JP4964705B2 - Image processing method, image processing apparatus, image processing system, image forming apparatus, program, and storage medium - Google Patents

Description

  The present invention relates to an image processing method, an image processing apparatus, an image processing system, an image forming apparatus, a program, and a storage medium.

  As an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, and a multifunction machine of these, for example, a liquid ejection apparatus including a recording head composed of a liquid ejection head (droplet ejection head) that ejects liquid droplets of a recording liquid (liquid) As a liquid while transporting a medium (hereinafter also referred to as “paper”, but the material is not limited, and a recording medium, a recording medium, a transfer material, recording paper, etc. are also used synonymously). The recording liquid (hereinafter referred to as ink) is attached to a sheet to form an image (recording, printing, printing, and printing are also used synonymously). Some image forming apparatuses perform image formation using an electrophotographic process.

  The image forming apparatus means an apparatus for forming an image by discharging a liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. This means not only giving images with meanings such as characters and figures to the medium, but also giving images without meaning such as patterns to the medium, forming a printing device and metal wiring. It also includes a device to perform. The liquid is not particularly limited as long as it is a liquid that can form an image.

Patent Document 1 and Patent Document 2 describe methods for improving the quality of black characters when printing out a color image containing frequently used black characters using such an image forming apparatus. As described above, there is one that performs image area separation processing.
Japanese Patent No. 2602681 Japanese Patent No. 2627753

In addition, the following can be mentioned as patent documents related to the present application.
JP 2004-112355 A JP 2005-045420 A Japanese Patent No. 3522880 Japanese Patent No. 3412987 Japanese Patent Application Laid-Open No. 07-212583 JP 2000-316095 A JP 2001-353888 A JP 2004-242040 A

  However, in order to perform the image area separation processing as described in Patent Documents 1 and 2 described above, there is a problem that the processing is burdened, so that high-speed processing is expensive.

  In addition, as described in Patent Document 1, in the process of increasing the undercolor removal amount of characters and line drawings by area determination such as black area detection and edge continuity, an attempt is made to increase the accuracy of area detection. Then, there is a problem that the amount of hardware becomes large.

  In addition, as described in Patent Document 2, in the process of once converting RGB data into a luminance color difference signal and then performing achromatic determination and edge determination, the LUT (Look Up Table) method is used to convert RGB data from RGB data. In the case of direct conversion to CMYK data, there is a problem that the conversion system becomes redundant and becomes redundant.

  The present invention has been made in view of the above problems, and when converting from RGB data to CMYK data, coloring of achromatic data can be reduced, gray balance can be stabilized with a simple circuit, and input can be performed. The purpose is to make the output black when is not completely black.

In order to solve the above problems, an image processing method according to the present invention includes:
In an image processing method for converting RGB input signals to CMYK output signals and generating image data of an image to be output by an image forming apparatus ,
Determining whether the saturation of the input signal is included in a predetermined range, and converting the saturation to achromatic when the saturation is within the predetermined range;
When performing the inking amount determination process for determining the amount of black to be generated based on the CMYK signal obtained by converting the input signal, the input tone value corresponding to the maximum black amount that the image forming apparatus can take is And a step of determining an inking amount using a correction parameter set to a value smaller than the maximum possible input gradation value.

  Here, the input signal is converted from the RGB color space to a signal in the HLS color space, and it is possible to determine whether or not the saturation in the HLS color space is included in a predetermined range.

An image processing apparatus according to the present invention includes:
In an image processing apparatus that converts RGB input signals into CMYK output signals and generates image data of an image to be output by the image forming apparatus .
Determining whether or not the saturation of the input signal falls within a predetermined range, and when the saturation is within the predetermined range, means for converting the saturation to achromatic; and
When performing the inking amount determination process for determining the amount of black to be generated based on the CMYK signal obtained by converting the input signal, the input tone value corresponding to the maximum black amount that the image forming apparatus can take is And a means for determining the inking amount using a correction parameter set to a value smaller than the maximum possible input gradation value.

An image processing system according to the present invention includes:
In an image processing system including an image processing apparatus that performs image processing for converting an RGB input signal into a CMYK output signal, and an image forming apparatus that outputs an image processed by the image processing apparatus.
The image processing apparatus includes:
Determining whether or not the saturation of the input signal falls within a predetermined range, and when the saturation is within the predetermined range, means for converting the saturation to achromatic; and
When performing the inking amount determination process for determining the amount of black to be generated based on the CMYK signal obtained by converting the input signal, the input tone value corresponding to the maximum black amount that the image forming apparatus can take is And a means for determining the inking amount using a correction parameter set to a value smaller than the maximum possible input gradation value.

An image forming apparatus according to the present invention includes:
In an image forming apparatus that converts an RGB input signal into a CMYK output signal to form an image,
Determining whether or not the saturation of the input signal falls within a predetermined range, and when the saturation is within the predetermined range, means for converting the saturation to achromatic; and
When performing the inking amount determination process for determining the amount of black to be generated based on the CMYK signal obtained by converting the input signal, the input tone value corresponding to the maximum black amount that the image forming apparatus can take is And a means for determining the inking amount using a correction parameter set to a value smaller than the maximum possible input gradation value.

The program according to the present invention is:
In a program for causing a computer to perform image processing for converting RGB input signals into CMYK output signals and generating image data of an image output by the image forming apparatus .
Determining whether the saturation of the input signal is included within a predetermined range, and when the saturation is within the predetermined range, converting the saturation into achromatic; and
When performing the inking amount determination process for determining the amount of black to be generated based on the CMYK signal obtained by converting the input signal, the input tone value corresponding to the maximum black amount that the image forming apparatus can take is The computer is configured to perform a process of determining the inking amount using a correction parameter set to a value smaller than the maximum possible input gradation value.

  The storage medium according to the present invention stores the program according to the present invention.

Image processing method according to the present invention, an image processing apparatus, an image processing system, an image forming apparatus, a program, according to the storage medium, in easy single structure, it is possible to reduce the coloring of achromatic data, black viewing of Can be improved.

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an image forming system including an image forming apparatus according to the present invention will be described with reference to a block diagram of FIG.
The image forming system includes an ink jet recording apparatus (also referred to as an ink jet printer) 1 as an image forming apparatus according to the present invention and an image reading apparatus (also referred to as a scanner) 2 connected to the ink jet recording apparatus 1. Has been. The inkjet recording apparatus 1 and the image reading apparatus 2 are directly connected, and the inkjet recording apparatus 1 controls the image reading apparatus 2. The ink jet recording apparatus 1 and the image reading apparatus 2 may be configured to be connected by a cable, a predetermined interface, or a network.

  As shown in FIG. 2, the control unit 10 of the ink jet recording apparatus 1 includes a printer driver 31 of an image processing apparatus (PC) 3 such as a personal computer, a scanner 2, and other external devices such as a digital camera (not shown), a memory card, and the like. The data input from the external storage device is received by the data receivers 11 and 12, respectively, and the received data is stored in the memory 14 via the image processor 13 or directly from the data receiver 11.

  Then, the data received by the image processing unit 13 and the data stored in the memory 14 are subjected to image processing, head output data is generated, compressed, and held in the memory 14. The image processing unit 13 performs processing for converting the RGB input signal (input data) received from the scanner 2 into a YMCK output signal by performing the image processing method according to the present invention.

  The head control unit 15 reads out the output image data stored in the memory at a predetermined timing and outputs the output image data to the recording head 16 that ejects droplets, and drives the recording head 16 to eject droplets from a required nozzle. .

  Further, the engine control unit 17 drives and controls the motor 18 and the like to carry the recording medium and move the carriage on which the recording head 16 is mounted. Further, detection signals from various sensors 19 and the like are input to the engine control unit 17.

  Here, the image processing unit 13, the head control unit 15, the engine control unit 17, and the like are configured by a microcomputer including a CPU, a ROM, a RAM, an ASIC, an I / F, and the like.

Therefore, image processing according to the present invention performed in the image processing unit 13 of the control unit 10 of the inkjet recording apparatus 1 will be described.
First, the overall flow will be described with reference to the functional block diagram of FIG. 3. The image data 40 given from the scanner 2 or the like is changed from the color space for monitor display to the color space for recording apparatus (image forming apparatus). CMM (Color Management Module) processing unit 42 that performs conversion (RGB color system → CMY color system), BG / UCR (black generation / Under Color Removal) processing unit that performs black generation / under color removal from CMY values 43, a total amount regulating unit 44 that corrects the CMYK signal according to the maximum total amount of recording color materials that can form an image with respect to the CMYK signal, a γ correction unit 45 that performs input / output correction reflecting device characteristics and user preferences, Not including zooming processing that performs enlargement processing according to the resolution of the device, and intermediate including multi-value / low-value matrix that replaces the pattern arrangement of dots that eject image data The processing unit (multi-value / low-value matrix) 46, the dot pattern data, which is the print image data obtained by the halftone process, is divided into data for each scan, and the data is further developed in accordance with each nozzle position for recording A rasterizing unit 47 is included, and an output 48 of the rasterizing unit 47 is stored in the memory 14.

Next, three processes of the color space conversion process for converting the input signal RGB into the output signal CMYK, the inking process, and the γ correction process in the image processing method according to the present invention will be specifically described.
First, inking / background removal (BG / UCR) processing will be described with reference to FIG.
Normally, K (black, black) ink has higher visibility per dot than C, M, and Y inks, so graininess is felt when black ink is used at low gradations where black begins to enter. For this reason, the graininess is improved by forming black with CMY composite black in the low gradation part where black starts to enter, and adding black ink when the density increases.

  That is, in the general inking process, as shown in FIG. 4, the gradation at which the use of black ink is started is set to a gradation of 25% or more of the input gradation.

  In addition, the background removal (UCR) process for the inking process is expressed by the following equation (1) as a process usually used for the inking unit. In the formula (1), p is called a UCR rate, and an arbitrary value of 0 <p ≦ 100% is selected.

  Therefore, specifically, the maximum background removal amount (UCR amount) is obtained by the following equation (2), and the UCR amount of each gradation is obtained by linearizing from the inking start gradation to the maximum gradation. .

  Furthermore, in the present invention, when a document containing black characters or a black image is read by the image reading apparatus 2 such as a scanner and printed out by the image forming apparatus, the processing is performed without reducing the quality of the black characters or the quality of the black image. As a method for doing this, as shown in FIG. 5, the inking amount is changed and set to the maximum at the gradation before the maximum gradation that the inkjet recording apparatus 1 can take. Specifically, the gradation that is the maximum black amount is changed to be 65 to 100%, for example, 70% of the maximum gradation that the image recording apparatus can take.

  As a result, the amount of black (K) can be positively used at an early gradation, so that the black of the signal input from the scanner 2 or the like is not (R, G, B = 0, 0, 0). However, the sharpness of black characters and the contrast of photographs and graphic images are enhanced by the dominance of black ink.

Next, the results of experiments conducted based on the present invention will be described.
As the environment of this experiment, the CIELAB value (light source D50) and the optical density of black (black) were taken for the black portion of the sample that was input and output by the image reading apparatus with a manuscript defined by JIS (Japanese Industrial Standards). Is. FIG. 6 is a graph showing the lightness and density when the gradation corresponding to the maximum black amount is changed every 8 gradations from 176 to 255 gradations (69% to 100%).

  In this experiment, the brightness and density are the same as those of the original at 184 gradations (72.1%), indicating that the conditions are optimum.

  However, since this optimum gradation depends on the performance of the image reading apparatus 2, it can be said that 72.1% gradation is a preferable condition for gradation with the maximum black amount in all environments. Absent.

  As a process for setting the maximum black amount (K amount) to a gradation before the maximum gradation, not only the blacking / background (BG / UCR) process described above but also a subsequent γ correction process is performed. be able to. That is, as shown in FIG. 7, the same effect as the BG / UCR process can be obtained by adjusting the γ curve related to K from a normal γ curve indicated by a broken line to a γ curve indicated by a solid line.

Next, an example in which the result of the BG / UCR process described above is taken into the CMM process will be described with reference to FIG.
The color space conversion (CMM) processing is generally processing for converting the monitor display color space RGB into the recording device color space CMY, that is, the first color signal having three variables as input and the same number of second colors as outputs. This is a process of converting to a color signal.

    On the other hand, in this example, the CMM process is a process of converting a first color signal having three or more inputs into a second variable color signal having four variables including black. Specifically, as shown in FIG. 8, when the color space value is converted into the color space value of the image forming apparatus based on the input data, the output value after the color space conversion processing for the input value is used as the color space processing conversion table. When using the (Look up Table) color space conversion table, the output values are K, C, M, and Y for the input values R, G, and B.

  In this case, as the color space processing conversion table (LUT), it is preferable to list the combinations of the output values K, C, Y, and M for all points corresponding to the input values R, G, and B of 0 to 255. In order to reduce the speed and increase the amount of data, in the implementation, interpolation points (preferably about 17 points from 0 to 255) are extracted, and interpolation methods such as linear interpolation, tetrahedral interpolation, and hexahedral interpolation are used. Is preferred.

  In this way, the color space conversion process for converting the first color signal having three or more inputs into the four color second color signal including black is performed, and the above-described inking / background removal process is substantially performed. In addition, the processing speed can be improved by adopting a configuration in which color space conversion processing is performed.

  When creating the color space conversion processing table, the maximum ink adhesion amount is taken into consideration by designing with reference to the parameters used in the total amount regulation processing, inking and background removal (BG / UCR) processing. Color space processing conversion table can be designed.

  Further, in this color space conversion process, as shown in FIG. 9, the RGB value of the input signal is converted into an HLS value, and the range of the saturation S value of the converted HLS value is determined in a predetermined range (for example, 1 to 1). 25%), and when the saturation is within the predetermined range, a process for converging the saturation S to achromatic (0%) is performed. Further, the converged HLS value is converted into an RGB value, and the subsequent processing is performed.

  An example of RGB → HLS conversion processing and HLS → RGB conversion processing at that time is shown below.

  As a result, even when the input value RGB obtained by reading a gray original with an image reading device or the like does not become gray (R = G = B), or when the saturation of each pixel constituting the current gray varies. The gray balance is stabilized by treating the value as an achromatic color within a certain range.

  FIG. 10 shows the result of an experiment performed in this process. In this experiment, a CIELAB value (light source D50) of a gray gradation portion is obtained for a sample obtained by inputting and outputting a document defined by JIS (Japanese Industrial Standard) with an image reading apparatus.

  As a result shown in FIG. 10, it can be seen that after the color space conversion process is performed, the variation range after the saturation correction is narrower and converged after the color balance conversion process.

  In addition, for the range of saturation S in color space conversion processing, and the gradation that becomes the maximum black amount in inking and γ correction processing, it is for general plain paper / recycled paper and glossy commercial / publishing printing Since coated paper has different paper properties depending on the recording medium, image quality can be further improved by setting optimum parameters according to the type of recording medium.

  In this way, the processing related to the enhancement of black characters and black images has been performed on the input device side such as a scanner or a printer driver. However, in the present invention, the processing is performed on the image forming device on the output side. Regardless of the processing, it is possible to output gray with a stable gray balance, and simultaneously output an image in which black is emphasized.

  Thus, according to the image processing method, the program, and the image forming apparatus according to the present invention, when converting the RGB input signal to the CMYK output signal, the saturation of the input signal is included within a predetermined range. Since the process of converting the saturation to achromatic and the process of changing the input tone value that is the maximum black amount when performing the inking process for generating black based on the input signal, the simple configuration is used. In addition, the coloring of the achromatic data can be reduced, and the black visibility can be improved.

Next, an example of a specific configuration of the above-described image forming apparatus will be described with reference to FIGS. FIG. 11 is a schematic side view illustrating an outline of a mechanism unit of the image forming apparatus, and FIG.
This image forming apparatus is a serial type image forming apparatus, and an image reading device (scanner 2) is disposed on an upper portion of an apparatus main body (inkjet recording device) 1.

  The apparatus main body 1 holds the carriage 233 slidably in the main scanning direction by main and slave guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 201A and 201B, and a timing belt is driven by a main scanning motor (not shown). And moving and scanning in the direction indicated by the arrow (carriage main scanning direction).

  The carriage 233 includes a liquid discharge head constituting a liquid discharge head unit according to the present invention for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). The recording heads 234a and 234b (referred to as “recording head 234” when not distinguished from each other) are arranged in a sub-scanning direction orthogonal to the main scanning direction with a nozzle row composed of a plurality of nozzles, and the ink droplet ejection direction is directed downward. Wearing.

  Each of the recording heads 234 has two nozzle rows. One nozzle row of the recording head 234a has black (K) droplets, the other nozzle row has cyan (C) droplets, and the recording head 234b has one nozzle row. One nozzle row ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets.

  The carriage 233 is also equipped with sub-tanks 235a and 235b (referred to as “sub-tank 35” when not distinguished) that constitute a liquid discharge head unit for supplying ink of each color corresponding to the nozzle row of the recording head 234. is doing. The sub tank 235 is supplementarily supplied with ink of each color from the ink cartridge 210 of each color via the supply tube 236 of each color.

  On the other hand, as a paper feeding unit for feeding the paper 242 stacked on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feeding) that separates and feeds the paper 242 one by one from the paper stacking unit 241. A separation pad 244 made of a material having a large coefficient of friction is provided opposite to the sheet roller 243 and the sheet feeding roller 243, and the separation pad 244 is urged toward the sheet feeding roller 243 side.

  In order to feed the sheet 242 fed from the sheet feeding unit to the lower side of the recording head 234, a guide member 245 for guiding the sheet 242, a counter roller 246, a conveyance guide member 247, and a tip pressure roller. And a conveying belt 251 which is a conveying means for electrostatically attracting the fed paper 242 and conveying it at a position facing the recording head 234.

  The conveyor belt 251 is an endless belt, and is configured to wrap around the conveyor roller 252 and the tension roller 253 so as to circulate in the belt conveyance direction (sub-scanning direction). In addition, a charging roller 256 that is a charging unit for charging the surface of the transport belt 251 is provided. The charging roller 256 is disposed so as to come into contact with the surface layer of the conveyor belt 251 and to rotate following the rotation of the conveyor belt 251. The transport belt 251 rotates in the belt transport direction when the transport roller 252 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the transport belt 251, a paper discharge roller 262, and a paper discharge roller 263 are provided. A paper discharge tray 203 is provided below the paper discharge roller 262.

  A duplex unit 271 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 271 takes in the paper 242 returned by the reverse rotation of the transport belt 251, reverses it, and feeds it again between the counter roller 246 and the transport belt 251. The upper surface of the duplex unit 271 is a manual feed tray 272.

  Further, a maintenance / recovery mechanism 281 that is a head maintenance / recovery device according to the present invention includes a recovery means for maintaining and recovering the nozzle state of the recording head 234 in the non-printing area on one side of the carriage 233 in the scanning direction. Is arranged. The maintenance / recovery mechanism 281 includes cap members (hereinafter referred to as “caps”) 282a and 282b (hereinafter referred to as “caps 282” when not distinguished) for capping each nozzle surface of the recording head 234, and nozzle surfaces. A wiper blade 283 that is a blade member for wiping the ink, and an empty discharge receiver 284 that receives liquid droplets for discharging the liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid. ing.

  In addition, in the non-printing area on the other side in the scanning direction of the carriage 233, the liquid that receives liquid droplets when performing idle ejection that ejects liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. An ink recovery unit (empty discharge receiver) 288 that is a recovery container is disposed, and the ink recovery unit 288 includes an opening 289 along the nozzle row direction of the recording head 234 and the like.

The control unit of this image forming apparatus is configured as shown in FIG. 13, for example.
That is, the control unit includes a memory that stores a program according to the present invention, which controls the entire image forming apparatus, and includes a main control unit 301 configured by a microcomputer that performs image processing according to the present invention, and print control. And a print control unit 302 composed of a microcomputer that manages the above.

  Then, the main control unit 301 includes a main scanning motor 331 and a conveyance roller 52 that move the carriage 233 in the main scanning direction in order to form an image on the paper 242 based on the printing processing information input from the communication circuit 300. The sub-scanning motor 332 that is driven to rotate is driven and controlled via the main scanning motor driving circuit 303 and the sub-scanning motor 304, and control such as sending print data to the print control unit 302 is performed.

  Further, the main control unit 301 receives a detection signal from a carriage position detection circuit 305 that detects the position of the carriage 233, and the main control unit 301 controls the movement position and movement speed of the carriage 233 based on the detection signal. To do. The carriage position detection circuit 305 detects the position and speed of the carriage 233 by, for example, reading and counting the number of slits of an encoder sheet arranged in the scanning direction of the carriage 233 with a photosensor mounted on the carriage 233. The main scanning motor driving circuit 303 rotates the main scanning motor 331 according to the carriage movement amount and speed input from the main control unit 301 to move the carriage 233 to a predetermined position at a predetermined speed.

  The main control unit 301 receives a detection signal from a conveyance amount detection circuit 306 that detects the movement amount of the conveyance belt 51, and the main control unit 301 moves the movement amount and movement speed of the conveyance belt 251 based on the detection signal. To control. The conveyance amount detection circuit 306 detects the conveyance amount and the conveyance speed by, for example, reading and counting the number of slits of the rotary encoder sheet attached to the rotation shaft of the conveyance roller 252 with a photosensor. The sub-scanning motor driving circuit 304 rotates the sub-scanning motor 332 in accordance with the transport amount input from the main control unit 301 and rotationally drives the transport roller 252 to move the transport belt 251 to a predetermined position at a predetermined speed. Move with.

  The main control unit 301 rotates the sheet feeding roller 243 once by giving a sheet feeding roller driving command to the sheet feeding roller driving circuit 307. The main control unit 301 rotationally drives the motor 333 of the maintenance / recovery mechanism 281 via the maintenance / recovery mechanism drive motor drive circuit 308 to move the cap 82 up and down, the wiper member 283 up and down, and drive the suction pump. Make it.

  The main control unit 301 drives and controls an ink supply motor for driving the pump of the supply unit via the ink supply motor drive circuit 311, and the ink cartridge 210 loaded in the cartridge loading unit 204 controls the head tank 235. Supply ink. At this time, the main controller 301 controls the replenishment supply based on a detection signal from the head tank full sensor 312 that detects that the head tank 235 is full.

  Further, the main control unit 301 takes in information stored in the nonvolatile memory 316 which is a storage unit provided in each ink cartridge 210 mounted in the cartridge loading unit 4 through the cartridge communication circuit 314 and performs a necessary process. To store and hold in an internal nonvolatile memory (for example, EEPROM).

  Further, the main control unit 301 controls reading of a document image by the image reading device 2 via the scanner control unit 315.

  Further, the main control unit 301 receives a detection signal from an environmental sensor 313 that detects environmental temperature and environmental humidity.

  The print control unit 302 generates pressure for discharging droplets of the recording head 31 based on the signal from the main control unit 301 and the carriage position and conveyance amount from the carriage position detection circuit 305 and the conveyance amount detection circuit 306. Data for driving the means is generated, and the above-mentioned image data is transferred to the head drive circuit 310 as serial data, and the transfer clock and latch signal necessary for transferring the image data and confirming the transfer, drop control, etc. In addition to outputting a signal (mask signal) etc. to the head drive circuit 310, it comprises a D / A converter, a voltage amplifier, a current amplifier, etc. for D / A converting the pattern data of the drive signal stored in the ROM. Drive waveform generation means and drive waveform selection means to be given to the head driver, one drive pulse (drive signal) or a plurality of drive parameters. Scan to generate a plurality including driving waveform drive signal group consisting of (a drive signal) output to the head drive circuit 310.

  The head drive circuit 310 selectively selects a drive signal that constitutes a drive waveform supplied from the print control unit 302 based on image data corresponding to one row of the print head 234 that is serially input. The recording head 234 is driven by applying it to a driving element (for example, a piezoelectric element) that generates energy for discharging the ink. At this time, by selecting a driving pulse (driving signal) of a driving signal group constituting a driving waveform, it is possible to eject droplets having different sizes and to sort dots having different sizes.

  In this image forming apparatus configured as described above, the sheets 242 are separated and fed one by one from the sheet feeding tray 202, and the sheet 242 fed substantially vertically upward is guided by the guide 245, and is conveyed to the conveyor belt 251 and the counter. It is sandwiched between the rollers 246 and conveyed, and further, the leading end is guided by the conveying guide 237 and pressed against the conveying belt 251 by the leading end pressing roller 249, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately applied to the charging roller 256, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 251 alternates, that is, in the sub-scanning direction that is the circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width. When the sheet 242 is fed onto the conveyance belt 251 charged alternately with plus and minus, the sheet 242 is attracted to the conveyance belt 251, and the sheet 242 is conveyed in the sub scanning direction by the circumferential movement of the conveyance belt 251.

  Therefore, by driving the recording head 234 according to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 242 has reached the recording area, the recording operation is finished and the paper 242 is discharged onto the paper discharge tray 203.

Next, the ink used in this image forming apparatus will be described.
Commonly used pigment-based inks are not particularly limited, but for example, the following pigments are preferably used. Moreover, you may use these pigments in mixture of multiple types.

  Examples of organic pigments include azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black. It is done.

  Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.

  The particle diameter of these pigments is preferably 0.01 to 0.30 [mu] m. If the particle diameter is 0.01 [mu] m or less, the light resistance and feathering are deteriorated because the particle diameter approaches that of the dye. On the other hand, if it is 0.30 μm or more, clogging of the discharge port or clogging with a filter in the printer occurs, and it is not possible to obtain discharge stability.

  The carbon black used in the black pigment ink is carbon black produced by the furnace method and the channel method, the primary particle size is 15 to 40 millimicrons, the specific surface area by the BET method is 50 to 300 square meters / g, The DBP oil absorption is preferably 40 to 150 ml / 100 g, the volatile content is 0.5 to 10%, and the pH value is 2 to 9. As such a thing, for example, no. 2300, no. 900, MCF-88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B (Mitsubishi Chemical Corporation), Raven700, 5750, 5250, 5000, 3500, 1255 (Columbia), Regal400R, 330R, 660R, MoguL, Monarch700, 800, 880, 900, 1000, 1100, 1300, Monarch 1400 (manufactured by Cabot), color black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, the same V, the same 140U, the same 140V, the special black 6, the same 5, the same 4A, the same 4 (manufactured by Degussa) and the like can be used, but are not limited thereto.

Specific examples of color pigments are listed below.
Examples of organic pigments include azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black. Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.

Specific examples according to color are as follows.
Examples of pigments that can be used for yellow ink include C.I. I. Pigment Yellow 1, 2, 2, 3, 12, 14, 16, 17, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 128, 129, 151, 154, etc., but are not limited thereto.

  Examples of pigments that can be used in magenta ink include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 123, 168, 184, 202, etc. However, it is not limited to these.

  Examples of pigments that can be used for cyan ink include C.I. I. Pigment blue 1, 2, 3, 15: 3, 15:34, 16, 22, 22, 60, C.I. I. Examples thereof include, but are not limited to, Bat Blue 4 and 60.

  In addition, the pigment contained in each ink used in the present invention may be newly produced for the present invention.

  The pigments listed above can be made into an inkjet recording liquid by dispersing them in an aqueous medium using a polymer dispersant or a surfactant. As a dispersant for dispersing such organic pigment powder, a normal water-soluble resin or a water-soluble surfactant can be used.

  Specific examples of water-soluble resins include styrene, styrene derivatives, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itacon. Examples thereof include block copolymers consisting of at least two monomers selected from acids, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, etc., random copolymers, or salts thereof. These water-soluble resins are alkali-soluble resins that are soluble in an aqueous solution in which a base is dissolved. Among them, a resin having a weight average molecular weight of 3000 to 20000 is used as a dispersion when used in an inkjet recording liquid. It is particularly preferred because of the advantages that it can be reduced in viscosity and can be easily dispersed.

  The simultaneous use of the polymer dispersant and the self-dispersing pigment is a preferable combination because an appropriate dot diameter can be obtained. The reason is not clear, but it is thought as follows.

  That is, the penetration into the recording paper is suppressed by containing the polymer dispersant. On the other hand, since the aggregation of the self-dispersing pigment is suppressed by containing the polymer dispersant, the self-dispersing pigment can smoothly spread in the lateral direction. Therefore, it is considered that the dots spread widely and thinly and ideal dots can be formed.

  Moreover, the following are mentioned as a specific example of the water-soluble surfactant which can be used as a dispersing agent. For example, anionic surfactants include higher fatty acid salts, alkyl sulfates, alkyl ether sulfates, alkyl ester sulfates, alkyl aryl ether sulfates, alkyl sulfonates, sulfosuccinates, alkyl allyls and alkyl naphthalene sulfonic acids. Examples thereof include salts, alkyl phosphates, polyoxyethylene alkyl ether phosphate esters, and alkyl allyl ether phosphates. Examples of the cationic surfactant include alkylamine salts, dialkylamine salts, tetraalkylammonium salts, benzalkonium salts, alkylpyridinium salts, imidazolinium salts, and the like. Furthermore, examples of the amphoteric surfactant include dimethylalkyl lauryl betaine, alkyl glycine, alkyl di (aminoethyl) glycine, imidazolinium betaine and the like. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, sucrose ester, glycerin ester polyoxyethylene ether, sorbitan Examples thereof include polyoxyethylene ethers of esters, polyoxyethylene ethers of sorbitol esters, fatty acid alkanolamides, polyoxyethylene fatty acid amides, amine oxides, and polyoxyethylene alkylamines.

  Further, the pigment can be provided with dispersibility by coating with a resin having a hydrophilic group and encapsulating the pigment.

  As a method for coating a water-insoluble pigment with an organic polymer and microencapsulating, all conventionally known methods can be used. Conventionally known methods include chemical production methods, physical production methods, physicochemical methods, mechanical production methods, and the like. Specifically, there are the following manufacturing methods.

Interfacial polymerization method (a method in which two types of monomers or two types of reactants are separately dissolved in a dispersed phase and a continuous phase, and both substances are reacted at the interface between them to form a wall film);

In-situ polymerization method (method of supplying a liquid or gas monomer and catalyst, or two reactive substances from either one of the continuous phase core particles to cause a reaction to form a wall film);

  ・ Liquid-cured coating method (method of forming a wall film by insolubilizing droplets of a polymer solution containing core material particles in a liquid with a curing agent);

-Coacervation (phase separation) method (a method in which a polymer dispersion in which core material particles are dispersed is separated into a coacervate (concentrated phase) and a dilute phase having a high polymer concentration to form a wall film);

・ Liquid drying method (preparing a liquid in which a core material is dispersed in a solution of a wall membrane material, placing the dispersion in a liquid in which the continuous phase of this dispersion is not miscible, and forming a composite emulsion to dissolve the wall membrane material. A method of forming a wall film by gradually removing the medium in the medium);

  Melt dispersion cooling method (using a wall film material that melts into a liquid state when heated and solidifies at room temperature, this material is heated and liquefied, the core material particles are dispersed in it, cooled to fine particles, and cooled to the wall. A method of forming a film);

・ Air suspension coating method (Method of forming a wall membrane by suspending powder core material particles in the air with a fluidized bed and suspending them in an air stream while spraying and mixing the coating solution of the wall membrane material) ;

-Spray drying method (a method in which the encapsulated stock solution is sprayed and contacted with hot air to evaporate and dry the volatile components to form a wall film);

  -Acid precipitation method (at least a part of anionic groups of organic polymer compounds containing anionic groups is neutralized with a basic compound to give solubility in water and kneaded in an aqueous medium with a colorant. Then, neutralize or acidify with an acidic compound, deposit organic compounds and fix them on the colorant, and then neutralize and disperse))

-Phase inversion emulsification method (a mixture containing an anionic organic polymer having dispersibility in water and a colorant is used as an organic solvent phase, and water is added to the organic solvent phase or And the like).

  Examples of organic polymers (resins) used as the material constituting the microcapsule wall membrane material include polyamide, polyurethane, polyester, polyurea, epoxy resin, polycarbonate, urea resin, melamine resin, phenol resin, and polysaccharide. , Gelatin, gum arabic, dextran, casein, protein, natural rubber, carboxypolymethylene, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, cellulose, ethyl cellulose, methyl cellulose, nitrocellulose, hydroxyethyl cellulose, acetic acid Cellulose, polyethylene, polystyrene, (meth) acrylic acid polymer or copolymer, (meth) acrylic acid ester polymer or copolymer, (meth) acrylic acid (Meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid copolymer, styrene-maleic acid copolymer, sodium alginate, fatty acid, paraffin, beeswax, water wax, hardened beef tallow, carnauba wax, albumin, etc. .

  Among these, organic polymers having an anionic group such as a carboxylic acid group or a sulfonic acid group can be used. Nonionic organic polymers include, for example, polyvinyl alcohol, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate or their (co) polymers, and 2-oxazoline cationic ring-opening polymers. Is mentioned. In particular, a complete saponified product of polyvinyl alcohol is particularly preferable because it has low water solubility and is easily dissolved in hot water but difficult to dissolve in cold water.

  Further, the amount of the organic polymer constituting the wall membrane material of the microcapsule is 1% by weight or more and 20% by weight or less based on the water-insoluble colorant such as an organic pigment or carbon black. By setting the amount of the organic polymer within the above range, the content of the organic polymer in the capsule is relatively low so that the pigment develops due to the organic polymer covering the pigment surface. Can be suppressed. If the amount of the organic polymer is less than 1% by weight, it is difficult to exert the effect of encapsulation. Conversely, if the amount exceeds 20% by weight, the color developability of the pigment is significantly reduced. In consideration of other characteristics, the amount of the organic polymer is preferably in the range of 5 to 10% by weight based on the water-insoluble colorant.

  That is, since a part of the color material is exposed without being substantially covered, it is possible to suppress a decrease in color developability, and conversely, a part of the color material is not substantially exposed without being exposed. Since it is coated, it is possible to simultaneously exhibit the effect that the pigment is coated. The number average molecular weight of the organic polymers used in the present invention is preferably 2000 or more from the viewpoint of capsule production. Here, “substantially exposed” means not the partial exposure associated with defects such as pinholes and cracks, but a state where it is intentionally exposed.

  Furthermore, if an organic pigment or self-dispersing carbon black, which is a self-dispersing pigment, is used as a colorant, the dispersibility of the pigment is improved even if the content of the organic polymer in the capsule is relatively low. In addition, since sufficient storage stability of the ink can be secured, it is more preferable for the present invention.

  It is preferable to select an organic polymer suitable for the microencapsulation method. For example, in the case of interfacial polymerization, polyester, polyamide, polyurethane, polyvinyl pyrrolidone, epoxy resin and the like are suitable. In the case of using the in-situ polymerization method, a polymer or copolymer of (meth) acrylic acid ester, (meth) acrylic acid- (meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid copolymer, Polyvinyl chloride, polyvinylidene chloride, polyamide and the like are suitable. In the case of the liquid curing method, sodium alginate, polyvinyl alcohol, gelatin, albumin, epoxy resin and the like are suitable. In the case of the coacervation method, gelatin, celluloses, casein and the like are suitable. In addition, in order to obtain a fine and uniform microencapsulated pigment, it is possible to use all conventionally known encapsulation methods other than those described above.

  When the phase inversion method or the acid precipitation method is selected as the microencapsulation method, anionic organic polymers are used as the organic polymers constituting the wall membrane material of the microcapsules. The phase inversion method is a composite or composite of an anionic organic polymer having self-dispersibility or solubility in water and a colorant such as a self-dispersion organic pigment or self-dispersion carbon black, or a self-dispersion method. A mixture of a colorant such as a dispersible organic pigment or self-dispersing carbon black, a curing agent, and an anionic organic polymer is used as an organic solvent phase, and water is added to the organic solvent phase, or the organic solvent is submerged in water. In this method, a solvent phase is introduced and microencapsulation is performed while self-dispersion (phase inversion emulsification) is performed. In the above phase inversion method, there is no problem even if the organic solvent phase is mixed with a recording liquid vehicle or additives. In particular, it is more preferable to mix a liquid medium of a recording liquid because a dispersion liquid for recording liquid can be directly produced.

  On the other hand, in the acid precipitation method, a part or all of the anionic group of the anionic group-containing organic polymer is neutralized with a basic compound, and a colorant such as a self-dispersing organic pigment or self-dispersing carbon black, A water-containing cake obtained by a production method comprising a step of kneading in an aqueous medium and a step of neutralizing and acidifying an acidic compound to precipitate an anionic group-containing organic polymer and fixing it to a pigment, This is a method of microencapsulation by neutralizing a part or all of an anionic group using a compound. By doing in this way, the aqueous dispersion containing the anionic microencapsulated pigment which is fine and contains many pigments can be manufactured.

  Examples of the solvent used for microencapsulation as described above include alkyl alcohols such as methanol, ethanol, propanol and butanol; aromatic hydrocarbons such as benzol, toluol and xylol; methyl acetate Esters such as ethyl acetate and butyl acetate; Chlorinated hydrocarbons such as chloroform and ethylene dichloride; Ketones such as acetone and methyl isobutyl ketone; Ethers such as tetrahydrofuran and dioxane; Cellosolves such as methyl cellosolve and butyl cellosolve Etc. The microcapsules prepared by the above method are once separated from these solvents by centrifugation or filtration, and then stirred and redispersed with water and the necessary solvent, and used for the intended present invention. To obtain a recording liquid capable of The average particle diameter of the encapsulated pigment obtained by the above method is preferably 50 nm to 180 nm.

  By coating the resin in this way, the pigment adheres firmly to the printed material, whereby the scratching property of the printed material can be improved.

  In order to make the recording liquid of the present invention have desired physical properties or to prevent clogging of the nozzles of the recording head due to drying, it is preferable to use a water-soluble organic solvent in addition to the coloring material. The water-soluble organic solvent includes a wetting agent and a penetrating agent. The wetting agent is added for the purpose of preventing clogging of the nozzles of the recording head due to drying. Specific examples of the wetting agent include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, 1,3-butanediol, 1,3-propanediol, and 2-methyl-1,3-propane. Diol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, 1,2 Polyhydric alcohols such as 1,4-butanetriol, 1,2,3-butanetriol, and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene Polyhydric alcohol alkyl ethers such as glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether and propylene glycol monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether Forehead: Nitrogen-containing heterocyclic compounds such as N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam; formamide, N-methylformamide, Amides such as formamide and N, N-dimethylformamide; monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethyl And amines such as ruamine, sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and thiodiethanol, propylene carbonate, ethylene carbonate, and γ-butyrolactone. These solvents are used alone or in combination with water.

  Further, the penetrant is added for the purpose of improving the wettability between the recording liquid and the recording material and adjusting the penetration speed. As the penetrant, those represented by the following general formulas (I) to (IV) and (A) are preferable. That is, a polyoxyethylene alkylphenyl ether surfactant of the following formula (I), an acetylene glycol surfactant of the formula (II), a polyoxyethylene alkyl ether surfactant of the following formula (III), a formula (IV ) Polyoxyethylene polyoxypropylene alkyl ether surfactant and (A) fluorosurfactant can reduce the surface tension of the liquid, thus improving wettability and increasing penetration rate. it can.

（Ｒは分岐していても良い炭素数６〜１４の炭化水素鎖、ｋは５〜２０）

(R is an optionally branched hydrocarbon chain having 6 to 14 carbon atoms, k is 5 to 20)

（ｍ、ｎは０〜４０）

(M and n are 0 to 40)

（Ｒは分岐していても良い炭素数６〜１４の炭化水素鎖、ｎは５〜２０）

(R is an optionally branched hydrocarbon chain having 6 to 14 carbon atoms, n is 5 to 20)

（Ｒは炭素数６〜１４の炭化水素鎖、ｍ、ｎは２０以下の数）

(R is a hydrocarbon chain having 6 to 14 carbon atoms, m and n are numbers of 20 or less)

（ｍは、０〜１０の整数、ｎは、１〜４０の整数を表す）。

(M represents an integer of 0 to 10, and n represents an integer of 1 to 40).

  Other than the compounds of the formulas (I) to (IV) and (A), for example, diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, Alkyl and aryl ethers of polyhydric alcohols such as tetraethylene glycol chlorophenyl ether, nonionic surfactants such as polyoxyethylene polyoxypropylene block copolymers, fluorine-based surfactants, lower alcohols such as ethanol and 2-propanol However, fluorine-based surfactants are particularly preferable.

  Examples of fluorosurfactants include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl betaines, perfluoroalkylamine oxide compounds. The structure shown by the general formula (A) is particularly preferable from the viewpoint of reliability. Further, commercially available fluorine compounds include Surflon S-111, S-112, S-113, S121, S131, S132, S-141, and S-145 (manufactured by Asahi Glass Co., Ltd.), Fullrad FC-93. , FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431, FC-4430 (manufactured by Sumitomo 3M), MegaFuck F-470, F-1405, F474 (Manufactured by Dainippon Ink & Chemicals, Inc.), Zonyl FS-300, FSN, FSN-100, FSO (manufactured by DuPont), Ftop EF-351, 352, 801, 802 (manufactured by Gemco) etc. can be easily obtained and used in the present invention. it can. Among these, Zonyl FS-300, FSN, FSN-100, and FSO (manufactured by DuPont), which are particularly excellent in reliability and color development, can be suitably used.

  The surface tension of the recording liquid (ink) used in the image forming method according to the present invention is more preferably 35 mN / m or less.

  The viscosity of the recording liquid (ink) used in the image forming method according to the present invention is preferably 1.0 to 20.0 cP, and from the viewpoint of ejection stability, it is 3.0 to 10.0 cP. More preferably it is.

  The pH of the recording liquid (ink) used in the image forming method according to the present invention is preferably 3 to 11, and 6 to 10 from the viewpoint of preventing corrosion of the metal member in contact with the liquid. Further preferred.

  The recording liquid can contain an antiseptic / antifungal agent. By containing an antiseptic / antifungal agent, the growth of bacteria can be suppressed, and the storage stability and image quality stability can be improved. As antiseptic / antifungal agents, benzotriazole, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, isothiazoline compounds, sodium benzoate, sodium pentachlorophenol, and the like can be used.

  Further, the recording liquid can contain a rust inhibitor. By containing a rust preventive agent, a coating can be formed on the metal surface in contact with the liquid, such as a head, and corrosion can be prevented. As the rust inhibitor, for example, acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and the like can be used.

  Further, the recording liquid can contain an antioxidant. By containing an antioxidant, even when radical species that cause corrosion are generated, the antioxidant can be prevented by eliminating the radical species.

  Typical examples of the antioxidant include phenolic compounds and amine compounds. Examples of the phenolic compounds include hydroquinone and gallate compounds, 2,6-di-tert-butyl-p-cresol, and stearyl. -Β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl- 6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-4-hydroxybenzyl) benzene, Hindered materials such as lith (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, tetrakis [methylene-3 (3 ′, 5′-di-tert-butyl-4-hydroxyphenyl) propionate] methane Phenol compounds are exemplified, and amine compounds include N, N′-diphenyl-p-phenylenediamine, phenyl-β-naphthylamine, phenyl-α-naphthylamine, N, N′-β-naphthyl-p-phenylene. Examples include diamine, N, N′-diphenylethylenediamine, phenothiazine, N, N′-di-sec-butyl-p-phenylenediamine, 4,4′-tetramethyl-diaminodiphenylmethane, and the like.

  Further, as the latter, sulfur compounds and phosphorus compounds are representative, but as sulfur compounds, dilauryl thiodipropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, dithiol. Examples include myristyl thiodipropionate, distearyl β, β′-thiodibutyrate, 2-mercaptobenzimidazole, dilauryl sulfide and the like, and phosphorus compounds include triphenyl phosphite, trioctadecyl phosphite, tridecyl. Examples include phosphite, trilauryl trithiophosphite, diphenylisodecyl phosphite, trinonylphenyl phosphite, distearyl pentaerythritol phosphite.

  The recording liquid can contain a pH adjusting agent. Examples of the pH adjuster include hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, lithium carbonate, Examples include alkali metal carbonates such as sodium carbonate and potassium carbonate, amines such as diethanolamine and triethanolamine, boric acid, hydrochloric acid, nitric acid, sulfuric acid, and acetic acid.

  In the highly penetrating pigment-based ink used in the present invention, the penetrability is further improved by adding a fluorine-based surfactant.

Specific examples of ink will be described below, but the present invention is not limited to this.
<Black ink>
Using a carbon black dispersion made of Cabot (sulfon group addition type self-dispersion type), the mixture was stirred with the following formulation, and then filtered through a 0.8 μm polypropylene filter to prepare an ink.
40 parts by weight of black dispersion
CAB-O-JET 200 (Sulfon group added type Cabot)
Acrylic silicone resin emulsion 8 parts by weight Nanocrill SBCX-2821 (Toyo Ink)
1,3-butanediol 18 parts by weight Glycerin 9 parts by weight
2-pyrrolidone 2 parts by weight Ethylhexanediol 2 parts by weight Fluorosurfactant FS-300 (manufactured by Du Pont) 2 parts by weight General formula (A) m = 6-8 n = 26 or more Proxel LV (manufactured by Avicia) ) 0.2 parts by weight Ion exchange water 20.8 parts by weight

<Color ink>
A copper phthalocyanine pigment-containing polymer fine particle dispersion was additionally prepared with reference to Preparation Example 3 of JP-A No. 2001-139849.
First, in preparing a polymer solution, the inside of a 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas introduction tube, reflux tube and dropping funnel was sufficiently replaced with nitrogen gas, and then 11.2 g of styrene, acrylic acid 2.8 g, 12.0 g of lauryl methacrylate, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer (manufactured by Toa Gosei Co., Ltd., trade name: AS-6) and 0.4 g of mercaptoethanol were added and the temperature was raised to 65 ° C. Warm up. Next, styrene 100.8 g, acrylic acid 25.2 g, lauryl methacrylate 108.0 g, polyethylene glycol methacrylate 36.0 g, hydroxyethyl methacrylate 60.0 g, styrene macromer (manufactured by Toagosei Co., Ltd., trade name: AS-6) A mixed solution of 36.0 g, mercaptoethanol 3.6 g, azobisdimethylvaleronitrile 2.4 g and methyl ethyl ketone 18 g was dropped into the flask over 2.5 hours. After completion of dropping, a mixed solution of 0.8 g of azobisdimethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobisdimethylvaleronitrile was added, and further aging was performed for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution having a concentration of 50%.

  28 g of the polymer solution obtained above, 26 g of copper phthalocyanine pigment, 13.6 g of 1 mol / L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone and 30 g of ion-exchanged water were sufficiently stirred. Thereafter, the mixture was kneaded 20 times using a three-roll mill (manufactured by Noritake Co., Ltd., trade name: NR-84A). The obtained paste was put into 200 g of ion-exchanged water and sufficiently stirred, and then methyl ethyl ketone and water were distilled off using an evaporator to obtain 160 g of a cyan polymer fine particle dispersion having a solid content of 20.0 wt%. .

  This dispersion was mixed and stirred with the following formulation, and then filtered through a 0.8 μm polypropylene filter to prepare an ink.

Cyan polymer fine particle dispersion 45 parts by weight
1,3-butanediol 21 parts by weight Glycerin 8 parts by weight Ethylhexanediol 2 parts by weight Fluorosurfactant FSN-100 (manufactured by Du Pont) 1 part by weight General formula (A) m = 1 to 9 n = 0 ~twenty five
Proxel LV (manufactured by Avicia) 0.5 parts by weight Ion-exchanged water 23.5 parts by weight

  In this way, by adding a fluorosurfactant in addition to water-soluble solvents (1,3-butanediol, ethylhexanediol), commercial and publishing are less permeable than so-called inkjet paper and plain paper. The coated paper for printing can also have a practical level of permeability.

Next, another example of the specific configuration of the image forming apparatus according to the present invention will be described with reference to FIG.
This image forming apparatus is an image forming apparatus (composite machine) that combines the function of an ink jet recording apparatus and a copying function, and an image forming unit (means) for forming an image in the apparatus main body 1001 (enclosure). ) 1002 and a sub-scanning conveyance unit (means) 1003 (both are collectively referred to as a printer engine unit), etc., and a recording medium (paper) from a paper feeding unit (means) 1004 provided at the bottom of the apparatus main body 1001 1005 is fed one by one, and the sub-scan transport unit 1003 transports the paper 1005 at a position facing the image forming unit 1002, while the image forming unit 1002 ejects droplets onto the paper 1005 to obtain a desired image. After forming (recording), the paper 1005 is discharged onto a paper discharge tray 1007 formed on the upper surface of the apparatus main body 1001 through the paper discharge conveyance unit 1006.

  The image forming apparatus also has an image reading unit (scanner) for reading an image above the discharge tray 1007 above the apparatus main body 1001 as an input system for image data (print data) formed by the image forming unit 1002. Part) 1011. In this image reading unit 1011, the scanning optical system 1015 including the illumination light source 1013 and the mirror 1014 and the scanning optical system 1018 including the mirrors 1016 and 1017 move, and the image of the document placed on the contact glass 1012. The scanned document image is read as an image signal by an image reading element 1020 disposed behind the lens 1019, and the read image signal is digitized and subjected to image processing, and the image-processed print data is printed. be able to. A contact plate 1010 is provided with a pressure plate 1010 for pressing the document.

  Furthermore, this image forming apparatus uses an image processing apparatus such as an external personal computer as an input system for image data (print image data) formed by the image forming unit 1002, and an image reading apparatus such as an image scanner. Data including print image data from the host side such as an imaging device such as a digital camera can be received via a cable or network, and the received print data can be processed and printed.

  Here, the image forming unit 1002 is guided on a carriage 1023 that is guided by a guide rod 1021 and can move in the main scanning direction (a direction perpendicular to the paper conveyance direction), as in the above-described ink jet recording apparatus (image forming apparatus). Is mounted with a recording head 1024 including one or a plurality of liquid ejection heads each having a nozzle array for ejecting droplets of different colors, and the carriage 1023 is moved in the main scanning direction by a carriage scanning mechanism to perform sub-scanning conveyance. A shuttle type is used in which droplets are ejected from the recording head 1024 while the sheet 1005 is fed in the sheet transport direction (sub-scanning direction) by the unit 1003. In addition, it can also be set as a line type by providing a line type head.

  The recording head 1024 has nozzle rows that discharge black (Bk) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink, respectively, and ink of each color from the sub tank 1025 mounted on the carriage 1023. Is supplied. Ink is supplied to the sub tank 1025 through a tube (not shown) from each color ink cartridge 1026 which is a main tank detachably mounted in the apparatus main body 1001.

  The sub-scanning conveyance unit 1003 is a drive roller between the conveyance roller 1032 and the driven roller 1033 for conveying the paper 1005 fed from below to the image forming unit 1002 by changing the conveyance direction by approximately 90 degrees. An endless conveying belt 1031, a charging roller 1034 to which an AC bias is applied to charge the surface of the conveying belt 1031, and a guide for guiding the conveying belt 1031 in a region facing the image forming unit 702. The member 1035, a pressing roller (pressure roller) 1036 that presses the sheet 1005 against the conveying roller 1032 at a position facing the conveying roller 1032, and the sheet 1005 on which an image is formed by the image forming unit 1002 are sent out to the paper discharge conveying unit 1006. A transport roller 1037 is provided.

  The conveyance belt 1031 of the sub-scan conveyance unit 1003 is configured to rotate in the sub-scanning direction by rotating the conveyance roller 1032 from the sub-scanning mode 1131 via the timing belt 1132 and the timing roller 1133.

  A paper feed unit 1004 can be inserted into and removed from the apparatus main body 1001, and a paper feed cassette 1041 for stacking and storing a large number of papers 1005 and a paper feed for separating and feeding the papers 1005 in the paper feed cassette 1041 one by one. A sheet roller 1042 and a friction pad 1043 and a sheet feeding / conveying roller 1044 serving as a registration roller for conveying the fed sheet 1005 to the sub-scanning conveying unit 1003 are provided. The paper feed roller 1042 is rotated by a paper feed motor 1141 composed of an HB type stepping motor via a paper feed clutch (not shown), and the paper feed transport roller 1044 is also rotationally driven by the paper feed motor 1141.

  A paper discharge transport unit 1006 includes a pair of paper discharge transport rollers 1061 and 1062 for transporting the paper 1005 on which image formation has been performed, a pair of paper discharge transport rollers 1063 and a pair of paper discharge rollers for sending the paper 1005 to the paper discharge tray 1007. 1064.

The control unit of the image forming apparatus is configured, for example, as shown in FIG.
The control unit 1200 includes a CPU 1201, a program executed by the CPU 1201, the ROM 1202 for storing other programs and fixed data, a RAM 1203 for temporarily storing image data, and the like, while the apparatus is powered off. 1 includes a main control unit 1210 that controls the entire apparatus, including a nonvolatile memory (NVRAM) 1204 for holding data and an ASIC 1205 that performs image processing such as halftone processing on an input image. .

  Further, the control unit 1200 is interposed between a host side such as an information processing apparatus serving as an image processing apparatus and the main control unit 1210, an external I / F 1211 for transmitting and receiving data and signals, a recording head, and the like. A print control unit 1212 including a head driver for driving and controlling 1024, a main scanning driving unit (motor driver) 1213 for driving a main scanning motor 1027 that moves and scans the carriage 1023, and a sub-scanning motor 1131 are driven. A sub-scanning driving unit 1214 for driving the paper feeding motor 1141, a paper feeding driving unit 1215 for driving the paper feeding motor 1141, and a paper discharging driving unit 1216 for driving the paper discharging motor 1103 that drives each roller of the paper discharging unit 1006. A double-sided drive unit 1217 for driving a double-sided refeed motor 1104 for driving each roller of a double-sided unit (not shown), and maintenance A recovery system driving unit 1218 for driving a maintenance and recovery motor 1105 for driving the recovery mechanism, and a AC bias supply unit 1219 for supplying AC bias to the charging roller 1034.

  Further, the control unit 1200 includes a solenoid drive unit (driver) 1222 that drives various solenoids (SOL) 1106, a clutch drive unit 1224 that drives electromagnetic cracks 1107 related to paper feed, and the like, and an image reading unit 1011. A scanner control unit 1225 for controlling.

  The main control unit 1210 inputs a detection signal of a temperature sensor 1108 that detects the temperature of the conveyor belt 1031 described above. The main control unit 1210 also receives detection signals from other sensors (not shown) but is not shown. Further, the main control unit 1210 captures necessary key inputs and outputs display information with the operation / display unit 1109 including various keys such as a numeric keypad and print start key provided on the apparatus main body 1001 and various displays. Do.

  Further, the main control unit 1210 includes an output signal (pulse) from the linear encoder 1101 for detecting the moving amount and moving speed of the carriage 1023, and a rotary encoder for detecting the moving speed and moving amount of the conveyor belt 1031. An output signal (pulse) from 1102 is input, and the main control unit 1210 performs main scanning via the main scanning driving unit 1213 and the sub-scanning driving unit 1214 based on the correlation between these output signals and each output signal. By driving and controlling the motor 1027 and the sub-scanning motor 1131, the carriage 1023 is moved, and the conveyance belt 1031 is moved to convey the paper 1005.

  The image forming operation in the image forming apparatus configured as described above will be briefly described. By applying a high voltage of a positive and negative rectangular wave as an alternating voltage from the AC bias supply unit 1219 to the charging roller 1034, the charging roller 1034 is Since it is in contact with the insulating layer (surface layer) of the conveyance belt 1031, positive and negative charges are alternately applied to the surface layer of the conveyance belt 1031 in a band shape in the conveyance direction of the conveyance belt 1031. Then, charging is performed with a predetermined charging width to generate an unequal electric field.

  Therefore, the sheet 1005 is fed from the sheet feeding unit 1004 or the like, and positive and negative charges are formed between the conveying roller 1032 and the presser roller 1036, and thus onto the conveying belt 1031 where an unequal electric field is generated. The paper 1005 is instantly polarized according to the direction of the electric field, and is attracted onto the transport belt 1031 by the electrostatic attraction force, and is transported as the transport belt 1031 moves.

  Then, while the paper 1005 is intermittently transported by the transport belt 1031, the recording liquid droplets are ejected from the recording head 1024 according to the print data on the paper 1005 to form (print) an image. The leading end side of the paper 1005 that has been performed is separated from the conveyor belt 1031 by a separation claw, and is discharged onto a paper discharge tray 1007 by a paper discharge conveyor 1006.

Next, an embodiment in which the image forming method according to the present invention is performed on the image processing apparatus side storing the program according to the present invention will be described with reference to FIG.
FIG. 16 is a block diagram illustrating an example of an image processing system according to the present invention. This image processing system includes one or a plurality of image processing apparatuses (also referred to as PCs) 400 including a personal computer that is an image processing apparatus, and an ink jet recording apparatus (also referred to as an ink jet printer) 500 as the image forming apparatus. Are connected by a predetermined interface or network.

  As shown in FIG. 17, in the image processing apparatus 400, a CPU 401 and various ROMs 402 and RAM 403, which are memory means, are connected by a bus line. The bus line is connected to a storage device 406 using a magnetic storage device such as a hard disk, an input device 404 such as a mouse and a keyboard, a monitor 405 such as an LCD or a CRT, and the like via a predetermined interface. A storage medium reading device that reads a storage medium such as an optical disk is connected, and a predetermined interface (external I / F) 407 that communicates with a network such as the Internet or an external device such as a USB is connected. Scanner) 408 is connected.

  The storage device 406 of the image processing apparatus 400 stores a printer driver as an image processing program including a program according to the present invention. This image processing program is installed in the storage device 406 by being read from the storage medium according to the present invention by a storage medium reader or downloaded from a network such as the Internet. With this installation, the image processing apparatus 400 becomes operable to perform the following image processing. Note that this image processing program may operate on a predetermined OS. Further, it may be a part of specific application software.

Here, an example in which the image processing method according to the present invention is executed by the program on the image processing apparatus 400 side will be described with reference to the functional block diagram of FIG.
A printer driver 411, which is a program according to the present invention on the image processing apparatus 400 (PC) side, is configured by each unit that performs processing similar to the processing in the image forming apparatus described above. In other words, the image data 410 given from the application software or the scanner 408 is converted from the color space for monitor display to the color space for the recording apparatus (image forming apparatus) (RGB color system → CMY color system). A CMM (Color Management Module) processing unit 412, a BG / UCR (black generation / under color removal) processing unit 413 that performs black generation / under color removal from CMY values, and an image forming apparatus for CMYK signals that serve as recording control signals. A total amount regulating unit 414 that corrects the CMYK signal in accordance with the maximum total amount value of the recording color material that can form an image, a γ correction unit 415 that performs input / output correction reflecting characteristics of the recording device and user's preference, an image forming device (not shown) Zooming processing that performs enlargement processing according to the resolution of the image, and the pattern arrangement of dots ejected from the image forming apparatus Halftone processing unit (multivalue / low value matrix) 416 including multivalue / low value matrix to be replaced, dot pattern data which is print image data obtained by halftone processing is divided into data for each scan, and further recorded A rasterizing unit 417 that develops data in accordance with each nozzle position for performing the above is output, and an output 418 of the rasterizing unit 417 is sent to the inkjet printer 500. A part of such image processing can also be executed on the ink jet printer 500 side.

  The image processing method according to the present invention can be preferably applied in the configuration of FIG. In the configuration shown in FIG. 8, an example will be described in which the inkjet recording apparatus 500 does not have a function of generating a dot pattern to be actually recorded upon receiving an image drawing or character print command in the apparatus. That is, a print command from application software executed by the image processing apparatus 400 serving as a host is subjected to image processing by a printer driver 411 incorporated as software in the image processing apparatus 400 (host computer) and output from the inkjet printer 500. An example will be described in which possible multi-value dot pattern data (print image data) is generated, rasterized, transferred to the ink jet printer 500, and the ink jet printer 500 is printed out.

  Specifically, in the image processing apparatus 400, an image drawing or character recording command from an application or operating system (for example, a description of the position and thickness and shape of a line to be recorded, a typeface of a character to be recorded, and the like) (Which describes the size, position, etc.) is temporarily stored in the drawing data memory. Note that these instructions are written in a specific print language.

  The command stored in the drawing data memory is interpreted by the rasterizer, and if it is a line recording command, it is converted into a recording dot pattern according to the designated position and thickness, etc. If there is image data, the outline information of the corresponding character is called from the font outline data stored in the image processing apparatus (host computer) 400 and converted into a recording dot pattern corresponding to the designated position and size. This is converted into a recording dot pattern as it is.

  Thereafter, image processing is performed on these recorded dot patterns (image data 410) and stored in the raster data memory. At this time, the image processing apparatus 400 rasterizes the recording dot pattern data with the orthogonal grid as the basic recording position. As described above, as image processing, for example, color management processing (CMM) for adjusting color, γ correction processing, halftone processing such as dither method and error diffusion method, background removal processing, and total ink amount restriction processing and so on. The recording dot pattern stored in the raster data memory is transferred to the ink jet recording apparatus 500 via the interface.

Therefore, the flow of image processing by the printer driver (program) on the image processing apparatus 400 side will be described with reference to the block diagram shown in FIG.
When a “print” instruction is issued from application software running on a data processing apparatus such as a personal computer, the printer driver determines the type of object in the object determination process 601 with respect to the input 600, and for each object, that is, a character. The image data 602, the line drawing image data 603, the graphics image data 604, and the image image data 605 are transferred, and processing is performed through the respective routes.

  That is, color adjustment processing 606 is performed for the characters 602, line drawings 603, and graphics 604. For characters, color matching processing 607, BG / UCR processing 609, total amount restriction processing 611 are performed, and character dither processing (halftone processing) 615 is performed. For line drawings and graphics, color matching processing 608, BG / UCR processing 610, total amount regulation processing 612, and γ correction processing 613 are performed, and graphics dither processing (halftone processing) 616 is performed.

  On the other hand, for the image 605, after performing color determination and compression method determination processing 621, in a normal case, after performing color adjustment processing 622 and color matching processing 623, BG / UCR processing 624, total amount regulation processing 625, γ correction processing 623 is performed, and error diffusion processing (halftone processing) 627 is further performed. In the case of two colors or less, after performing image thinning processing 631, color adjustment processing 632, color matching processing 233a or indexless processing (processing without color matching) 633b, BG / UCR processing 624, total amount regulation Processing 625 and γ correction processing 626 are performed, and error diffusion processing (halftone processing) 627 is further performed.

  Note that the line drawing and graphics may branch before reaching the color adjustment process 606, and may be transferred to the color matching process 632 in the case of an image via the ROP process 641.

  The image data processed for each object in this manner is also combined with the original one image data, and is passed to the image forming apparatus through a rasterizing process (not shown).

  Therefore, in the CMM processing unit 412, the BG / UCR processing unit 413, and the γ correction unit 415 in the printer driver 411, as described in the above-described embodiment of the image forming apparatus, RGB input signals are converted into CMYK output signals. When converting, it is determined whether or not the saturation of the input signal is within a predetermined range, and when the saturation is within the predetermined range, the saturation is converted to achromatic and converted to the input signal. When the blacking process for generating black is performed based on this, a process for changing the input tone value that is the maximum black amount is performed.

  Thereby, it is possible to reduce the coloring of the achromatic data with a simple configuration and improve the black visibility.

1 is a block explanatory diagram illustrating a configuration of an image forming apparatus according to the present invention. FIG. 2 is an explanatory block diagram illustrating an overview of a control unit of the image forming apparatus. It is a block explanatory view explaining the flow of the image processing unit of the control unit. It is explanatory drawing with which it uses for description of a general BG / UCR process. It is explanatory drawing with which it uses for description of the inking process (BG / UCR process) in this invention. It is explanatory drawing with which it uses for description of the experiment example at the time of performing the inking process of this invention. It is explanatory drawing with which it uses for description when performing the inking process of this invention by (gamma) correction process. It is explanatory drawing which shows an example of the look-up table used by a CMM process. It is explanatory drawing with which it uses for description of the color conversion process of this invention. It is explanatory drawing with which it uses for description of the experiment example at the time of performing the color conversion process of this invention. FIG. 2 is an explanatory side view illustrating an example of a specific configuration of the image forming apparatus according to the present invention. Similarly it is principal part plane explanatory drawing. It is a block diagram which similarly shows the outline | summary of a control part. It is side surface explanatory drawing which shows the other example of the specific structure of the image forming apparatus which concerns on this invention. It is a block diagram which similarly shows the outline | summary of a control part. It is a block explanatory view showing an example of an image processing system concerning the present invention. It is a block explanatory view showing an example of an image processing device in the system. FIG. 3 is a block diagram functionally explaining an example of a configuration of a printer driver as a program according to the present invention. FIG. 3 is a block explanatory diagram illustrating details of a flow of image processing in the printer driver.

Explanation of symbols

1. Image forming apparatus (inkjet recording apparatus)
2. Image reading device (scanner)
DESCRIPTION OF SYMBOLS 13 ... Image processing part 15 ... Print control part 42 ... CMM processing part 43 ... BG / UCR processing part 45 ... Gamma correction part 301 ... Main control part 307 ... Print control part 400 ... Image processing apparatus 500 ... Inkjet printer 411 ... Printer driver (program)
412 ... CMM processing unit 413 ... BG / UCR processing unit 415 ... γ processing unit 1002 ... Image forming unit

Claims (7)

In an image processing method for converting RGB input signals to CMYK output signals and generating image data of an image to be output by an image forming apparatus,
Determining whether the saturation of the input signal is included in a predetermined range, and converting the saturation to achromatic when the saturation is within the predetermined range;
When performing the inking amount determination process for determining the amount of black to be generated based on the CMYK signal obtained by converting the input signal, the input tone value corresponding to the maximum black amount that the image forming apparatus can take is And a step of determining an inking amount using a correction parameter set to a value smaller than a maximum possible input gradation value.   2. The image processing method according to claim 1, wherein the input signal is converted from an RGB color space to an HLS color space signal, and whether or not the saturation on the HLS color space is included within a predetermined range. An image processing method characterized by discriminating. In an image processing apparatus that converts RGB input signals into CMYK output signals and generates image data of an image to be output by the image forming apparatus .
Determining whether or not the saturation of the input signal falls within a predetermined range, and when the saturation is within the predetermined range, means for converting the saturation to achromatic; and
When performing the inking amount determination process for determining the amount of black to be generated based on the CMYK signal obtained by converting the input signal, the image forming apparatus determines an input tone value corresponding to the maximum black amount that can be taken. An image processing apparatus comprising: means for determining an inking amount using a correction parameter set to a value smaller than a maximum possible input gradation value. In an image processing system including an image processing apparatus that performs image processing for converting an RGB input signal into a CMYK output signal, and an image forming apparatus that outputs an image processed by the image processing apparatus.
The image processing apparatus includes:
Determining whether or not the saturation of the input signal falls within a predetermined range, and when the saturation is within the predetermined range, means for converting the saturation to achromatic; and
When performing the inking amount determination process for determining the amount of black to be generated based on the CMYK signal obtained by converting the input signal, the input tone value corresponding to the maximum black amount that the image forming apparatus can take is An image processing system comprising: means for determining an inking amount using a correction parameter set to a value smaller than a maximum input gradation value that can be taken. In an image forming apparatus that converts an RGB input signal into a CMYK output signal to form an image,
Determining whether or not the saturation of the input signal falls within a predetermined range, and when the saturation is within the predetermined range, means for converting the saturation to achromatic; and
When performing the inking amount determination process for determining the amount of black to be generated based on the CMYK signal obtained by converting the input signal, the input tone value corresponding to the maximum black amount that the image forming apparatus can take is An image forming apparatus comprising: means for determining an inking amount using a correction parameter set to a value smaller than a maximum input gradation value that can be taken. In a program for causing a computer to perform image processing for converting RGB input signals into CMYK output signals and generating image data of an image output by the image forming apparatus.
Determining whether the saturation of the input signal is included within a predetermined range, and when the saturation is within the predetermined range, converting the saturation into achromatic; and
When performing the inking amount determination process for determining the amount of black to be generated based on the CMYK signal obtained by converting the input signal, the input tone value corresponding to the maximum black amount that the image forming apparatus can take is A program for causing a computer to perform a process of determining an inking amount using a correction parameter set to a value smaller than a maximum possible input gradation value.   A storage medium in which the program according to claim 6 is stored.

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