Image processing device, method, program

Abstract

The present invention provides an image processing device that further improves image quality at the edges of objects. [Solution] In the first edge pixel group, the ratio of dots placed in the second region is smaller than the ratio of dots placed in the first region, and in the second edge pixel group, the ratio of dots placed in the first region is smaller than the ratio of dots placed in the second region. The positional relationship between the row of dots placed in the first region of each pixel in the scanning direction of the object and the row of dots placed in the second region of each pixel in the scanning direction of the object is uniformly shifted in the scanning direction so that the width of the object in the scanning direction becomes narrower.

Description

Technical Field

[0001] The present invention relates to an image processing apparatus, method, and program.

Background Art

[0002] In a recording apparatus that records coloring materials on a recording medium, a technique (hereinafter referred to as edge processing) for detecting an edge of an image and changing a recording process is generally known in order to improve the sharpness of recorded characters and lines. In Patent Document 1, a technique for thinning out recording dots of edge pixels of an object is disclosed in an inkjet recording apparatus in order to reduce image quality deterioration due to bleeding of the recorded ink on the recording medium.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When only thinning out dots at the edge of an object as described in Patent Document 1, since ink bleeds around the arranged dots, it was insufficient to obtain a desired quality on the recording medium.

[0005] An object of the present invention is to provide an image processing apparatus, method, and program that further improve the image quality at the edge portion of an object.

Means for Solving the Problems

[0006] To solve the above problems, the image processing apparatus according to the present invention comprises a recording means for recording dots on a recording medium by ejecting ink droplets onto the recording medium, the recording means capable of recording dots at a resolution higher than the resolution of image data, and the recording means being movable relative to the recording medium in the scanning direction, and a dot placement means for performing a process of placing dots on pixels based on the image data including an object, wherein the recording means has a first nozzle row capable of recording dots on a first region of each pixel of the object, and a second nozzle row capable of recording dots on a second region of each pixel of the object, the first region and the second region are arranged in a direction perpendicular to the scanning direction, and as a result of processing by the dot placement means, the dots are located at the first end of the object in the scanning direction. In a first group of edge pixels adjacent to the boundary between the object and the outside of the object, the ratio of dots arranged in the second region is smaller than the ratio of dots arranged in the first region. In a second group of edge pixels located at the second end, which is different from the first end and opposite to the first end in the scanning direction, and adjacent to the boundary, the ratio of dots arranged in the first region is smaller than the ratio of dots arranged in the second region. The positional relationship between the row of dots arranged in the first region of each pixel in the scanning direction of the object and the row of dots arranged in the second region of each pixel in the scanning direction of the object is uniformly shifted in the scanning direction such that the width of the object in the scanning direction becomes narrower. [Effects of the Invention]

[0007] According to the present invention, image quality at the edges of an object can be further improved. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view showing an overview of the recording section. [Figure 2] This is a diagram showing the configuration of a printing system. [Figure 3]This diagram shows the processing performed in the image processing unit. [Figure 4] This is a diagram illustrating edge pattern detection. [Figure 5] This is a diagram illustrating edge pattern detection. [Figure 6] This diagram shows the processing performed in the image processing unit. [Figure 7] This diagram illustrates the color separation quantization process and the nozzle separation process. [Figure 8] This diagram shows the dot arrangement pattern and the reference index pattern. [Figure 9] This is a diagram illustrating the structure of the recording head. [Figure 10] This diagram illustrates the color separation quantization process and the nozzle separation process. [Figure 11] This diagram illustrates the flight characteristics of the main droplet and satellite droplets. [Figure 12] This diagram schematically illustrates how the main droplet and satellite droplets land on the recording medium. [Figure 13] This diagram schematically illustrates how the main droplet and satellite droplets land on the recording medium. [Figure 14] This is a diagram to explain edge processing. [Figure 15] This is a diagram to explain edge processing. [Figure 16] This is a diagram to explain how to adjust the position of the dots. [Figure 17] This is a diagram to explain how to adjust the position of the dots. [Figure 18] This is a diagram to explain edge processing. [Figure 19] This is a diagram showing the arrangement of dots. [Figure 20] This is a diagram showing the arrangement of dots. [Figure 21] This is a diagram to explain edge processing. [Figure 22] This is a diagram showing the arrangement of dots. [Figure 23] This diagram illustrates the case where the input image is square. [Figure 24] It is a diagram showing the process performed by the image processing unit. [Figure 25] It is a diagram for explaining the process using a quantization table. [Figure 26] It is a diagram showing the process performed by the image processing unit.

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0010] <Structure of the Recording Device> Hereinafter, with reference to FIG. 1, the structure of the recording device in the present embodiment will be described. FIG. 1 is a perspective view showing an overview of a recording unit in a recording device 2 (hereinafter, also simply referred to as a recording device). A recording medium P (hereinafter, also simply referred to as a recording medium) fed to the recording unit is conveyed in the -Y direction (sub-scanning direction) as the conveying roller 101 rotates by a nip portion between the conveying roller 101 disposed on the conveying path and a pinch roller 102 driven thereby. The platen 103 is provided at a recording position facing a surface (nozzle surface) where nozzles of an inkjet recording head H are formed, and supports the back surface of the recording medium P from below, thereby maintaining a constant distance between the surface of the recording medium P and the nozzle surface of the recording head H. The recording medium P in the area where recording has been performed on the platen 103 is conveyed in the -Y direction as the discharge roller 105 rotates while being nipped by the discharge roller 105 and a flapper 106 driven thereby, and is discharged to a paper discharge tray 107.

[0011] The recording head H is detachably mounted on the carriage 108 with its nozzle surface facing the platen 103 or the recording medium. The carriage 108 is capable of reciprocating along two guide rails 109 and 110 in the X direction, which is the main scanning direction, by the driving force of a carriage motor (not shown), and during this movement, the recording head H performs an ejection operation in accordance with the ejection signal. The ±X direction in which the carriage 108 moves is perpendicular to the -Y direction in which the recording medium is transported, and is called the main scanning direction. In contrast, the -Y direction of recording medium transport is called the sub-scanning direction. By alternately repeating the main scanning (movement accompanied by ejection) of the carriage 108 and the recording head H and the transport of the recording medium (sub-scanning), an image is formed on the recording medium P in stages. Hereafter, the main scanning of the recording head H in the +X direction will be called the forward scan, and the main scanning in the -X direction will be called the reverse scan. The above describes the structure of the recording device in this embodiment.

[0012] <Structure of the recording head> The structure of the recording head in this embodiment will be described below with reference to Figure 9. Figures 9(a) to 9(c) are schematic diagrams of the recording head H used in this embodiment as seen from the top surface of the recording device. The recording head H has recording chips 1105 and 1106, which each receive recording signals from the main body of the recording device via contact pads (not shown) and are supplied with the power necessary to drive the recording head. As shown in Figure 9(a), the recording chip 1105 has a nozzle row 1101 (hereinafter also referred to as the black nozzle row) in which a plurality of nozzles for ejecting black ink are arranged in the Y direction. Similarly, the recording chip 1106 has a nozzle row 1102 for ejecting cyan ink, a nozzle row 1103 for ejecting magenta ink, and a nozzle row 1104 for ejecting yellow ink.

[0013] Figure 9(b) is a magnified view of the black nozzle row 1101. Figure 9(c) is a magnified view of one of the three nozzle rows, 1102, 1103, and 1104, i.e., the cyan, magenta, and yellow nozzle rows. This magnified view is common to all color inks. On either side of the ink chambers 1107 and 1110 are nozzles 1108 and 1111 that eject ink. Directly below each nozzle (on the +Z side) are ejection heaters 1109 and 1112. When voltage is applied, heaters 1109 and 1112 generate heat and create bubbles, ejecting ink from each nozzle. Nozzle 1108 has 832 openings, and nozzle 1111 has 768 openings. Nozzle 1108 ejects black ink and consists of Ev row 1121 (hereinafter also referred to as Ev nozzle row) and Od row 1122 (hereinafter also referred to as Od nozzle row), which are arranged in the Y direction with a pitch of 600 dpi. The Ev nozzle row is positioned with a half-pitch offset in the -Y direction relative to the Od nozzle row. By performing recording scanning using the black nozzle row 1101 with this configuration, a recording density of 1200 dpi can be achieved on the recording medium. Similarly, the cyan nozzle row 1102, magenta nozzle row 1103, and yellow nozzle row 1104 are arranged with Ev row 1123-1125 and Od row 1126-1128, which are arranged in the Y direction with a pitch of 600 dpi. Here, column Ev 1123 and column Od 1126 correspond to the cyan nozzle row, column Ev 1124 and column Od 1127 correspond to the magenta nozzle row, and column Ev 1125 and column Od 1128 correspond to the yellow nozzle row. Columns Ev 1123-1125 are positioned with a half-pitch offset in the -Y direction relative to columns Od 1126-1128.

[0014] In this embodiment, the recording head H has a recording chip with a row of black nozzles and a recording chip with rows of cyan, magenta, and yellow nozzles, but it is not limited to this configuration. Specifically, the row of black nozzles, cyan nozzles, magenta nozzles, and yellow nozzles may all be mounted on a single chip. Alternatively, the recording head equipped with the recording chip with the row of black nozzles and the recording head equipped with the recording chips with rows of cyan, magenta, and yellow nozzles may be separate. Alternatively, the row of black nozzles, cyan nozzles, magenta nozzles, and yellow nozzles may each be mounted on separate recording heads. Furthermore, the recording head H in this embodiment uses a so-called bubble jet method, which ejects ink by applying voltage to a heater to generate heat, but it is not limited to this configuration. Specifically, it may use an electrostatic actuator or a piezoelectric element to eject ink. The above describes the structure of the recording head in this embodiment.

[0015] <Flight characteristics of main droplets and satellites dependent on scanning direction> Depending on its structure, a recording head may have flight characteristics for main droplets and satellites separated from ink droplets that depend on the scanning direction. Figure 11 illustrates an example of the flight characteristics of main droplets and satellites of ink ejected from nozzles arranged in an Ev nozzle row mounted on a recording head having such characteristics.

[0016] Figure 11(a) shows a cross-sectional view of a nozzle included in the Ev nozzle row. Ink is supplied from the ink tank that stores ink through the common ink channel on the left side of the figure. Ink droplets are ejected by the pressure of bubbles generated by heating the heating element 1501. At this time, if the flow resistance is strong in the right direction in the figure, asymmetry in the direction of the ink channel occurs, resulting in asymmetrical bubble shapes and meniscus shapes during foaming and defoaming, and an ejection characteristic in which the trail curves towards the side farther from the ink channel on the left.

[0017] Figure 11(b) shows the flight characteristics of the main droplet and satellite of ink droplets ejected from the nozzle as explained using Figure 11(a). In Figure 11(a), the trail curves in the opposite direction from the ink flow path on the left, so the centers of the satellite dots (hereinafter simply referred to as satellites) 1503 and 1504 are shifted to the right in the figure relative to the center of the main droplet 1502.

[0018] Figure 11(c) shows a cross-sectional view of a nozzle included in the Od nozzle row, where ink is supplied from the ink tank that stores ink through the common ink channel on the right. Ink droplets are ejected by the pressure of bubbles generated by heating the heating element 1505. At this time, if the flow resistance is strong in the left direction in the figure, asymmetry in the direction of the ink channel occurs, resulting in asymmetrical bubble shapes and meniscus shapes during foaming and defoaming, and an ejection characteristic in which the trail curves towards the side farther from the ink channel on the right.

[0019] Figure 11(d) shows the flight characteristics of the main droplet and satellite of ink droplets ejected from the nozzle as explained using Figure 11(c). In Figure 11(c), the tail curves in the opposite direction to the ink flow path on the right, so the centers of satellites 1507 and 1508 are shifted to the left in the figure relative to the center of the main droplet 1506.

[0020] In this embodiment, the recording head H is assumed to have characteristics that cause ink droplets to fly, as shown in Figures 11(a) to 11(d). Note that the flow resistance indicated by the arrows in Figures 11(a) and 11(c) can occur regardless of the scanning direction of the recording head H.

[0021] The characteristics of ink droplet flight, which differ from those shown in Figures 11(a) to 11(d), will be explained below with reference to Figures 11(e) to 11(h).

[0022] Figure 11(e) shows a cross-sectional view of a nozzle included in the Ev nozzle row, where ink is supplied from the ink tank that stores ink through the common ink channel on the left. Ink droplets are ejected by the pressure of bubbles generated by heating the heating element 1501. At this time, if the flow resistance is strong in the left direction in the figure, asymmetry in the direction of the ink channel occurs, resulting in asymmetrical bubble shapes and meniscus shapes during foaming and defoaming, and an ejection characteristic in which the trail curves towards the ink channel on the left.

[0023] Figure 11(f) shows the flight characteristics of the main droplet and satellite of ink droplets ejected from the nozzle as explained using Figure 11(e). In Figure 11(e), the tail curves in the direction of the ink flow path on the left, so the centers of satellites 1503 and 1504 are shifted to the left in the figure relative to the center of the main droplet 1502.

[0024] Figure 11(g) shows a cross-sectional view of a nozzle included in the Od nozzle row, where ink is supplied from the ink tank that stores ink through the common ink channel on the right. Ink droplets are ejected by the pressure of bubbles generated by heating the heating element 1505. At this time, if the flow resistance is strong in the rightward direction in the figure, asymmetry in the direction of the ink channel occurs, resulting in asymmetrical bubble shapes and meniscus shapes during foaming and defoaming, and an ejection characteristic in which the trail curves towards the ink channel on the right.

[0025] Figure 11(h) shows the flight characteristics of the main droplet and satellite of ink droplets ejected from the nozzle as explained using Figure 11(g). In Figure 11(g), the tail curves in the direction of the ink flow path on the right, so the centers of satellites 1507 and 1508 are shifted to the right in the figure relative to the center of the main droplet 1506.

[0026] The above describes the flight characteristics of the main droplet and satellite depending on the scanning direction of the recording head. As in this example, the flight characteristics of the main droplet and satellite do not have to be symmetrical depending on the scanning direction of the recording head; the flight distance of the main droplet and satellite may differ between the first scanning direction and the second scanning direction, which is the opposite of the first scanning direction. Furthermore, the description is not limited to differences in the flight characteristics of the main droplet and satellite caused by the nozzle structure as described above. For example, the flight characteristics of the main droplet and satellite may differ between the front nozzle row and the rear nozzle row in the direction of travel of the recording head H due to the influence of airflow generated by scanning and ink ejection of the recording head H (not shown). In this embodiment, the recording head H is described as having the characteristics of ink droplet flight as shown in Figures 11(a) to 11(d) above.

[0027] Figures 12(a) to 12(h) schematically illustrate how the main droplet 1502, satellite 1503, and satellite 1504 land on the recording medium according to the scanning direction of the carriage, when the ejection from the nozzles of the Ev nozzle row has the flight characteristics of a main droplet and satellite as shown in Figure 11(b). In the figures, arrows pointing horizontally represent the force applied in the scanning direction of the carriage, and downward arrows represent the force applied by ink ejection. Figures 12(a), 12(b), 12(c), and 12(d) show the time-series progression until landing in the first scanning direction where the carriage moves to the right in the figures.

[0028] In Figure 12(a), the center of satellite 1503 is ahead of the center of main droplet 1502 in the direction of travel, and the center of satellite 1504 is ahead of the center of satellite 1503 in the direction of travel. In Figure 12(b), main droplet 1502 lands on the recording medium, and satellites 1503 and 1504 continue their flight. In Figure 12(c), satellite 1503 lands in an area that does not overlap with the ink coating area by main droplet 1502, and satellite 1504 continues its flight. In Figure 12(d), satellite 1504 lands in an area that does not overlap with the ink coating areas by main droplet 1502 and satellite 1503. As a result, satellites 1503 and 1504 land at positions distant from the landing position of main droplet 1502.

[0029] Figures 12(e), 12(f), 12(g), and 12(h) show the timeline of events leading up to impact in the second scanning direction, where the carriage moves to the left in the figure. In Figure 12(e), the center of satellite 1503 is behind the center of main droplet 1502 in the direction of travel, and the center of satellite 1504 is behind the center of satellite 1503 in the direction of travel. In Figure 12(f), main droplet 1502 has impacted the recording medium, and satellites 1503 and 1504 are continuing their flight. In Figure 12(g), satellite 1503 has impacted an area overlapping with the ink coating area by main droplet 1502, and satellite 1504 is continuing its flight. In Figure 12(h), satellite 1504 has impacted an area overlapping with the ink coating area by either main droplet 1502 or satellite 1503. As a result, satellites 1503 and 1504 land in close proximity to the impact point of main droplet 1502.

[0030] Figures 13(a) to 13(h) schematically illustrate how the main droplet 1506, satellite 1507, and satellite 1508 land on the recording medium according to the scanning direction of the carriage, when the ejection from the nozzles of the Od nozzle row has the flight characteristics of a main droplet and satellite as shown in Figure 11(d). In the figures, arrows pointing horizontally represent the force applied in the scanning direction of the carriage, and downward arrows represent the force applied by ink ejection. Figures 13(a), 13(b), 13(c), and 13(d) show the time-series progression until landing in the first scanning direction where the carriage moves to the right in the figures.

[0031] In Figure 13(a), the center of satellite 1507 is behind the center of main droplet 1506 in the direction of travel, and the center of satellite 1508 is behind the center of satellite 1507 in the direction of travel. In Figure 13(b), main droplet 1506 lands on the recording medium, and satellites 1507 and 1508 continue their flight. In Figure 13(c), satellite 1507 lands in an area overlapping with the ink coating area by main droplet 1506, and satellite 1508 continues its flight. In Figure 13(d), satellite 1508 lands in an area overlapping with the ink coating area by either main droplet 1506 or satellite 1507. As a result, satellites 1507 and 1508 land in close proximity to the landing position of main droplet 1506.

[0032] Figures 13(e), 13(f), 13(g), and 13(h) show the time-series progression until impact in the second scanning direction, where the carriage moves to the left in the figure. In Figure 13(e), the center of satellite 1507 is ahead of the center of main droplet 1506 in the direction of travel, and the center of satellite 1508 is ahead of the center of satellite 1507 in the direction of travel. In Figure 13(f), main droplet 1506 has impacted the recording medium, and satellites 1507 and 1508 are continuing their flight. In Figure 13(g), satellite 1507 has impacted an area that does not overlap with the ink-coated area by main droplet 1506, and satellite 1508 is continuing its flight. In Figure 13(h), satellite 1508 has impacted an area that does not overlap with the ink-coated area by main droplet 1506 and satellite 1507. As a result, satellites 1507 and 1508 land at locations distant from the impact point of main droplet 1506.

[0033] The above describes the flight characteristics of the main droplet and satellite depending on the scanning direction of the carriage, and the impact positions of the main droplet and satellite on the recording medium. Hereafter, the characteristics described in Figures 11(a) to 11(d), Figure 12, and Figure 13 will be referred to as the "first flight characteristics." On the other hand, depending on the structure of the recording head, there may be a characteristic in which the positional relationship between the main droplet and satellite on the recording medium is approximately the same regardless of the scanning direction and nozzle row, and this characteristic will be referred to as the "second flight characteristics." For simplicity, in this embodiment, the head having the second flight characteristics is assumed to be a recording head in which the satellite either does not impact on the recording medium or impacts at the same position as the main droplets 2001 and 2002, as shown in Figure 20(a).

[0034] <Printing System Configuration> Figure 2(a) shows an example of a printing system configuration including an image forming apparatus 10 equipped with a recording device 2. As an example, Figure 2(a) shows a cloud print system in which a terminal device 11, a cloud print server 12, and an image forming apparatus 10 are connected via a network 13. The cloud print server 12 is a server device that provides cloud print services. In other words, in the configuration of Figure 2(a), the image forming apparatus 10 is a cloud print-compatible printer. The network 13 is a wired network, a wireless network, or a network that includes both. For example, the network 13 could be the internet, a WAN, or a VPN environment. However, the printing system is not limited to a cloud print system. For example, the network 13 may be configured as an in-house LAN, or the terminal device 11 and the image forming apparatus 10 may be configured to be directly connected without going through the network 13. In Figure 2(a), one terminal device 11 and one image forming apparatus 10 are shown, but there may be multiple terminal devices 11 and image forming apparatus 10. Also, the cloud print server 12 may be a server system composed of multiple information processing devices. Furthermore, the printing system may be a cloud printing system that integrates multiple cloud printing services.

[0035] Terminal device 11 is an information processing device such as a PC, tablet, or smartphone, and has a cloud printer driver for the cloud print service installed. On terminal device 11, the user can run any application software. For example, based on image data generated on a printing application, a print job and print data are generated via the cloud printer driver. The print job and print data are transmitted via the cloud print server 12 to the image forming apparatus 10 registered with the cloud print service. The image forming apparatus 10 is a device that prints on a recording medium such as paper, and prints an image on the recording medium based on the received print data.

[0036] <Control system configuration> The configuration of the control system in this embodiment will be described below with reference to Figure 2(b). Figure 2(b) is a schematic diagram of the image processing device 100. In this embodiment, the image processing device 100 will be described as being included in the image forming apparatus 10. However, the image processing device 100 may be configured as a device connected to the image forming apparatus 10, which includes the printer 2 and the scanner 202. For example, the image processing device 100 may be configured inside the host computer 201. In that case, the image processing device 100 does not need to include the recording head control unit 213 and the scanner IF control unit 205.

[0037] The host computer 201 is an information processing device that performs tasks such as creating print jobs consisting of necessary input image data and recording condition information for recording, and corresponds to, for example, the terminal device 11 in Figure 2(a). Recording condition information includes information such as the type and size of the recording paper and the recording quality.

[0038] The scanner 202 is a scanner device connected to the image processing unit 100. It optically reads a document placed on the scanner bed and converts the generated analog data into digital data via an AD converter. Scanning by the scanner 202 is performed by sending a scan job from the host computer 201 to the image processing unit 100, but is not limited to this. It can also be performed by a dedicated UI device connected to the image processing unit 100 or the scanner 202.

[0039] ROM206 is a readable memory that stores a program for controlling the image processing device 100. The CPU203 controls the image processing device 100 by executing the program stored in ROM206. The host IF control unit 204 communicates with the host computer 201, receives print jobs, and stores them in RAM207. RAM207 is a read / write memory used as an execution area for programs and a storage area for data.

[0040] The image processing unit 208 generates nozzle data, which is broken down into recordable nozzle units, from the input image data stored in the RAM 207 according to the recording conditions included in the print job. The generated nozzle data is stored in the RAM 207. The internal structure of the image processing unit 208 includes a decoder unit 209, a scan image correction unit 216, an image analysis unit 210, a color separation / quantization unit 211, and a nozzle separation processing unit 212.

[0041] The recording head control unit 213 generates recording data based on nozzle data stored in the RAM 207 and controls the recording head H in the printer 2. Furthermore, the recording head control unit 213 sets multiple ejection position adjustment values ​​stored in the RAM 207 to nozzle rows 1121 to 1128 and controls the ejection position of the nozzles included in nozzle rows 1121 to 1128 during the main scan of the recording head H. The control of the ejection position is performed using an encoder strip (not shown) mounted on the recording device 2. The shared bus 215 is connected to the CPU 203, host IF control unit 204, scanner IF control unit 205, ROM 206, RAM 207, and image processing unit 208. Communication between connected components is possible via the shared bus 215. The above describes the configuration of the control system in this embodiment.

[0042] <Overall Flow> The following describes the flow of edge processing, ejection position adjustment, and image recording according to this embodiment. Edge processing is a process that includes detecting edge pixels located at the boundary between an object and the outside of that object. Figure 3(a) is a flowchart showing the process performed by the image processing unit 208 in this embodiment. In this embodiment, the process in Figure 3(a) can convert input image data into nozzle data. The process in Figure 3(a) is performed by the image processing unit 208, but the image processing unit 208 may operate under the control of the CPU 203. In that case, in other words, the process in Figure 3(a) can also be said to be performed by the CPU 203.

[0043] In S301, the image processing unit 208 acquires input image data from the RAM 207. In S302, the decoder unit 209 performs decoding on the acquired input image data. The storage format of the input image data can vary, but it is common to use a compressed format such as JPEG to reduce the amount of communication between the host computer 201 and the image processing device 100. If the storage format is JPEG, the decoder unit 209 decodes the JPEG and converts it to a bitmap format (an information format in which an image is recorded as a continuous value of pixel values). When the host computer 201 communicates with the image processing device 100 via a dedicated driver, a dedicated storage format may be used. If both the driver and the image processing device 100 have a dedicated storage format that is convenient for them, the decoder unit 209 can convert it to the dedicated storage format. For example, it is possible to apply a storage format with different compression ratios to areas where information needs to be retained with fine precision and areas where it does not, in accordance with the characteristics of the inkjet recording device. If image quality is prioritized over reducing data usage, the input image data can be in bitmap format, in which case the decoder unit 209 can simply output the bitmap format as the conversion result.

[0044] In S303, the image analysis unit 210 performs image analysis using the bitmap image obtained from the decoding. In this embodiment, by analyzing the image, it is estimated, based on the features within the image, whether the target pixel is at the edge of the paper white or a pixel formed with a different ink relative to the target pixel. It is also estimated whether the target pixel is located at the edge in the shape formed by the pixel group, either up, down, left, or right.

[0045] Figure 3(b) shows the internal processing flow for the image analysis process performed in S303. In S401, the image analysis unit 210 converts the bitmap image resulting from the decoding into a luminance value. For example, if the bitmap image data is RGB 3-channel information, it is converted into luminance Y 1-channel information. Note that if the image data sent from the user by the application is already represented in luminance, S401 does not need to be performed.

[0046] In S402, the image analysis unit 210 converts the luminance Y data into binary data for edge detection. In this embodiment, as an example, threshold data Th, which is provided in advance in accordance with the recording mode of the printer, is used to convert it into binary data (Bin) according to the following conditional equation (1). The following binary data generation equation is just an example, and the design of the inequality condition and the form of the equation are not limited to this.

[0047] IF Y > Th : Bin = 0 else : Bin = 1 ···(1) In this embodiment, image analysis is performed using luminance as an indicator. In inkjet recording devices, the gradations for which black ink is used in color separation are limited. This is because black ink causes a large change in paper density with each drop relative to the paper white, and using a large amount of black ink from light gradations tends to lead to a decrease in image quality in terms of granularity. For this reason, compared to other color inks, it is easier to determine the ink generation position of black ink based on the luminance information of the input image. By setting the threshold data Th mentioned above to an appropriate value, it is possible to set a luminance value corresponding to the gradation in which a predetermined amount or more of black ink after ink separation begins to be ejected relative to the luminance information. In this embodiment, it is possible to control the number and arrangement of black ink dots, as well as the number and arrangement of other color ink dots adjacent to the black ink, and using luminance values ​​is in line with this control. However, this embodiment is not limited to this. For example, color separation may be performed in advance for this analysis process to accurately identify the pixels from which black ink as a predetermined color component is generated. If color separation is performed in advance, it is possible to understand not only the pixels from which cyan, magenta, and yellow ink are generated, as well as the ejection amounts, so a more detailed analysis is possible. In some cases, the input image data may contain information useful for analysis, such as being in CMYK format instead of RGB format. If the ejection amounts of cyan, magenta, and yellow inks are known, it may be possible to make decisions such as considering small ejection amounts to be the same as white paper and performing analysis of black ink occurring in the area equivalent to white paper on the paper surface. In this embodiment, these decisions are expressed using threshold data Th. The threshold data Th may be updated sequentially from the degree of wear of each nozzle in nozzle row 1101 to 1104 of the recording head in the recording device.

[0048] In S403, the image analysis unit 210 performs edge pattern detection using binary data.

[0049] Figures 4(a) and 4(b) show examples of pattern information for edge pattern detection. Each set of pattern information consists of two types: "for generating pattern matching data" and "for generating edge pattern detection results." For the pattern matching data generation information, bitwise AND processing is performed on each pixel of the rectangular region of binary data obtained in S402. The pattern matching data obtained as a result of the bitwise AND processing contains only the information necessary to detect edge patterns within the rectangular region. The edge pattern detection result generation information is used to perform pattern matching processing on the pattern matching data. If a perfect match is found as a result of the pattern matching processing, the rectangular region is determined to be a predetermined edge pattern. The determination result is linked to the central pixel within the rectangular region.

[0050] Figure 4(a) shows pattern information for determining that the target pixel is "the left and right ends of a 1-dot vertical line". The pattern matching data generation information is set to perform edge pattern detection on a 3x3 pixel grid including the target pixel. Pixels assigned "0" in the pattern matching data generation information are considered pixels that are not considered in pattern matching, regardless of how the binary data is formed. Next, the edge pattern detection result generation information corresponds to the predetermined edge pattern described above, and in this example, only the three pixels in the center column vertically are set to "1" within the 3x3 pixel grid. This information is equivalent to determining whether the three pixels in the center column vertically are low brightness and the other six pixels are high brightness. If the pattern matching data perfectly matches this pattern, it can be seen that at least the left and right sides have high brightness features = paper white or low-density color ink, and the target pixel and the areas above and below it have low brightness features = black ink.

[0051] Figure 4(b) shows pattern information for determining that a target pixel is not only "at the left and right ends of a 1-dot vertical line" but also "part of a 1-dot 1-space." A "1-dot 1-space" refers to a pattern in which multiple 1-dot vertical lines are arranged at 1-dot intervals. By expanding the range of the pattern matching data generation information to 7x3 pixels, information surrounding the 1-dot line to which the target pixel belongs can also be included in the determination.

[0052] Figure 4(c) shows the results of sequentially performing pattern matching on binary data using Figures 4(a) and 4(b). When the pattern matching data generation information and edge pattern detection result generation information from Figure 4(a) are applied to the target binary data, the result is determined to be a "match". When the pattern matching data generation information and edge pattern detection result generation information from Figure 4(b) are applied, the result is determined to be a "mismatch". Based on the detection results of the two patterns, it can be seen that the target binary data is "the left and right ends of a 1-dot vertical line" and "not part of a 1-dot 1-space".

[0053] Based on the above method, it is possible to detect a variety of edge patterns. In this embodiment, the target of pattern matching is 7x7 pixels, but this is just one example. For example, if it is sufficient to detect the patterns in Figure 4(a) and Figure 4(b), then 7x3 pixels are sufficient for pattern matching. On the other hand, if it is desired to individually detect line shapes of 4 dots or more, 7x7 pixels may not be sufficient, and a wider area may be set as the target. Expanding the target area requires more work memory to hold the binary data to be compared and more work memory to hold the pattern matching information. The work memory corresponds to RAM 207. If the image analysis unit 210 is a dedicated circuit and it is desired to process multiple pixels in parallel clk for pattern matching, the number of processing registers and processing circuits will also increase. In addition, since the pattern matching information needs to be stored in the ROM 206 of the image processing device 100 in advance, the capacity of ROM 206 is also required. When checking edge patterns in detail and in diverse ways, a large amount of pattern matching information is required. Therefore, the design must take into account the memory capacity and the increase in analysis time due to the increased number of comparisons. Implementing a "0" = "not considered in pattern matching" judgment in the pattern matching data generation information contributes to reducing memory capacity and the number of comparisons. Another configuration that reduces memory capacity is to perform pattern matching with different variations by processing such as rotation and phase shift, as shown in Figure 5. In the upper part of Figure 5, the pattern matching information shown in Figure 4(a) is rotated by 90 degrees, and using the processed pattern information, it can be determined that it is the upper and lower ends of a 1-dot horizontal line. In the lower part of Figure 5, the pattern information shown in Figure 4(a) is shifted horizontally by 1 pixel, and using the processed pattern matching information, it can be determined that it is an adjacent pixel to a 1-dot vertical line. In Figure 5, the variations are increased by processing the pattern matching information, but it is also possible to increase the variations by processing the binary data side.

[0054] As shown in Figure 4(c), applying multiple pattern matching pieces sequentially can narrow down the judgment results and obtain information that could not be obtained from individual pattern matching pieces. For example, in Figure 4(c), once a pattern "matches" the pattern in Figure 4(a), it may be unnecessary to perform the pre-prepared judgment regarding lines with 2 or more dots. Also, as shown in Figure 4(b), applying only pattern matching pieces that determine more detailed information about 1-dot lines can reduce the number of comparisons. Furthermore, by applying Figures 4(a) and 4(b), it can be determined that the target binary data is "the left and right ends of a 1-dot vertical line" and "not part of a 1-dot 1-space". By deriving this information from the results of both Figures 4(a) and 4(b), rather than preparing individual pattern matching pieces that can be obtained, it is effective in reducing memory usage.

[0055] Based on the above, this embodiment can determine whether a pixel requires special processing, such as thinning out dots or changing the arrangement of dots.

[0056] The results determined by the image analysis process in S303 are output in an information format suitable for processing in subsequent steps. For example, the determination result can be expressed as a 3-bit multi-value such as: Not detected (not matching any detection pattern) = 0, Top edge detected = 1, Bottom edge detected = 2, Left edge detected = 3, Right edge detected = 4, Adjacent to any edge = 5. Alternatively, a 5-bit representation with each bit assigned is also possible, such as: Not detected = 00000, Top edge detected = 00001, Bottom edge detected = 00010, Left edge detected = 00100, Right edge detected = 01000, Adjacent to any edge = 10000. The former reduces the amount of data transmitted to the next process. The latter has the advantage of reducing the processing load by allowing bit processing to be used in the next process. Here, we describe transmitting five pieces of information to the subsequent steps, but as explained in the explanation within S303, "pattern matching information can be expressed in various ways," so it is also possible to detect and transmit more information than the control information required in the subsequent processing steps.

[0057] Figures 6 and 7(a) show examples of the internal processing flows for the color separation quantization process performed in S304 and the nozzle separation process performed in S305, respectively. As a premise for the following explanation, the bitmap image resulting from the decoding in S302 is assumed to have 8-bit 256-level brightness values ​​for each pixel arranged at 600 dpi for R (red), G (green), and B (blue). Furthermore, in the edge information detected in S303, the upper edge (first edge) is defined as the pixel on the side where Bin changes from 1 to 0 and Bin=1 in the -Y direction, the lower edge (second edge) in the +Y direction, the right edge (fourth edge) in the +X direction, and the left edge (third edge) in the -X direction. The nozzles for each color of the recording head H are arranged at 1200 dpi in the Y direction for each color. Therefore, each pixel is recorded using the nozzles of the consecutive Ev row (hereinafter referred to as Ev nozzles) and the nozzles of the Od row (hereinafter referred to as Od nozzles). Here, the nozzle located on the upper end side of each pixel is defined as the upstream nozzle, and the nozzle located on the lower end side of each pixel is defined as the downstream nozzle. In this embodiment, the upstream nozzles correspond to the Ev nozzles, and the downstream nozzles correspond to the Od nozzles. In other words, in this embodiment, the recording resolution in the Y direction is twice that of the resolution of the image data used for edge pattern detection.

[0058] In the color correction process of S801, the color separation quantization unit 211 converts the RGB data of each pixel into R'G'B' data represented in a color space specific to the recording device. A specific conversion method can be, for example, by referring to a lookup table stored in memory beforehand.

[0059] In S802, the color separation quantization unit 211 performs color separation processing on the R'G'B' data. Specifically, it refers to a lookup table stored in memory beforehand and converts the luminance values ​​R'G'B' of each pixel into 8-bit 256-level density values ​​CMYK corresponding to the ink colors used by the recording device. Furthermore, the color separation quantization unit 211 duplicates the density value data of one or more of the CMYK colors, generating a total of two identical data sets. For simplicity, the following example shows the generation of black data K1 and K2. Note that K1 and K2 are applied to the Ev nozzle and Od nozzle of the black nozzle array 1101, respectively, through processing described later.

[0060] In steps S803-805, the color separation quantization unit 211 uses the density value K1 and the result determined in S303 to perform separate gradation correction processing based on whether the pixel to be processed is at the second edge or not. Furthermore, in steps S806-808, the color separation quantization unit 211 uses the density value K2 and the result determined in S303 to perform separate gradation correction processing based on whether the pixel to be processed is at the first edge or not. Gradation correction processing is a correction process to ensure that the input density value and the optical density represented by the recording medium P have a linear relationship. This correction process converts the 8-bit 256-gradation density values ​​K1 and K2 into 8-bit 256-gradation density values ​​K1'K2'. If the pixel is detected as being at the second edge in S303, the density value K1 is converted to K1'=0 in S805; otherwise, it is converted to K1' in the first gradation correction processing in S804. On the other hand, if the pixel in question is detected as being at the first edge in S303, the density value K2 is converted to K2'=0 in S808; otherwise, it is converted to K2' in the first tone correction processing in S807. Figures 7(b) and 7(c) show examples of settings for the first tone correction processing, where In corresponds to density values ​​K1 and K2, and Out corresponds to density values ​​K1' and K2', respectively. For simplicity, this explanation shows an example where In and Out have a linear relationship.

[0061] In S809, the color separation quantization unit 211 performs quantization on the density value K1' using an arbitrary quantization table as shown in Figure 25(b), converting it into 4-bit 3-value quantized data (quantized values) of "0000", "0001", and "0010". The specific processing in the conversion is as follows: The color separation quantization unit 211 doubles the density value K1' once, then divides it by 255, the maximum value of the quantization table, and calculates the quotient Q and remainder E for each pixel. At this time, Q can be 0, 1, or 2, and E can be 0 to 254. However, when Q=2, E=0. The remainder E of each pixel is then compared with the value D of the cell in the quantization table corresponding to that pixel. As a result, if "Q=2" or "Q=1 and E>D", the quantized data is set to "0010". If "Q=1 and E≦D" or "Q=0 and E>D", the quantized data is set to "0001". Then, if "Q=0 and E≦D", the quantized data is set to "0000". Through the above processing, 3-value quantized data is generated. If the size of the quantization table is smaller than the input image, the table can be repeatedly applied to the X and Y directions of the input image. In this example, the values ​​are represented as low density, intermediate density, and high density. Furthermore, in S810~812, the color separation quantization unit 211 uses the result determined in S303 to set a value in the most significant bit based on whether the pixel to be processed is at the first edge or not, and outputs 4-bit quantized data K1''. Specifically, if the pixel is detected to be at the first edge, the most significant bit is set to 1 in S812, and otherwise the most significant bit is set to 0 in S811. Similarly, in S813, the color separation quantization unit 211 performs quantization processing on the density value K2' using an arbitrary quantization table and converts it into 4-bit 3-value quantized data of "0000", "0001", and "0010". In this example, the values ​​are represented as low density, intermediate density, and high density. Furthermore, in S814-816, the decomposition quantization unit 211 uses the result determined in S303 to set a value in the most significant bit based on whether the pixel to be processed is at the second edge or not, and outputs 4-bit quantized data K2''. Specifically, if it is detected to be at the second edge, the most significant bit is set to 1 in S816, and otherwise, the most significant bit is set to 0 in S815.

[0062] In S305, the nozzle decomposition processing unit 212 performs index expansion processing on the quantized data K1'' and K2'' output in S304. In the index expansion processing of this embodiment, a pre-prepared index pattern is used to convert the 600 × 600 dpi quantized data K1'' and K2'' into 600 dpi binary nozzle data K1p and K2p. The quantized data K1'' is converted to nozzle data K1p in the first index expansion processing in S817 of Figure 7(a), and the quantized data K2'' is converted to nozzle data K2p in the second index expansion processing in S818. An index pattern is, in other words, a dot arrangement pattern for arranging dots in pixels.

[0063] Figures 8(a) to 8(d) show examples of dot placement patterns and reference index patterns used in the index expansion process. Figure 8(a) shows the dot placement pattern for the first index expansion process. If the quantized data K1'' of a single pixel at 600dpi x 600dpi indicates "0000" or "1000", no dot is placed in that pixel. If the quantized data K1'' indicates "0001", pattern A, which places a dot, and pattern B, which does not place a dot, are prepared. If the quantized data K1'' indicates "0010", "1001", or "1010", a dot is always placed in that pixel. Figure 8(b) shows the dot placement pattern for the second index expansion process. If the quantized data K2'' of a single pixel at 600dpi x 600dpi indicates "0001", pattern A, which does not place a dot, and pattern B, which places a dot, are prepared. If the quantized data K2'' represents "0000", "1000", "0010", "1001", or "1010", the process is the same as the first index expansion process. Figure 8(c) shows an example of a reference index pattern. In this embodiment, different index patterns are used in the first index expansion process in S817 and the second index expansion process in S818, but both are created based on the reference index pattern in Figure 8(c). In the reference index pattern, each square corresponds to a 1-pixel area of ​​600 dpi × 600 dpi, and it is determined whether to place dots in pattern A or pattern B for each pixel. The nozzle decomposition processing unit 212 generates nozzle data K1p for each pixel after the first index expansion process as data for the Ev nozzle of the black nozzle row 1101 corresponding to each pixel, and stores it in the RAM 207. Furthermore, the nozzle decomposition processing unit 212 generates the nozzle data K2p for each pixel after the second index expansion process as data for the Od nozzle of the black nozzle row 1101 corresponding to each pixel, and stores it in the RAM 207. Figure 8(d) shows the binary data at 600 dpi in the X direction and 1200 dpi in the Y direction after the index expansion process, and the positional relationship between that data and the nozzles of the black nozzle row 1101, when the quantization data of each pixel is uniformly "0001" (intermediate density).As shown in the figure, in the data in the Y direction, the 0th, 2nd, 4th... dots are formed by the Ev nozzle, and the 1st, 3rd, 5th... dots are formed by the Od nozzle. As a result, for each pixel of the 600dpi x 600dpi input image data, recording and non-recording are set for each nozzle in the black nozzle row 1101, and recording and non-recording are set for 600dpi x 1200dpi. The above describes the flow of edge processing according to this embodiment.

[0064] The recording head control unit 213 sets the Ev nozzle data and ejection position adjustment values ​​for the Ev nozzle row stored in the RAM 207 to the Ev nozzle row. Furthermore, the recording head control unit 213 sets the Od nozzle data and ejection position adjustment values ​​for the Od nozzle row stored in the RAM 207 to the Od nozzle row. Based on this data and the ejection position adjustment values, the recording head H records an image on the recording medium in the main scanning direction. Here, the ejection position adjustment values ​​include a reference value stored in the ROM 206 and a correction value from the reference value predetermined for each recording mode and image object. Furthermore, it may also include a value corrected from the reference value based on an ejection position adjustment function arbitrarily performed by the user. In addition, the ejection position adjustment values ​​may be relative position information with respect to the position of the recording head H identified by the encoder strip of the printer 2, or they may be relative time information. The above describes the flow of ejection position adjustment and image recording according to this embodiment.

[0065] <Processing other than the black nozzle row> In this embodiment, only the black data has been described for processing from S803 onwards. However, in S802, data other than black data, namely cyan, magenta, and yellow density value data, are also output. These can be processed in the same way as the black data. Alternatively, different processing may be used, as shown below.

[0066] Figure 10 shows an example of the internal processing flow for the color separation quantization process performed in S304 and the nozzle separation process performed in S305 for cyan, magenta, and yellow. S4701 and S4702 are the same as S801 and S802. Also, S4703 and S4704 are the same as S804 and S809, so their explanations are omitted.

[0067] In S4705, the color separation quantization unit 211 uses the result determined in S303 to output 4-bit quantization data C'', M'', Y'', based on which edge the pixel to be processed is adjacent to. Here, "which edge" refers to, for example, the first edge, the second edge, etc. Specifically, if the pixel is detected to be adjacent to which edge, the most significant bit of the quantization data is set to 1 in S4707; otherwise, the most significant bit of the quantization data is set to 0 in S4706.

[0068] In S4708, the nozzle decomposition processing unit 212 performs index expansion processing on the quantized data C'', M'', and Y'' output in S304. In this example, the index expansion processing uses a pre-prepared index pattern to convert the 600dpi x 600dpi quantized data C'', M'', and Y'' into 600dpi x 600dpi binary nozzle data C1p, C2p, M1p, M2p, Y1p, and Y2p.

[0069] Figures 10(c) and 10(d) show examples of dot placement patterns used in the index expansion process. Figure 10(c) shows the placement pattern for Y'', and Figure 10(d) shows the placement patterns for C'' and M''. The dot placement patterns in Figures 10(c) and 10(d) are concatenated vertically with 600dpi x 1200dpi placement information. When quantized data C'', M'', and Y'' represent "0000" and "1000" respectively, no dots of that color are placed above or below the corresponding pixel. When quantized data C'', M'', and Y'' represent "0001", pattern A is prepared, where a dot of that color is placed above, and pattern B is prepared, where a dot of that color is placed below. When quantized data C'', M'', and Y'' represent "0010", a dot of that color is always placed above or below the corresponding pixel. For quantized data C'' and M'', even when representing "1010", a dot of that color is always placed above or below the corresponding pixel. On the other hand, if the quantized data Y'' indicates "1010", pattern A is prepared, in which the dot of that color is placed on the upper side, and pattern B is prepared, in which the dot of that color is placed on the lower side. The reference index pattern is the same as in Figure 8(c). The nozzle decomposition processing unit 212 then generates the upper data from the upper and lower arrangement information of the cyan dots of each pixel as nozzle data C1p, which is used as data for the Ev nozzle of the cyan nozzle row 1102 corresponding to each pixel, and stores it in the RAM 207. Furthermore, the nozzle decomposition processing unit 212 generates the lower data from the upper and lower arrangement information of the cyan dots of each pixel as nozzle data C2p, which is used as data for the Od nozzle of the cyan nozzle row 1102 corresponding to each pixel, and stores it in the RAM 207. The same applies to magenta and yellow. As a result, for cyan and magenta, the dot arrangement is the same regardless of whether the pixel is adjacent to any edge or not, so no dot thinning is performed. On the other hand, for yellow, if the pixel is adjacent to any edge or not, dot thinning is performed. Here, we explained that dot thinning is performed for yellow when it is adjacent to any edge, but this is not limited to yellow; cyan and magenta dots may also be thinned when they are adjacent to any edge.The above describes the processing other than the black nozzle row. This description is common to all the embodiments described below.

[0070] <First Embodiment> The following will explain an example of edge processing using this embodiment, based on the flow shown in Figures 3 to 8, using Figures 14 to 17. Figure 14(a) shows the input image used in this explanation, with vertical lines arranged as image objects. Here, the vertical lines are images that extend uniformly in the direction of the nozzle arrangement of the recording head H. In Figure 14(a), pixels are arranged at 600 dpi, and each pixel has 8 bits and 256 gradations for R, G, and B, and all of them are so-called black pixels with a brightness value of 0, and the line has a pixel width of 6 pixels in the X direction, which is the direction that intersects with the nozzle arrangement direction.

[0071] The input image is first acquired by the image processing unit 208 in S301, and then decoded by the decoder unit 209 in S302. For simplicity, the decoded image is assumed to be the same as that shown in Figure 14(a). In S303, the image analysis unit 210 detects which edge each pixel corresponds to in the decoded image. Figure 14(b) shows the luminance Y data after luminance conversion in S401. Figure 14(c) shows the binary data obtained by binarizing the luminance Y data with Th=50 in S402. Figure 14(d) shows the results of edge detection for the above binary data. In Figure 14(d), "0" indicates no detection, "1" indicates the left edge, and "2" indicates the right edge opposite to the left edge in the scanning direction of the recording head.

[0072] Next, in S304, the image decoded in S302 is subjected to color separation quantization processing by the color separation quantization unit 211 based on the edge detection result in S303. Figure 14(e) shows the density values ​​K1 and K2 after the color separation processing in S802. Figure 14(f) shows the density value K1' after the gradation correction processing in S803 to S805, where S803 determines the second edge as the right edge. Therefore, the pixels that are "2" in Figure 14(d), i.e., the right edge pixels, have a density value of 0. Figure 14(g) shows the density value K2' after the gradation correction processing in S806 to S808, where S806 determines the first edge as the left edge. Therefore, the pixels that are "1" in Figure 14(d), i.e., the left edge pixels, have a density value of 0. Figure 15(a) shows the quantized data K1'' after going through S809 to S812, and Figure 15(b) shows the quantized data K2'' after going through S813 to S816. Here, both S809 and S813 show examples where the intensity value 128 is quantized as "0001" and the intensity value 255 is quantized as "0010". Also, the definitions of the first end and second end in S810 and S814 are the same as in S803 and S806. Therefore, as shown in Figure 15(a), among the pixels with K1'=255 in Figure 14(f), the pixels that are "1" in Figure 14(d), i.e., the leftmost pixels, have quantized data of "1010", and the other pixels have "0010". On the other hand, as shown in Figure 15(b), among the pixels with K2'=255 in Figure 14(g), the pixel that is "2" in Figure 14(d), i.e., the rightmost pixel, has a quantized data of "1010", while the other pixels have a quantized data of "0010".

[0073] Next, in S305, the image quantized in S304 is subjected to index expansion processing by the nozzle decomposition processing unit 212. Figures 15(c) and 15(d) show the nozzle data K1p and nozzle data K2p after the index expansion processing in S817 and S818. Figure 15(e) shows the dot arrangement when the recording head H having second flight characteristics records at 600dpi × 1200dpi based on the nozzle data K1p and nozzle data K2p. Comparing Figures 14(b), 14(d), and 15(e), it can be seen that in Figure 14(b), among the pixels with a brightness value of 0, the pixels that are neither at the left edge nor the right edge in Figure 14(d) are dots arranged in the respective 600dpi × 1200dpi regions in Figure 15(e). Furthermore, among the pixels with a brightness value of 0 in Figure 14(b), the pixels identified as the leftmost in Figure 14(d) show that only the upstream nozzle, i.e., the Ev nozzle, has a dot placed on it, as can be seen in Figure 15(e). Additionally, among the pixels with a brightness value of 0 in Figure 14(b), the pixels identified as the rightmost in Figure 14(d) show that only the downstream nozzle, i.e., the Od nozzle, has a dot placed on it, as can be seen in Figure 15(e).

[0074] In this embodiment, the dot arrangement shown in Figure 15(e) is not recorded directly onto the recording medium; rather, the dot positions are further adjusted in S501 by the ejection position adjustment value set by the recording head control unit 213.

[0075] Figures 16(a) to 16(e) illustrate one example, where Ev nozzles in the Ev nozzle row and Od nozzles in the Od nozzle row form a dot for a non-edge pixel at point B on the recording medium. For simplicity, it is assumed that when the recording head is not scanning, the ink droplets ejected from the Ev nozzles and the ink droplets ejected from the Od nozzles are both oriented horizontally in the Z direction.

[0076] Figures 16(a) and 16(c) show the case where the dot position is not adjusted, in other words, when the Ev nozzle row and the Od nozzle row aim at the same location relative to point B. As shown in Figure 16(a), the ink droplets ejected from each nozzle follow a trajectory as shown in 1601 due to the inertia of the recording head H in the scanning direction before landing on the recording medium. Therefore, the recording head control unit 213 determines, based on the encoder strip and ejection position adjustment value, that the Ev nozzle row has reached point A on the recording medium and ejects the Ev nozzle at that timing, causing the ink droplet 1602 to land on point B. Subsequently, when the Od nozzle row has reached point A on the recording medium and ejects the Od nozzle at that timing, the ink droplet 1603 to land on point B. Figure 16(c) shows the case when the recording head H performs a rescan, and the ink droplets ejected from each nozzle follow a trajectory as shown in 1606 due to the inertia of the recording head H in the -X direction before landing on the recording medium. Therefore, the recording head control unit 213 determines, based on the encoder strip and ejection position adjustment value, that the Od nozzle row has reached point E on the recording medium, and ejects the Od nozzle at that timing, causing the ink droplet 1607 to land at point B. Subsequently, when it determines that the Ev nozzle row has reached point E on the recording medium, it ejects the Ev nozzle at that timing, causing the ink droplet 1608 to land at point B. As a result, the dot arrangement shown in Figure 15(e) is formed regardless of the scanning direction of the recording head H, and the landing dot width in the X direction at that time is D1. Note that even when dots from Ev nozzles and Od nozzles are mixed at both the left and right edges, as in known edge processing techniques, the landing dot width in the X direction is approximately the same as D1.

[0077] In contrast, Figures 16(b) and 16(d) show the forward scan and reverse scan when adjusting the dot position. In the case of a forward scan, as shown in Figure 16(b), the recording head control unit 213 determines, based on the encoder strip and ejection position adjustment value, that the Ev nozzle row has reached point A on the recording medium and ejects the Ev nozzle at that timing, causing the ink droplet 1604 to land at point B. Subsequently, the recording head control unit 213 determines, based on the encoder strip and ejection position adjustment value, that the Od nozzle row has reached point C, which is offset in the -X direction from point A on the recording medium, and ejects the Od nozzle at that timing. This causes the ink droplet 1605 to land at point D, which is offset in the -X direction from point B on the recording medium. Here, by setting the ejection position adjustment value to a higher resolution than the recording resolution, the distance in the X direction between points B and D can be adjusted with a resolution of less than 1 pixel width. In the case of a rescan, as shown in Figure 16(d), the recording head control unit 213 determines, based on the encoder strip and ejection position adjustment value, that the Od nozzle row has reached point F, which is offset in the -X direction from point E on the recording medium, and ejects the Od nozzle at that timing. This causes the ink droplet 1609 to land at point D. Subsequently, when the unit determines that the Ev nozzle row has reached point E on the recording medium, it ejects the Ev nozzle, causing the ink droplet 1610 to land at point B. Figure 16(e) shows the dot arrangement formed in the forward scan and rescan by this adjustment, and the flight characteristics of the recording head H in this figure are the same as in Figure 15(e). Compared to Figure 15(e), the landing positions of the dots formed by the Od nozzles are uniformly offset in the -X direction, and the landing dot width D2 in the X direction is smaller than D1. Furthermore, since the position offset amount can be set to less than 1 pixel width, D2 can also be adjusted to less than 1 pixel width. In other words, it is possible to adjust the width of the lines formed on the recording medium to less than 1 pixel width.

[0078] Note that while Figures 16(a) to 16(e) illustrate an example where ejection position adjustment is performed using only the Od nozzle row, this is not always the case. Figures 17(a) to 17(c) show an example where adjustment is performed using both the Ev nozzle row and the Od nozzle row. In the case of forward scanning, as shown in Figure 17(a), the recording head control unit 213 ejects the Ev nozzles when it determines, based on the encoder strip and ejection position adjustment value, that the Ev nozzle row has reached point G, which is offset in the +X direction from point A on the recording medium. This causes the ink droplet 1701 to land at point H, which is offset in the +X direction from point B on the recording medium. Subsequently, the recording head control unit 213 ejects the Od nozzles when it determines, based on the encoder strip and ejection position adjustment value, that the Od nozzle row has reached point I, which is offset in the -X direction from point A on the recording medium. This causes the ink droplet 1702 to land at point J, which is offset in the -X direction from point B on the recording medium. Here, the distance in the X direction between point H and point J is equal to the distance in the X direction between point B and point D in Figures 16(b) and 16(d), and the distance in the X direction between point H and point B is equal to the distance in the X direction between point J and point B. In the case of double scanning, as shown in Figure 17(b), the recording head control unit 213 ejects the Od nozzle when it determines, based on the encoder strip and ejection position adjustment value, that the Od nozzle row has reached point K, which is offset in the -X direction from point E on the recording medium. This causes the ink droplet 1703 to land on point J on the recording medium. Subsequently, the recording head control unit 213 ejects the Ev nozzle when it determines, based on the encoder strip and ejection position adjustment value, that the Ev nozzle row has reached point L, which is offset in the +X direction from point E on the recording medium. This causes the ink droplet 1704 to land on point H on the recording medium. Figure 17(c) shows the dot arrangement formed during forward and reverse scanning by this adjustment, and the flight characteristics of the recording head H in this figure are the same as in Figure 15(e). Compared to Figure 15(e), the impact positions of the dots formed by the Ev nozzle are offset in the +X direction, and the impact positions of the dots formed by the Od nozzle are offset in the -X direction, and the impact dot width D3 in the X direction is smaller than D1 and equal to D2. In other words, as with Figure 16(e), it is possible to make the line width formed on the recording medium thinner.

[0079] In this embodiment, an example is shown where black vertical lines are placed on a white background, but this is not the only case. In particular, if the background is not white, in the dot arrangement of Figure 16(e), no dots are placed in area 1613, and depending on the contrast with the background color, that area may appear white. On the other hand, in the case of Figure 17(c), areas 1707 and 1708 are created as areas where no dots are placed, but since the width in the X direction of these areas is half that of area 1613, the possibility of those areas appearing white can be reduced. In this embodiment, an example is shown where the distance in the X direction between point H and point B is equal to the distance in the X direction between point J and point B, i.e., the ratio of the two is 1:1, but this is not the only case. Even if the ratio is set to other values ​​such as 2:1, it is possible to make the line width formed on the recording medium thinner. The same applies to variations in the position adjustment amount in the embodiments described later.

[0080] Up to this point, we have shown an example where the recording head H has a second flight characteristic, but it may also be a head with a first flight characteristic. Figures 20(a), 20(b), 20(d), and 20(e) illustrate this example. Figure 20(a) shows the case when ink droplets generated by the Ev nozzle and Od nozzle of the recording head H having a second flight characteristic in a single ejection are aimed at the same point on the X-axis of the recording medium. As shown in the figure, both the dots from the Ev nozzle and the dots from the Od nozzle do not land in a different position from the main droplets 2001 and 2002 regardless of the scanning direction, so that their respective center positions 2003 and 2004 land at the same position on the X-axis. Figure 20(b) shows the case when ink droplets generated by the Ev nozzle and Od nozzle of the recording head H having a first flight characteristic in a single ejection are aimed at the same point on the X-axis of the recording medium. As shown in the figure, during forward scanning, the dots from the Od nozzle do not have satellites that land at positions different from the main droplet 2007, but the dots from the Ev nozzle have satellites (2006) that land at positions different from the main droplet 2005. In reverse scanning, the characteristics of the Ev nozzle and Od nozzle are reversed compared to forward scanning. In such cases, the landing position shown in the figure is sometimes aimed at improving the granularity of the recorded image. Specifically, instead of aligning the center 2010 of the main droplet 2005 and the center 2009 of the main droplet 2007 at the same point on the X-axis, the landing position is set so that the center 2009 aligns with a position 2008 that is approximately equivalent to the centroid position of the combined main droplet 2005 and satellite 2006. Here, the center 2009 is approximately equivalent to the centroid position of the main droplet 2007. In other words, the landing position is set so that the centroid positions of the dot group from the Ev nozzle and the dot group from the Od nozzle are approximately the same on the X-axis.

[0081] Figures 20(d) and 20(e) show the dot arrangement formed when processing S301 to S501 is performed on the input image shown in Figure 14(a), using the impact position relationship shown in Figure 20(b) as the reference position. Figure 20(d) shows the dot arrangement for forward scanning, and Figure 20(e) shows the dot arrangement for reverse scanning. Both figures show the case where the ejection position adjustment based on S501 is performed only on the Od nozzle row, and the dashed lines in the figures show the position of the dots formed by the Od nozzles when no ejection position adjustment is performed. As shown in the figures, in all cases the dots formed by the Od nozzles are uniformly offset in the -X direction, and the impact dot widths D4 and D5 in the X direction are smaller than before the ejection position adjustment. Furthermore, by adjusting the ejection position of the Od nozzle row by less than 1 pixel width, the satellite 2013 ejected by the Ev nozzle in forward scanning is located inside the main droplet 2014 of the Od nozzle after the ejection position adjustment. Similarly, satellite 2016 ejected by the Od nozzle during rescanning is located inside the main droplet 2015 ejected by the Ev nozzle. In other words, in a recording head H with the first flight characteristics, it is possible to narrow the line width formed on the recording medium and suppress the reduction in edge sharpness caused by satellites, regardless of the scanning direction.

[0082] Although Figures 20(d) and 20(e) show an example where the discharge position adjustment based on S501 is performed only on the Od nozzle row, similar effects can be obtained by adjusting the positions of the Ev nozzle row and the Od nozzle row, as shown in Figures 17(a) and 17(b).

[0083] <Second Embodiment> The second embodiment will now be described in terms of its differences from the first embodiment. In the first embodiment, the processing was described for a case where the input image object is a vertical line with a width of 6 pixels and the width of the edge in the X direction is 1 pixel. In such a case, as shown in Figures 16(e) and 17(c), the dot density of the end regions 1611, 1612, 1705, and 1706 after dot position adjustment is greater than the density of the end regions 1531 and 1532 in Figure 15(e). Generally, a smaller dot density at the edge results in less ink bleeding on the recording medium and better edge sharpness. In this embodiment, the processing will be described for a case where the width of the edge is 2 pixels, as this configuration reduces the line width formed on the recording medium and the density of dot placement. Note that S301 to S302 are the same as in the first embodiment and will therefore not be described.

[0084] In the image analysis processing performed in S303, the image analysis unit 210 detects the first pixel at the left edge and the second pixel adjacent to it during edge detection in S403, and detects these together as the left edge. Similarly, it detects the first pixel at the right edge and the second pixel adjacent to it, and detects these together as the right edge. Figure 18(a) shows the result of edge determination for the binary data in Figure 14(c). Here, "0" in Figure 14(c) indicates no detection, "1" indicates the left edge, and "2" indicates the right edge. The subsequent S304 to S305 are the same as in the first embodiment, so the explanation is omitted. Figure 18(b) shows the dot arrangement after the index expansion processing in S305 of this embodiment. As shown in Figure 18(b), dots are placed only for the Ev nozzle in the 2-pixel width at the left edge, and dots are placed only for the Od nozzle in the 2-pixel width at the right edge.

[0085] Next, in S501, the dot position is adjusted by the ejection position adjustment value set by the recording head control unit 213. This process is the same as in the first embodiment, so the explanation is omitted. Figure 19(a) shows the dot arrangement in Figure 18(b) after the ejection position adjustments shown in Figures 16(b) and 16(d) have been made, and Figure 19(b) shows the dot arrangement in Figure 18(b) after the ejection position adjustments shown in Figures 17(a) and 17(b) have been made. Note that Figure 19 shows the case where the recording head H has a second flight characteristic. As shown in the figure, the density of dots in the edge regions 1901, 1902, 1903, and 1904 after dot position adjustment is smaller than the density of the edge regions 1611, 1612, 1705, and 1706 in Figures 16(e) and 17(c), and is approximately the same as the density of the edge regions 1531 and 1532 in Figure 15(e). This makes it possible to obtain sharp edges with less ink bleeding on the recording medium by further reducing the dot density in the edge regions while narrowing the line width formed on the recording medium by dot position adjustment, similar to the first embodiment.

[0086] Furthermore, the process of setting the edge width to 2 pixels as described in this embodiment is also effective when the recording head H has the first flight characteristics. In addition to cases where the positions of the main droplet and satellite on the recording medium are relatively close, as shown in Figure 20(b), it is also effective when multiple satellites 2011 land on the recording medium, or when the distance between the main droplet 2005 and satellite 2011 is large, as shown in Figure 20(c). Note that in Figure 20(c) as described above, the reference position is set to the case where the center of gravity position 2012, which is approximately the same as the center of gravity position of the dot group by the Ev nozzle, and the center of gravity position 2009, which is the center of gravity position of the dot group by the Od nozzle, land so that they are approximately the same on the X axis.

[0087] Figure 20(f) shows the dot arrangement during forward scanning when the impact position relationship shown in Figure 20(c) is used as the reference position, and processing S301 to S305 is performed on the input image shown in Figure 14(a) with the edge width set to 1 pixel, similar to the first embodiment. As shown in the figure, the position in the X direction of satellite 2017, which is ejected from the Ev nozzle and lands at the position furthest from the main droplet, is not significantly different from the position of dot 2018 of the Od nozzle. If ejection position adjustment is performed based on S501 from this point, depending on the adjustment value, satellite 2017 may be positioned outside the edge, as shown in Figure 20(g), which may reduce the sharpness of the edge.

[0088] In contrast, in this embodiment, when the edge width is 2 pixels, the dot arrangement during forward scanning after processing S301 to S305 is shown in Figure 20(h), and the dot arrangement during forward scanning after further ejection position adjustment based on S501 is shown in Figure 20(i). As shown in the figure, even when the ejection position is adjusted, the position of satellite 2017 in the X direction from the Ev nozzle is located inside the dot 2018 of the Od nozzle. Furthermore, the impact dot width D7 in the X direction is smaller than D6 before the ejection position adjustment. In other words, even with a recording head H that has the first flight characteristics and where the impact positions of the main droplet and satellite are far apart, by adjusting the ejection position with an edge width of 2 pixels, it is possible to narrow the line width formed on the recording medium and suppress the reduction in edge sharpness due to the satellite. Although Figure 20(i) shows the case where only the Od nozzle row is adjusted based on S501, similar effects can be obtained by adjusting the positions of the Ev nozzle row and the Od nozzle row, as shown in Figures 17(a) and 17(b). Furthermore, although Figure 20(i) shows the dot arrangement during the forward scan, similar effects can be obtained during the reverse scan as well.

[0089] <Third Embodiment> The third embodiment will now be described in terms of its differences from the first and second embodiments. In the first and second embodiments, an example was shown in which the input image was a vertical line with a pixel width of 6 pixels in the X direction. In this embodiment, the processing for vertical lines with other pixel widths will be described. Note that S301 to S302 are the same as in the first embodiment and will therefore not be described. The recording head H will be described as having a first flight characteristic with Figure 20(c) as the reference position.

[0090] Figure 21 shows the results of edge detection performed by the image analysis unit 210 in the image analysis process performed in S303, when the input image is a vertical line with a pixel width of 1 to 4 pixels in the X direction (hereinafter referred to as 1-pixel vertical line to 4-pixel vertical line). Here, "0" in the figure indicates no detection, "1" indicates the left edge, and "2" indicates the right edge. Figures 22(a) to 22(f) show the dot arrangement on the recording medium after processing in S303 to S501 on Figures 21(a) to 21(f).

[0091] In the case of a vertical line with a width of 1 pixel, as shown in Figure 21(a), the image analysis unit 210 does not detect the vertical line portion as "0," i.e., as an end, and the dot arrangement becomes as shown in Figure 22(a), and the dots on the recording medium are not thinned out. This is because, as in the first embodiment, if the dots were thinned out, in the case of a 1-pixel vertical line, the number of dots on the recording medium would be halved, and since the object itself is thin, there is a risk that the change in density due to thinning would be easily noticeable to the user. In this case, the impact position of the Od nozzle may change from the original dashed line position depending on the discharge position adjustment value set in S501, but the effect on the impact dot width D8 in the X direction is negligible.

[0092] In the case of a vertical line with a width of 2 pixels, as shown in Figure 21(b), the image analysis unit 210 detects the left and right pixels as the leftmost "1" and rightmost "2", respectively, and the dot arrangement is as shown in Figure 22(b). In this case, the impact position of the Od nozzle may change from the original dashed line position depending on the discharge position adjustment value set in S501, but the effect on the impact dot width D9 in the X direction is negligible. As shown in the figure, the positions of the main droplet of the Ev nozzle and the main droplet of the Od nozzle are closer together due to the discharge position adjustment, so depending on the flight characteristics of the recording head H, D9 may become smaller due to the discharge position adjustment. In the case of a 2-pixel vertical line, the arrangement may also be as shown in Figures 21(e) and 22(e). That is, the image analysis unit 210 does not detect the leftmost pixel of the 2-pixel vertical line as "0", i.e., as the end, and the dot arrangement may not have the leftmost pixel thinned out as shown in Figure 22(e). Even in this case, the impact dot width D12 in the X direction is the same as D9, and the reduction in the number of dots on the recording medium makes it difficult to see the change in density due to thinning. The effect is the same even if the image analysis unit 210 detects the leftmost pixel of the two-pixel vertical line as the leftmost "1" and the rightmost pixel as "0", i.e., not detected as an edge.

[0093] In the case of a vertical line with a width of 3 pixels, as shown in Figure 21(c), the image analysis unit 210 detects the leftmost and central pixels as "1" and the rightmost pixel as "2", and the dot arrangement is as shown in Figure 22(c). In this case, the impact position of the Od nozzle changes from the original dashed line position due to the discharge position adjustment value set in S501, but the effect on the impact dot width D10 in the X direction is negligible. As shown in the figure, the positions of the main droplet of the Ev nozzle and the main droplet of the Od nozzle are closer due to the discharge position adjustment, so depending on the flight characteristics of the recording head H, D10 may become smaller due to the discharge position adjustment. The image analysis unit 210 may also detect the central pixel as "2". Furthermore, in the case of a 3-pixel vertical line, the arrangement may be as shown in Figures 21(f) and 22(f). In other words, the image analysis unit 210 does not detect the central pixel of the three-pixel vertical line as "0," i.e., as an edge, and the dot arrangement does not require the central pixel to be thinned out, as shown in Figure 22(f). Even in this case, the impact dot width D13 in the X direction is the same as D10, and the reduction in the number of dots on the recording medium makes it difficult to visually perceive the change in density due to thinning.

[0094] In the case of a vertical line with a width of 4 pixels, as shown in Figure 21(d), the image analysis unit 210 detects the leftmost pixel and its adjacent pixels as "1" (left end), and the rightmost pixel and its adjacent pixels as "2" (right end), resulting in the dot arrangement shown in Figure 22(d). In this case, the impact position of the Od nozzle changes from the original dashed line position according to the ejection position adjustment value set in S501, and the impact dot width D11 in the X direction becomes smaller than before the ejection position adjustment. That is, it becomes possible to narrow the line width formed on the recording medium. Note that the pixels adjacent to the ends do not have to be in the form shown in Figures 21(d) and 22(d). For example, the image analysis unit 210 does not have to detect the left side, right side, or both sides of the pixels adjacent to the ends as "0", i.e., the ends, and does not need to thin out the dots corresponding to those parts. Even in this case, depending on the flight characteristics of the recording head H, the impact dot width in the X direction can be made smaller than before the ejection position adjustment, and the reduction in the number of dots on the recording medium decreases, making it difficult to visually perceive the change in density due to thinning.

[0095] For vertical lines with a width of 5 pixels or more, as in the first and second embodiments, the image analysis unit 210 detects only the left and right end pixels, or in addition to the pixels adjacent to the ends, as ends, and performs the processing in S303 to S501. This makes it possible to reduce the impact dot width in the X direction compared to before the ejection position adjustment, as in the first and second embodiments, and to narrow the line width formed on the recording medium.

[0096] In this embodiment, an example of adjusting only the Od nozzle row as the discharge position adjustment based on S501 is shown, but the embodiment is not limited to this. For example, as described in the first embodiment, a similar effect can be obtained even if the discharge positions of the Ev nozzle row and the Od nozzle row are adjusted respectively.

[0097] <Fourth Embodiment> The fourth embodiment will now be described in terms of its differences from the first to third embodiments. In the first to third embodiments, an example was shown in which the input image was a vertical line with a predetermined width in the X direction, i.e., the scanning direction of the recording head. In this embodiment, as an example of another image, the processing when the input image is a square image as shown in Figure 23(a) will be described. Note that S301 to S302 are the same as in the first embodiment and will therefore not be described. Furthermore, the recording head H will be described as having a first flight characteristic with Figure 20(c) as the reference position.

[0098] Figures 23(b) and 23(c) illustrate an example of processing the input image shown in Figure 23(a) by treating the edge width as 1 pixel. In the image analysis process performed in S303, the image analysis unit 210 detects the leftmost and topmost pixels together as "1" during edge detection in S403. Similarly, it detects the rightmost and bottommost pixels together as "2". The detection result is shown in Figure 23(b), and the dot arrangement obtained after S501 is shown in Figure 23(c). In the discharge position adjustment in S501, the dot position of the Od nozzle is shifted by Z1 in the -X direction relative to the dot position of the Ev nozzle. As shown in the figures, the dot arrangement density is reduced in all edge regions (top, bottom, left, and right) compared to areas other than the edges, thus reducing the reduction in sharpness of the edges on all sides. Furthermore, by adjusting the ejection position of S501, the impact dot width D22 in the X direction can be made approximately equal to the impact dot width D21 in the Y direction, resulting in line widths being approximately equal both vertically and horizontally on the recording medium, thus enabling the recording of images that are less likely to be perceived as unnatural by the user.

[0099] Figures 23(d) and 23(e) show the result when the input image shown in Figure 23(a) is processed with an edge width of 2 pixels. In the image analysis process performed in S303, the image analysis unit 210 detects the first pixel at the left edge and its adjacent second pixel, and the first pixel at the bottom edge and its adjacent second pixel together as "1" during edge detection in S403. Similarly, it detects the first pixel at the right edge and its adjacent second pixel, and the first pixel at the top edge and its adjacent second pixel together as "2". The detection result is shown in Figure 23(d), and the dot arrangement obtained after S501 is shown in Figure 23(e). In the discharge position adjustment in S501, the dot position of the Od nozzle is shifted by Z2 in the -X direction relative to the dot position of the Ev nozzle, where Z2 is greater than Z1. As shown in Figure 23(e), the dot arrangement density is reduced in all edge regions (top, bottom, left, and right) compared to areas other than the edges, thus reducing the decrease in sharpness of the edges on all sides. Furthermore, by setting the detection of the vertical direction in the image analysis unit 210 in the opposite direction to that shown in Figure 23(b), the impact dot width D23 in the Y direction is smaller than D21. In addition, by setting the amount of displacement caused by the ejection position adjustment of S501 to Z2, which is greater than Z1, it is possible to make the impact dot width D24 in the X direction approximately the same as D23. In other words, compared to the impact state shown in Figure 23(c), it is possible to record an image with even thinner and sharper line widths in both the vertical and horizontal directions on the recording medium while maintaining the same level of reduction in edge sharpness.

[0100] In this embodiment, the dot arrangement shown in Figure 23(c) has an edge width of 1 pixel, and the dot arrangement shown in Figure 23(e) has an edge width of 2 pixels. These can be switched within the printer 2. This switching process can be performed by the image forming apparatus 10 based on information about the recording mode received from the terminal device 11, such as whether or not it is a mode to improve line thickness due to ink bleeding on the recording medium. Figures 24(a) and 24(b) show examples of this process. Figure 24(a) is a flowchart of the image analysis process performed in S303, and Figure 24(b) is a flowchart of the setting of the ejection position adjustment value performed in S501. If the line thickness improvement mode is not set in the terminal device 11, the image analysis unit 210 performs the processes in S2402 and S2403. The edge detection result at that time is, for example, shown in Figure 23(b). Furthermore, the head control unit 213 performs the process in S2407. Here, the ejection position adjustment values ​​A and B are values ​​to achieve the dot arrangement shown in Figure 23(c), that is, an arrangement in which the position of the dot of the Od nozzle is shifted by Z1 in the -X direction relative to the position of the dot of the Ev nozzle. Depending on the configuration of the printer 2 and the recording head H, even if Z1 is 0, D21 and D22 may be approximately equivalent. In this case, Z1 may be 0. On the other hand, when the line thickness improvement mode is set in the terminal device 11, the image analysis unit 210 performs the processes of S2404 and S2405. The edge detection result at that time is, for example, shown in Figure 23(d). Furthermore, the head control unit 213 performs the process of S2408. Here, the ejection position adjustment values ​​C and D are values ​​to achieve the dot arrangement shown in Figure 23(e), that is, an arrangement in which the position of the dot of the Od nozzle is shifted by Z2 in the -X direction relative to the position of the dot of the Ev nozzle. As a result, the dot arrangement in Figure 23(c) and the dot arrangement in Figure 23(e) can be switched within the printer 2, and the user can adjust the line width formed on the recording medium.

[0101] In this embodiment, an example of adjusting only the Od nozzle row is shown as a configuration for adjusting the discharge position, but this is not limited to this. For example, as described in the first embodiment, the same effect as in this embodiment can be obtained even if the discharge positions of the Ev nozzle row and the Od nozzle row are adjusted separately.

[0102] (Regarding other embodiments) In the second to fourth embodiments, examples were shown where the edge width was 2 pixels at both the left and right ends, but this is not the only way. For example, the edge width may be 3 pixels or more, or the same effect as in this embodiment can be obtained even if the edge width differs at the left and right ends. This configuration can be achieved by making the pixels that are determined to be the left end "1" or the right end "2" different in S303.

[0103] Furthermore, in the embodiments described above, a configuration was described in which the dots for the nozzle row used in pixels determined by the image analysis unit 210 to be either edge are not thinned out, but the system is not limited to this. This configuration can be realized by the flowchart shown in Figure 26(a) and the gradation correction shown in Figure 26(b). The difference between Figure 26(a) and Figure 6 described above is that the processes S2601 and S2602 are added after S804, and the processes S2603 and S2604 are added after S807. In S2601 to S2602, the color separation quantization unit 211 performs a second gradation correction process on the density value K1' that was processed in the first gradation correction process in S804, but only if the pixel to be processed is at the first edge. Similarly, in S2603 to S2604, the color separation quantization unit 211 performs a second gradation correction process on the density value K2' that was processed in the first gradation correction process in S807, but only if the pixel to be processed is at the second edge. Figure 26(b) shows an example of the settings for the second tone correction process, where In represents the density values ​​K1' and K2' before processing, and Out represents the density values ​​K1' and K2' after processing. In the second tone correction process, In=Out up to a predetermined tone value (96 in the figure), and Out remains constant for In above that value. This allows the density values ​​of edge pixels to be reduced, making it possible to thin out the dots in the nozzle row used for pixels that the image analysis unit 210 has determined to be edge pixels.

[0104] Furthermore, although the embodiments described above show a so-called completely exclusive example in which only the Ev nozzle row is used for the leftmost and adjacent pixels, and only the Od nozzle row is used for the rightmost and adjacent pixels, the embodiment is not limited to this. For the purpose of maintaining the density of edge pixels, etc., both nozzle rows may be used for recording only some pixels at each edge, as long as the line width formed on the recording medium is not impaired. For example, this can be achieved by replacing S805 and S808 in Figure 6 with the third tone correction process shown in Figure 26(b). In the third tone correction process, In is the density values ​​K1 and K2, Out is the density values ​​K1' and K2' after processing, and the slope Out / In is sufficiently less than 1.

[0105] Furthermore, although the embodiments described above show examples of using an arbitrary quantization table in the quantization of density value data, a correlation may be established between the Ev nozzle row, the Od nozzle row, and their discharge position adjustment values. Figure 25(a) shows this process, which is performed by the color separation quantization unit 211 before the quantization process in S813. The color separation quantization unit 211 first obtains the discharge position adjustment values ​​set in S501 in S2501, and then calculates the relative shift amount Z of the Ev nozzle row and the Od nozzle row in the next S2502. Here, Z is positive when the dots of the Od nozzles are shifted in the -X direction relative to the Ev nozzles. Next, in S2503, the color separation quantization unit 211 calculates Dz = Z / (resolution of discharge position adjustment value / recording resolution) as the shift amount of the quantization table. At this time, Dz may be truncated or rounded. Then, in S2504, the color separation quantization unit 211 generates a table that is shifted in the -X direction by the Dz column to the quantization table applied to the Ev nozzle row in S809, and sets it as the quantization table to be applied to the Od nozzle row. Specifically, if Figure 25(b) is the quantization table used in S809 and Dz is 1, the quantization table in Figure 25(c) is set as the quantization table to be applied to the Od nozzle row. Alternatively, if the table reading start position in S809 is 2505, the same quantization table may be set for the Od nozzle row, and the table reading start position may be set to 2506. As a result, even if the ejection position adjustment value is set in S501, the quantization table can be applied to correspond to the adjusted dot position, making it possible to keep the granularity in the case of a halftone input image approximately constant regardless of the adjustment value.

[0106] Furthermore, although the above embodiments were described as examples where all concentration value data is converted to three values ​​during quantization, this is not limited to this, as long as the features and configuration are similar. It may also be converted to two values ​​or four or more values. Furthermore, although the above embodiments were described on the premise that the recording head has Ev nozzle rows and Od nozzle rows that are positioned differently in the Y direction, this is not limited to this, as long as the features and configuration are similar. Any of the above embodiments can be applied as long as there are multiple nozzle rows arranged, even if they are positioned at the same location in the Y direction.

[0107] Furthermore, although each embodiment has been described as a serial-type image processing device, it is not limited to this as long as the features and configuration are similar. A line-type recording head may be used, or a configuration in which serial-type heads are arranged vertically may be used. Furthermore, although each embodiment described above has been described as an inkjet printer, it is not limited to this as long as the features and configuration are similar. For example, it may be a laser printer using toner, or a copier.

[0108] Furthermore, although the bitmap data area and the like were described as areas within RAM in the embodiments described above, this is not limited to any rewritable storage device. For example, a separate HDD or eMMC (Embedded Multi Media Card) may be provided in addition to the RAM, and the entire data area may be placed within the storage area of ​​the HDD or eMMC, or only a part of the data area may be placed there.

[0109] The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0110] Furthermore, although the above embodiments have described image processing, including edge processing, being performed within the image forming apparatus 10, this is not limited to this, as long as the features and configuration are similar. Specifically, for example, some or all of the image processing, including edge processing, may be performed in an external device to the image forming apparatus 10, and subsequent processing may be performed within the image forming apparatus 10 based on the processing results.

[0111] This embodiment includes the following image processing apparatus, method, and program. (Item 1) A recording means for recording dots on a recording medium by ejecting ink droplets onto the recording medium, the recording means capable of recording dots at a resolution higher than the resolution of image data, and the recording means being movable relative to the recording medium in the scanning direction, A dot placement means that performs a process of placing dots on pixels based on the image data including an object, Equipped with, The recording means includes a first nozzle row capable of recording dots for a first region of each pixel of the object, and a second nozzle row capable of recording dots for a second region of each pixel of the object, wherein the first region and the second region are arranged in a direction perpendicular to the scanning direction. As a result of processing by the dot placement means, In the first group of edge pixels located at the first end of the object in the scanning direction and adjacent to the boundary between the object and the outside of the object, the ratio of dots arranged in the second region is smaller than the ratio of dots arranged in the first region. In a second edge pixel group located at a second end that is different from the first end and opposite to the first end in the scanning direction, and adjacent to the boundary, the ratio of dots arranged in the first region is smaller than the ratio of dots arranged in the second region. The positional relationship between the row of dots arranged in the first region of each pixel in the scanning direction of the object and the row of dots arranged in the second region of each pixel in the scanning direction of the object is uniformly shifted in the scanning direction such that the width of the object in the scanning direction becomes narrower. An image processing apparatus characterized by the following: (Item 2) The dots are placed in the first region of all first edge pixels included in the first group of first edge pixels at the first end, The dots are arranged in the second region of all second edge pixels included in the second edge pixel group at the second end. The image processing apparatus according to item 1, characterized in that it is a picture processing apparatus. (Item 3) No dots are placed in the second region of all of the first edge pixels at the first end. No dots are placed in the first region of all of the second edge pixels at the second end. The image processing apparatus according to item 2, characterized in that (Item 4) Dots are placed in at least a portion of the first region of all first edge pixels included in the first group of first edge pixels at the first end, Dots are arranged for at least a portion of the second region of all second edge pixels included in the second edge pixel group at the second end. The image processing apparatus according to item 1, characterized in that it is a picture processing apparatus. (Item 5) No dots are placed in the second region of all of the first edge pixels at the first end. No dots are placed in the first region of all of the second edge pixels at the second end. The image processing apparatus according to item 4, characterized in that (Item 6) The image processing apparatus according to any one of items 1 to 5, characterized in that the amount of the displacement is less than 1 pixel width. (Item 7) The image processing apparatus according to any one of items 1 to 6, characterized in that the centroid of each dot arranged in the first region of each pixel in the scanning direction of the object is located at the center of each pixel in the scanning direction. (Item 8) The centroid of each dot located in the first region of each pixel in the scanning direction of the object is shifted in the first direction from the center of each pixel in the scanning direction. The centroid of each dot located in the second region of each pixel in the scanning direction of the object is shifted in the second direction from the center of each pixel in the scanning direction. The first direction and the second direction are opposite directions in the scanning direction. An image processing apparatus according to any one of items 1 to 6, characterized in that (Item 9) The image processing apparatus according to any one of items 1 to 6, characterized in that the dots recorded on the recording medium include satellite dots recorded on the recording medium by the satellite when the ink droplet is separated into a main droplet and a satellite. (Item 10) The image processing apparatus according to item 9, characterized in that even if the dots in the second region of a pixel adjacent to the first edge pixel included in the first edge pixel group on the inside of the object are accompanied by the satellite dots, the satellite dots are recorded on the inside of the object in the scanning direction relative to the dots in the first region of the first edge pixel. (Item 11) The image processing apparatus according to item 9 or 10, characterized in that even if the dots in the first region of a pixel adjacent to the inside of the object with respect to the second edge pixel included in the second edge pixel group are accompanied by the satellite dots, the satellite dots are recorded further inside the object in the scanning direction than the dots in the second region of the second edge pixel. (Item 12) As a result of processing by the dot placement means, Even with respect to the first edge pixels included in the first edge pixel group, the ratio of dots placed in the second region is smaller than the ratio of dots placed in the first region. Even with respect to the second edge pixels included in the second edge pixel group, the ratio of dots placed in the first region is smaller than the ratio of dots placed in the second region. An image processing apparatus according to any one of items 9 to 11, characterized in that (Item 13) The image processing apparatus according to item 1, characterized in that the dots recorded on the recording medium do not include satellite dots recorded on the recording medium by the satellite when the ink droplet is separated into a main droplet and a satellite. (Item 14) As a result of processing by the dot placement means, Even with respect to the first edge pixels included in the first edge pixel group, the ratio of dots placed in the second region is smaller than the ratio of dots placed in the first region. Even with respect to the second edge pixels included in the second edge pixel group, the ratio of dots placed in the first region is smaller than the ratio of dots placed in the second region. The image processing apparatus according to item 13, characterized in that (Item 15) The image processing apparatus according to any one of items 1 to 14, characterized in that the amount by which the positional relationship shifts in the scanning direction when the image processing apparatus is operating in the second recording mode is smaller than the amount by which the positional relationship shifts in the scanning direction when the image processing apparatus is operating in the first recording mode. (Item 16) The image processing apparatus according to any one of items 1 to 14, characterized in that when the image processing apparatus operates in a first recording mode, the positional relationship is changed to be shifted in the scanning direction, and when the image processing apparatus operates in a second recording mode, the positional relationship is not changed. (Item 17) The object has a third end in a direction perpendicular to the scanning direction and a fourth end on the opposite side of the third end in that direction. The second recording mode is a recording mode in which, in each of the third edge pixel group located at the third end and adjacent to the boundary, and the fourth edge pixel group located at the fourth end and adjacent to the boundary, the ratio in which dots are placed in the region further from the boundary between the first region and the second region is smaller than the ratio in which dots are placed in the region closer to the boundary. The first recording mode is a recording mode in which, in each of the third edge pixel group and the fourth edge pixel group, the ratio of dots placed in the region closer to the boundary between the first region and the second region is smaller than the ratio of dots placed in the region further from the boundary. The image processing apparatus according to item 15, characterized in that... (Item 18) The system further comprises a quantization means that performs quantization processing using a quantization table in which quantization values ​​are defined based on the aforementioned image data, The quantization means performs the quantization process using a first quantization table for the first region and uses a second quantization table for the second region. An image processing apparatus according to any one of items 1 to 17, characterized in that (Item 19) The image processing apparatus according to item 18, characterized in that the second quantization table is a quantization table created from the first quantization table based on an amount that changes the positional relationship to shift in the scanning direction. (Item 20) A recording means for recording dots on a recording medium by ejecting ink droplets onto the recording medium, the recording means capable of recording dots at a resolution higher than the resolution of image data, and the recording means being movable relative to the recording medium in the scanning direction, A detection means for detecting edge pixels adjacent to the boundary between an object and the outside of the object, A quantization means that performs quantization processing based on the image data including the object, A dot placement means that performs a process of placing dots on pixels using a dot placement pattern corresponding to the quantized value after the quantization process, Equipped with, The recording means includes a first nozzle row capable of recording dots for a first region of each pixel of the object, and a second nozzle row capable of recording dots for a second region of each pixel of the object, wherein the first region and the second region are arranged in a direction perpendicular to the scanning direction. The detection means detects a first group of edge pixels located at the first end of the object in the scanning direction, and a second group of edge pixels located at the second end, which is different from the first end and on the opposite side of the scanning direction from the first end. The dot placement means is, In the first edge pixel group, the ratio of dots to be placed in the second region is smaller than the ratio of dots to be placed in the first region. In the second group of edge pixels, the ratio of dots to be placed in the first region is smaller than the ratio of dots to be placed in the second region. The positional relationship between the row of dots arranged in the first region of each pixel in the scanning direction of the object and the row of dots arranged in the second region of each pixel in the scanning direction of the object is uniformly shifted in the scanning direction such that the width of the object in the scanning direction becomes narrower. An image processing apparatus characterized by the following: (Item 21) The image processing apparatus according to item 20, characterized in that if the object does not have a predetermined pixel width in the scanning direction, detection by the detection means is not performed. (Item 22) The image processing apparatus according to item 20 or 21, characterized in that, if the object is an object having a width of 2 pixels in the scanning direction, any pixel in the direction of the pixel width is not detected as an edge pixel by the detection means. (Item 23) The image processing apparatus according to any one of items 20 to 22, characterized in that, if the object is an object having a width of 3 pixels in the scanning direction, the pixel in the center in the direction of the pixel width is not detected as the edge pixel by the detection means. (Item 24) The image processing apparatus according to any one of items 20 to 22, characterized in that, if the object is an object having a width of 3 pixels in the scanning direction, the pixel in the center in the direction of the pixel width is detected as the edge pixel by the detection means. (Item 25) A method performed in an image processing device, The aforementioned image processing device is A recording means for recording dots on a recording medium by ejecting ink droplets onto the recording medium, the recording means capable of recording dots at a resolution higher than the resolution of image data, and the recording means being movable relative to the recording medium in the scanning direction, The recording means includes a first nozzle row capable of recording dots for a first region of each pixel of an object included in the image data, and a second nozzle row capable of recording dots for a second region of each pixel of the object, wherein the first region and the second region are arranged in a direction perpendicular to the scanning direction. The aforementioned method, A dot placement step, which performs a process of placing dots on pixels based on the image data, It has, As a result of the processing in the dot placement step, In the first group of edge pixels located at the first end of the object in the scanning direction and adjacent to the boundary between the object and the outside of the object, the ratio of dots arranged in the second region is smaller than the ratio of dots arranged in the first region. In a second edge pixel group located at a second end that is different from the first end and opposite to the first end in the scanning direction, and adjacent to the boundary, the ratio of dots arranged in the first region is smaller than the ratio of dots arranged in the second region. The positional relationship between the row of dots arranged in the first region of each pixel in the scanning direction of the object and the row of dots arranged in the second region of each pixel in the scanning direction of the object is uniformly shifted in the scanning direction such that the width of the object in the scanning direction becomes narrower. A method characterized by the following: (Item 26) A method performed in an image processing device, The aforementioned image processing device is A recording means for recording dots on a recording medium by ejecting ink droplets onto the recording medium, the recording means capable of recording dots at a resolution higher than the resolution of image data, and the recording means being movable relative to the recording medium in the scanning direction, The recording means includes a first nozzle row capable of recording dots for a first region of each pixel of an object included in the image data, and a second nozzle row capable of recording dots for a second region of each pixel of the object, wherein the first region and the second region are arranged in a direction perpendicular to the scanning direction. The aforementioned method, A detection step for detecting edge pixels adjacent to the boundary between the object and the outside of the object, A quantization step which performs quantization processing based on the aforementioned image data, A dot placement step involves placing dots on pixels using a dot placement pattern corresponding to the quantized values ​​after the quantization process, It has, In the detection step, a first group of edge pixels located at the first end of the object in the scanning direction, and a second group of edge pixels located at the second end, which is different from the first end and on the opposite side of the scanning direction from the first end, are detected. In the dot placement process, In the first edge pixel group, the ratio of dots to be placed in the second region is smaller than the ratio of dots to be placed in the first region. In the second group of edge pixels, the ratio of dots to be placed in the first region is smaller than the ratio of dots to be placed in the second region. The positional relationship between the row of dots arranged in the first region of each pixel in the scanning direction of the object and the row of dots arranged in the second region of each pixel in the scanning direction of the object is uniformly shifted in the scanning direction such that the width of the object in the scanning direction becomes narrower. A method characterized by the following: (Item 27) A program for causing a computer to function as one of the means of an image processing apparatus described in any one of items 1 through 19. (Item 28) A program for causing a computer to function as one of the means of an image processing apparatus described in any one of items 20 to 24.

[0112] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0113] 10 Image forming apparatus: 100 Image processing apparatus: 203 CPU: 208 Image processing unit: 209 Decoder unit: 210 Image analysis unit: 211 Color separation quantization unit: 212 Nozzle separation unit

Claims

1. A recording means for recording dots on a recording medium by ejecting ink droplets onto the recording medium, the recording means capable of recording dots at a resolution higher than the resolution of image data, and the recording means being movable relative to the recording medium in the scanning direction, A dot placement means that performs a process of placing dots on pixels based on the image data including an object, Equipped with, The recording means includes a first nozzle row capable of recording dots for a first region of each pixel of the object, and a second nozzle row capable of recording dots for a second region of each pixel of the object, wherein the first region and the second region are arranged in a direction perpendicular to the scanning direction. As a result of processing by the dot placement means, In the first group of edge pixels located at the first end of the object in the scanning direction and adjacent to the boundary between the object and the outside of the object, the ratio of dots arranged in the second region is smaller than the ratio of dots arranged in the first region. In a second edge pixel group located at a second end that is different from the first end and opposite to the first end in the scanning direction, and adjacent to the boundary, the ratio of dots arranged in the first region is smaller than the ratio of dots arranged in the second region. The positional relationship between the row of dots arranged in the first region of each pixel in the scanning direction of the object and the row of dots arranged in the second region of each pixel in the scanning direction of the object is uniformly shifted in the scanning direction such that the width of the object in the scanning direction becomes narrower. An image processing apparatus characterized by the following:

2. The dots are placed in the first region of all first edge pixels included in the first group of first edge pixels at the first end, The dots are arranged in the second region of all second edge pixels included in the second edge pixel group at the second end. The image processing apparatus according to feature 1.

3. No dots are placed in the second region of all of the first edge pixels at the first end. No dots are placed in the first region of all of the second edge pixels at the second end. The image processing apparatus according to claim 2.

4. Dots are placed in at least a portion of the first region of all first edge pixels included in the first edge pixel group at the first end, Dots are arranged for at least a portion of the second region of all second edge pixels included in the second edge pixel group at the second end. The image processing apparatus according to feature 1.

5. No dots are placed in the second region of all of the first edge pixels at the first end. No dots are placed in the first region of all of the second edge pixels at the second end. The image processing apparatus according to feature 4.

6. The image processing apparatus according to claim 1, characterized in that the amount of the displacement is less than one pixel width.

7. The image processing apparatus according to claim 1, characterized in that the centroid of each dot arranged in the first region of each pixel in the scanning direction of the object is located at the center of each pixel in the scanning direction.

8. The centroid of each dot located in the first region of each pixel in the scanning direction of the object is shifted in the first direction from the center of each pixel in the scanning direction. The centroid of each dot located in the second region of each pixel in the scanning direction of the object is shifted in the second direction from the center of each pixel in the scanning direction. The first direction and the second direction are opposite directions in the scanning direction. The image processing apparatus according to feature 1.

9. The image processing apparatus according to claim 1, characterized in that the dots recorded on the recording medium include satellite dots recorded on the recording medium by the satellite when the ink droplet is separated into a main droplet and a satellite.

10. The image processing apparatus according to claim 9, characterized in that even if the dots in the second region of a pixel adjacent to the first edge pixel included in the first edge pixel group on the inside of the object are accompanied by the satellite dots, the satellite dots are recorded on the inside of the object in the scanning direction relative to the dots in the first region of the first edge pixel.

11. The image processing apparatus according to claim 9, characterized in that even if the dots in the first region of a pixel adjacent to the inside of the object with respect to the second edge pixel included in the second edge pixel group are accompanied by the satellite dots, the satellite dots are recorded further inside the object in the scanning direction than the dots in the second region of the second edge pixel.

12. As a result of processing by the dot placement means, Even with respect to the first edge pixels included in the first edge pixel group, the ratio of dots placed in the second region is smaller than the ratio of dots placed in the first region. Even with respect to the second edge pixels included in the second edge pixel group, the ratio of dots placed in the first region is smaller than the ratio of dots placed in the second region. The image processing apparatus according to feature 9.

13. The image processing apparatus according to claim 1, characterized in that the dots recorded on the recording medium do not include satellite dots recorded on the recording medium by the satellite when the ink droplet is separated into a main droplet and a satellite.

14. As a result of processing by the dot placement means, Even with respect to the first edge pixels included in the first edge pixel group, the ratio of dots placed in the second region is smaller than the ratio of dots placed in the first region. Even with respect to the second edge pixels included in the second edge pixel group, the ratio of dots placed in the first region is smaller than the ratio of dots placed in the second region. The image processing apparatus according to feature 13.

15. The image processing apparatus according to claim 1, characterized in that the amount by which the positional relationship shifts in the scanning direction when the image processing apparatus is operating in the second recording mode is smaller than the amount by which the positional relationship shifts in the scanning direction when the image processing apparatus is operating in the first recording mode.

16. The image processing apparatus according to claim 1, characterized in that when the image processing apparatus operates in a first recording mode, the positional relationship is changed to be shifted in the scanning direction, and when the image processing apparatus operates in a second recording mode, the positional relationship is not changed.

17. The object has a third end in a direction perpendicular to the scanning direction, and a fourth end on the opposite side of the third end in that direction. The second recording mode is a recording mode in which, in each of the third edge pixel group located at the third end and adjacent to the boundary, and the fourth edge pixel group located at the fourth end and adjacent to the boundary, the ratio in which dots are placed in the region further from the boundary between the first region and the second region is smaller than the ratio in which dots are placed in the region closer to the boundary. The first recording mode is a recording mode in which, in each of the third edge pixel group and the fourth edge pixel group, the ratio of dots placed in the region closer to the boundary between the first region and the second region is smaller than the ratio of dots placed in the region further from the boundary. The image processing apparatus according to feature 15.

18. The system further comprises a quantization means that performs quantization processing using a quantization table in which quantization values ​​are defined based on the aforementioned image data, The quantization means performs the quantization process using a first quantization table for the first region and uses a second quantization table for the second region. The image processing apparatus according to feature 1.

19. The image processing apparatus according to claim 18, characterized in that the second quantization table is a quantization table created from the first quantization table based on an amount that changes the positional relationship to shift in the scanning direction.

20. A recording means for recording dots on a recording medium by ejecting ink droplets onto the recording medium, the recording means capable of recording dots at a resolution higher than the resolution of image data, and the recording means being movable relative to the recording medium in the scanning direction, A detection means for detecting edge pixels adjacent to the boundary between an object and the outside of the object, A quantization means that performs quantization processing based on the image data including the object, A dot placement means that performs a process of placing dots on pixels using a dot placement pattern corresponding to the quantized value after the quantization process, Equipped with, The recording means includes a first nozzle row capable of recording dots for a first region of each pixel of the object, and a second nozzle row capable of recording dots for a second region of each pixel of the object, wherein the first region and the second region are arranged in a direction perpendicular to the scanning direction. The detection means detects a first group of edge pixels located at the first end of the object in the scanning direction, and a second group of edge pixels located at the second end, which is different from the first end and on the opposite side of the first end in the scanning direction. The dot placement means is, In the first edge pixel group, the ratio of dots to be placed in the second region is smaller than the ratio of dots to be placed in the first region. In the second group of edge pixels, the ratio of dots to be placed in the first region is smaller than the ratio of dots to be placed in the second region. The positional relationship between the row of dots arranged in the first region of each pixel in the scanning direction of the object and the row of dots arranged in the second region of each pixel in the scanning direction of the object is uniformly shifted in the scanning direction such that the width of the object in the scanning direction becomes narrower. An image processing apparatus characterized by the following:

21. The image processing apparatus according to claim 20, characterized in that if the object does not have a predetermined pixel width in the scanning direction, detection by the detection means is not performed.

22. The image processing apparatus according to claim 20, characterized in that, if the object is an object having a width of 2 pixels in the scanning direction, any pixel in the direction of the pixel width is not detected as an edge pixel by the detection means.

23. The image processing apparatus according to claim 20, characterized in that, if the object is an object having a width of 3 pixels in the scanning direction, the pixel in the center in the direction of the pixel width is not detected as an edge pixel by the detection means.

24. The image processing apparatus according to claim 20, wherein, if the object is an object having a width of 3 pixels in the scanning direction, the pixel in the center in the direction of the pixel width is detected as the edge pixel by the detection means.

25. A method performed in an image processing device, The aforementioned image processing device is A recording means for recording dots on a recording medium by ejecting ink droplets onto the recording medium, the recording means capable of recording dots at a resolution higher than the resolution of image data, and the recording means being movable relative to the recording medium in the scanning direction, The recording means includes a first nozzle row capable of recording dots for a first region of each pixel of an object included in the image data, and a second nozzle row capable of recording dots for a second region of each pixel of the object, wherein the first region and the second region are arranged in a direction perpendicular to the scanning direction. The aforementioned method, A dot placement step is performed to place dots on pixels based on the aforementioned image data. It has, As a result of the processing in the dot placement step, In the first group of edge pixels located at the first end of the object in the scanning direction and adjacent to the boundary between the object and the outside of the object, the ratio of dots arranged in the second region is smaller than the ratio of dots arranged in the first region. In a second edge pixel group located at a second end that is different from the first end and opposite to the first end in the scanning direction, and adjacent to the boundary, the ratio of dots arranged in the first region is smaller than the ratio of dots arranged in the second region. The positional relationship between the row of dots arranged in the first region of each pixel in the scanning direction of the object and the row of dots arranged in the second region of each pixel in the scanning direction of the object is uniformly shifted in the scanning direction such that the width of the object in the scanning direction becomes narrower. A method characterized by the following:

26. A method performed in an image processing device, The aforementioned image processing device is A recording means for recording dots on a recording medium by ejecting ink droplets onto the recording medium, the recording means capable of recording dots at a resolution higher than the resolution of image data, and the recording means being movable relative to the recording medium in the scanning direction, The recording means includes a first nozzle row capable of recording dots for a first region of each pixel of an object included in the image data, and a second nozzle row capable of recording dots for a second region of each pixel of the object, wherein the first region and the second region are arranged in a direction perpendicular to the scanning direction. The aforementioned method, A detection step for detecting edge pixels adjacent to the boundary between the object and the outside of the object, A quantization step which performs quantization processing based on the aforementioned image data, A dot placement step involves placing dots on pixels using a dot placement pattern corresponding to the quantized values ​​after the quantization process, It has, In the detection step, a first group of edge pixels located at the first end of the object in the scanning direction, and a second group of edge pixels located at the second end, which is different from the first end and opposite to the first end in the scanning direction, are detected. In the dot placement process, In the first edge pixel group, the ratio of dots to be placed in the second region is smaller than the ratio of dots to be placed in the first region. In the second group of edge pixels, the ratio of dots to be placed in the first region is smaller than the ratio of dots to be placed in the second region. The positional relationship between the row of dots arranged in the first region of each pixel in the scanning direction of the object and the row of dots arranged in the second region of each pixel in the scanning direction of the object is uniformly shifted in the scanning direction such that the width of the object in the scanning direction becomes narrower. A method characterized by the following:

27. A program for causing a computer to function as each means of the image processing apparatus according to any one of claims 1 to 19.

28. A program for causing a computer to function as each means of the image processing apparatus according to any one of claims 20 to 24.

Images