JP2008000959A - Inkjet recording apparatus and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus capable of suppressing boundary bleeding and recording a black image with a high quality, and an image processing method. <P>SOLUTION: The inkjet recording apparatus uses a recording head delivering ink, delivers a black ink and a color ink from the recording head, forms respective black dots and color dots on a recording medium, and records an image having a black region and a color region. In this inkjet recording apparatus, in the color region of the image, a black N dot surrounding pixel detecting means for detecting a partial region of N pixels (N is an integer of at least 2) from the boundary of the black region, and a thinning-out means for thinning out with a smaller thinning-out ratio as the distance from the boundary of the black region is far away to the partial region of N pixels, are provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus and an image processing method, and more particularly to an ink jet recording apparatus and an image processing method for performing recording using black ink and at least one color ink.

  2. Description of the Related Art Conventionally, inkjet recording apparatuses that record on various recording media are capable of high-density and high-speed recording operations, and are therefore applied as printers or portable printers as output media of various apparatuses and products. It has become.

  In general, an ink jet recording apparatus includes a carriage on which recording means (recording head) and an ink tank are mounted, a transport means for transporting a recording medium, and a control means for controlling them. The recording head for ejecting ink droplets from a plurality of ejection openings is serially scanned in the direction (main scanning direction) perpendicular to the recording paper transport direction (sub-scanning direction), while the recording medium is recorded at the recording width during non-recording. Is intermittently conveyed by the same amount.

  This recording method performs recording by ejecting ink onto a recording medium according to a recording signal, and is widely used as a quiet recording method with low running cost. In recent years, many products using a plurality of colors of ink and applied to color recording have been put into practical use.

  In such a color ink jet recording apparatus, since black ink is frequently used for recording characters and the like, recording sharpness, sharpness, and high recording density are required. Therefore, a technique is known in which the penetrability of the black ink with respect to the recording medium is reduced and the coloring material in the black ink is prevented from penetrating into the recording medium (Patent Document 1).

  On the other hand, when two types of color inks are applied adjacently to a recording medium, the color inks are mixed with each other at the boundary portion, causing a phenomenon (bleeding) that degrades the quality of the color image. . In order to prevent this, a technique for increasing the permeability to the recording medium and preventing the color inks from being mixed on the surface of the recording medium is known (Patent Document 2).

  However, since black ink has low penetrability, blur (boundary bleeding) may occur in the boundary region between black and color in an image where black and color are in contact with each other. As a result, the quality of the color recording image may be significantly reduced. In order to suppress the blur in the boundary area between black and color, a first method is to provide fixing means such as a heat fixing device. As a result, by fixing the ink on the recording medium at a high speed, it becomes possible to prevent the recorded image itself from being stained (smeared) or border bleeding due to the actual fixing ink.

  Further, as a second method, there is a method in which a color ink having high penetrability is recorded over a black ink recording area. Since the black ink is recorded on the recording medium wetted by the color ink, the black ink is easily fixed on the recording medium, and smear can be suppressed. Furthermore, boundary bleeding can be suppressed by using an ink set in which black and color inks react and aggregate.

  Further, in the second method described above, there is a method in which smear and boundary bleeding are both suppressed by giving a necessary amount of color ink to the smear-preventing region and the boundary-preventing region.

JP 09-25442 A JP 55-65269 A

However, in the method of providing fixing means such as a heat fixing device, there is a risk that the provision of the fixing means increases the size of the apparatus and increases the cost. Furthermore, since the paper feeding is intermittent in the serial printer, there is a possibility that unevenness of feeding may occur when the fixing device is passed.
Further, in the method of recording color ink with high penetrability overlaid on the black ink recording area, the amount of ink applied to the recording medium increases. As a result, the printer waits for a certain period of time until the ink dries, and the throughput may decrease. In addition, when color inks are overlaid and recorded, the sharpness of black images may be deteriorated and the quality of black characters may be deteriorated. In addition, in the method of applying the necessary amount of color ink to each of the area for preventing smear and the area for preventing boundary bleeding, the color ink adjacent to the black ink area is similarly recorded. It is a highly permeable ink. For this reason, there is a possibility that the black ink and the color ink adjacent to each other bleed and cause bleeding.

  In addition, the method using the reaction liquid requires a separate recording head and tank for that purpose.

  By the way, as another method for suppressing the boundary bleeding described above, it is conceivable to avoid the contact between the black ink and the color ink as much as possible by thinning out images of one or both of the black and color boundaries. However, if the image at the boundary is simply thinned out, the image quality may be impaired. For example, if the color ink area is thinned out at a constant thinning rate regardless of the distance from the boundary with the black ink area, the portion that does not need to be thinned out is thinned out, resulting in a low-quality image in which the density near the boundary is reduced. There is a case.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an ink jet recording apparatus capable of suppressing boundary bleeding and recording a high-quality black image.

  Therefore, in the present invention, a recording head that discharges ink is used, black ink and color ink are discharged from the recording head, black and color dots are formed on the recording medium, and an image having a black region and a color region. In the ink jet recording apparatus for recording the image, in the color area of the image, a black N dot neighboring pixel detecting means for detecting a partial area of N pixels (N is an integer of 2 or more) from a boundary with the black area, and the N pixel It is characterized by having thinning means for performing thinning at a small thinning rate as the distance from the boundary with the black region increases with respect to the partial region of minutes.

  According to the above configuration, the thinning rate of the color ink region can be lowered as the distance from the boundary with the black ink region increases. As a result, it is possible to perform the minimum thinning necessary for suppressing bleeding. As a result, it is possible to record a sharp black image in which edges such as black characters are emphasized, and good image recording can be performed.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

(First embodiment)
1. Basic Configuration FIG. 1 is a perspective view showing a configuration of an ink jet recording apparatus applied in the first embodiment.

  Reference numeral 102 denotes an ink cartridge, which includes an ink tank that stores four color inks (black (K), cyan (C), magenta (M), and yellow (Y)), and a recording head 101. Reference numeral 103 denotes a paper feed roller, 104 denotes an auxiliary roller, and 107 denotes a recording medium. The paper feed roller 103 rotates in the direction of the arrow shown in the drawing while holding the recording medium 107 together with the auxiliary roller 104 to feed the recording medium 107. These rollers 103 and 104 also play a role of suppressing the recording medium 107. Reference numeral 106 denotes a carriage that supports the ink cartridge 102. By alternately repeating the recording main scan in which the carriage 106 scans in the column direction while recording is performed by the recording head 101 and the sub-scan in which the recording medium is conveyed in the row direction by the conveyance roller 103, an image is recorded on the recording medium 107. Form. The carriage 106 is controlled to stand by at a home position indicated by a dotted line in the drawing when the recording apparatus is not performing recording or when performing a recovery operation of the recording head.

  That is, when the carriage 106 positioned at the home position before the start of recording receives a recording start command, it drives the recording element provided in the recording head 101 while moving in the main scanning direction to record the recording head on the recording medium 107. The area corresponding to the width is recorded. When recording is completed up to the end of the recording medium along the scanning direction of the carriage, the carriage returns to the original home position and performs recording in the main scanning direction again. The paper feed roller 103 rotates in the sub-scanning direction and feeds paper by a necessary width before the subsequent print scan starts after the previous print scan ends. By repeating such operations, recording on the recording medium is completed. A recording operation for ejecting ink from the recording head 101 is performed based on control from a recording control unit (not shown).

  In order to increase the recording speed, recording is not performed only during main scanning in one direction (outward path), but recording is also performed in the return path when the carriage 102 is returned to the home position after one scanning is completed. May be.

  In the recording apparatus described above, the ink tank and the recording head 101 are detachably held by the carriage 106. However, an ink jet cartridge in which the ink tank and the recording head 101 are integrated may be used. Good. Furthermore, a multi-color integrated recording head that can eject a plurality of colors of ink from one recording head may be used.

  Further, capping means (not shown) for capping the front surface (discharge port surface) of the head is provided at a position where the above recovery operation is performed. The capping unit is implemented by a recovery unit (not shown) that performs a head recovery operation such as removing thickened ink and bubbles in the recording head in the cap state. Further, a cleaning blade (not shown) or the like is provided on the side of the capping unit and supported so as to be able to protrude toward the recording head 101, and can come into contact with the front surface of the recording head. Thus, after the recovery operation, the cleaning blade is projected into the moving path of the recording head, and unnecessary ink droplets and dirt on the front surface of the recording head are wiped off as the recording head moves.

  FIG. 2 is a perspective view showing the recording head 101.

  The recording head 101 has a plurality of ejection ports 200 formed at a predetermined pitch, and generates ink ejection energy along the wall surface of each liquid path 202 connecting the common liquid chamber 201 and each ejection port 200. A recording element 203 is provided for this purpose. The recording element 203 and its circuit are made on silicon using semiconductor manufacturing technology. Further, a temperature sensor (not shown) and a sub-heater (not shown) are collectively formed on the same silicon by the same process as the semiconductor manufacturing process. A silicon plate 208 on which these electrical wirings are made is bonded to a heat radiating aluminum base plate 207. Further, the circuit connecting portion 211 on the silicon plate and the printed board 209 are connected by an extra fine wire 210, and a signal from the recording apparatus main body is received through the signal circuit 212. The liquid path 202 and the common liquid chamber 201 are formed by a plastic cover 206 made by injection molding. The common liquid chamber 201 is connected via an ink tank, a joint pipe 204, and an ink filter 205, and ink is supplied to the common liquid chamber 201 from the ink tank. The ink supplied from the ink tank to the common liquid chamber 201 and temporarily stored enters the liquid path 202 by capillary action and forms a meniscus at the discharge port 200 to keep the liquid path 202 filled. At this time, when the recording element 203 is energized through an electrode (not shown) to generate heat, the ink on the recording element 203 is rapidly heated to generate bubbles in the liquid path 202, and the expansion of the bubbles causes a discharge port. Ink droplets 213 are ejected from 200.

  FIG. 3 is a block diagram illustrating a control configuration for executing recording control of each unit of the apparatus configuration.

  In the figure, showing a control circuit, 300 is an interface for inputting a recording signal, 301 is an MPU, 302 is a program ROM for storing a control program executed by the MPU 301, and 303 is a dynamic RAM (DRAM). The DRAM 303 can store various data (recording signals, recording data supplied to the head, etc.), and can also store the number of recording dots, the number of ink recording head replacements, and the like. Reference numeral 304 denotes a gate array that controls supply of print data to the print head, and also controls data transfer between the interface 300, MPU 301, and DRAM 303. Reference numeral 305 denotes a conveyance motor (LF motor) for conveying the recording paper, and reference numeral 306 denotes a carrier motor (CR motor) for conveying the recording head. Reference numerals 307 and 308 denote motor drivers for driving the transport motor 305 and the carrier motor 306, respectively. Reference numeral 309 denotes a head driver that drives the recording head 101.

2. Characteristic Configuration FIG. 4 is a block diagram showing a flow of generation of recording data.

  FIG. 5 is a flowchart showing a process for generating recording color data.

  The recording data is generated by detecting (E1000) the black one-dot neighboring pixel data (D1001) from the original black image data (D1000) mainly recording characters and the like (S501). Similarly, detection (E1001) of black 2-dot vicinity pixel data (D1002) is performed (S501), and detection (E1002) of black 3-dot vicinity pixel data (D1003) is performed (S501).

  Further, the selection of the color to be thinned out (E1006) based on the original cyan (C) data (D1005), original magenta (M) data (D1006), and original yellow (Y) data (D1007) before thinning out the color data. This is performed (S502). Based on these data, the thinning target color data (D1004) is created.

  Next, C thinning data 1 (D1017) is created using the thinning target color data (D1004), black 1-dot neighboring pixel data (D1001), and C mask 1 (D1008) (S503). Further, M thinning data 1 (D1018) is created using thinning target color data (D1004), black one-dot neighboring pixel data (D1001), and M mask 1 (D1009). Further, Y thinning data 1 (D1019) is created using thinning target color data (D1004), black one-dot neighboring pixel data (D1001), and Y mask 1 (D1010).

  Similarly, C thinning data 2 (D1020) is created using thinning target color data (D1004), black 2-dot neighboring pixel data (D1002), and C mask 2 (D1011) (S504). Further, M thinning data 2 (D1020) is created using thinning target color data (D1004), black 2-dot neighboring pixel data (D1002), and M mask 2 (D1012). Further, Y thinning data 2 (D1021) is created using thinning target color data (D1004), black 2-dot neighboring pixel data (D1002), and mask 2 (D1013).

  Further, C thinning data 3 (D1023) is created using the thinning target color data (D1004), black 3-dot neighboring pixel data (D1003), and C mask 3 (D1014) (S505). Further, M thinning data 3 (D1024) is created using thinning target color data (D1004), black 3-dot neighboring pixel data (D1003), and M mask 3 (D1015). Further, Y thinning data 3 (D1025) is created using thinning target color data (D1004), black 3-dot neighboring pixel data (D1003), and Y mask 3 (D1016).

  Using these C thinning data 1, 2, 3 (D1017, D1020, D1023) and the original C data (D1005), recording C data (D1029) is generated (S506). Similarly, M data for recording (D1030) is generated using M thinning data 1, 2, 3 (D1018, D1021, D1024) and original M data (D1006) (S506). Also, Y data for recording (D1031) is generated using Y thinning data 1, 2, 3 (D1019, D1022, D1025) and original Y data (D1007) (S506).

  Hereinafter, a method for generating recording data will be specifically described.

  First, a method of creating black 1-dot neighborhood pixel data (D1001), black 2-dot neighborhood pixel data (D1002), and black 3-dot neighborhood pixel data (D1003) from the original black image data (D1000) will be described in detail. In the present embodiment, the black dot vicinity image data is generated for the 1 to 3 dot vicinity image of the original black image data. However, the present invention is not limited to an image in the vicinity of 1 to 3 dots, and may be only an image in the vicinity of 1 dot or an image in the vicinity of 1 to 4 dots or more. can do.

  FIG. 6 is a flowchart showing a procedure for creating black one-dot neighborhood image data (D1001). In order to create black 1-dot neighborhood image data, a 3 × 3 matrix is used.

  First, it is determined whether the pixel of interest in the original black image (D1000) is the center of the 3 × 3 matrix and the total number of black dots present in the 3 × 3 matrix is 1 or more (S601). If the total number of black dots is 1 or more, the bit of the pixel of interest is turned on (S602). On the other hand, if the total number of black dots is less than 1, the bit of the pixel of interest is turned off (S603). Next, the pixel of interest is shifted (S604). All of the processing from S601 to S604 is performed on the pixel data of the original black image (D1000). When the processing of all data is finished (S605), the process is finished (S606). Data created by these processes is black one-dot neighborhood image data (D1001).

  FIG. 7 is a diagram illustrating a detection example of black one-dot proximity pixel image data (D1001).

  FIG. 7A shows a 3 × 3 matrix centered on the pixel of interest. FIG. 7B shows an original black image. The original black data (D1000) is processed while sequentially shifting the 3 × 3 matrix one pixel at a time. When the total number of black dots in the matrix is 1 or more, the bit of the pixel of interest is turned on. As a result, when all the pixels of the original black data (D1000) are processed, a black 1-dot proximity pixel (D1001) as shown in FIG. 7C is detected. As shown in FIG. 7C, data obtained by extending one dot with respect to the original black data (D1000) is obtained by this processing.

  FIG. 8 is a flowchart showing a procedure for creating black 2-dot vicinity image data (D1002). In order to create black 2-dot neighborhood image data, a 5 × 5 matrix is used.

  First, it is determined whether the pixel of interest in the original black image (D1000) is the center of a 5 × 5 matrix and the total number of black dots present in the 5 × 5 matrix is 1 or more (S801). If the total number of black dots is 1 or more, the bit of the target pixel is turned on (S802). On the other hand, if the total number of black dots is less than 1, the bit of the pixel of interest is turned off (S803). Next, the target pixel is shifted (S804). The processes from S801 to S804 are all performed on the pixel data of the original black image (D1000). When the processing of all data is finished (S805), the process is finished (S806). Data created by these processes is black 2-dot neighborhood image data (D1002).

  FIG. 9 is a diagram illustrating a detection example of black 2-dot proximity pixel image data (D1002).

  FIG. 9A shows a 5 × 5 matrix centered on the pixel of interest. FIG. 9B shows an original black image. The original black data (D1000) is processed while sequentially shifting the 5 × 5 matrix one pixel at a time. When the total number of black dots in the matrix is 1 or more, the bit of the pixel of interest is turned on. As a result, when all the pixels of the original black data (D1000) are processed, a black 2-dot proximity pixel (D1002) as shown in FIG. 9C is detected. As shown in FIG. 9C, data obtained by extending two dots with respect to the original black data (D1000) is obtained by this processing.

  FIG. 10 is a flowchart showing a procedure for creating black three-dot neighborhood image data (D1003). A 7 × 7 matrix is used to create black 3-dot neighborhood image data.

  First, it is determined whether the pixel of interest in the original black image (D1000) is the center of a 7 × 7 matrix, and the total number of black dots present in the 7 × 7 matrix is 1 or more (S1001). If the total number of black dots is 1 or more, the bit of the target pixel is turned on (S1002). On the other hand, if the total number of black dots is less than 1, the bit of the pixel of interest is turned off (S1003). Next, the pixel of interest is shifted (S1004). The processes from S1001 to S1004 are all performed on the pixel data of the original black image (D1000). When the processing of all data is finished (S1005), the process is finished (S1006). Data created by these processes becomes black three-dot neighborhood image data (D1003).

  FIG. 11 is a diagram illustrating a detection example of black three-dot proximity pixel image data (D1003).

  FIG. 11A shows a 7 × 7 matrix centered on the pixel of interest. FIG. 11B shows an original black image. The original black data (D1000) is processed while sequentially shifting the 7 × 7 matrix pixel by pixel. When the total number of black dots in the matrix is 1 or more, the bit of the pixel of interest is turned on. As a result, when all the pixels of the original black data (D1000) are processed, a black 3-dot proximity pixel (D1003) as shown in FIG. 11C is detected. As shown in FIG. 11 (c), data obtained by extending three dots with respect to the original black data (D1000) is obtained by this processing.

  In the present embodiment, the threshold value of the total number of black dots is 1 or more, but an optimal value may be used in accordance with the characteristics of the ink and the characteristics of the printing apparatus.

  Next, a method of creating black dot vicinity thinning target data will be described in detail.

  FIG. 12 is a diagram illustrating a black dot vicinity thinning target image.

  The black 1-dot neighborhood thinning target image data (D2001) shown in FIG. 12A is data obtained by ANDing the data obtained by inverting the original black data (D1000) and the black 1-dot neighborhood pixel data (D1001). (See 1003 in FIG. 4E.)

  The black 2-dot neighborhood pixel data (D2002) shown in FIG. 12B is obtained by ANDing data obtained by inverting the black 1-dot neighborhood pixel data (D1001) and the black 2-dot neighborhood pixel data (D1002). Data (see E1004 in FIG. 4).

  The black 3-dot neighborhood pixel data (D2003) shown in FIG. 12C is obtained by ANDing data obtained by inverting the black 2-dot neighborhood pixel data (D1002) and the black 3-dot neighborhood pixel data (D1003). Data (see 1005 in FIG. 4E).

  Next, a method for creating the thinning target color data (D1004) will be described in detail.

  FIG. 13 is a block diagram showing a flow when creating thinning target color data (D1004) from original color data (D1005, D1006, D1007).

  Monochromatic C data (D1033) is generated by taking the logical product of the original C data (D1005), the original M data (D1006) inverted, and the original Y data (D1007) inverted. Monochromatic M data (D1034) is generated by ANDing the inverted version of the original C data (D1005), the original M data (D1006), and the inverted version of the original Y data (D1007). Monochromatic Y data (D1035) is generated by ANDing the original C data (D1005), the original M data (D1006), and the original Y data (D1007). As a result, for example, monochromatic C data (D1033) is data that enters pixels where only original C data exists in each pixel.

  Further, the logical product of the original C data (D1005), the original M data (D1006), and the inverted version of the original Y data (D1007) is obtained to generate CM secondary color data (D1036). The MY secondary color data (D1037) is generated by taking the logical product of the inverted version of the original C data (D1005), the original M data (D1006), and the original Y data (D1007). The logical product of the original C data (D1005), the original M data (D1006) inverted, and the original Y data (D1007) is obtained to generate YC secondary color data (D1038). As a result, for example, CM secondary color data (D1036) includes data in pixels in which original C data and original M data exist in each pixel.

  Further, the logical product of the original C data (D1005), the original M data (D1006), and the original Y data (D1007) is obtained to generate CMY tertiary color data (D1039). As a result, the CMY tertiary color data (D1039) contains data in pixels where all of the original C data, original M data, and original Y data exist in each pixel.

  Then, a thinning color selection (E1006) is performed from these data (D1033 to D1039). Here, data selected by each selector is selected, and null data (D1040), that is, all zero data is selected for data that is not selected. The logical sum of all of these selected data is calculated, and thinning target color data (D1004) is created.

  FIG. 14A shows an original color image, and FIG. 14B shows an example of thinning target color data (D1004). For example, in the case of using an ink with noticeable bleeding at the boundary between the Y ink and the black ink, in the thinning color selection (E1006), the monochrome Y data (D1040), the MY secondary color data (D1037) and the YC secondary color data ( D0138) is selected. When the logical sum of the monochromatic Y data (D1040), the MY secondary color data (D1037), and the YC secondary color data (D0138) is taken, the color image to be thinned becomes an image shown in FIG. The thinning target color data (D1004) created by this processing is the target of the following processing.

  In the present embodiment, the case of using the ink with noticeable bleeding at the boundary between the Y ink and the black ink will be described with respect to the case of thinning out the primary color and the secondary color using the yellow ink. Is not limited to this. In other words, thinning color selection can be selected based on various factors such as the type of recording medium and ink, and the characteristics of the recording apparatus.

  Next, a method of creating the black neighborhood thinning target color data (D2004, D2005, D2006) will be described in detail.

  The black 1-dot neighborhood thinning target color data (D2004) is data obtained by ANDing the black 1-dot neighborhood thinning data (D2001) and the thinning target color data (D1004), as indicated by E1007 in FIG. The black 2-dot neighborhood thinning target color data (D2005) is data obtained by ANDing the black 2-dot neighborhood thinning data (D2002) and the thinning target color data (D1004), as indicated by E1008 in FIG. The black 3-dot neighborhood thinning target color data (D2006) is data obtained by ANDing the black 3-dot neighborhood thinning data (D2003) and the thinning target color data (D1004) as indicated by E1008 in FIG.

  FIG. 14 shows the relationship between the original color image recorded by CMY, the thinning target color image (D1004), the black neighboring thinning target image (D2001 to D2003), and the black neighboring thinning target color image (D2004 to D2006). FIG.

  14A shows an original color image recorded by CMY, and FIG. 14B shows a thinning target color image (D1004) that is an image obtained by excluding the thinning color selected in E1006 from the original color image. Show. In the present embodiment, a case where yellow, green (G), and red (R) are selected as thinning target colors will be described.

  FIG. 14F shows a black 1-dot neighborhood thinning target color image (D2004). The thinning-out target color data (D1004) shown in FIG. 14B and the black 1-dot neighborhood thinning image shown in FIG. D2001) and logical product. FIG. 14G shows a black 2-dot neighborhood thinning target color image (D2005). The thinning-out target color data (D1004) shown in FIG. 14B and the black 2-dot neighborhood thinning image shown in FIG. D2002) and logical product. FIG. 14H shows a black 3-dot vicinity thinning target color image (D2006), the thinning-out target color data (D1004) shown in FIG. 14B and the black 3-dot vicinity thinning image shown in FIG. D2004) and logical product.

  As can be seen from FIGS. 14F, 14G, and 14H, only the boundary region between black and the color to be thinned is detected by this process. That is, boundary bleeding can be prevented by thinning out the color dots in the boundary region.

  Next, a method of creating color thinning data 1 (D1017, D1018, D1019) for thinning out the vicinity of one black dot will be described in detail. Here, the C mask 1, the M mask 1, and the Y mask 1 are masks determined based on the ratios of the thinning amounts of the respective color inks. The same applies to the C mask 2, the M mask 2, the Y mask 2, the C mask 3, the M mask 3, and the Y mask 3.

  As indicated by E1010 in FIG. 4, C thinning data 1 (D1017) is a logical product of a black one-dot thinning target color image (D2004) and a C mask 1 (D1008). As indicated by E1011 in FIG. 4, M thinning data 1 (D1018) is a logical product of a black 1-dot neighborhood thinning target color image (D2004) and an M mask 1 (D1009). As indicated by E1012 in FIG. 4, Y thinning data 1 (D1019) is a logical product of a black 1-dot neighborhood thinning target color image (D2004) and a Y mask 1 (D1009).

  FIG. 15 is a diagram showing an example of the color thinning mask 1 for thinning the boundary portion of the first dot between black and the color to be thinned. FIG. 15A shows color pixel data (D2004) for black one-dot proximity thinning. FIGS. 15B, 15C, and 15D respectively show C mask 1 (D1008), M mask 1 (D1009), and Y mask 1 (D1010) for generating a predetermined amount of thinning data. FIGS. 15E, 15F, and 15G show C thinning data 1 (D1017), M thinning data 1 (D1018), and Y thinning data 1 (D1019), respectively. These are the logical products of the black 1-dot neighborhood thinning target color image (D2004) and the C, M, Y mask 1 (D1008, D1009, D1010).

  In this embodiment, the ratio of the thinning amount of each color is 0% for cyan, 0% for magenta, and 100% for yellow. However, the ratio of the thinning amount for each color depends on the characteristics of the ink and the configuration of the printing apparatus. Can be set to an appropriate value.

  Next, a method of creating color thinning data 2 (D1020, D1021, D1022) for thinning out the vicinity of two black dots will be described in detail.

  As indicated by E1013 in FIG. 4, C thinning data 2 (D1020) is a logical product of the black 2-dot neighborhood thinning target color image (D2005) and the C mask 2 (D1011). As indicated by E1014 in FIG. 4, M thinning data 2 (D1021) is a logical product of the black 2-dot neighborhood thinning target color image (D2005) and the M mask 2 (D1012). As indicated by E1015 in FIG. 4, Y thinning data 2 (D1022) is a logical product of the black 2-dot neighborhood thinning target color image (D2005) and the Y mask 2 (D1013).

  FIG. 16 is a diagram illustrating an example of the color thinning mask 2 for thinning the boundary portion of the second dot between black and the color to be thinned. FIG. 16A shows the black 2-dot proximity thinning target color pixel data (D2005). FIGS. 16B, 16C, and 16D respectively show a C mask 2 (D1011), an M mask 2 (D1012), and a Y mask 2 (D1013) for generating a predetermined amount of thinning data. FIGS. 16E, 16F, and 16G show C thinning data 2 (D1020), M thinning data 2 (D1021), and Y thinning data 2 (D1022), respectively. These are the logical products of the black 2-dot neighborhood thinning target color image (D2005) and the C, M, Y mask 2 (D1011, D1012, D1013).

  In this embodiment, the ratio of the thinning amount of each color is 0% for cyan, 0% for magenta, and 50% for yellow, but the ratio of the thinning amount for each color depends on the characteristics of the ink and the configuration of the printing apparatus. Can be set to an appropriate value.

  Next, a method of creating color thinning data 3 (D1023, D1024, D1025) for thinning the vicinity of three black dots will be described in detail. As indicated by E1016 in FIG. 4, C thinning data 3 (D1023) is a logical product of the black 3-dot neighborhood thinning target color image (D2006) and the C mask 3 (D1014). As indicated by E1017 in FIG. 4, the M thinning data 3 (D1024) is a logical product of the black 3-dot neighborhood thinning target color image (D2006) and the M mask 3 (D1015). As indicated by E1018 in FIG. 4, Y thinning data 3 (D1025) is a logical product of the black 3-dot neighborhood thinning target color image (D2006) and the Y mask 3 (D1016).

  FIG. 17 is a diagram showing an example of the color thinning mask 3 for thinning the boundary portion of the third dot between black and the color to be thinned. FIG. 17A shows black 3-dot proximity thinning target color pixel data (D2006). FIGS. 17B, 17C, and 17D respectively show C mask 3 (D1014), M mask 3 (D1015), and Y mask 3 (D1016) for generating a predetermined amount of thinning data. FIGS. 17E, 17F, and 17G show C thinning data 3 (D1023), M thinning data 3 (D1024), and Y thinning data 3 (D1025), respectively. These are the logical products of the black 3-dot neighborhood thinning target color image (D2006) and the C, M, Y mask 3 (D1014, D1015, D1016).

  In this embodiment, the ratio of the thinning amount of each color is 0% for cyan, 0% for magenta, and 25% for yellow. However, the ratio of the thinning amount for each color depends on the characteristics of the ink and the configuration of the printing apparatus. Can be set to an appropriate value.

  The dot arrangement method in the above-described C, M, Y masks 1, 2, 3 (D1008 to D1016) may be regular or may be pseudo-random.

  Next, a method of creating recording color (C, M, Y) data (D1029, D1030, D1031) will be described in detail.

  First, a logical sum of C thinning data 1 (D1017), C thinning data 2 (D1020), and C thinning data 3 (D1023) is calculated to create a C thinning mask (D2007). The created C thinning mask is inverted to create an inverted C thinning mask (D0126). Then, a logical product of the inverted C thinning mask (D0126) and the original C data (D1005) is calculated to create recording C data (D0129).

  Similarly, M thinning data 1 (D1018), M thinning data 2 (D1021), and M thinning data 3 (D1024) are ORed to create an M thinning mask (D2008). The created M thinning mask is inverted to create an inverted M thinning mask (D0127). Then, the logical product of the inverted C thinning mask (D0127) and the original C data (D1006) is calculated to create M data for recording (D0130). Further, a logical sum of Y thinning data 1 (D1019), Y thinning data 2 (D1022), and Y thinning data 3 (D1025) is taken to create a Y thinning mask (D2008). The created Y thinning mask is inverted to create an inverted Y thinning mask (D0128). Then, a logical product of the inverted Y thinning mask (D0128) and the original Y data (D1007) is obtained to create recording Y data (D0131).

  Note that the original black data (D1000) is not processed and becomes black data for recording (D1032).

  FIG. 18 is a diagram illustrating an example of a color thinning mask, a reverse color thinning mask, and recording color data.

  FIG. 18A is a diagram showing a C thinning mask (D2007) created by calculating the logical sum of C thinning data 1 (D1017), C thinning data 2 (D1020), and C thinning data 3 (D1023). is there. FIG. 18B is a diagram showing an M thinning mask (D2008) created by performing a logical sum of M thinning data 1 (D1018), M thinning data 2 (D1021), and M thinning data 3 (D1024). is there. FIG. 18C is a diagram showing a Y-thinning mask (D2009) created by calculating a logical sum of Y-thinning data 1 (D1019), Y-thinning data 3 (D1022), and Y-thinning data 3 (D1025). is there.

  18D, 18E, and 18F show inverted color thinning masks (D0126, D0127, D0128) obtained by inverting the color thinning masks (D2007, D2008, D2009), respectively.

  Further, FIGS. 18G, 18H, and 18I show recording color data (D0129, D0130, D0131). These are created by taking the logical product of the inverted color thinning mask (D0126, D0127, D0128) and the original color data (D1005, D1006, D1007).

  The recording image recorded by the above processing is shown in FIG. As shown in the figure, with respect to the color selected by the thinning color, the thinning is gradually changed by gradually changing the thinning amount of the thinning mask. That is, the color data in the boundary area between black and color can be thinned out step by step for each pixel, and the color ink area thinning rate can be lowered as the distance from the boundary with the black ink area increases. Therefore, it is possible to perform the minimum thinning necessary for suppressing bleeding.

  In the present embodiment, the color thinning region is limited to three stages, but it is preferable to take appropriate stages according to the characteristics of the ink and the configuration of the recording apparatus.

FIG. 2 is a perspective view illustrating a configuration of a recording apparatus applied in the first embodiment of the present invention. FIG. 3 is a perspective view showing a recording head applied in the first embodiment of the present invention. It is a block diagram shown about the control structure for performing the recording control of each part of the apparatus structure in the 1st Embodiment of this invention. It is a block diagram which shows the flow of the production | generation of the recording data in the 1st Embodiment of this invention. 3 is a flowchart showing a process for generating recording color data according to the first embodiment of the present invention. It is a flowchart which shows the preparation procedure of the black 1 dot vicinity image data in the 1st Embodiment of this invention. It is a figure which shows the example of a detection of the black 1 dot proximity pixel image data in the 1st Embodiment of this invention. It is a flowchart which shows the preparation procedure of the black 2 dot vicinity image data in the 1st Embodiment of this invention. It is a figure which shows the example of a detection of the black 2 dot adjacent pixel image data in the 1st Embodiment of this invention. It is a flowchart which shows the preparation procedure of black 3 dot vicinity image data in the 1st Embodiment of this invention. It is a figure which shows the example of a detection of the black 3 dot proximity pixel image data in the 1st Embodiment of this invention. It is a figure which shows the black dot vicinity thinning-out target image in the 1st Embodiment of this invention. FIG. 5 is a block diagram illustrating a flow when creating thinning target color data from original color data according to the first embodiment of the present invention. FIG. 4 is a diagram illustrating a relationship among an original color image, a thinning target color image, a black vicinity thinning target image, and a black vicinity thinning target color image according to the first embodiment of the present invention. It is a figure which shows the example of the color thinning mask 1 in the 1st Embodiment of this invention. It is a figure which shows the example of the color thinning mask 2 in the 1st Embodiment of this invention. It is a figure which shows the example of the color thinning mask 3 in the 1st Embodiment of this invention. It is a figure which shows the example of the color thinning-out mask, reverse color thinning-out mask, and recording color data in the 1st Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Recording head 102 Ink cartridge 103 Paper feed roller 104 Auxiliary roller 106 Carriage 107 Recording medium

Claims (6)

Inkjet recording apparatus that uses a recording head that discharges ink, discharges black ink and color ink from the recording head, forms dots of black and color on a recording medium, and records an image having a black area and a color area In
In the color area of the image, black N dot neighboring pixel detection means for detecting a partial area of N pixels (N is an integer of 2 or more) from the boundary with the black area;
Thinning means for performing thinning at a small thinning rate as the distance from the boundary with the black region increases with respect to the partial region for N pixels;
An ink jet recording apparatus comprising:   The black N dot neighboring pixel detecting means counts the total number of pixels in which black data exists in a matrix centered on the pixel of interest, and when the count exceeds a threshold, The inkjet recording apparatus according to claim 1, wherein:   The thinning means is a logical combination of data obtained by inverting the image data of the black region, partial region data for N pixels, image data of the color region, and a mask with a thinning rate that decreases with increasing distance. 3. The ink jet recording apparatus according to claim 1, wherein thinning is performed by product. Inkjet recording apparatus that uses a recording head that discharges ink, discharges black ink and color ink from the recording head, forms dots of black and color on a recording medium, and records an image having a black area and a color area In the image processing method for generating the dot data of
In the color area of the image, a black N dot neighboring pixel detection step of detecting a partial area of N pixels (N is an integer of 2 or more) from the boundary with the black area;
A thinning step of thinning out the partial region for N pixels at a thinning rate as the distance from the boundary with the black region increases.
An image processing method comprising:   The black N dot neighboring pixel detection step counts the total number of pixels in which black data exists in a matrix centered on the pixel of interest, and when the number of counts exceeds a threshold, the pixel of interest is black N dot neighboring pixel. The image processing method according to claim 4, wherein: The thinning-out process includes logic obtained by inverting the image data of the black area, data of the partial area for the N pixels, image data of the color area, and a mask with a thinning ratio that is smaller as the distance is longer. 6. The image processing method according to claim 4, wherein thinning is performed by product.

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