Printing apparatus, its control method, and computer program

Abstract

To provide a printer, a control method thereof and a computer program which can perform printing with suitable halftone processing according to a printing medium.SOLUTION: A control device 30 included in a printer 1 executes halftone processing (S4) and printing processing (S5). Before executing the printing processing (S5), it executes acquisition processing (S2) of acquiring medium information indicating a type of a printing medium A on which an image is printed, and decision processing (S3) of deciding one of plural types of conversion methods about the halftone processing as a first conversion method used in the halftone processing on the basis of the medium information.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a printing apparatus such as an inkjet printer, a control method thereof, and a computer program.

Background Art

[0002] Conventionally, printing apparatuses that eject ink onto various types of printing media to form images have been known (see Patent Document 1). When a paper jam occurs in the paper supplied from a predetermined paper feed port during printing in the printing apparatus of Patent Document 1, depending on the paper type, an alternative paper is supplied from another paper feed port and printed. Here, the paper type refers to the type of paper quality of the paper, and examples include plain paper, thick paper, recycled paper, letterhead, colored paper, printed paper, high-color paper, and the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when the printing medium is different, since its surface shape and material are also different, the form of the ink after landing on the printing medium also becomes different. For example, in a printing medium in which ink is less likely to bleed compared to a printing medium in which ink is likely to bleed, the granularity of the landed ink is more likely to be noticeable. In addition, although there are multiple methods known as halftone processing for expressing the shading of an image in multiple tones by controlling the landing density of multiple ink droplets, the ease of noticing the granularity and the likelihood of generating periodic patterns in the printed image differ depending on the method adopted.

[0005] Therefore, an object of the present disclosure is to provide a printing apparatus capable of printing by a suitable halftone process according to a printing medium, a control method thereof, and a computer program. [Means for solving the problem]

[0006] The printing apparatus according to this disclosure includes a head for printing an image on multiple types of printing media by ejecting ink based on image data, and a control device. The control device performs a halftone process for converting the image data into data for ejecting ink from the head using a predetermined conversion method, and a printing process for ejecting ink from the head based on the data obtained from the halftone process. Furthermore, before performing the printing process, the control device performs an acquisition process for acquiring media information indicating the type of printing medium on which the image will be printed, and a determination process for determining, based on the media information, one of multiple conversion methods for the halftone process to be used as a first conversion method for the halftone process.

[0007] The method for controlling a printing apparatus according to this disclosure is a method for controlling a printing apparatus equipped with a head that ejects ink based on image data to print an image on multiple types of printing media, and includes: a halftone processing that converts the image data into data for ejecting ink from the head using a predetermined conversion method; and a printing process that ejects ink from the head based on the data on which the halftone processing has been performed, and further includes: an acquisition process performed before the printing process to acquire media information indicating the type of printing media on which the image will be printed; and a determination process that, based on the media information, determines one of multiple types of conversion methods for the halftone processing as a first conversion method to be used for the halftone processing.

[0008] The computer program of this disclosure is a computer program to be executed by a computer in a printing apparatus comprising a head for printing an image on multiple types of printing media by ejecting ink based on image data, and a computer, wherein the computer is caused to execute: a halftone processing which converts the image data into data for ejecting ink from the head by a predetermined conversion method; a printing process which ejects ink from the head based on the data on which the halftone processing has been performed; and further, before executing the printing process, an acquisition process which is caused to acquire media information indicating the type of printing medium on which the image will be printed; and a determination process which, based on the media information, determines one of multiple conversion methods for the halftone processing as a first conversion method to be used for the halftone processing. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide a printing apparatus capable of printing with a suitable halftone process depending on the printing medium, a control method thereof, and a computer program. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram of the printing apparatus relating to this disclosure. [Figure 2] Figure 2 is a block diagram showing the functional configuration of a printing device. [Figure 3] Figure 3 is a flowchart showing a series of operations, including a first example of the decision process related to halftone processing performed by the control unit. [Figure 4] Figure 4 is a diagram showing an example of correspondence information stored in a memory device. [Figure 5] Figure 5 is a flowchart showing the operation of the control unit when it determines the first conversion method based on the media information. [Figure 6] Figure 6 is a flowchart showing a series of operations, including a second example of the decision process related to halftone processing performed by the control unit. [Figure 7]Figure 7 is a flowchart showing a series of operations, including a third example of a decision process related to halftone processing performed by the control unit. [Figure 8] Figure 8 is a flowchart showing the determination process of the first conversion method related to the modified example, which is performed by the control device. [Figure 9] Figure 9 is a flowchart showing a specific example of the first image evaluation process in Figure 8. [Figure 10] Figure 10 is a flowchart showing the process of storing color-coded evaluation LUTs in a memory device. [Figure 11] Figure 11 is a diagram showing an example of a color-coded evaluation LUT. [Figure 12] Figure 12 is a flowchart showing a specific example of the second image evaluation process in Figure 9. [Figure 13] Figure 13 is a schematic diagram illustrating a specific example of the second image evaluation process. [Figure 14] Figure 14 is a schematic diagram illustrating a specific example of the second image evaluation process. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the following, the same reference numerals will be used for the same or corresponding elements throughout all drawings, and redundant explanations will be omitted.

[0012] <Printing device configuration> Figure 1 is a schematic diagram of a printing apparatus 1 according to this disclosure. The printing apparatus 1 prints an image on a printing medium A using ink ejected from a head 10 based on image data. In the following, an example using an inkjet printer as such a printing apparatus 1 will be described.

[0013] The printing apparatus 1 is of a serial head type, and a process of discharging inks of a plurality of colors while the head 10 moves to form an image and a process of conveying the printing medium A are alternately performed. Hereinafter, the conveying direction of the printing medium A is referred to as the front-rear direction. And, of the two directions orthogonal to the front-rear direction, the moving direction in which the head 10 moves is referred to as the left-right direction, and the remaining one direction is referred to as the up-down direction. However, the arrangement direction of the printing apparatus 1 is not limited to this.

[0014] The head 10 included in the printing apparatus 1 is housed in the housing 1A of the printing apparatus 1, and has a nozzle row 12 in which a plurality of nozzles 11 that open downward to discharge ink are arranged in the front-rear direction. The printing apparatus 1 of the present disclosure has a plurality of nozzle rows 12. For example, at least one row of nozzle rows 12 is formed on the head 10 for each color of ink. A drive element 13 (see FIG. 2) is provided for each nozzle 11 on the head 10. The drive element 13 is a piezoelectric element, a heating element, an electrostatic actuator, or the like, and applies pressure for discharging ink from the corresponding nozzle 11 to the ink in the head 10 by driving.

[0015] The printing apparatus 1 includes a platen 14 disposed opposite to the head 10. The platen 14 is positioned at a predetermined distance below the head 10, and supports the printing medium A from below by a flat upper surface.

[0016] The printing apparatus 1 includes a conveying device 15 for conveying the printing medium A on the platen 14. The conveying device 15 has, for example, two conveying rollers 16 and a conveying motor 17 (see FIG. 2). The two conveying rollers 16 are arranged apart from each other in the front-rear direction with the platen 14 interposed therebetween, and are connected to the rotating shaft of the conveying motor 17 via a speed reducer. Therefore, when the conveying motor 17 is driven, the two conveying rollers 16 rotate about their axial centers, and convey the printing medium A on the platen 14 in the front-rear direction.

[0017] The printing apparatus 1 includes a scanning device 18 that moves the head 10 in the left-right direction. The scanning device 18 includes a carriage 19, two guide rails 20, an endless belt 21, and a scanning motor 22 (see Figure 2). The carriage 19 is a housing that supports the head 10. The two guide rails 20 extend left and right across the platen 14 and are positioned front to back, with the head 10 sandwiched between them. These two guide rails 20 support the carriage 19 so that it can move in the left-right direction.

[0018] The endless belt 21 is wound around two pulleys 23 located near both the left and right ends of one of the guide rails 20, and is connected to the carriage 19 at predetermined points. The scanning motor 22 has its rotating shaft connected to one of the pulleys 23 via a reduction gear. Therefore, when the scanning motor 22 is driven to rotate, the endless belt 21 moves, and the carriage 19 supporting the head 10 moves left and right along the guide rail 20.

[0019] The printing apparatus 1 includes a plurality of tanks 24 for storing ink of each color to be supplied to the print head 10. These tanks 24 are housed inside the housing 1A by opening a retractable cover (not shown) provided on the housing 1A. The printing apparatus 1 of this disclosure uses four inks, for example, cyan, yellow, magenta, and black, and accordingly includes four tanks 24. One end of a flexible tube 25 is connected to each tank 24, and the other end is connected to the ink supply port of the print head 10, so that the ink from each tank 24 is sent to the print head 10 through the tube 25.

[0020] Figure 2 is a block diagram showing the functional configuration of the printing apparatus 1. As shown in Figure 2, the printing apparatus 1 includes a control device 30, and a storage device 31, an interface 32, a head drive circuit 33, a transport drive circuit 34, a scanning drive circuit 35, an output device 36, an input device 37, and a camera 38 connected to the control device 30.

[0021] The control device 30 is, for example, a computer and includes circuits such as a processor like an MPU or an integrated circuit like an ASIC. The storage device 31 is a memory accessible from the control device 30 and includes, for example, RAM and ROM. Of these, the RAM temporarily stores image data and various data used during calculations by the control device 30. The ROM stores computer programs and data for various data processing. Therefore, the control device 30 controls the operation of each part of the printing device 1 by executing computer programs while referring to the data stored in the storage device 31.

[0022] Interface 32 is a connection device that connects the control device 30 to external devices of the printing device 1. Examples of external devices include other computers, communication networks, recording media, displays, and other printing devices. The printing device 1 acquires image data and print setting information from external devices, such as computers, via this interface 32. Examples of this image data include raster data representing an image to be printed on printing medium A.

[0023] The head drive circuit 33 is electrically connected to each drive element 13 of the head 10 and controls the operation of each drive element 13. Specifically, the control device 30 outputs a control signal to the head drive circuit 33 to drive the drive elements 13, and the head drive circuit 33 generates a drive signal based on the input control signal and outputs this drive signal to each drive element 13. As a result, each drive element 13 is driven based on the corresponding drive signal and operates to apply a predetermined ejection pressure to the ink in the head 10 at a predetermined timing. Therefore, the ejection timing and the size of the ejected ink (volume of the ink droplet) from each nozzle 11 can be controlled.

[0024] The transport drive circuit 34 is electrically connected to the transport motor 17 of the transport device 15, and the operation of the transport motor 17 is controlled by the control device 30 via the transport drive circuit 34. As a result, the transport device 15 can transport the printing medium A on the platen 14 intermittently or continuously in the forward and backward directions, and can also stop and hold it at a predetermined position on the platen 14.

[0025] The scanning drive circuit 35 is electrically connected to the scanning motor 22 of the scanning device 18, and the operation of the scanning motor 22 is controlled by the control device 30 via the scanning drive circuit 35. As a result, the scanning device 18 can move the carriage 19 that supports the head 10 in the left and right directions at different speeds, and can also stop the carriage 19 at any position within its range of motion.

[0026] The output device 36 is a device that outputs various types of information, including alarms, to the outside, such as a display and a speaker. The display can output information to the user by showing images or text, and the speaker can output information to the user by emitting sound. The input device 37 is a device that accepts input of information from the outside, such as a touch panel or a physical switch, and is located in a position that can be operated by the user, such as the top or front of the housing 1A of the printing device 1. It accepts operations from the user and outputs the accepted operation information to the control device 30. The camera 38 is, for example, a CMOS sensor with multiple photodiodes, and is located inside the housing 1A in a position facing the platen 14 from above. It photographs the surface of the printing medium A supported on the platen 14, and the captured image is output to the control device 30.

[0027] <Printing operation> In such a printing apparatus 1, the control device 30 acquires image data via the interface 32 and performs halftone processing and printing based on this image data. Halftone processing is a process that converts image data into printing data for ejecting ink from the head 10, and in particular, it is a process that converts the data so that it can represent gradation and other grayscale images with ink droplets of a predetermined volume. Specifically, halftone processing is a process that reduces the gradation of the colors used in the image data to four colors: cyan, yellow, magenta, and black, and converts the image to be printed based on the image data into four gradations: no dots, small dots, medium dots, and large dots. The control device 30 can perform multiple conversion methods in halftone processing, for example, it can perform a dithering method using binary values ​​(first method), an error diffusion method using binary values ​​(second method), a dithering method using quaternary values ​​(third method), and an error diffusion method using quaternary values ​​(fourth method).

[0028] Since each method is publicly known, only a brief explanation will be given here. The dithering method using binary values ​​(first method) is a data conversion method in which the image data is divided into small blocks, the grayscale values ​​of each block are compared with a predetermined threshold to convert them into binary values, and one of the binary values ​​is assigned to ink ejection and the other to no ink ejection. For example, in the case of binary values, high-capacity ink ejection is assigned to ink ejection. In contrast, the dithering method using quaternary values ​​(third method) is a data conversion method in which three thresholds are set, the grayscale values ​​of the blocks are compared with these thresholds to convert them into quaternary values, and high-capacity ink ejection, medium-capacity ink ejection, low-capacity ink ejection, and no ink ejection are assigned to each of the four values.

[0029] The binary error diffusion method (second method) is similar to the binary dithering method, but differs in that it adds the error between the original intensity value of a given block and the intensity value of that block after data transformation to the original intensity value of an adjacent block before performing data transformation on that adjacent block. Furthermore, the quaternary error diffusion method (fourth method) has three thresholds set compared to the binary error diffusion method, so that each block is quaternaryized.

[0030] The first to fourth methods, which are conversion methods for halftone processing, have the following characteristics. For example, the time required to convert data using each method to create print data is shortest for the first method, followed by the second, third, and fourth methods in increasing order. The size of the print data created is relatively small for the first and second methods, and also relatively small for the third and fourth methods, but larger than that of the first and second methods. The degree to which periodicity such as shading can be perceived in an image printed using the converted print data (periodicity) is greatest for the first method, roughly the same for the second and third methods, and least for the fourth method. The degree to which granularity can be perceived in an image based on the print data, in other words, the degree to which granularity is visible when looking at ink that has landed on the printing medium A after performing halftone processing (granularity) is relatively high for the first and second methods, roughly the same for the third and fourth methods, and smaller than that of the first and second methods.

[0031] The control device 30 performs printing using print data created by performing halftone processing using one of the conversion methods described above. For example, the control device 30 transports the printing medium A using the transport device 15 and stops it at a predetermined position on the platen 14, and then moves the head 10 in the left-right direction using the scanning device 18, while ejecting ink from the nozzles 11 of the head 10 and landing it on the printing medium A. The printing device 1 prints an image corresponding to the image data on the printing medium A by alternately repeating the transport of the printing medium A and the ejection of ink.

[0032] Furthermore, there are multiple types of printing media A that the printing device 1 can print on, such as cloth (first medium), paper other than glossy paper (non-glossy paper: second medium), and glossy paper and resin film (third medium). These also have the following characteristics (properties) regarding periodicity and graininess. That is, in terms of both periodicity and graininess, the first medium is the least noticeable, followed by the second medium and then the third medium, in that order of increasing noticeableness.

[0033] <Operation of the control device> The printing apparatus 1 according to this disclosure determines a conversion method according to the type of printing medium A when performing halftone processing. That is, as described above, there are multiple types of data conversion methods that can be performed with halftone processing, and each type has its own characteristics. Also, as described above, there are multiple types of printing medium A, and each type has its own characteristics. Therefore, the printing apparatus 1 performs a "determination process" to determine a halftone processing conversion method (first conversion method) according to the type of printing medium A used, in response to a request for a printed image. The operation of the control device 1 in relation to this determination process will be described below.

[0034] <Example 1 of decision processing> Figure 3 is a flowchart showing a series of operations, including an example (first example) of the decision process related to halftone processing performed by the control device 30. When the control device 30 receives a print job, it performs each process according to this flowchart. As shown in Figure 3, the control device 30 performs the process of acquiring image data (step S1). Specifically, image data is input from an external device such as a computer via the interface 32 and acquired. The control device 30 also performs the process of acquiring media information (acquisition process) (step S2).

[0035] Here, media information refers to information indicating the type of printing medium A on which the image is printed, and in this disclosure, it includes the three types of first to third media as described above. Media information may be acquired based on an image of the printing medium A supported by the platen 14 captured by the camera 38. Alternatively, if the control device 30 acquires print setting information, including print resolution and media information, along with image data in step S1 via the interface 32, media information may be acquired from this print setting information. Specifically, a print job consists of header information and image data, and the control device 30 acquires the print job via the interface 32. The control device 30 further acquires print setting information from the header information. Furthermore, this information may be acquired by input from an external device, or based on input from the user to the input device 37.

[0036] Next, a decision process is performed to determine the conversion method to be used for halftone processing based on the media information (step S3). That is, in this decision process, one of several types of conversion methods for halftone processing (including the first to fourth methods described above) is determined to be the first conversion method to be used for halftone processing based on the media information.

[0037] Next, the control device 30 performs halftone processing according to the first conversion method determined in this determination process (step S4). That is, the halftone processing using the first conversion method converts the image data to create print data. Then, the control device 30 uses this print data to perform printing processing, ejecting ink from the nozzles 11 of the head 10 to form an image on the printing medium A (step S5).

[0038] This allows for the execution of halftone processing using a conversion method appropriate to the type of printing medium A being used.

[0039] Incidentally, the following embodiment can be exemplified as a specific example (first example) of the decision process in step S3 described above. The storage device 31 of this disclosure stores correspondence information (for example, table information) that associates the type of printing medium A with the type of halftone processing conversion method. Then, in the decision process, a first decision process (step S3-01) may be executed to determine the first conversion method based on the medium information obtained in step S2 and the correspondence information stored in the storage device 31.

[0040] Figure 4 is a diagram showing an example of correspondence information stored in the storage device 31. As shown in Figure 4, this correspondence information shows the correspondence between the first to third media types related to the type of printing medium A and the first to fourth methods related to the type of halftone processing conversion method. Furthermore, this correspondence information is created from two perspectives: the perspective of suppressing graininess within the range visible to the human eye (graininess suppression perspective), and the perspective of avoiding excessive graininess beyond that range, as this leads to longer data conversion times and increased data size (over-spec avoidance perspective).

[0041] Specifically, for the first medium, the first and second methods are deemed appropriate, while the third and fourth methods are considered over-specified. For the second medium, the first and second methods are deemed unsuitable due to residual graininess, while the third method is deemed appropriate, and the fourth method is considered over-specified. For the third medium, the first to third methods are deemed unsuitable, while the fourth method is deemed appropriate.

[0042] In the first decision process (step S3-01), the control device 30 determines the first conversion method based on the media information and correspondence information. That is, it determines which of the first to third media the media information acquired in step S2 was, and determines the conversion method corresponding to the determined type of media as the first conversion method. In the example in Figure 4, there may be multiple types of conversion methods that correspond to one type of media, but in that case, one type of conversion method should be determined by considering other characteristics of each type of conversion method. For example, in Figure 4, the first method and the second method correspond to the first media, but in the case of printing where suppression of periodicity is required in the printed image, the second method, which can suppress periodicity more effectively, can be determined as the first conversion method.

[0043] Instead of determining the first conversion method based on the correspondence information described above, the first conversion method may be determined according to the following flowchart. Figure 5 is a flowchart showing the operation of the control device 30 when it determines the first conversion method based on the media information. As shown in Figure 5, the control device 30 determines whether or not the printing medium A is the first medium based on the acquired media information (step S21). If it is determined to be the first medium (S21: YES), it determines the first or second method as the first conversion method, prioritizing it over the other methods (S22). For example, the control device 30 stores a flag in the storage device 31 for selecting the second method from the first to fourth methods regarding the type of conversion method for halftone processing.

[0044] Furthermore, if the control device 30 determines in step S21 that the printing medium A is not the first medium (S21: NO), it then determines whether the printing medium A is the second medium (step S23). If it determines that the printing medium A is the second medium (S23: YES), it prioritizes the third method over the other methods and selects the first conversion method (step S24). For example, the control device 30 stores a flag in the storage device 31 for selecting the third method from the first to fourth methods related to the type of halftone processing conversion method. On the other hand, if the control device 30 determines in step S23 that the printing medium A is not the second medium (S23: NO), that is, if the printing medium A is the third medium, it prioritizes the fourth method over the other methods and selects the first conversion method (step S25). For example, the control device 30 stores a flag in the storage device 31 for selecting the fourth method from the first to fourth methods related to the type of halftone processing conversion method.

[0045] In addition, as shown in step S22 of the example in Figure 5, there may be cases where multiple conversion methods correspond to one type of medium. In such cases, as in the case of Figure 4, one type of conversion method should be determined by considering other characteristics of each type of conversion method (for example, periodicity).

[0046] <Second example of decision processing> Figure 6 is a flowchart showing a series of operations, including another example (second example) of the decision process related to halftone processing performed by the control device 30. When the control device 30 receives a print job, it performs each process according to this flowchart. In the operations shown in Figure 6, it performs image data acquisition (S1), media status acquisition (S2), halftone processing (S4), and printing (S5), similar to Figure 3. On the other hand, the decision process (S3) performs an operation different from the first decision process (S3-01) in Figure 3. Therefore, the decision process (S3) will be described in detail here.

[0047] In the decision process (S3) of the second example, based on the media information acquired in step S2, the control device 30 performs an output process (S3-11) in which it outputs information (candidate information) regarding one or more candidate types of conversion methods for halftone processing to the outside using the output device 36. The candidate information output to the outside in this output process is the type of conversion method selected by the control device 30 from among multiple types of conversion methods, and the selection method can be the method described with reference to Figure 4 or Figure 5, for example.

[0048] Next, the control device 30 performs a first reception process (step S3-12) in which it receives a designation of one type from the one or more types output in the output process (S3-11) via the input device 37. That is, by referring to the outputted candidate information, the user operates the input device 37, such as a touch panel, to specify one type, and the control device 30 accepts the specified type. Then, the control device 30 performs a second determination process (step S3-13) in which it determines the conversion method for the one type received in the first reception process (S3-12) as the first conversion method. After that, the halftone processing (S4) and printing processing (S5) are sequentially executed using the determined first conversion method.

[0049] According to the decision-making process described in this second example, the control device 30 narrows down the types of conversion methods, for example, from the viewpoint of suppressing graininess or avoiding over-specification. The user can then decide on the conversion method for halftone processing to be used in printing by referring to the narrowed-down types. Therefore, when the user decides on one conversion method from among multiple conversion methods, the control device 30 narrows down the candidates in advance, making it easier for the user to make a final decision.

[0050] <Example 3 of decision processing> Figure 7 is a flowchart showing a series of operations, including yet another example (third example) of the decision process related to halftone processing performed by the control device 30. When the control device 30 receives a print job, it performs each process according to this flowchart. In the operations shown in Figure 7, it performs image data acquisition (S1), media status acquisition (S2), halftone processing (S4), and printing (S5), similar to Figure 3. On the other hand, the decision process (S3) performs an operation different from the first decision process (S3-01) in Figure 3. Therefore, the decision process (S3) will be described in detail here.

[0051] In the decision process (S3) for the third example, based on the media information acquired in step S2, the control device 30 performs a provisional process to provisionally determine one of the halftone processing conversion methods as the first conversion method (step S3-21). The method for determining the first conversion method in this provisional process can be the method described with reference to Figure 4 or Figure 5, for example. Furthermore, the information regarding the type of first conversion method determined in this provisional process only needs to be temporarily stored internally by the printing device 1 in the storage device 31 or the like, and does not need to be output externally by the output device 36 or the like.

[0052] Next, the control device 30 performs a second reception process in which it receives a designation of one of several types of conversion methods from the input device 37 (step S3-22). That is, regardless of the type of conversion method provisionally determined in step S3-21, it receives a designation of one type from the user from among all types of conversion methods that the printing device 1 can perform in halftone processing.

[0053] Next, the control device 30 performs a determination process to determine whether the first conversion method provisionally determined in step S3-21 and the user-specified conversion method received in step S3-22 are of different types (step S3-23). ​​If it is determined that they are different (S3-23: YES), it performs an alarm process to notify the user (step S3-24). For example, the output device 36 outputs an alarm in the form of text, light, or sound indicating that the user-specified conversion method is different from the first conversion method predetermined by the control device 30.

[0054] Subsequently, the control device 30 performs a final decision process to determine the first conversion method (step S3-25). For example, it accepts a re-specification of the conversion method by the user who has confirmed the alarm, and determines (updates) this re-specified conversion method as the first conversion method. For example, the control device 30 stores the re-specified conversion method in the storage device 31. On the other hand, if it is determined in step S3-23 that there is no difference (S3-23: NO), then in step S3-25, the user-specified conversion method (i.e., the same as the provisionally determined first conversion method) is determined as the final first conversion method. For example, the control device 30 stores the provisionally determined conversion method in the storage device 31. After that, halftone processing (S4) and printing processing (S5) are sequentially executed using the determined first conversion method.

[0055] Furthermore, regarding the case where a user re-specifies a conversion method in step S3-25, if the re-specified conversion method differs from the first conversion method provisionally determined in step S3-21, the alarm process (S3-24) may be executed again. Alternatively, if a re-specification is accepted, the re-specified conversion method may be finalized as the first conversion method regardless of whether or not it differs from the first conversion method provisionally determined in step S3-21.

[0056] According to the decision-making process described in this third example, while accepting the user's specification regarding the type of halftone processing conversion method, an alarm can be issued to notify the user if the specified type is undesirable, for example, from the standpoint of suppressing graininess or avoiding over-specification. Therefore, the user can freely and easily determine a suitable halftone processing conversion method corresponding to the type of printing medium A.

[0057] <Variation> In the embodiments described above, an example was given in which the first conversion method used for halftone processing is determined based on the media information of the printing medium A. However, the type may also be determined by considering the image to be printed. In this modification, a method for determining the type of the first conversion method based on the printing medium A and the image to be printed is described. Such a method can be applied, for example, to the determination process shown in step S3 of the flowchart in Figures 3, 6, and 7.

[0058] Figure 8 is a flowchart showing the determination process of the first conversion method related to a modified example performed by the control device 30. As shown in Figure 8, the control device 30 performs a first image evaluation process (step S10) that calculates an evaluation value when the image is printed, based on the image data acquired in step S1 and the media information acquired in step S2. More specifically, based on the image data acquired in step S1, an image evaluation value is calculated for each type of halftone processing conversion method, which quantifies the evaluation when the image is printed on a printing medium A of the type indicated by the media information acquired in step S2. In this case, the evaluation concerns the visibility of graininess.

[0059] Next, the control device 30 compares a predetermined threshold value related to the image evaluation value with the image evaluation value for each conversion method calculated in step S10, and executes a third determination process for determining the first conversion method (step S11). Here, the threshold value related to the image evaluation value is a numerical value indicating the granularity level required for the image to be printed, and is included in, for example, the print setting information acquired together with the acquisition of the image data (S1), and is stored in the storage device 31. Therefore, in step S11, the control device 30 compares the threshold value stored in the storage device 31 with the image evaluation value.

[0060] <Details of S10> FIG. 9 is a flowchart showing a specific example of the first image evaluation process in step S10. Here, a method for calculating an image evaluation value related to the image to be printed will be described more specifically. As shown in FIG. 9, in the first image evaluation process (S10), a second image evaluation process for acquiring an image evaluation value for each type of halftone processing conversion method is executed based on the color-by-color evaluation value related to the pixel colors included in the image to be printed (step S20).

[0061] Here, the color-by-color evaluation value is a value indicating an evaluation of a patch image formed on the print medium A by discharging ink corresponding to this color value for a plurality of color values, and this evaluation is, here, an evaluation related to the visibility of granularity. Such color-by-color evaluation values are stored in advance in the storage device 31 for each type of print medium A and each type of halftone processing conversion method.

[0062] The color-specific evaluation values ​​will be described in detail. Figure 10 is a flowchart showing the process of storing the color-specific evaluation LUT, which is a lookup table for color-specific evaluation values, in the storage device 31. This storage process is performed, for example, before the printing device 1 is shipped as a product. As shown in Figure 10, the printing device 1 first prints a patch image (step S100). The patch image is a pattern image having patches, which are small images filled with the same color, for each of several colors (patch colors). The printing device 1 may have patches corresponding to all colors that it can print, but for convenience, it may be a pattern image that includes patches corresponding to colors every predetermined number of grids (for example, 9 grids).

[0063] These patch images are printed for each type of printing medium A and each type of halftone processing conversion method. Therefore, if printing medium A is one of the first to third media mentioned above, and the type of halftone processing conversion method is one of the first to fourth methods mentioned above, 12 patterns of printing results are obtained.

[0064] Next, the visibility of the graininess of each patch in the printed patch image is quantitatively evaluated (step S101). The evaluation of graininess may be done by a person visually judging and assigning a numerical value, or it may be done using a known numerical evaluation method for graininess. As a known numerical evaluation method, for example, methods using RMS (Root Mean Square), which is expressed as the root mean square of the deviation from the average concentration, or a Graininess Scale can be employed.

[0065] The evaluation value of each patch evaluated in step S101 is a color-by-color evaluation value. FIG. 11 shows an example of a color-by-color evaluation LUT in which color-by-color evaluation values for patches corresponding to each color of 9 grids are defined. As shown in FIG. 11, in the color-by-color evaluation LUT, color-by-color evaluation values are defined corresponding to each patch color. On the other hand, the color-by-color evaluation value for a patch may vary depending on the type of the printing medium A and the type of the conversion method for halftone processing. Therefore, a color-by-color evaluation LUT as shown in FIG. 11 is created for each type of the printing medium A and for each type of the conversion method for halftone processing.

[0066] Then, the color-by-color evaluation LUT (that is, the color-by-color evaluation value which is the evaluation value of each patch) for each type of the printing medium A and for each type of the conversion method for halftone processing created in this way is stored in the storage device 31 (step S102).

[0067] In the second image evaluation process printing (S20) of FIG. 9, the control device 30 refers to the above-described color-by-color evaluation LUT corresponding to the acquired medium information, and based on the color-by-color evaluation value regarding the pixel color included in the image to be printed, acquires the image evaluation value for each type of the conversion method for halftone processing.

[0068] <Details of S20> FIG. 12 is a flowchart showing a specific example of the second image evaluation process in step S20 above. Here, an example of a method for calculating an image evaluation value based on the color-by-color evaluation value will be described. As shown in FIG. 12, in the second image evaluation process, a division process for dividing the image to be printed into a plurality of regions is executed based on the image data (step S30). Each region may be, for example, a rectangular region in which each side is less than or equal to the length in the front-rear direction of the nozzle row 12.

[0069] Next, the control device 30 performs region-specific evaluation processing (step S31). In this region-specific evaluation processing, it refers to a color-specific evaluation LUT corresponding to one type of printing medium A indicated by the acquired media information, and determines region-specific evaluation values ​​indicating the evaluation for each region based on the color-specific evaluation values ​​for the pixel colors contained in each region, for each region and for each type of halftone processing conversion method. Then, it performs a third image evaluation processing to acquire an image evaluation value for the entire image based on the region-specific evaluation values ​​for all regions contained in the image data (step S32).

[0070] The operation of steps S30 to S32 will be described in more detail with reference to the specific examples shown in Figures 13 and 14. Figure 13(A) is an example of image 100 shown by the image data acquired in step S1. In the division process (S30), the control device 30 divides this image 100 into multiple regions 101 as shown in Figure 13(B). In Figure 13(B), in addition to image 100, one region 101 (101A) is shown in an enlarged view.

[0071] Next, in the region-specific evaluation process (S31), the control device 30 obtains a color-specific evaluation value for each pixel color included in each region by referring to the color-specific evaluation LUT. In the example in Figure 13(C), a color-specific evaluation value

[20] is obtained by referring to the color-specific evaluation LUT for the RGB value [190,128,64] of one pixel 102 included in region 101A. In addition, a color-specific evaluation value

[40] is obtained by referring to the color-specific evaluation LUT for the RGB value [192,208,240] of another pixel 103 included in region 101A.

[0072] In the region-specific evaluation process (S31), for each region 101, color evaluation values ​​are obtained for the color values ​​of all pixels contained within it, and a region-specific evaluation value, which is the evaluation value of this region 101, is determined based on all the obtained color evaluation values. As a method for obtaining the region-specific evaluation value from the color evaluation values, for example, the arithmetic mean can be used. In that case, the color evaluation values ​​for all pixels in the region 101 are added together, and the region-specific evaluation value can be obtained by dividing the added value by the number of pixels contained in this region 101.

[0073] Figure 14(A) shows an example in which region-specific evaluation values ​​

[30] are obtained for region 101A by region-specific evaluation processing (S31). In the region-specific evaluation processing (S31), region-specific evaluation values ​​are obtained for all regions 101 in the same manner. Figure 14(B) shows an example in which the region-specific evaluation values ​​obtained for all regions 101 are displayed overlaid on the corresponding regions. In the third image evaluation processing (S32), image evaluation values ​​are obtained based on these region-specific evaluation values.

[0074] In one example of the third image evaluation process (S32), the maximum or minimum value is extracted from the region-specific evaluation values ​​for all regions 101, and one of them is determined to be the image evaluation value for this image. In Figure 14(B), the maximum value

[50] and the minimum value

[10] are obtained from the region-specific evaluation values ​​for all regions 101 contained in image 100. Therefore, one of these is determined to be the image evaluation value. In this modified example, a larger numerical value is assigned to the evaluation value for colors in which graininess is easily visible. Therefore, in this case, from the viewpoint of graininess suppression, it is preferable to determine the maximum value from the region-specific evaluation values ​​for all regions 101 as the image evaluation value. Accordingly, in the example in Figure 14(B), the image evaluation value is determined to be

[50] .

[0075] In the third decision process (S11) shown in Figure 8, the image evaluation value obtained as described above is compared with the threshold value stored in the storage device 31 to determine the first conversion method, which is the conversion method used for halftone processing. Specifically, the image evaluation value described above is obtained for each type of conversion method for halftone processing. For example, suppose the image evaluation value when printed using each method is

[80] for the first method,

[50] for the second method,

[20] for the third method, and

[10] for the fourth method. On the other hand, suppose the threshold value for the image evaluation value stored in the storage device 31 is

[40] .

[0076] In this case, as mentioned above, the evaluation value is an indicator of how easily graininess is visible, so in order to suppress graininess, a method in which the image evaluation value is below a threshold is preferable, and in the above example, the third and fourth methods can be judged to be preferable. Accordingly, in the third decision process (S11), one of the third and fourth methods is selected as the first conversion method.

[0077] Furthermore, as in this example, if there are multiple conversion methods that result in an image evaluation value below a threshold, the first conversion method may be determined to be the one that results in the maximum or minimum image evaluation value among the multiple conversion methods. In the above case, the method that results in the maximum image evaluation value is the third method, and selecting the third method allows for reduced data conversion time and data size while suppressing graininess. The method that results in the minimum image evaluation value is the fourth method, and selecting the fourth method minimizes graininess.

[0078] However, when there are multiple types of conversion methods that result in an image evaluation value below a threshold, the method for selecting one type is not limited to this. One type may also be selected by considering periodicity and other conditions.

[0079] According to the modified operation described above, it is possible to determine the type of halftone processing conversion method that corresponds to the content of the image data to be printed, taking into consideration not only the type of printing medium A. Therefore, it is possible to achieve printing that is more suitable for the desired quality.

[0080] The printing device 1 described above uses a serial head system, but is not limited to this. The printing device 1 may also use a line head system.

[0081] Furthermore, the printing apparatus 1 includes tanks 24, with one end of a flexible tube 25 connected to each tank 24 and the other end connected to the ink supply port of the head 10, and ink from each tank 24 is sent to the head 10 through the tube 25, but is not limited to this. The tanks 24 may be ink cartridges. The tanks 24 may also be mounted on a carriage 19 and move together with the head 10. The carriage 19 may also include a sub-tank, which may relay the ink sent from each tank 24 to the head 10 through the tube 25.

[0082] In the embodiments of this disclosure, the printing apparatus 1 was a color printing apparatus, but it may also be a monochrome printing apparatus. Furthermore, the halftone processing was a process of reducing the gradation of the colors used in the image data to four colors: cyan, yellow, magenta, and black, and converting the image to be printed based on the image data into four gradations: no dots, small dots, medium dots, and large dots, but is not limited to this. In the case of a monochrome printing apparatus, the halftone processing may be a process of converting the image to be printed based on the image data into four gradations: no dots, small dots, medium dots, and large dots.

[0083] In embodiments of this disclosure, the dithering method using binary data (first method) is a data conversion method in which an image represented by image data is divided into small blocks, the grayscale value of each block is compared with a preset threshold to binarize it, and ink ejection is assigned to one of the binary values ​​and non-ejection is assigned to the other. In the case of binary data, the ink ejection assigned is a high-capacity ink ejection, but is not limited to this. In the case of binary data, the ink ejection assigned is a medium-capacity ink ejection or a low-capacity ink ejection.

[0084] In the modified example shown in Figure 13(C), a color-specific evaluation value

[20] is obtained by referring to a color-specific evaluation LUT for the RGB value [190,128,64] of one pixel 102 included in region 101A, and a color-specific evaluation value

[40] is obtained by referring to a color-specific evaluation LUT for the RGB value [192,208,240] of another pixel 103 included in region 101A, but this is not limited to this. The color-specific evaluation LUT may be configured such that a color-specific evaluation value

[40] is obtained by referring to a color-specific evaluation LUT for the RGB value [190,128,64] of one pixel 102 included in region 101A, and a color-specific evaluation value

[20] is obtained by referring to a color-specific evaluation LUT for the RGB value [192,208,240] of another pixel 103 included in region 101A. In other words, in Figure 14(B), the maximum value

[50] and minimum value

[10] were obtained from the region-specific evaluation values ​​of all regions 101 included in image 100. However, the color-coded evaluation LUT may be configured such that the relationship between the maximum value

[50] and the minimum value

[10] is reversed, with the maximum value

[50] representing the minimum value

[10] and the minimum value

[10] representing the maximum value

[50] .

[0085] In the modified example, the image evaluation values ​​when printed using each method were

[80] for the first method,

[50] for the second method,

[20] for the third method, and

[10] for the fourth method, but are not limited to these. The above-mentioned color-specific evaluation LUT may be used to make the image evaluation values ​​when printed using each method

[10] for the first method,

[20] for the second method,

[50] for the third method, and

[80] for the fourth method. However, it is assumed that the threshold value for the image evaluation value stored in the storage device 31 is

[40] . When the image evaluation values ​​when printed using each method are

[10] for the first method,

[20] for the second method,

[50] for the third method, and

[80] for the fourth method, in order to suppress graininess, the method in which the image evaluation value is above the threshold is preferable, and in the above example, the third and fourth methods are judged to be preferable.

[0086] Furthermore, the functions of each element disclosed in this specification can be realized using various processors and circuits configured or programmed to perform the described functions. A processor can be considered a circuit, and the circuits, units, or means disclosed in this specification are either hardware that performs the described functions or hardware programmed to perform such functions.

[0087] All the embodiments described above may be combined with each other, provided that they do not exclude one another. Furthermore, many improvements and other embodiments of the present invention will be apparent to those skilled in the art from the above description. Therefore, the above description should be interpreted as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of its structure and / or function can be substantially modified without departing from the spirit of the invention. [Industrial applicability]

[0088] This disclosure can be applied to a printing apparatus, a control method thereof, and a computer program that can print using a halftone process suitable for the printing medium. [Explanation of symbols]

[0089] 1 Printing device 10 heads 11 nozzles 12 nozzle rows 30 Control device 31 Storage device 36 Output device 37 Input devices A Print media

Claims

A head that ejects ink based on image data to print an image on a plurality of types of printing media, a control device, an output device that outputs an alarm to the outside, and an input device that receives input of information from the outside, and the control device performs halftone processing for converting the image data into data for causing the head to eject ink by a predetermined conversion method, and printing processing for causing the head to eject ink based on the data on which the halftone processing has been performed, and further, before executing the printing processing, acquisition processing for acquiring media information indicating the type of the printing media on which the image is to be printed, and determination processing for determining, based on the media information, one conversion method out of a plurality of types of conversion methods related to the halftone processing as a first conversion method to be used in the halftone processing, and further second reception processing for receiving, by the input device, designation of one type out of a plurality of types of conversion methods, and alarm processing for outputting an alarm to the outside by the output device when the designated type of conversion method is different from the first conversion method, a printing apparatus.

2. further comprising a storage device in which correspondence information associating the type of the printing media with the type of the conversion method of the halftone processing is stored, the determination processing includes first determination processing for determining the first conversion method based on the media information and the correspondence information, The printing apparatus according to claim 1.

3. A head that ejects ink based on image data to print an image on a plurality of types of printing media, a control device, and the control device performs halftone processing for converting the image data into data for causing the head to eject ink by a predetermined conversion method, and printing processing for causing the head to eject ink based on the data on which the halftone processing has been performed, and further, before executing the printing processing, acquisition processing for acquiring media information indicating the type of the printing media on which the image is to be printed, and determination processing for determining, based on the media information, one conversion method out of a plurality of types of conversion methods related to the halftone processing as a first conversion method to be used in the halftone processing, The conversion methods for the halftone process include a first method which is the dither method using binary values, a second method which is the error diffusion method using binary values, a third method which is the dither method using four values, and a fourth method which is the error diffusion method using four values, In the determination process, when the printing medium is the first medium, the control device determines the first conversion method by prioritizing the first method or the second method over other methods. Printing device.

4. A head that ejects ink based on image data to print an image on a plurality of types of printing media, A control device, The control device, A halftone process for converting the image data into data for ejecting ink from the head by a predetermined conversion method, A printing process for ejecting ink from the head based on the data after the halftone process is executed, Furthermore, before executing the printing process, An acquisition process for acquiring medium information indicating the type of the printing medium on which the image is to be printed, Based on the medium information, a determination process for determining one conversion method from a plurality of types of conversion methods related to the halftone process as the first conversion method used in the halftone process, The conversion methods for the halftone process include a first method which is the dither method using binary values, a second method which is the error diffusion method using binary values, a third method which is the dither method using four values, and a fourth method which is the error diffusion method using four values, In the determination process, when the printing medium is the second medium, the control device determines the first conversion method by prioritizing the third method over other methods. Printing device.

5. A head that ejects ink based on image data to print an image on a plurality of types of printing media, A control device, The control device, A halftone process for converting the image data into data for ejecting ink from the head by a predetermined conversion method, A printing process for ejecting ink from the head based on the data after the halftone process is executed, Furthermore, before executing the printing process, An acquisition process for acquiring medium information indicating the type of the printing medium on which the image is to be printed, Based on the medium information, a determination process for determining one conversion method from a plurality of types of conversion methods related to the halftone process as the first conversion method used in the halftone process, The conversion method for the halftone processing includes a first method which is a dithering method using binary values, a second method which is an error diffusion method using binary values, a third method which is a dithering method using quaternary values, and a fourth method which is an error diffusion method using quaternary values. In the determination process, if the printing medium is a third medium, the control device prioritizes the fourth method over other methods and determines the first conversion method. Printing device.

6. An output device that outputs information to the outside, It further includes an input device that accepts information from external sources, The aforementioned decision process is, Output processing that outputs information regarding one or more types of the conversion method to the outside using the output device based on the media information, A first reception process in which the input device receives the designation of one of the one or more types output, The process includes a second determination process that determines a specified type of conversion method as the first conversion method, A printing apparatus according to any one of claims 3 to 5.

7. A head for ejecting ink based on image data to print an image on multiple types of printing media, A control device is provided, The control device is Halftone processing is performed to convert the aforementioned image data into data for ejecting ink from the head using a predetermined conversion method. A printing process is performed in which ink is ejected from the head based on the data from which the halftone processing has been performed. Furthermore, before performing the aforementioned printing process, An acquisition process to acquire media information indicating the type of printing medium on which the image is printed, Based on the media information, a determination process is performed to determine one of the multiple types of conversion methods for the halftone processing as the first conversion method to be used for the halftone processing. Furthermore, a first image evaluation process is performed, which quantifies the evaluation of printing the image on the type of printing medium indicated by the acquired media information, based on the image data, for each type of halftone processing conversion method. The device further comprises a memory device that stores threshold values ​​related to the aforementioned image evaluation values, The aforementioned decision process is, The third determination process includes determining the first conversion method based on the threshold value and the image evaluation value stored in the storage device, The storage device further stores color-specific evaluation values ​​for each type of printing medium and each type of halftone processing conversion method, which indicate an evaluation of the patch image formed on the printing medium by ejecting ink corresponding to each of the multiple color values. The control device is A second image evaluation process is performed to obtain the image evaluation value for each type of halftone processing conversion method, based on the color-specific evaluation value for the pixel colors contained in the image to be printed. Printing device.

8. The carriage supports the head and moves in the direction of movement, The head is composed of a plurality of nozzles for ejecting the ink and has a nozzle row extending in a direction intersecting the direction of movement. The control device is Based on the image data, a division process is performed to divide the image to be printed into multiple regions less than or equal to the length of the nozzle row, A region-specific evaluation process is performed to determine a region-specific evaluation value that indicates the evaluation of the region based on the color-specific evaluation value for the pixel color included in the region, for each region and for each type of halftone processing conversion method. A third image evaluation process is performed to obtain the image evaluation value based on the region-specific evaluation values ​​for all the regions included in the image data. The printing apparatus according to claim 7.

9. The control device is The maximum or minimum value among the region-specific evaluation values ​​for all of the aforementioned regions is determined to be the image evaluation value. The printing apparatus according to claim 8.

10. The control device is If there are multiple types of halftone processing conversion methods in which the image evaluation value is below a predetermined threshold, then from among the multiple types of conversion methods, the one in which the image evaluation value is the maximum value or the one in which the image evaluation value is the minimum value is further selected. A printing apparatus according to any one of claims 7 to 9.

11. The aforementioned evaluation is the degree to which the ink that has landed on the printing medium after the halftone processing appears granular when viewed. A printing apparatus according to any one of claims 7 to 10.

12. A control method for a printing apparatus comprising a head that ejects ink based on image data to print images on multiple types of printing media, an output device that outputs an alarm to the outside, and an input device that receives input of information from the outside, Halftone processing is performed to convert the aforementioned image data into data for ejecting ink from the head using a predetermined conversion method. The printing process includes ejecting ink from the head based on the data on which the halftone processing has been performed, Furthermore, the following is performed before the printing process: An acquisition process to acquire media information indicating the type of printing medium on which the image is printed, The process includes a determination process that, based on the media information, determines one of several types of conversion methods for the halftone processing to be used as the first conversion method for the halftone processing, moreover, A second reception process in which the input device receives the specification of one of several types of conversion methods, The system includes an alarm process in which the output device outputs an alarm to the outside if the type of specified conversion method differs from the first conversion method, A method for controlling a printing device.

13. A method for controlling a printing apparatus equipped with a head that ejects ink based on image data to print an image on multiple types of printing media, Halftone processing is performed to convert the aforementioned image data into data for ejecting ink from the head using a predetermined conversion method. The printing process includes ejecting ink from the head based on the data on which the halftone processing has been performed, Furthermore, the following is performed before the printing process: An acquisition process to acquire media information indicating the type of printing medium on which the image is printed, The process includes a determination process that, based on the media information, determines one of several types of conversion methods for the halftone processing to be used as the first conversion method for the halftone processing, The conversion method for the halftone processing includes a first method which is a dithering method using binary values, a second method which is an error diffusion method using binary values, a third method which is a dithering method using quaternary values, and a fourth method which is an error diffusion method using quaternary values. In the determination process, if the printing medium is the first medium, the first conversion method is determined, prioritizing the first method or the second method over the other methods. A method for controlling a printing device.

14. A control method for a printing apparatus equipped with a head that ejects ink based on image data to print an image on multiple types of printing media, Halftone processing is performed to convert the aforementioned image data into data for ejecting ink from the head using a predetermined conversion method. The printing process includes ejecting ink from the head based on the data on which the halftone processing has been performed, Furthermore, the following is performed before the printing process: An acquisition process to acquire media information indicating the type of printing medium on which the image is printed, The process includes a determination process that, based on the media information, determines one of several types of conversion methods for the halftone processing to be used as the first conversion method for the halftone processing, The conversion method for the halftone processing includes a first method which is a dithering method using binary values, a second method which is an error diffusion method using binary values, a third method which is a dithering method using quaternary values, and a fourth method which is an error diffusion method using quaternary values. In the aforementioned determination process, if the printing medium is a second medium, the third method is prioritized over other methods and the first conversion method is determined. A method for controlling a printing device.

15. A control method for a printing apparatus equipped with a head that ejects ink based on image data to print an image on multiple types of printing media, Halftone processing is performed to convert the aforementioned image data into data for ejecting ink from the head using a predetermined conversion method. The printing process includes ejecting ink from the head based on the data on which the halftone processing has been performed, Furthermore, the following is performed before the printing process: An acquisition process to acquire media information indicating the type of printing medium on which the image is printed, The process includes a determination process that, based on the media information, determines one of several types of conversion methods for the halftone processing to be used as the first conversion method for the halftone processing, The conversion method for the halftone processing includes a first method which is a dithering method using binary values, a second method which is an error diffusion method using binary values, a third method which is a dithering method using quaternary values, and a fourth method which is an error diffusion method using quaternary values. In the aforementioned determination process, if the printing medium is a third medium, the fourth method is prioritized over the other methods and the first conversion method is determined. A method for controlling a printing device.

16. A control method for a printing apparatus equipped with a head that ejects ink based on image data to print an image on multiple types of printing media, Halftone processing is performed to convert the aforementioned image data into data for ejecting ink from the head using a predetermined conversion method. The printing process includes ejecting ink from the head based on the data on which the halftone processing has been performed, Furthermore, the following is performed before the printing process: An acquisition process to acquire media information indicating the type of printing medium on which the image is printed, The process includes a determination process that, based on the media information, determines one of several types of conversion methods for the halftone processing to be used as the first conversion method for the halftone processing, Furthermore, the first image evaluation process includes, based on the image data, calculating an image evaluation value that quantifies the evaluation of printing the image on the type of printing medium indicated by the acquired media information, for each type of halftone processing conversion method. The printing apparatus further comprises a storage device in which threshold values ​​relating to the image evaluation value are stored, The aforementioned decision process is, The third determination process includes determining the first conversion method based on the threshold value and the image evaluation value stored in the storage device, The storage device further stores color-specific evaluation values ​​for each type of printing medium and each type of halftone processing conversion method, which indicate an evaluation of the patch image formed on the printing medium by ejecting ink corresponding to each of the multiple color values. Furthermore, the process includes a second image evaluation process that acquires the image evaluation value for each type of halftone processing conversion method based on the color-specific evaluation value relating to the pixel colors contained in the image to be printed. A method for controlling a printing device.

17. A computer program to be executed by the computer in a printing apparatus comprising a head that ejects ink based on image data to print images on multiple types of printing media, a computer, an output device that outputs alarms to the outside, and an input device that receives input of information from the outside, To the aforementioned computer, Halftone processing is performed to convert the aforementioned image data into data for ejecting ink from the head using a predetermined conversion method. A printing process is performed in which ink is ejected from the head based on the data from which the halftone processing has been performed. Furthermore, before executing the aforementioned printing process, An acquisition process to obtain media information indicating the type of printing medium on which the image is printed, Based on the media information, a determination process is performed to determine one of the multiple conversion methods related to the halftone processing as the first conversion method to be used for the halftone processing. moreover, A second reception process in which the input device receives the specification of one of several types of conversion methods, If the type of specified conversion method differs from the first conversion method, the output device will perform an alarm process that outputs an alarm to the outside. Computer program.

18. A computer program to be executed by a computer in a printing apparatus comprising a head for ejecting ink based on image data to print an image on multiple types of printing media, and a computer, To the aforementioned computer, Halftone processing is performed to convert the aforementioned image data into data for ejecting ink from the head using a predetermined conversion method. A printing process is performed in which ink is ejected from the head based on the data from which the halftone processing has been performed. Furthermore, before executing the aforementioned printing process, An acquisition process to obtain media information indicating the type of printing medium on which the image is printed, Based on the media information, a determination process is performed to determine one of the multiple conversion methods related to the halftone processing as the first conversion method to be used for the halftone processing. The conversion method for the halftone processing includes a first method which is a dithering method using binary values, a second method which is an error diffusion method using binary values, a third method which is a dithering method using quaternary values, and a fourth method which is an error diffusion method using quaternary values. In the determination process, if the printing medium is the first medium, the first conversion method is determined, prioritizing the first method or the second method over the other methods. Computer program.

19. A computer program to be executed by a computer in a printing apparatus comprising a head for ejecting ink based on image data to print an image on multiple types of printing media, and a computer, To the aforementioned computer, Halftone processing is performed to convert the aforementioned image data into data for ejecting ink from the head using a predetermined conversion method. A printing process is performed in which ink is ejected from the head based on the data from which the halftone processing has been performed. Furthermore, before executing the aforementioned printing process, An acquisition process to obtain media information indicating the type of printing medium on which the image is printed, Based on the media information, a determination process is performed to determine one of the multiple conversion methods related to the halftone processing as the first conversion method to be used for the halftone processing. The conversion method for the halftone processing includes a first method which is a dithering method using binary values, a second method which is an error diffusion method using binary values, a third method which is a dithering method using quaternary values, and a fourth method which is an error diffusion method using quaternary values. In the aforementioned determination process, if the printing medium is a second medium, the third method is prioritized over other methods and the first conversion method is determined. Computer program.

20. A computer program to be executed by a computer in a printing apparatus comprising a head for ejecting ink based on image data to print an image on multiple types of printing media, and a computer, To the aforementioned computer, Halftone processing is performed to convert the aforementioned image data into data for ejecting ink from the head using a predetermined conversion method. A printing process is performed in which ink is ejected from the head based on the data from which the halftone processing has been performed. Furthermore, before executing the aforementioned printing process, An acquisition process to obtain media information indicating the type of printing medium on which the image is printed, Based on the media information, a determination process is performed to determine one of the multiple conversion methods related to the halftone processing as the first conversion method to be used for the halftone processing. The conversion method for the halftone processing includes a first method which is a dithering method using binary values, a second method which is an error diffusion method using binary values, a third method which is a dithering method using quaternary values, and a fourth method which is an error diffusion method using quaternary values. In the aforementioned determination process, if the printing medium is a third medium, the fourth method is prioritized over the other methods and the first conversion method is determined. Computer program.

21. A computer program to be executed by a computer in a printing apparatus comprising a head for ejecting ink based on image data to print an image on multiple types of printing media, and a computer, To the aforementioned computer, Halftone processing is performed to convert the aforementioned image data into data for ejecting ink from the head using a predetermined conversion method. A printing process is performed in which ink is ejected from the head based on the data from which the halftone processing has been performed. Furthermore, before executing the aforementioned printing process, An acquisition process to obtain media information indicating the type of printing medium on which the image is printed, Based on the media information, a determination process is performed to determine one of the multiple conversion methods related to the halftone processing as the first conversion method to be used for the halftone processing. Furthermore, a first image evaluation process is performed, which quantifies the evaluation of printing the image on the type of printing medium indicated by the acquired media information, based on the image data, for each type of halftone processing conversion method. The printing apparatus further comprises a storage device in which threshold values ​​relating to the image evaluation value are stored, The aforementioned decision process is, The third determination process includes determining the first conversion method based on the threshold value and the image evaluation value stored in the storage device, The storage device further stores color-specific evaluation values ​​for each type of printing medium and each type of halftone processing conversion method, which indicate an evaluation of the patch image formed on the printing medium by ejecting ink corresponding to each of the multiple color values. Furthermore, the computer is instructed to perform a second image evaluation process, which acquires the image evaluation value for each type of halftone processing conversion method based on the color-specific evaluation value relating to the pixel colors contained in the image to be printed. Computer program.

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