easy understanding. Further, in the coordinates added to the drawings, the Z-axis direction is the vertical direction, the + Z direction is the upward direction, the X-axis direction is the front-rear direction, the -X direction is the forward direction, the Y-axis direction is the left-right direction, and the + Y direction is the left direction. The XY plane is a horizontal plane.

(Embodiment 1)
FIG. 1 is a front view showing a configuration of a printing system 1 according to the first embodiment, and FIG. 2 is a block diagram of the same.
The printing system 1 includes a printer 100 as a “printing apparatus” and an image processing apparatus 110 connected to the printer 100. The printer 100 is an ink jet printer that prints a desired image on a roll paper 5 as a long “print medium” supplied in a rolled state based on print data received from the image processing apparatus 110. It is.

<Basic configuration of image processing apparatus>
The image processing apparatus 110 includes a printer control unit 111, an input unit 112, a display unit 113, a storage unit 114, and the like, and controls a print job that causes the printer 100 to perform printing. The image processing apparatus 110 is configured using a personal computer as a preferred example.
Software that operates the image processing apparatus 110 includes general image processing application software (hereinafter referred to as an application) that handles image data to be printed, print data for controlling the printer 100 and causing the printer 100 to execute printing. Includes printer driver software to be generated (hereinafter referred to as printer driver).
That is, the image processing apparatus 110 generates print data for causing the printer 100 to execute printing based on the image data.

The printer control unit 111 includes a CPU 115, an ASIC 116, a DSP 117, a memory 118, a printer interface unit (I / F) 119, and the like, and performs centralized management of the entire printing system 1.
The input unit 112 is information input means as a human interface. Specifically, for example, a port to which a keyboard or an information input device is connected.
The display unit 113 is an information display unit (display) as a human interface, and is related to information input from the input unit 112, an image to be printed on the printer 100, and a print job under the control of the printer control unit 111. Information etc. are displayed.
The storage unit 114 is a rewritable storage medium such as a hard disk drive (HDD) or a memory card. The storage unit 114 stores software (a program operated by the printer control unit 111) that operates the image processing apparatus 110, images to be printed, and print jobs. Related information and the like are stored.
The memory 118 is a storage medium that secures an area for storing a program for the CPU 115 to operate, a work area for the operation, and the like, and includes a storage element such as a RAM or an EEPROM.

<Basic configuration of printer 100>
The printer 100 includes a printing unit 10, a moving unit 20, a control unit 30, and the like. The printer 100 that has received the print data from the image processing apparatus 110 controls the printing unit 10 and the moving unit 20 by the control unit 30 to print an image on the roll paper 5 (image formation).
The print data is image formation data obtained by converting image data so that the printer 100 can print the image data using an application and printer driver included in the image processing apparatus 110, and includes a command for controlling the printer 100.
The image data includes, for example, general full color image information or text information obtained by a digital camera or the like.

The printing unit 10 includes a head unit 11, an ink supply unit 12, and the like.
The moving unit 20 includes a scanning unit 40, a transport unit 50, and the like. The scanning unit 40 includes a carriage 41, a guide shaft 42, a carriage motor (not shown), and the like. The conveyance unit 50 includes a supply unit 51, a storage unit 52, a conveyance roller 53, a platen 55, and the like.

  The head unit 11 includes a print head 13 and a head control unit 14 having a plurality of nozzles (nozzle rows) that eject printing ink (hereinafter referred to as ink) as ink droplets. The head unit 11 is mounted on the carriage 41 and reciprocates in the scanning direction along with the carriage 41 moving in the scanning direction (X-axis direction shown in FIG. 1). While the head unit 11 (printing head 13) moves in the scanning direction, the ink droplets are ejected onto the roll paper 5 supported by the platen 55 under the control of the control unit 30 to thereby form a row of dots along the scanning direction. (Raster line) is formed on the roll paper 5.

The ink supply unit 12 includes an ink tank and an ink supply path (not shown) that supplies ink from the ink tank to the print head 13.
As the ink, for example, as an ink set made of a dark ink composition, a four-color ink set obtained by adding black (K) to a three-color ink set of cyan (C), magenta (M), and yellow (Y), etc. There is. Further, for example, eight colors including ink sets such as light cyan (Lc), light magenta (Lm), light yellow (Ly), and light black (Lk) made of a light ink composition in which the density of each color material is lightened. There are ink sets. The ink tank, the ink supply path, and the ink supply path to the nozzle that ejects the same ink are provided independently for each ink.

A piezo method is used as a method for ejecting ink droplets (inkjet method). The piezo method is a method in which a pressure corresponding to a print information signal is applied to ink stored in a pressure chamber by a piezoelectric element (piezo element), and ink droplets are ejected (discharged) from a nozzle communicating with the pressure chamber for printing.
The method for ejecting ink droplets is not limited to this, and other printing methods may be used in which ink is ejected in droplets to form dot groups on a print medium.

The moving unit 20 (scanning unit 40, conveying unit 50) moves the roll paper 5 relative to the head unit 11 (printing head 13) under the control of the control unit 30.
The guide shaft 42 extends in the scanning direction and supports the carriage 41 in a slidable contact state, and the carriage motor serves as a driving source for reciprocating the carriage 41 along the guide shaft 42. That is, the scanning unit 40 (carriage 41, guide shaft 42, carriage motor) moves the carriage 41 (that is, the print head 13) in the scanning direction along the guide shaft 42 under the control of the control unit 30.

The supply unit 51 rotatably supports a reel on which the roll paper 5 is wound in a roll shape, and sends the roll paper 5 to the conveyance path. The storage unit 52 rotatably supports a reel that winds up the roll paper 5, and winds up the roll paper 5 that has been printed from the conveyance path.
The transport roller 53 includes a drive roller that moves the roll paper 5 in the transport direction (Y-axis direction shown in FIG. 1) that intersects the scanning direction, a driven roller that rotates as the roll paper 5 moves, and the like. Is conveyed from the supply unit 51 to the storage unit 52 via the printing region of the printing unit 10 (the region in which the print head 13 scans and moves on the upper surface of the platen 55).

The control unit 30 includes an interface unit (I / F) 31, a CPU 32, a memory 33, a drive control unit 34, and the like, and controls the printer 100.
The interface unit 31 is connected to the printer interface unit 119 of the image processing apparatus 110 and transmits / receives data between the image processing apparatus 110 and the printer 100. The image processing apparatus 110 and the printer 100 may be directly connected by a cable or the like, or may be indirectly connected via a network or the like. Further, data transmission / reception may be performed between the image processing apparatus 110 and the printer 100 via wireless communication.
The CPU 32 is an arithmetic processing device for controlling the entire printer 100.
The memory 33 is a storage medium that secures an area for storing a program for the CPU 32 to operate, a work area for the operation, and the like, and includes a storage element such as a RAM or an EEPROM.
The CPU 32 controls the printing unit 10 and the moving unit 20 via the drive control unit 34 according to the program stored in the memory 33 and the print data received from the image processing apparatus 110.

The drive control unit 34 controls the drive of the printing unit 10 (head unit 11 and ink supply unit 12) and the moving unit 20 (scanning unit 40 and transport unit 50) based on the control of the CPU 32. The drive control unit 34 includes a movement control signal generation circuit 35, a discharge control signal generation circuit 36, and a drive signal generation circuit 37.
The movement control signal generation circuit 35 is a circuit that generates a signal for controlling the movement unit 20 (scanning unit 40, conveyance unit 50) in accordance with an instruction from the CPU 32.
The ejection control signal generation circuit 36 generates a head control signal for selecting a nozzle for ejecting ink, selecting an ejection amount, controlling ejection timing, and the like according to an instruction from the CPU 32 based on the print data. It is.
The drive signal generation circuit 37 is a circuit that generates a basic drive signal including a drive signal for driving the piezoelectric element of the print head 13.
The drive control unit 34 selectively drives the piezoelectric elements corresponding to the respective nozzles based on the head control signal and the basic drive signal.

  With the above configuration, the control unit 30 moves the carriage 41 that supports the print head 13 along the guide shaft 42 with respect to the roll paper 5 supplied to the printing region by the conveyance unit 50 (the supply unit 51 and the conveyance roller 53). Roll paper in the transport direction (+ Y direction) intersecting the scanning direction by the transport unit 50 (transport roller 53) and the pass operation of ejecting (applying) ink droplets from the print head 13 while moving in the scanning direction (X-axis direction) A desired image is formed (printed) on the roll paper 5 by repeating the conveying operation of moving the paper 5.

<Basic functions of the printer driver in the prior art>
FIG. 3 is an explanatory diagram of basic functions of a printer driver in the prior art.
Printing on the roll paper 5 is started when print data is transmitted from the image processing apparatus 110 to the printer 100. The print data is generated by the printer driver. That is, the printer driver has a function as a “print data generation unit” described later.
Hereinafter, print data generation processing in the prior art will be described with reference to FIG.

  The printer driver receives image data from the application, converts it into print data in a format that can be interpreted by the printer 100, and outputs the print data to the printer 100. When converting image data from an application into print data, the printer driver performs resolution conversion processing, color conversion processing, halftone processing, rasterization processing, command addition processing, and the like.

The resolution conversion process is a process for converting the image data output from the application into a resolution (printing resolution) when printing on the roll paper 5. For example, when the print resolution is specified as 720 × 720 dpi, the vector format image data received from the application is converted into bitmap format image data having a resolution of 720 × 720 dpi. Each pixel data of the image data after the resolution conversion process is composed of pixels arranged in a matrix. Each pixel has a gradation value of, for example, 256 gradations in the RGB color space. That is, the pixel data after resolution conversion indicates the gradation value of the corresponding pixel.
Pixel data corresponding to one column of pixels arranged in a predetermined direction among pixels arranged in a matrix is called raster data. The predetermined direction in which the pixels corresponding to the raster data are arranged corresponds to the moving direction (scanning direction) of the print head 13 when printing an image.

The color conversion process is a process for converting RGB data into data in the CMYK color system space. The CMYK colors are cyan (C), magenta (M), yellow (Y), and black (K), and the image data in the CMYK color system space is data corresponding to the ink color that the printer 100 has. Therefore, for example, when the printer 100 uses 10 types of inks of the CMYK color system, the printer driver generates image data in a 10-dimensional space of the CMYK color system based on the RGB data.
This color conversion processing is performed based on a table (color conversion lookup table LUT) in which gradation values of RGB data and gradation values of CMYK color system data are associated with each other. Note that the pixel data after the color conversion processing is, for example, CMYK color system data of 256 gradations represented by the CMYK color system space.

  The halftone process is a process of converting high gradation number (256 gradations) data into gradation number data that can be formed by the printer 100. By this halftone processing, data indicating 256 gradations indicates, for example, 1-bit data indicating 2 gradations (with or without dots) or 4 gradations (without dots, small dots, medium dots, large dots). Converted to 2-bit data. Specifically, from the dot generation rate table corresponding to the gradation value (0 to 255) and the dot generation rate, the dot generation rate corresponding to the gradation value (for example, in the case of 4 gradations, no dot, small Pixel data is created so that dots are formed in a dispersed manner using the dither method, error diffusion method, etc. at the obtained generation rate. The

  The rasterizing process is a process of rearranging pixel data arranged in a matrix (for example, 1-bit or 2-bit data as described above) according to the dot formation order at the time of printing. The rasterizing process includes an allocating process for allocating image data composed of pixel data after halftone processing to each pass operation in which the print head 13 (nozzle array) ejects ink droplets while scanning and moving. When the allocation process is completed, the pixel data arranged in a matrix is allocated to the actual nozzles forming each raster line constituting the print image.

The command addition process is a process for adding command data corresponding to the printing method to the rasterized data. The command data includes, for example, transport data related to transport specifications (such as the amount of movement and speed in the transport direction) of the print medium (roll paper 5).
These processes by the printer driver are performed by the ASIC 116 and the DSP 117 (see FIG. 2) under the control of the CPU 115, and the generated print data is transmitted to the printer 100 via the printer interface unit 119 by the print data transmission process. Is done.

<Nozzle row>
FIG. 4 is a plan view showing the configuration of the print head 13.
The print head 13 includes the above-described eight inks (cyan (C), magenta (M), yellow (Y), black (K), light cyan (Lc), light magenta (Lm), light yellow (Ly), and light. It is configured as an aggregate in which eight ink ejection heads 131 corresponding to black (Lk) are bundled in the scanning direction (X-axis direction).
In each ink discharge head 131, 32 nozzle chips 132 are arranged in two rows in the X-axis direction so as to form a staggered arrangement.
In the nozzle chip 132, nozzles with 400 holes per row are formed in two rows in the X-axis direction at intervals of 360 per inch.
With such a configuration, the print head 13 can form 25000 dots of 8 colors in the transport direction (Y-axis direction) at a pitch of 720 (720 dpi) per inch.

<Print density unevenness>
In the printing system 1 having the above-described configuration, the density unevenness of the printed image and the stripe unevenness visually recognized in the scanning direction due to the pitch deviation of the dots formed on the roll paper 5 and the variation in the size of the ink droplets to be ejected. May occur.

There are various factors that cause the pitch deviation of dots. For example, as a result of manufacturing variations of the print head 13, there is a result of assembly accuracy of a plurality of nozzle chips 132. If there is an error in the assembly position of the nozzle tip 132, the pitch of the dots formed by the nozzle located at the joint between the adjacent nozzle tips 132 may deviate from a predetermined pitch.
Further, for example, there is one based on the feeding accuracy in the transport system of the roll paper 5. If there is an error in the feed amount of the roll paper 5, the positional relationship of dots before and after feeding, that is, the dot pitch may deviate from a predetermined pitch.
Further, for example, there is a method depending on the processing accuracy of the nozzle formed in the nozzle tip 132. When the processing accuracy of the nozzles varies, dot pitch deviation occurs when the direction in which ink is ejected varies.
Factors that cause variations in the size of ejected ink droplets include, for example, nozzle processing accuracy and changes in the operating nozzle state (such as thickened ink and foreign matter adhering to the periphery of the nozzle tip). is there.

FIG. 5 is a conceptual diagram for imagining the sizes of the small dots, medium dots, and large dots described above, which are indicated by small dots DS, medium dots DM, and large dots DL, respectively.
FIG. 6 is a conceptual diagram illustrating an example of streak unevenness. FIG. 6 shows a case where the dot pitch formed by the nozzle located at the joint between the nozzle tip 132a and the nozzle tip 132b is printed from the predetermined pitch P1 in the whole surface printing with the medium dots DM (the dots are spread at the minimum pitch). A case where the pitch P2 is larger than P1 is shown. In this case, uneven stripes having low density due to the gaps between dots formed in the area of the pitch P2 (uneven spots that form white stripes when black dots are formed on the white roll paper 5) are visually recognized.

FIG. 7 is a conceptual diagram showing another example of streaks.
FIG. 7 shows a case where the pitch of the dots formed by the nozzle located at the joint between the nozzle tip 132a and the nozzle tip 132b is printed from the predetermined pitch P1 in the whole surface printing with the medium dots DM (the dots are spread at the minimum pitch). A case where the pitch P3 is smaller than P1 is shown. In this case, streaks with high density due to overlapping of dots formed in the area of the pitch P3 (unevenness that becomes black streaks when black dots are formed on the white roll paper 5) are visually recognized.

When such a stripe unevenness is recognized, the visually recognized stripe unevenness can be reduced by performing correction for changing the dot size of the region where the stripe unevenness occurs.
FIG. 8 shows a correction for increasing the dot size (changing the medium dot DM to the large dot DL) in the region where the gap is generated in order to reduce the uneven stripe density that is lowered due to the dot gap as shown in FIG. This shows an example in which a decrease in density is suppressed by performing.
Further, in FIG. 9, in order to reduce the stripe unevenness in which the density increases due to the overlapping of dots as shown in FIG. 7, the dot size of the area where the dots overlap is reduced (the medium dot DM is changed to the small dot DS). An example is shown in which an increase in density is suppressed by performing correction.

  Such correction can be performed by clarifying correction target pixel data and correction contents (dot size replacement contents) for pixel data arranged in a matrix after rasterization. That is, it can be performed by providing the printer driver with a correction function. Specifically, pixel data arranged in a matrix in the correction function of the printer driver based on information obtained by capturing a print image and evaluating the position (dot pitch) of the formed dots by image processing or the like Among these, correction (dot size change) is performed on the pixel data determined to be corrected.

  However, such a correction has a problem that the image quality may be lowered. That is, the degree of deterioration in image quality due to forming dots having a size different from the predetermined size by performing correction, rather than the degree of deterioration in image quality due to the difference in pitch between adjacent dots with respect to the predetermined pitch. This is a problem that sometimes becomes larger. Specifically, for example, in an image having a low image density (dot density), if the pitch of adjacent dots is larger than a predetermined pitch, a dot corresponding to the predetermined size is larger. In some cases, the density unevenness that is visually recognized becomes more conspicuous.

<Correction Function of Image Processing Device According to this Embodiment>
On the other hand, the image processing apparatus 110 according to the present embodiment corrects the image density of the predetermined print area of the print image printed by the printer 100 and the correction content for each dot of the dot data corresponding to the correction print area including the predetermined print area. The dot data is corrected on the basis of the area correction information for designating.
This will be specifically described below.

<Evaluation of print image>
First, evaluation of a print image for determining a correction target area, a correction degree, and the like will be described. The image processing apparatus 110 determines whether or not correction is necessary, a correction target area, a correction degree, and the like based on print image evaluation data obtained as a result of print image evaluation and print data to be corrected.
There are several evaluation modes for evaluating a printed image. Specifically, a full area evaluation mode for performing evaluation over the entire surface of the printable area (printable area) of the printer 100, and a predetermined area evaluation for evaluating an area (predetermined area) set in advance according to the specifications of the printer 100 Mode, a designated area evaluation mode in which an area designated by the user of the printer 100 (designated area) is evaluated.

<Full evaluation mode>
The full evaluation mode is an evaluation mode in which a print image printed on the entire printable area of the printer 100 is captured, and the degree of printing unevenness is digitized together with the position information by image processing.
The digitization of the degree of printing unevenness divides a captured print image into predetermined areas (hereinafter referred to as predetermined print areas SA), and the density measured for each predetermined print area SA (predetermined print area SA obtained by image processing). Is stored together with position information of the predetermined print area SA. The information to be stored may not be information on all the predetermined printing areas SA but only information on the predetermined printing areas SA in which the difference from the ideal density (gradation value) without uneven printing exceeds a predetermined threshold. .
The predetermined threshold is a preset threshold that determines whether or not to perform correction, and is a value of a difference between an ideal density (tone value) and a predetermined density.
The predetermined density is a density (tone value) that is determined to be corrected by visually confirming uneven printing. When the predetermined print area SA is darker than the ideal density (gradation value) which is higher than the predetermined density, the predetermined print area SA is corrected so that the density becomes lighter. ) When the density is lower than the thinner predetermined density, correction is performed so that the density becomes higher.
The printed image to be evaluated is preferably an image in which medium dots DM that tend to show a difference (unevenness) in density (gradation value) are formed on the entire surface of the printable area with the minimum pitch, but the present invention is not limited to this. Absent.

  In addition, the digitization of the degree of printing unevenness is not limited to this method. For example, the pitch between all dots in the predetermined printing area SA is measured, and the average pitch is used as the density (tone value) of the predetermined printing area SA. ) May be stored as an alternative value. In this case, the print image is preferably an image in which small dots DS for which the center of gravity of each dot can be easily obtained are formed on the entire surface of the printable area with the minimum pitch, but the present invention is not limited to this.

  The predetermined print area SA is an area used as a correction unit when correcting the print image, and is composed of an area of 4 × 4 or more in the dot matrix. Based on the density (tone value) of the predetermined print area SA, dot data corresponding to an area including the predetermined print area SA (corrected print area RA described later) is corrected. That is, in order to reduce the printing unevenness of the predetermined print area SA as a correction unit to be corrected, the dot data of a plurality of dots constituting the corrected print area RA including the predetermined print area SA is corrected. The predetermined print area SA and the corrected print area RA are the same in the other evaluation modes.

<Predetermined area evaluation mode>
In the predetermined area evaluation mode, a print image of an area (predetermined area) set in advance according to the specifications of the printer 100 among the print images printed in the printable area is captured, and the degree of printing unevenness is determined by position processing by image processing. It is an evaluation mode that is digitized together.
The predetermined area set in advance according to the specifications of the printer 100 is an area including, for example, dots formed by nozzles located at the joints of the nozzle chips 132. Further, for example, this is an area that includes an area where dots formed in steps before and after the roll paper 5 is stepped during printing by the transport system of the printer 100 are adjacent. These areas can be set in advance according to the specifications of the printer 100 and the printing specifications.

FIG. 10 is a conceptual diagram illustrating an example of a predetermined area.
In the example illustrated in FIG. 10, a region including black streaks when a black streak is generated due to a pitch shift of dots formed by nozzles located at the joints of the nozzle tips 132 is indicated by a one-dot chain line. A region surrounded by the one-dot chain line is a predetermined region.

The numerical value of the degree of printing unevenness divides a print image of a predetermined area into predetermined areas (predetermined print area SA (see FIG. 10)), and the density (predetermined print obtained by image processing) measured for each predetermined print area SA. The average gradation value of the area SA) is stored together with the position information of the predetermined printing area SA. The information to be stored may not be information on all the predetermined print areas SA but only information on the predetermined print areas SA in which the difference from the ideal density (tone value) without uneven printing exceeds a predetermined threshold.
The print image in this case is preferably an image in which medium dots DM, which tend to show a difference (unevenness) in density (gradation value), are formed on the entire surface of the printable area with the minimum pitch, but are not limited thereto. . In addition, the image need not be an image printed on the entire printable area, and may be an image printed on an area including a predetermined area set in advance according to the specifications of the printer 100.

  In addition, the digitization of the degree of printing unevenness is not limited to this method. For example, the pitch between all dots in the predetermined printing area SA is measured, and the average pitch is used as the density (tone value) of the predetermined printing area SA. ) May be stored as an alternative value. In this case, the print image is preferably an image in which small dots DS for which the center of gravity of each dot can be easily obtained are formed on the entire surface of the printable area with the minimum pitch, but the present invention is not limited to this. In addition, the image need not be an image printed on the entire printable area, and may be an image printed on an area including a predetermined area set in advance according to the specifications of the printer 100.

<Specified area evaluation mode>
In the designated area evaluation mode, a print image of an area (designated area) designated by the user of the printer 100 among the print images printed in the printable area is picked up, and the degree of printing unevenness is numerically displayed together with the position information by image processing. This is an evaluation mode.
The user can visually recognize the print image printed in the printable area and can designate an area including an area where correction is desired to be performed as the designated area. The designation is performed by, for example, displaying a print image on the display unit 113 (see FIGS. 1 and 2) and designating a range including an area where correction is desired from the input unit 112 for the image. Can do.

The numerical value of the degree of uneven printing is obtained by dividing a print image in a specified area into predetermined areas (predetermined print areas SA) and measuring the density measured for each predetermined print area SA (the average floor of the predetermined print areas SA obtained by image processing). (Adjustment value) is stored together with position information of the predetermined print area SA. The information to be stored may not be information on all the predetermined print areas SA but only information on the predetermined print areas SA in which the difference from the ideal density (tone value) without uneven printing exceeds a predetermined threshold.
The print image in this case is preferably an image in which medium dots DM, which tend to show a difference (unevenness) in density (gradation value), are formed on the entire surface of the printable area with the minimum pitch, but are not limited thereto. . For example, it is more preferable if it is a print image that significantly represents the content that the user wants to correct.

  In addition, the digitization of the degree of printing unevenness is not limited to this method. For example, the pitch between all dots in the predetermined printing area SA is measured, and the average pitch is used as the density (tone value) of the predetermined printing area SA. ) May be stored as an alternative value. In this case, the print image is preferably an image in which small dots DS for which the center of gravity of each dot can be easily obtained are formed on the entire surface of the printable area with the minimum pitch, but the present invention is not limited to this.

  In any of the above-described evaluation modes, the print image evaluation data includes the density (average gradation value of the predetermined print area SA obtained by image processing) measured for each predetermined print area SA with position information. Information (image density of the predetermined print area SA) is included. The print image evaluation data and information (area correction information RD to be described later) specifying the correction content for each dot of the dot data corresponding to the area to be corrected (corrected print area RA) including the predetermined print area SA. Based on this, the dot data is corrected, that is, the print image is corrected.

<Correction of print image>
FIG. 11 is a conceptual diagram illustrating a functional configuration of the printer driver 200 included in the image processing apparatus 110 according to the present embodiment.
The image processing apparatus 110 according to this embodiment includes a print data generation unit 201 and a correction unit 202 in a printer driver 200 as functional units configured by software.
The print data generation unit 201 is a functional unit that generates the print data PD1 based on the image data GD, and is a program having the basic functions of the printer driver in the prior art described with reference to FIG.
The correction unit 202 corrects the print data PD1 based on the above-described print image evaluation data (print image evaluation data AD shown in FIG. 11) and area correction information RD described later, and causes the printer 100 to execute printing. Is a program that generates
In the print image evaluation data AD, as described above, the information (predetermined print) is obtained by digitizing the density (average gradation value of the predetermined print area SA obtained by image processing) measured for each predetermined print area SA with position information. Image density of area SA).

<Area correction information>
The area correction information RD is information for specifying the correction content for each dot of the dot data corresponding to the corrected print area RA including the predetermined print area SA.
In the present embodiment, the area correction information RD includes a correction priority dot table DOT in which correction priority for each dot of dot data corresponding to the correction print area RA is determined.
FIG. 12 is a conceptual diagram showing an example of the correction priority dot table DOT.
The correction priority dot table DOT is a matrix table corresponding to the dot matrix of the correction print area RA. The predetermined print area SA is an area of 4 × 4 or more, and the corrected print area RA is an area including the predetermined print area SA. The correction priority dot table DOT is a matrix table corresponding to the dot matrix of the correction print area RA. That is, the correction priority dot table DOT is a 4 × 4 or more matrix table.

  Here, for ease of understanding, an example in which the predetermined print area SA, the correction print area RA, and the correction priority dot table DOT are all configured by a 4 × 4 matrix will be described. That is, each element in each matrix corresponds to each element at the same position. Specifically, based on information obtained by digitizing the density (gradation value) obtained by the 4 × 4 dots included in the predetermined printing area SA (image density of the predetermined printing area SA), a pair of the predetermined printing area SA is provided. The correction of dot data of a plurality of dots constituting the correction print area RA corresponding to 1 is performed according to the correction priority for each dot indicated by each element of the matrix table of the correction priority dot table DOT. This will be specifically described below.

The numerical values shown in the circles arranged in a matrix shown in FIG. 12 represent the priority order for correcting the dots (dot data) constituting the correction print area RA. According to the degree of correction, dot data is corrected according to this priority order.
For example, when the image density of the predetermined print area SA is lower than the predetermined density, the dot data corresponding to the correction print area RA is changed in order of the correction priorities determined in the correction priority dot table DOT based on the degree. Correct so that the size becomes larger. That is, as the degree of correction for the correction print area RA, a maximum of 16 levels from the degree of priority 1 dot to all 16 dots can be designated. As the degree, for example, it is possible to set 8 levels of 2 each and 4 levels of 4 each.
Similarly, when the image density of the predetermined print area SA is higher than the predetermined density, the dot data corresponding to the correction print area RA is dot-ordered in the order of the correction priority set in the correction priority dot table DOT based on the degree. Is corrected so as to reduce the size of.
Note that the correction stage (the number of dots to be corrected according to the priority order) corresponding to the degree of image density (the degree of difference from the predetermined density) of the predetermined printing area SA is set based on sufficient evaluation in advance. .

  If correction cannot be performed in the correction direction (that is, for example, in the print data PD1, the correction target dot in the correction print area RA is composed of large dots DL and cannot be corrected larger), correction is performed. In this case, a method of correcting dots of the next priority may be used.

Further, when the image density corresponding to the predetermined print area SA obtained from the print data PD1 exceeds a predetermined value, the correction unit 202 performs the above-described correction. In other words, when the image density corresponding to the predetermined print area SA obtained from the print data PD1 is equal to or lower than a predetermined value, the correction unit 202 does not perform the above-described correction.
Here, the predetermined value of the image density is an image density that becomes a threshold value at which the uneven density of the printed image is warped by performing the correction. For example, in a light image, when the dot size of an area where the dot pitch is large is corrected to be a large dot size, density unevenness may be warped and corrected with this threshold as a boundary. Do not do. The predetermined value of the image density as the threshold value is desirably determined in advance based on sufficient evaluation.

FIG. 13 is a flowchart for explaining the series of correction processes described above.
FIG. 14 is a conceptual diagram for explaining a relationship such as a predetermined density, a predetermined threshold, and a degree of difference.
The image processing method according to the present embodiment includes a print data generation step of generating print data (print data PD1) for causing the printer 100 to print a print image formed by a plurality of dots based on the image data GD; And a correction step of correcting dot data indicating the size of the dots. Further, the correction process specifies area correction information for designating the image density of the predetermined print area SA of the print image printed by the printer 100 and the correction content for each dot of the dot data corresponding to the corrected print area RA including the predetermined print area SA. This is a step of correcting dot data based on RD.
Hereinafter, the correction process will be described in detail with reference to FIG.

In the printer driver 200, the print data generation unit 201 generates the print data PD1 (print data generation process), and the correction unit 202 acquires the generated print data PD1 (step S1).
Next, the correction unit 202 acquires print image evaluation data AD (step S2). The print image evaluation data AD is evaluated in advance and stored in the storage unit 114 (see FIG. 2). The print image evaluation data AD can be selected by the user from the results of the plurality of evaluation modes described above.

Next, the correction unit 202 refers to the print image evaluation data AD, and in order to perform correction for each predetermined print area SA, position information (position in the print image matrix) of one predetermined print area SA to be corrected. Is acquired (step S3).
Next, the correction unit 202 acquires the image density of the print data PD1 corresponding to the position (position of one predetermined print area SA to be corrected), and whether the image density exceeds a predetermined value (V1). (Step S4). Here, the predetermined value (V1) serving as a determination threshold is set in advance and stored in the storage unit 114.

When the image density of the print data PD1 corresponding to the position of the predetermined print area SA to be corrected is equal to or less than a predetermined value (V1), the correction unit 202 enters the correction print area RA corresponding to the predetermined print area SA. Corresponding dot data is not corrected (proceed to step S9).
When the image density of the print data PD1 corresponding to the position of the predetermined print area SA to be corrected exceeds a predetermined value (V1), the correction unit 202 refers to the print image evaluation data AD and determines the predetermined correction target. The image density of the print area SA (the average gradation value of the predetermined print area SA) is acquired (step S5). The correction unit 202 determines in advance whether the difference between the image density of the predetermined print area SA to be corrected and the ideal density (gradation value) without printing unevenness is the above-described predetermined threshold (V2 (whether to perform correction). It is determined whether or not the threshold value is exceeded (step S6).

When the difference between the image density of the predetermined print area SA to be corrected and the ideal density (gradation value) without uneven printing is equal to or less than a predetermined threshold value (V2), the correction unit 202 enters the predetermined print area SA. The dot data corresponding to the corresponding corrected print area RA is not corrected (proceed to step S9).
When the difference between the image density of the predetermined print area SA to be corrected and the ideal density (gradation value) without uneven printing exceeds a predetermined threshold value (V2), the correction unit 202 acquires area correction information RD. The correction priority dot table DOT is referred to (step S7).

The correction unit 202 corrects the correction priority dot table based on the image density of the predetermined print area SA to be corrected (difference between the image density of the predetermined print area SA to be corrected and an ideal density (tone value) without uneven printing). From the higher priority specified by DOT, the dot data of the number of dots corresponding to the degree is corrected (correction step, step S8).
For example, when the difference between the image density of the predetermined printing area SA and the ideal density (gradation value) with no printing unevenness is lower than a predetermined density that becomes a predetermined threshold value (V2), the degree (degree lower than the predetermined density) Based on the above, dot data corresponding to the correction print area RA are corrected so as to increase the dot size in the order of the correction priorities determined in the correction priority dot table DOT.
Further, when the image density of the predetermined printing area SA is higher than a predetermined density at which a predetermined threshold (V2) is different from an ideal density (gradation value) without printing unevenness, the degree (a degree higher than the predetermined density). Based on the above, the dot data corresponding to the correction print area RA are corrected so that the size of the dots becomes smaller in the order of the correction priorities determined in the correction priority dot table DOT.
The predetermined threshold value (V2) in the direction darker than the ideal density (gradation value) without uneven printing and the predetermined threshold value (V2) in the direction thinner than the ideal density (tone value) are not necessarily the same size. Good.

  The correction unit 202 determines whether or not the above processing has been completed for all the predetermined print areas SA to be corrected included in the print image evaluation data AD (step S9), and if not, returns to step S3 and completes. Until it is done, the same processing is continued.

As described above, according to the image processing apparatus, the printing system, the image processing method, and the program according to the present embodiment, the following effects can be obtained.
According to the present embodiment, the correction unit 202 performs the correction content for each dot of the dot data corresponding to the image density of the predetermined print area SA of the print image printed by the printer 100 and the correction print area RA including the predetermined print area SA. The dot data is corrected based on the area correction information RD that designates. Since dot data is corrected based on the image density of the predetermined print area SA of the print image printed by the printer 100, more appropriate correction can be performed on the density of the print image. In addition, since the dot data is corrected based on the area correction information RD that specifies the correction content for each dot of the dot data corresponding to the correction print area RA including the predetermined print area SA of the print image printed by the printer 100, the correction print is performed. Correction can be performed based on information set more appropriately for each area RA. That is, for example, in contrast to the conventional correction method in which the corresponding dot size is changed corresponding to the change in the inter-dot distance, the predetermined print area SA is based on the density of the predetermined print area SA that changes due to the change in the inter-dot distance. Since dot-by-dot correction of dot data corresponding to the corrected print area RA including is performed for each corrected print area RA based on the area correction information RD evaluated and prepared in advance, more appropriate correction can be performed. it can.

  In addition, when the image density corresponding to the predetermined print area SA obtained from the print data PD1 exceeds a predetermined value (V1), the correction unit 202 performs correction. That is, when the image density obtained from the print data PD1 is equal to or lower than the predetermined value (V1), no correction is performed. Therefore, depending on the image density, it is possible to prevent the correction from being performed when the effect of performing the correction cannot be obtained or when the reverse effect is assumed.

  In addition, area correction information RD that specifies the correction content for each dot of the dot data corresponding to the correction print area RA including the predetermined print area SA determines the correction priority for each dot of the dot data corresponding to the correction print area RA. The corrected priority dot table DOT is included. That is, based on the image density of the predetermined print area SA of the print image printed by the printer 100, correction can be performed in units of the correction print area RA, and according to the correction priority set for each dot in the area. Stepwise correction can be performed.

  Further, since the correction priority dot table DOT in which the correction priority for each dot is determined is a matrix table having a size of 4 × 4 or more corresponding to the dot arrangement of the correction print area RA, the correction priority dot table DOT is 4 × 4 or more. It is possible to perform correction set more appropriately in a wide area.

  Further, when the image density of the predetermined print area SA is lower than the predetermined density, the correction unit 202 corresponds to the correction print areas RA in the order of the correction priorities determined in the correction priority dot table DOT based on the degree. The dot data is corrected so that the dot size becomes large. That is, when the image density is lower than the predetermined density, correction can be performed to a more appropriate image density by correcting the dot size to be larger. Further, since the dot sizes are corrected in the order of the correction priorities determined in advance in the correction priority dot table DOT, more appropriate correction can be performed.

  Further, when the image density of the predetermined print area SA is higher than the predetermined density, the correction unit 202 corresponds to the correction print areas RA in the order of the correction priorities determined in the correction priority dot table DOT based on the degree. The dot data is corrected so that the dot size is reduced. That is, when the image density is higher than the predetermined density, correction can be performed to a more appropriate image density by correcting the dot size to be small. Further, since the dot sizes are corrected in the order of the correction priorities determined in advance in the correction priority dot table DOT, more appropriate correction can be performed.

  Further, since the printing system 1 includes the image processing apparatus 110, it is possible to obtain a print image corrected more appropriately.

  The image processing method according to the present embodiment also includes a print data generation step for generating print data for causing the printer 100 to print a print image formed by a plurality of dots based on the image data, and the size of the dots. And a correction step for correcting dot data indicating. Further, the correction process specifies area correction information for designating the image density of the predetermined print area SA of the print image printed by the printer 100 and the correction content for each dot of the dot data corresponding to the corrected print area RA including the predetermined print area SA. This is a step of correcting dot data based on RD. Since dot data is corrected based on the image density of the predetermined print area SA of the print image printed by the printer 100, more appropriate correction can be performed on the density of the print image. In addition, since the dot data is corrected based on the area correction information RD that specifies the correction content for each dot of the dot data corresponding to the correction print area RA including the predetermined print area SA of the print image printed by the printer 100, the correction print is performed. Correction can be performed based on information set more appropriately for each area RA.

  In addition, the program configuring the printer driver 200 according to the present embodiment causes the image processing apparatus 110 to function including the image processing method described above, and thus more appropriately for the printer 100 including the image processing apparatus 110. The corrected print image can be printed.

  In this embodiment, correction can be performed by clarifying correction target pixel data and correction contents (dot size replacement contents) for pixel data arranged in a matrix after rasterization processing. However, the correction timing is not limited to after the rasterizing process. That is, the correction unit 202 may perform correction processing not on the print data PD1 but on data in the middle of generating the print data PD1.

(Embodiment 2)
Next, an image processing apparatus according to the second embodiment will be described. In the description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.
In the first embodiment, the area correction information RD has been described as including the correction priority dot table DOT in which the correction priority for each dot of the dot data corresponding to the correction print area RA is defined. However, the present invention is not limited to this. Not what you want. In the present embodiment, the area correction information RD includes a dot correction table DRT that specifies the correction level for each dot of the dot data corresponding to the corrected print area RA. The second embodiment is the same as the first embodiment except that the configuration of the area correction information RD and the correction method associated therewith are different.

FIG. 15 is a conceptual diagram for explaining an example of the dot correction table DRT.
The dot correction table DRT is a matrix table corresponding to the dot matrix of the correction print area RA. The predetermined print area SA is an area of 4 × 4 or more, and the corrected print area RA is an area including the predetermined print area SA. The dot correction table DRT is a matrix table corresponding to the dot matrix of the corrected printing area RA. That is, the dot correction table DRT is a 4 × 4 or more matrix table.

  Here, for the sake of easy understanding, an example in which the predetermined print area SA, the corrected print area RA, and the dot correction table DRT are all configured by a 4 × 4 matrix will be described. That is, each element in each matrix corresponds to each element at the same position. Specifically, based on information obtained by digitizing the density (gradation value) obtained by the 4 × 4 dots included in the predetermined printing area SA (image density of the predetermined printing area SA), a pair of the predetermined printing area SA is provided. The correction of dot data of a plurality of dots constituting the correction print area RA corresponding to 1 is performed according to the correction level for each dot indicated by each element of the matrix table of the dot correction table DRT. This will be specifically described below.

  The numerical values shown in the circles arranged in a matrix shown in FIG. 15 indicate the correction level for each dot constituting the correction print area RA. The signs of + and − given to the numerical values in the circle indicate the correction direction. Specifically, + means that the dot is corrected in the larger direction, and-means that the dot is corrected in the smaller direction. The numerical value indicates the degree of correction. Specifically, in the correction range in four states of large dot DL, medium dot DM, small dot DS, and no dot, 1 is, for example, correcting medium dot DM to large dot DL or small dot DS in one step. 2 means a two-stage correction, for example, a large dot DL is corrected to a small dot DS. Therefore, for example, when the dot in the corrected print area RA of the print data PD1 is the large dot DL and the corresponding dot correction table DRT data is -1, the dot is corrected to the medium dot DM. In the correction range in the four states of large dot DL, medium dot DM, small dot DS, and no dot, the maximum value indicating the degree of correction is 3, and 0 means no correction is performed.

As described above, the dot correction table DRT is a matrix table that defines the positions of dots to be corrected and the details of the correction. A plurality of dot correction tables DRT are prepared in advance corresponding to the degree of image density of the predetermined print area SA (the degree of difference from the predetermined density), and in actual correction, the predetermined print area obtained by evaluation is prepared. Correction is executed by selecting a dot correction table DRT corresponding to the degree of SA image density (degree of difference from the predetermined density).
If correction cannot be performed in the correction direction (that is, for example, in the print data PD1, the correction target dot in the correction print area RA is composed of large dots DL and cannot be corrected larger), correction is performed. Do not do.

16 to 19 show examples of four dot correction tables DRT1 to DRT4 prepared in advance for correcting the above-described black streaks.
The dot correction table DRT1 shown in FIG. 16 is a dot correction table DRT applied when the degree of image density in the predetermined print area SA (degree of difference from the predetermined density) exceeds a threshold value 1 at which correction is to be performed. is there. The dot at the position indicated by -1 is corrected to a dot smaller by one step.
The dot correction table DRT2 shown in FIG. 17 is a dot correction table DRT that is applied when the degree of image density in the predetermined print area SA (the degree of difference from the predetermined density) exceeds a threshold value 2 that is larger than the threshold value 1. More dots at the position indicated by -1 are corrected to one step smaller dots.
The dot correction table DRT3 shown in FIG. 18 is a dot correction table DRT that is applied when the degree of image density in the predetermined print area SA (the degree of difference from the predetermined density) exceeds a threshold value 3 that is larger than the threshold value 2. More dots at the position indicated by -1 are corrected to one step smaller dots.
A dot correction table DRT4 shown in FIG. 19 is a dot correction table DRT that is applied when the degree of image density in the predetermined print area SA (the degree of difference from the predetermined density) exceeds a threshold 4 that is larger than the threshold 3. The dots at all positions indicated by -1 are corrected to dots that are one step smaller.

As described above, the dot correction tables DRT1 to DRT4 to be corrected in accordance with the degree of unevenness visually recognized as black stripes are used when correcting a region where black stripes are likely to occur in the above-described predetermined area evaluation mode. Useful. That is, based on the density of the predetermined print area SA corresponding to the degree of unevenness visually recognized as a black streak, the dot data correction corresponding to the corrected print area RA including the predetermined print area SA is evaluated and prepared in advance. Based on the area correction information RD to be performed, correction is performed in units of corrected printing area RA, so that more appropriate correction can be performed.
A plurality of dot correction tables DRT are prepared in advance corresponding to the degree of image density (degree of difference from the predetermined density) in the predetermined printing area SA, assuming white lines and other printing irregularities in addition to black lines. In actual correction, the dot correction table DRT corresponding to the degree of image density (degree of difference from the predetermined density) of the predetermined printing area SA obtained by the evaluation is selected and correction is executed.

  As described above, according to the image processing apparatus of the present embodiment, the following effects can be obtained.

  The area correction information RD that specifies the correction content for each dot of the dot data corresponding to the correction print area RA including the predetermined print area SA is the dot correction that specifies the correction level for each dot of the dot data corresponding to the correction print area RA. Consists of tables. That is, based on the image density of the predetermined print area SA of the print image printed by the printer 100, correction can be performed in units of the correction print area RA, and according to the correction level specified for each dot in the area. Appropriate corrections can be made.

  Further, since the dot correction table for designating the correction level for each dot of the dot data corresponding to the correction print area RA is a matrix table having a size of 4 × 4 or more corresponding to the dot arrangement of the correction print area RA. More appropriately set correction can be performed in a wider area of 4 × 4 or more.

  Further, there are a plurality of dot correction tables for specifying the correction level for each dot of the dot data corresponding to the correction print area RA, corresponding to the degree of difference between the image density and the predetermined density of the predetermined print area SA, and the correction unit 202. However, correction is performed by selecting a dot correction table corresponding to the degree of difference from the plurality of dot correction tables. Therefore, it is possible to perform correction more appropriately according to the degree of difference between the image density of the predetermined print area SA and the predetermined density.

  DESCRIPTION OF SYMBOLS 1 ... Printing system, 5 ... Roll paper, 10 ... Printing part, 11 ... Head unit, 12 ... Ink supply part, 13 ... Print head, 14 ... Head control part, 20 ... Moving part, 30 ... Control part, 31 ... Interface 32: CPU, 33: Memory, 34: Drive control unit, 35: Movement control signal generation circuit, 36: Discharge control signal generation circuit, 37 ... Drive signal generation circuit, 40 ... Scanning unit, 41 ... Carriage, 42 ... Guide shaft 50 ... Conveying part 51 ... Supply part 52 ... Storage part 53 ... Conveying roller 55 ... Platen 100 ... Printer 110 ... Image processing apparatus 111 ... Printer control part 112 ... Input part 113 ... Display unit 114 ... Storage unit 115 ... CPU 116 ... ASIC 117 ... DSP 118 ... Memory 119 ... Printer interface unit 131 ... I Click ejection head, 132 ... nozzle tip 200 ... printer driver, 201 ... print data generating unit, 202 ... correction unit.

Claims (12)

A print data generation unit that generates print data for causing the printing apparatus to print a print image formed by a plurality of dots based on the image data;
A correction unit that corrects dot data indicating the size of the dots, and
The correction unit is
An image density of a predetermined print area of the print image printed by the printing apparatus;
An image processing apparatus that corrects the dot data based on area correction information that specifies correction contents for each dot of the dot data corresponding to the corrected print area including the predetermined print area.   The image processing apparatus according to claim 1, wherein the correction unit performs the correction when an image density corresponding to the predetermined print area obtained from the print data exceeds a predetermined value.   3. The area correction information includes a correction priority dot table in which a correction priority for each dot of the dot data corresponding to the correction print area is determined. An image processing apparatus according to 1. When n and m are integers of 4 or more,
The image processing apparatus according to claim 3, wherein the correction priority dot table is an n × m matrix table corresponding to the arrangement of the dots in the correction print area. The correction unit is
When the image density of the predetermined print area is lower than the predetermined density, based on the degree, the dot data corresponding to the correction print area is changed to the dot in the order of the correction priority set in the correction priority dot table. 5. The image processing apparatus according to claim 3, wherein the correction is performed so that the size of the image becomes larger. The correction unit is
When the image density of the predetermined print area is higher than the predetermined density, the dot data corresponding to the corrected print area is converted to the dot in order of the correction priority set in the correction priority dot table based on the degree. The image processing apparatus according to claim 3, wherein the correction is made so that the size of the image becomes smaller.   The said area correction information is comprised including the dot correction table which designates the correction level for every said dot of the said dot data corresponding to the said correction printing area, The structure of Claim 1 or 2 characterized by the above-mentioned. Image processing device. When n and m are integers of 4 or more,
The image processing apparatus according to claim 7, wherein the dot correction table is an n × m matrix table corresponding to the arrangement of the dots in the correction print area. The correction unit is
Performing the correction by selecting the dot correction table corresponding to the degree of difference from a plurality of the dot correction tables corresponding to the degree of difference between the image density of the predetermined print area and the predetermined density. The image processing apparatus according to claim 7, wherein the image processing apparatus is characterized. The image processing apparatus according to any one of claims 1 to 9,
And a printing apparatus that performs printing based on print data generated by the image processing apparatus. A print data generation step of generating print data for causing the printing apparatus to print a print image formed by a plurality of dots based on the image data;
A correction step for correcting dot data indicating the size of the dots included in the print data, and
The correction step includes
An image density of a predetermined print area of the print image printed by the printing apparatus;
An image processing method comprising: correcting the dot data based on area correction information that specifies correction contents for each dot of the dot data corresponding to the corrected print area including the predetermined print area. .   A program for causing an image processing apparatus to function including the image processing method according to claim 11.

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