Patent Grant
10814619
This application claims priority from Japanese patent application No. 2018-173135 filed on Sep. 15, 2018, the entire subject-matter of which is incorporated herein by reference.
The present disclosure relates to image processing for a printing execution device configured to form a plurality of types of dots on a printing medium.
A printer configured to print an image by ejecting ink from nozzles of a printing head has been known. In the related-art printer, for example, when a temperature of the ink is relatively low, a viscosity of the ink is increased, so that delay in ink supply from an accommodation part of the ink to the printing head is likely to occur. When the delay in ink supply occurs, an image quality is deteriorated due to thinning of a printed image, for example.
There has been proposed a related-art technology of increasing the number of passes to print the band when the number of continuous ejections of dots counted in a band is larger than a threshold value corresponding to a temperature of the printing head.
Illustrative aspects of the disclosure provide technology capable of suppressing delay in ink supply and suppressing a situation where a printing speed is lowered owing to the suppressing of delay in ink supply.
According to one illustrative aspect, there may be provided an image processing device for a printing execution device, the printing execution device comprising: a printing head having a plurality of nozzles configured to eject ink; an ink supplier configured to supply the ink to the printing head; and a first scanning device configured to execute a first scanning of moving a printing medium relative to the printing head in a first direction, the printing head being configured to form on the printing medium a plurality of types of dots comprising a first type of dot and a second type of dot, the second type of dot being larger than the first type of dot, the image processing device being configured to: determine whether a specific condition is satisfied, the specific condition indicating that the ink supply from the ink supplier to the printing head may be delayed; generate dot data by using image data, the dot data indicating a formation state of a dot for each pixel, the generating comprising: in a case the specific condition is not satisfied, generating first dot data by executing first generation processing; and in a case the specific condition is satisfied, generating second dot data by executing second generation processing, a ratio of the first type of dots included in an image based on specific second dot data generated by using specific image data being greater than a ratio of the first type of dots included in an image based on specific first dot data generated by using the specific image data, a ratio of the second type of dots included in the image based on the specific second dot data being smaller than a ratio of the second type of dots included in the image based on the specific first dot data, and total number of dots included in the image based on the specific second dot data being larger than total number of dots included in the image based on the specific first dot data; and output, to the printing execution device, printing data based on the dot data.
In a case expressing the same density, in general, the smaller the dots are used, the smaller the used amount of ink is. According to the above configuration, in the image to be printed, when the specific condition, which indicates that the ink supply from the ink supplier to the printing head may be delayed, is satisfied, the ratio of the first type of dots is increased and the ratio of the second type of dots larger than the first type of dots is decreased, as compared to a case where the specific condition is not satisfied. As a result, when the ink supply from the ink supplier to the printing head may be delayed, it is possible to suppress the delay in ink supply in order that the used amount of the ink is suppressed. Also, since it is possible to suppress the delay in ink supply simply by changing the type of dots to be used, it is possible to suppress a situation where a printing speed is lowered so as to suppress the delay in ink supply.
The technology of the present disclosure may be performed in a variety of forms, such as a printing apparatus, a control method of the printing execution device, a printing method, a non-transitory computer-readable medium for performing functions of the apparatus and method, a recording medium having the non-transitory computer-readable medium recorded therein, and the like.
Illustrative aspects of the invention will be described in detail with reference to the following figures wherein:
In the above-described related-art technology, a printing speed may be lowered in order that the number of passes to print the band is increased.
Therefore, illustrative aspects of the disclosure provide technology capable of suppressing delay in ink supply and suppressing a situation where a printing speed is lowered owing to the suppressing of delay in ink supply.
Hereinafter, illustrative embodiments of the disclosure will be described.
A-1: Configuration of Printer 200
Hereinafter, an illustrative embodiment will be described.
The printer 200 includes, for example, a printing mechanism 100, a CPU 210 as a controller of the printer 200, a non-volatile storage device 220 such as a hard disk drive, a volatile storage device 230 such as a RAM, an operation interface 260 such as buttons and a touch panel for obtaining a user's operation, a display 270 such as a liquid crystal monitor, and a communicator 280. The communicator 280 includes a wired or wireless interface for connecting to a network NW. The printer 200 is communicatively connected to an external apparatus, for example, a terminal apparatus 300 via the communicator 280.
The volatile storage device 230 provides a buffer area 231 for temporarily storing therein a variety of intermediate data that are generated when the CPU 210 performs processing. In the non-volatile storage device 220, a computer program PG and a control table group TG are stored. In the first illustrative embodiment, the computer program PG is a control program for controlling the printer 200. The computer program PG and the control table group TG may be provided while being stored in the non-volatile storage device 220 upon shipment of the printer 200. Instead of this configuration, the computer program PG and the control table group TG may be downloaded from a server or may be provided while being stored in a DVD-ROM and the like. The CPU 210 is configured to execute the computer program PG, thereby executing image processing to be described later, for example. Thereby, the CPU 210 controls the printing mechanism 100 to print an image on a printing medium (for example, a sheet). The control table group TG is a table for determining a parameter to be used in the image processing. The control table group TG will be described later.
The printing mechanism 100 is configured to form dots on a sheet M by using inks (ink droplets) of cyan (C), magenta (M), yellow (Y) and black (K), thereby performing color printing. The printing mechanism 100 includes a printing head 110, a head driver 120, a main scanning device 130, a conveyor 140, an ink supplier 150 and a temperature sensor 170.
The conveyor 140 is configured to convey the sheet M in a conveying direction (+Y direction, in
The ink supplier 150 is configured to supply ink to the printing head 110. The ink supplier 150 includes a cartridge mounter 151, tubes 152, and a buffer tank 153. A plurality of ink cartridges KC, CC, MC, YC in which inks are accommodated is detachably mounted to the cartridge mounter 151, and the inks are supplied from the ink cartridges. The buffer tank 153 is arranged above the printing head 110 mounted to the carriage 133, and is configured to temporarily accommodate therein each ink of CMYK to be supplied to the printing head 110. The tube 152 is a flexible tube configured to interconnect the cartridge mounter 151 and the buffer tank 153 and becoming a flow path of the ink. The ink in each ink cartridge is supplied to the printing head 110 through the cartridge mounter 151, the tube 152 and the buffer tank 153. The buffer tank 153 is provided with a filter (not shown) for removing foreign matters mixed in the ink.
Positions of the nozzle rows NC, NM, NY, NK in the main scanning direction are different, and positions thereof in a sub-scanning direction overlap each other. For example, in the example of
Each nozzle NZ is connected to the buffer tank 153 through an ink flow path (not shown) formed in the printing head 110. Actuators (not shown, piezoelectric elements, in the first illustrative embodiment) for ejecting the inks along the respective ink flow paths in the printing head 110 are provided.
The head driver 120 (
The temperature sensor 170 is a well-known temperature sensor including a temperature measurement resistance member and the like, and is provided in the vicinity of the printing head 110 of the printer 200. The temperature sensor 170 is configured to output a signal indicative of a temperature of the printing head 110 of the printer 200.
A-2. Outline of Printing
The CPU 210 is configured to print a printed image on the sheet M by alternately executing more than once partial printing of causing the printing head 110 to eject the inks to form dots on the sheet M while causing the main scanning device 130 to perform the main scanning, and a sub-scanning (conveyance of the sheet M) by the conveyor 140.
As shown in
In
Here, when the ink is ejected from the nozzles NZ during the printing, the ink in the buffer tank 153 (
The delay in ink supply is likely to occur when flowability of the ink is lowered. For example, the lower a temperature (hereinafter, also referred to as ‘head temperature Th’) of the printing head 110 of the printer 200 (the printing mechanism 100) is, the more the delay in ink supply is likely to occur. The reason is that as the head temperature Th is lowered, a viscosity of the ink is increased, resulting in a decrease in flowability of the ink. Here, a cumulative-used amount TA of ink is an index value indicative of a cumulative used amount of specific ink (any one of C, M, Y and K) up to now since the manufacturing of the printer 200. The larger the cumulative-used amount TA of ink is, the more the delay of specific ink supply is likely to occur. The reason is that as the cumulative-used amount TA of ink increases, an accumulation amount of foreign matters in a filter for removing the foreign matters in the ink increases, resulting in an increase in flow path resistance of the ink and a decrease in flowability of the ink. Also, a pass-used amount PA of ink is an index value indicative of a used amount of the specific ink to be used for partial image printing in the single partial printing. The larger the pass-used amount PA of ink is, the more the delay of specific ink supply is likely to occur. The reason is that since the specific ink is used in a short time, the specific ink supply cannot keep up with the used amount. In image processing to be described later, a scheme for suppressing the delay in ink supply is made.
A-3. Image Processing
In S100, the CPU 210 controls the conveyor 140 to convey one sheet M from a print tray (not shown) to a predetermined initial position.
In S105, the CPU 210 obtains the head temperature Th of the printing head 110 of the printer 200, based on a signal from the temperature sensor 170.
In S110, the CPU 210 obtains the cumulative-used amount TA of each ink to be used for printing from the non-volatile storage device 220. The cumulative-used amount TA of ink is recorded for each ink of CMYK in a predetermined area of the non-volatile storage device 220. The CPU 210 calculates a used amount of ink of each color based on the number of dots formed by the printing and updates the cumulative-used amount TA of ink whenever executing the printing, for example. In S110, for example, in the case of monochrome printing, the cumulative-used amount TA of black (K) ink is obtained, and in the case of color printing, the cumulative-used amount TA of each ink of CMYK is obtained.
In S115, the CPU 210 obtains, based on the head temperature Th and the cumulative-used amount TA of ink, a determination threshold value JT (%) corresponding to each ink to be used for printing, from a threshold value table TT.
In S120, the CPU 210 obtains partial image data, which corresponds to a partial image to be printed by the single partial printing, of the image data, as notice partial image data, and stores the same in a buffer area 231. For example, the CPU 210 obtains the notice partial image data by receiving the notice partial image data from the terminal apparatus 300. The partial image data is RGB image data expressing a color for each pixel with RGB values, for example. When the obtained partial image data is not the RGB image data, the CPU 210 executes rasterization processing for the partial image data and converts the same into RGB image data.
In S125, the CPU 210 executes color conversion processing for the notice partial image data. The color conversion processing is processing of converting the RGB image data into CMYK image data expressing a color for each pixel with CMYK values. The CMYK values are color values of a CMYK color system, and include gradation values (component values) of four color components C, M, Y and K, i.e., a plurality of component values corresponding to a color of ink. The color conversion processing is executed using a color conversion profile (for example, look-up table) in which the RGB values and the color values (CMYK values) of the CMYK color system are associated. The number of gradations of each component value of the CMYK values is, for example, 256.
In S130, the CPU 210 selects one color from the colors (four colors of C, M, Y and K, in the first illustrative embodiment) of inks to be used for printing as a notice ink color.
In S135, the CPU 210 calculates an index value EV of the pass-used amount PA of ink for the notice ink color. As described above, the pass-used amount PA of ink is the used amount of the specific ink to be used for printing of the partial image in the single partial printing. For example, for a plurality of pixels included in the notice partial image data, a value (also referred to as an integration value TV) obtained by integrating component values corresponding to the notice ink color is calculated. Then, a ratio (%) of the integration value TV to a maximum value TVmax of the integration value TV is calculated as the index value EV (EV=100×(TV/TVmax)). The maximum value TVmax is a value obtained by multiplying the number of pixels of the notice partial image by the maximum value (255, in the first illustrative embodiment) of the component value.
In S140, the CPU 210 determines whether the calculated index value EV is equal to or greater than the determination threshold value JT obtained in S115.
When it is determined that the index value EV is smaller than the determination threshold value JT (S140: NO), since an amount per unit time in which the ink having the notice ink color is to be ejected is relatively small, delay in ink supply in the notice ink color does not occur. For this reason, in this case, in S145, the CPU 210 determines a type of dot to be used for the notice ink color and a threshold value of halftone processing as a default. In the default, four types of dots “small”, “medium”, “large” and “extra-large” are used in the first illustrative embodiment. The threshold value of the halftone processing is determined for each size of dots to be used for printing. For this reason, in S145, threshold values Ts, Tm, Tb, Tbb corresponding to four types of dots “small”, “medium”, “large” and “extra-large” are determined. The threshold values Ts, Tm, Tb, Tbb are determined to be threshold values Ts0, Tm0, Tb0, Tbb0 of the default recorded in a threshold value table HT with reference to the threshold value table HT shown in
When the index value EV is equal to or greater than the determination threshold value JT (S140: YES), since an amount per unit time in which the ink having the notice ink color is to be ejected is relatively large, delay in ink supply in the notice ink color may occur. For this reason, in this case, in S150, the CPU 210 calculates a difference ΔV between the index value EV and the determination threshold value JT (ΔV=EV−JT). In S155, the CPU 210 determines a type of dot to be used for printing of an image (also referred to as ‘notice partial image’) based on the notice partial image data, and a threshold value of the halftone processing, in correspondence to the difference ΔV. The type of dot and the threshold value are determined with reference to the threshold value table HT shown in
An ink amount necessary to form dots having the same area (in other words, an ink amount necessary to express the same density) is greater in a case where a small number of dots having a relatively large size are used, as compared to a case where a large number of dots having a relatively small size are used. The reason is that while a spotting area of ink is proportional to a square of a diameter of an ink liquid droplet, an amount (volume) of ink is proportional to a cube of the diameter of the ink liquid droplet. For this reason, in order to express the same density with a smaller amount of ink than a case where the threshold value of the default is used, it is preferable that a ratio of dot having a first size to dots to be used for printing of the notice partial image is set greater than the case where the threshold value of the default is used, and a ratio of dot having a second size greater than the first size is set smaller than the case where the threshold value of the default is used.
Here, when a specific threshold value is determined to be a value (i.e., a value corresponding to a high density) greater than the threshold value of the default, a probability that a dot corresponding to the specific threshold value will be formed becomes lower than the case where the threshold value of the default is used. For example, when the threshold value Tb corresponding to the large dot is determined to be a value (Tb>Tb0) greater than the threshold value Tb0 of the default, a probability that the large dot is to be formed is smaller than the case where the threshold value Tb of the default is used.
Considering the above situations, for example, as shown in the threshold value table HT of
When the difference ΔV is 5% or greater and smaller than 15%, the types of dots to be used are determined to be the three types “small”, “medium” and “large”, and the threshold values Ts, Tm, Tb corresponding to the three types of dots are determined to be the threshold values Ts0, TmS, Tb0. That is, in this case, the threshold values Ts, Tb corresponding to the small dot and the large dot are determined to be the threshold values Ts0, Tb0 of the default. The threshold value Tb corresponding to the medium dot is determined to be the threshold value TmS smaller than the threshold value Tm0 of the default (TmS<Tm0). The extra-large dot is not used. For example, when the value, which can be taken as the gradation value of each component value of the CMYK values, is 0 to 255, the threshold value TmS is, for example, 16. As a result, in this case, the ratio of the extra-large dot to the dots to be used for printing of the notice partial image is reduced (becomes zero (0)), the ratio of the large dot is reduced and the ratio of the medium dot is increased, as compared to the case where the difference ΔV is 0% or greater and smaller than 5%. Also, the ratio of the small dot to the dots to be used for printing of the notice partial image is substantially the same, as compared to the case where the difference ΔV is 0% or greater and smaller than 5%. Therefore, as compared to the case where the difference ΔV is 0% or greater and smaller than 5%, the used amount of ink to be used when performing the partial printing is reduced.
When the difference ΔV is 15% or greater, the types of dots to be used are determined to be the two types “small” and “medium”, and the threshold values Ts, Tm corresponding to the two types of dots are determined to be the threshold values TsS, TmS. That is, in this case, the threshold values Ts, Tm corresponding to the small dot and the medium dot are determined to be the threshold values TsS, TmS smaller than the threshold value Ts0, Tm0 of the default (TsS<Ts0, TmS<Tm0). The extra-large dot and the large dot are not used. For example, when the value, which can be taken as the gradation value of each component value of the CMYK values, is 0 to 255, the threshold value TsS is, for example, 2. As a result, in this case, the ratio of the large dot to the dots to be used for printing of the notice partial image is reduced (becomes zero (0)), and the ratios of the small dot and the medium dot are increased, as compared to the case where the difference ΔV is 5% or greater and smaller than 15%. Therefore, as compared to the case where the difference ΔV is 5% or greater and smaller than 15%, the used amount of ink to be used when performing the partial printing is reduced.
As can be seen from the above descriptions, in S155, the types of dots to be used for printing of the notice partial image and the threshold value of the halftone processing are determined so that the greater the difference ΔV is, the smaller the used amount of ink when executing the notice partial printing is.
In S160, the CPU 210 executes the halftone processing for data of the notice ink color of the notice partial image data (CMYK image data) having undergone the color conversion processing, thereby generating dot data, which indicates a formation state of dot for each pixel, for the notice ink color. A value (also referred to as ‘dot value’) of each pixel included in the dot data is any one of values indicative of formation states of the five types of dots, specifically, five values indicative of five types of dots “extra-large dot”, “large dot”, “medium dot”, “small dot” and “no dot”. In the halftone processing, the threshold values determined in S155 are used. The halftone processing will be described later in detail.
In S165, the CPU 210 determines whether all the ink colors have been processed as the notice ink color. When it is determined that there is an ink color not processed yet (S165: NO), the CPU 210 returns to S130. When it is determined that all the ink colors have been processed (S165: YES), the CPU 210 proceeds to S170. At the time when the processing proceeds to S170, the dot data for printing the notice partial image has been generated for all the ink colors.
In S170, the CPU 210 generates printing data by using the dot data. For example, the CPU 210 executes processing of rearranging the dot data in order to be used when the printing mechanism 100 performs the printing and processing of adding a printer control code and a data identification code to the dot data, thereby generating the printing data.
In S175, the CPU 210 controls the main scanning device 130 and the printing head 110 of the printing mechanism 100 to execute the partial printing by using the printing data. Thereby, the notice partial image is printed on the sheet M.
In S180, the CPU 210 controls the conveyor 140 to convey the sheet M by a predetermined amount (specifically, the nozzle length D).
In S185, the CPU 210 determines whether all the partial image data has been processed. In other words, the CPU 210 determines whether the printing of the print image based on the image data has been completed. When it is determined that all the partial image data has been processed (S185: YES), the CPU 210 ends the image processing. When it is determined that there is the partial image data not processed yet (S185: NO), the CPU 210 returns to S120.
A-4. Halftone Processing
The halftone processing of S160 shown in
In S205, the CPU 210 obtains an error value Et to be added to the notice pixel by using a matrix MTX (
In S210, the CPU 210 calculates, as a corrected gradation value V1 (V1=Vin+Et), a sum of the error value Et and a gradation value (also referred to as ‘input gradation value Vin’) of the component, which corresponds to the notice ink color, of the CMYK values of the notice pixel.
In S212, the CPU 210 determines whether it has been determined in S145 or S155 of
In S213, the CPU 210 determines whether it has been determined in S145 or S155 of
In S215, the CPU 210 compares the corrected gradation value V1 and the threshold value Tbb corresponding to the extra-large dot. The threshold value Tbb has been already determined in S145 or S155 of
In S225, the CPU 210 compares the corrected gradation value V1 and the threshold value Tb corresponding to the large dot. The threshold value Tb has been already determined in S145 or S155 of
In S235, the CPU 210 compares the corrected gradation value V1 and the threshold value Tm corresponding to the medium dot. The threshold value Tm has been already determined in S145 or S155 of
In S245, the CPU 210 compares the corrected gradation value V1 and the threshold value Ts corresponding to the small dot. The threshold value Ts has been already determined in S145 or S155 of
In S255, the CPU 210 determines the dot value of the component corresponding to the notice ink color of the notice pixel, as a value (also referred to as ‘OFF’) indicative of non-formation of a dot, and proceeds to S260.
In S260, the CPU 210 calculates a value obtained by subtracting a density value Vb of a dot to be formed (i.e., a density value Vb corresponding to the determined dot value) from the corrected gradation value V1, as the error value E1 (E1=V1−Vb) of the notice pixel. For example, when the value, which can be taken as the gradation value of each component value of the CMYK values, is 0 to 255, the density value Vb corresponding to each of the four types of dots “small”, “medium”, “large” and “extra-large” is 32, 64, 128 and 255, respectively.
In S265, the CPU 210 stores the calculated error value E1 of the notice pixel in an address, which corresponds to the notice pixel, in the error buffer.
In S270, the CPU 210 determines whether all the pixels of the notice partial image have been processed as the notice pixel. When it is determined that there is a pixel not processed yet (S270: NO), the CPU 210 returns to S200. When it is determined that all the pixels have been processed (S270: YES), the CPU 210 ends the halftone processing.
According to the first illustrative embodiment, when the index value EV is smaller than the determination threshold value JT (S140: NO), the first halftone processing using the threshold value of the default is executed (S145 and S160 in
In the second halftone processing, the threshold value Tbb corresponding to the extra-large dot is determined to be the threshold value TbbB greater than the threshold value Tbb0 of the default or the dot value is not determined to be “extra-large dot ON” (
Even when the threshold value or the type of dot to be used is changed, since the density of the printed image based on the generated dot data is kept in the halftone processing of
As described above, when expressing the same density, in general, as the small dots are used, the used amount of the ink is reduced. Therefore, according to the first illustrative embodiment, in the image to be printed, when the specific condition, which indicates that the ink supply from the ink supplier 150 to the printing head 110 may be delayed, is satisfied, the ratio of dots smaller than the extra-large dot increases and the ratio of extra-large dots decreases, as compared to the case where the specific condition is not satisfied. As a result, when the ink supply from the ink supplier 150 to the printing head 110 may be delayed, the used amount of the ink is suppressed, so that it is possible to suppress the delay in ink supply. Also, since it is possible to suppress the delay in ink supply simply by changing the type of dot to be used, it is possible to suppress a situation where the printing speed is lowered so as to suppress the delay in ink supply. For example, in order to suppress the delay in ink supply, a method where a printing pause time is provided between the single partial printing and next partial printing is considered. In this case, the printing speed is lowered due to the printing pause time. However, according to the first illustrative embodiment, it is possible to suppress such malfunction in the first illustrative embodiment.
In the meantime, when the small number of large dots is used, the used amount of the ink is increased, as compared to the case where the large number of small dots is used. However, since the ejection of the ink is stabilized, positional deviation of dots is difficult to occur. The reason is that the large ink liquid droplet is less likely to be influenced by air resistance between the ejection and the spotting and is thus difficult to flow, as compared to the small ink liquid droplet. For this reason, when the small number of large dots is used, color shift and blurring due to the position deviation of dots are difficult to occur. In the first illustrative embodiment, when the delay in ink supply does not occur (when the specific condition is not satisfied), the threshold value of the default is used. Therefore, when the delay in ink supply does not occur, the small number of large dots is used, as compared to the case where the delay in ink supply may occur, so that it is possible to suppress the positional deviation of dots, thereby improving an image quality of the printed image OI.
Also, in the first illustrative embodiment, since the total number of dots included in the printed image based on the specific second dot data is greater than the total number of dots included in the image based on the specific first dot data, it is possible to suppress the situation where the printing density is lowered so as to suppress the delay in ink supply. For example, in order to suppress the delay in ink supply, a method where the density of the printed image is reduced by reducing the number of dots to be included in the printed image is considered. In this case, since the density of the printed image is reduced, the image quality of the printed image may be lowered. However, according to the first illustrative embodiment, it is possible to suppress such malfunction.
Also, according to the first illustrative embodiment, in the first halftone processing to be executed when the specific condition is not satisfied, when the corrected gradation value V1 of the notice pixel based on the image data indicates a density equal to or greater than the threshold value Tbb0, the extra-large dot corresponding to the notice pixel is determined to be formed (
Also, according to the first illustrative embodiment, the printed image based on the first dot data generated in the first halftone processing includes the extra-large dot and the dots (for example, “small”, “medium” and “large” dots) smaller than the extra-large dot (
Also, according to the first illustrative embodiment, the CPU 210 determines whether the specific condition is satisfied, for each ink of C, M, Y and K (S140 in
Also, according to the first illustrative embodiment, the CPU 210 determines whether the specific condition is satisfied, in each partial printing for printing the partial image (S140 in
Also, according to the first illustrative embodiment, since the CPU 210 of the printer 200 executes the image processing of
In a second illustrative embodiment, the head driver 120 (
The processing of S300 to S325 in
In S320, like S320 of
In S330, the CPU 210 calculates the index value EV of the pass-used amount PA of ink for each ink of C, M, Y and K. The index value EV of one ink color is calculated in the same method as the first illustrative embodiment.
In S335, the halftone processing is executed for the notice partial image data (CMYK image data) having undergone the color conversion processing, thereby generating dot data indicative of formation states of dots for each pixel and each color component (each ink color). The dot data generated in S335 is referred to as first dot data in the second illustrative embodiment. In the halftone processing, a well-known method, for example, an error collection method or a dithering method is used. A value (also referred to as ‘dot value’) of each pixel included in the dot data is any one of values indicative of formation states of four types of dots, specifically, four values indicative of formation states of four types of dots “large dot”, “medium dot”, “small dot” and “no dot”. In the halftone processing, the threshold values Ts0, Tm0, Tb0 of the default of the first illustrative embodiment are used.
In S340, the CPU 210 determines whether the index value EV of at least one color of the index values EV of the respective inks of C, M, Y and K calculated already in S330 is equal to or greater than the determination threshold value JT. When it is determined that the index value EV of at least one color is equal to or greater than the determination threshold value JT (S340: YES), the CPU 210 executes processing of S345 to S355 by using the first dot data, thereby generating processed dot data. The processed dot data generated in S345 to S355 is referred to as second dot data, in the second illustrative embodiment. When it is determined that the index values EV of all the ink colors are smaller than the determination threshold value JT (S340: NO), the CPU 210 skips the processing of S345 to S355. Therefore, in this case, the second dot data is not generated.
In S345, the CPU 210 calculates a difference ΔVm between a maximum index value EVm of the index values EV of the respective ink colors of C, M, Y and K and the determination threshold value JT (ΔVm=EVm−JT).
In S350, the CPU 210 determines a replacement ratio Rb of the large dot, in correspondence to the difference ΔVm. The replacement ratio Rb is determined with reference to the setting table RT of
In S355, the CPU 210 executes dot replacement processing for the first dot data, thereby generating processed dot data (second dot data). The dot replacement processing is processing of replacing each large dot of a replacement target of the large dots in the dot image based on the first dot data with two medium dots.
In the dot replacement processing, the CPU 210 specifies a plurality of large dots in the dot image DI1, based on the first dot data. The CPU 210 determines large dots, which correspond to the replacement ratio Rb, of the plurality of specific large dots, as large dots of a replacement target. For example, the large dot of the replacement target is randomly selected from the plurality of specific large dots. In
An ink amount to be used when printing the dot image DI2 becomes smaller than an ink amount to be used when printing the dot image DI1. In the second illustrative embodiment, since an area of one large dot is substantially the same as a summed area of two medium dots, a density of the dot image DI1 and a density of the dot image DI2 are substantially the same.
In S360, the CPU 210 generates printing data by using the dot data. The dot data to be used is the second dot data when the processing of S345 to S355 is executed, and is the first dot data when the processing of S345 to S355 is not executed.
In S365, the CPU 210 controls the main scanning device 130 and the printing head 110 of the printing mechanism 100 by using the printing data, thereby executing the partial printing. In S370, the CPU 210 controls the conveyor 140 to convey the sheet M by a predetermined amount (specifically, the nozzle length D).
In S375, the CPU 210 determines whether all the partial image data has been processed. In other words, the CPU 210 determines whether the printing of the printed image based on the image data has been completed. When it is determined that all the partial image data has been processed (S375: YES), the CPU 210 ends the image processing. When it is determined that there is partial image data not processed yet (S375: NO), the CPU 210 returns to S320.
According to the second illustrative embodiment, like the first illustrative embodiment, when the specific condition, which indicates that the ink supply from the ink supplier 150 to the printing head 110 may be delayed, is not satisfied (S340: NO), the dot image DI1 (
Also, in the second illustrative embodiment, the dot data generation processing (also referred to as ‘first generation processing’), which is executed when the specific condition is not satisfied (NO in S340 of
Also, in the second illustrative embodiment, when generating the second dot data by executing the processing of S355, the replacement ratio Rb, which indicates the ratio of dots, which are to be replaced with the medium dots, of the large dots in the dot image DI1, is determined on the basis of the difference ΔVm (S345 and S350 in
Also, in the second illustrative embodiment, it is determined whether the specific condition is satisfied for each of C, M, Y and K (S340 in
(1) In the first illustrative embodiment, the four types of dots “small”, “medium”, “large” and “extra-large” are used for printing. However, the present disclosure is not limited thereto. For example, the three types of dots “small”, “medium” and “large” may be used, and the two types of dots “small” and “medium” may be used. In general, a plurality of types of dots including a first type of dots and a second type of dots larger than the first type of dots may be used. A ratio of the first type of dots included in the image based on the specific second dot data, which is generated using the specific image data, is greater than a ratio of the first type of dots included in the image based on the specific first dot data, which is generated using the specific image data, and a ratio of the second type of dots included in the image based on the specific second dot data is smaller than a ratio of the second type of dots included in the image based on the specific first dot data. This applies to the second illustrative embodiment, too.
(2) In the first illustrative embodiment, when the specific condition, which indicates that the ink supply may be delayed, is satisfied, the different types of dots are used in correspondence to the difference ΔV, and the threshold values of the different halftone processing are used in correspondence to the difference ΔV (S155 in
(3) In the second illustrative embodiment, when the specific condition, which indicates that the ink supply may be delayed, is satisfied, the different replacement ratios Rb are used in correspondence to the difference ΔVm (S350 in
(4) In the second illustrative embodiment as described above, in the dot replacement processing, one large dot is replaced with two medium dots. However, the present disclosure is not limited thereto. For example, the different dot replacement processing may be adopted, in correspondence to the sizes of “large”, “medium” and “small” dots to be formed. For example, one large dot may be replaced with three small dots or one large dot may be replaced with one medium dot and one small dot. Alternatively, two large dots may be replaced with three medium dots. Generally speaking, when the first type of dot (for example, the small dot and the medium dot) and the second type of dot (for example, the large dot) larger than the first type of dot are used, the dot image DI2 after the replacement processing may be an image obtained by replacing the second type of N dots (N: an integer of 1 or greater) in the dot image DI1 before the replacement processing with the first type of M dots (M: an integer greater than N (M>N)).
(5) In the first illustrative embodiment described above, since the error collection method is used in the halftone processing, when the specific condition is satisfied, the threshold values Vs, Vm, Vb, Vbb used in the error collection method are changed to values, which are different from the values in the case where the specific condition is not used. Instead of this configuration, when an error diffusion method is used in the halftone processing, a threshold value to be used in the error diffusion method is changed. Also, when a dithering method is used in the halftone processing, a threshold value to be used in the dithering method is changed. For example, in the dithering method, four types of threshold values corresponding to the four types of dots “extra-large”, “large”, “medium” and “small” are set for each pixel by a dither matrix. When the specific condition is satisfied, the threshold value corresponding to the extra-large dot is changed to a value greater than a value in the case where the specific condition is not satisfied, and the threshold values corresponding to the large dot and the medium dot are changed to values greater than values in the case where the specific condition is not satisfied, for example.
(6) In the respective illustrative embodiment as described above, it is determined whether the specific condition, which indicates that the ink supply may be delayed, is satisfied in each partial printing (S140 in
(7) In the respective illustrative embodiment as described above, the condition indicating that the delay in ink supply may occur is determined using the head temperature Th, the cumulative-used amount TA of ink and the index value EV. However, the present disclosure is not limited thereto. For example, only the head temperature Th and the index value EV may be used. In this case, for example, in the threshold value table TT of
(8) In addition, instead of the index value EV, a separate index value relating to the used amount of the ink may be adopted. For example, the separate index value may be a total number of dots of each ink to be formed when printing the notice partial image. Also, instead of the cumulative-used amount TA of ink, a separate index value relating to the cumulative-used amount of ink may be adopted. For example, the separate index value may be a cumulative number of printed sheets or may be a cumulative number of replacement times of the ink cartridge. It can be said that the greater the cumulative number of printed sheets or the cumulative number of replacement times is, the larger the cumulative-used amount TA of ink is. Therefore, it can be said that the cumulative number of printed sheets is an index value relating to the cumulative-used amount TA of ink.
(9) In the printing mechanism 100 of the above illustrative embodiments, the sub-scanning in which the conveyor 140 conveys the sheet M to move the sheet M relative to the printing head 110 in the conveying direction is performed. Instead of this configuration, the sub-scanning may be performed by moving the printing head 110 relative to the fixed sheet M in an opposite direction to the conveying direction.
In the above illustrative embodiments, the printing mechanism 100 is a serial printer including the main scanning device 130 and configured to drive the printing head 110 for performing the partial printing during the main scanning. Instead of this configuration, the printing mechanism 100 may be a so-called line printer in which the main scanning device 130 is not provided and a printing head including a plurality of nozzles aligned over substantially the same length as a width of the sheet M in a direction perpendicular to the conveying direction is provided. In the line printer, the printing is executed without performing the main scanning. In this case, since there is no concept of the partial printing, it may be determined whether the specific condition is satisfied whenever the printed image OI is printed, as described above, for example.
(10) As the printing medium, instead of the sheet M, other media such as an OHP film, a CD-ROM, and a DVD-ROM may be adopted.
(11) In the above illustrative embodiments, the device configured to execute the image processing of
As can be seen from the above descriptions, in the respective illustrative embodiment as described above, the printing mechanism 100 is an example of the printing execution device. Like this modified aspects, when the terminal apparatus 300 executes the image processing, the entire printer 200 configured to execute the printing is an example of the printing execution device.
(12) The device configured to execute the image processing of
(13) In the respective illustrative embodiments as described above, some of the configuration performed by hardware may be replaced with software, and some or all of the configuration performed by software may be replaced with hardware. For example, some of the image processing shown in
Although the present disclosure has been described with reference to the illustrative embodiments and the modified embodiments, the present disclosure may be provided so as to easily understand the present disclosure, not to limit the present disclosure. The present disclosure can be changed and improved without departing from the scope thereof, and the present disclosure may include equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-173135 | Sep 2018 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5610637 | Sekiya | Mar 1997 | A |
| 6042219 | Higashino | Mar 2000 | A |
| 6375309 | Taneya | Apr 2002 | B1 |
| Number | Date | Country |
|---|---|---|
| 2004-066550 | Mar 2004 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20200086639 A1 | Mar 2020 | US |
