JP2003274168A - Image processor, image processing method, program and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processor capable of performing high-speed processing with a simple configurastion even in an image processing form with the number of more gradation and performing error diffusion processing that effectively operates even to positional deviation of the dot position. <P>SOLUTION: In image formation control by a host device 51, a threshold table Table1 for magenta is referred to, a threshold Table1(Mt) corresponding to a total density value Mt is read, and the threshold Table1(Mt) corresponding to the total density value Mt is compared with a total density value Ct. An output quantization value Cout is determined in accordance with comparison results of the total density value Ct and the threshold Table1(Mt), and an error amount is calculated on the basis of the output quantization value Cout to diffuse the error to ambient pixels. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, an image processing method, which performs error diffusion processing on multi-valued image data composed of a plurality of density components and outputs the result of the error diffusion processing,
The present invention relates to programs and storage media.

[0002]

2. Description of the Related Art Conventionally, an error diffusion method has been known as a pseudo gradation process for expressing a multi-valued image in binary ("An Adaptive
Algorithm for Spatial Gray Scale "in society for I
nformation Display 1975 Symposium Digest of Techni
cal Papers, 1975, 36). In this method, the pixel of interest is P,
The density is v, peripheral pixels P0, P1, P2 of the target pixel P,
Assuming that the density of P3 is v0, v1, v2, v3 and the threshold for binarization is T, the binarization error E in the pixel of interest P is empirically determined by the weighting factors W0, W1, W2, W3. In this method, the pixels are distributed to the peripheral pixels P0, P1, P2, and P3, and the average density is made macroscopically equal to the density of the original image.

For example, if the output binary data is o     If v ≧ T, o = 1, E = v−Vmax     If v <T, o = 0, E = v-Vmin (1)     (However, Vmax: maximum density, Vmin: minimum density)     v0 = v0 + E × W0 (2)     v1 = v1 + E × W1 (3)     v2 = v2 + E × W2 (4)     v3 = v3 + E × W3 (5)     (Example of weighting factor: W0 = 7/16, W1 = 1/16, W2 = 5/16, W3 = 3/1 6) It can be expressed as.

Conventionally, when a multi-valued image is output using four color inks of cyan (C), magenta (M), yellow (Y), and black (K) in a color ink jet printer or the like, each color is independent. Pseudo gradation processing is performed using the error diffusion method or the like. Therefore, even if the visual characteristics of one color are excellent, it is not always possible to obtain good visual characteristics when two or more colors overlap.

To solve this problem, Japanese Patent Laid-Open No. 8-2
Japanese Patent Laid-Open No. 79920 and Japanese Patent Application Laid-Open No. 11-10918 disclose pseudo halftones in which good visual characteristics can be obtained even when two or more colors overlap by using an error diffusion method by combining two or more colors. A processing method is disclosed.

Further, in Japanese Unexamined Patent Publication No. 9-139841, after performing pseudo intermediate gradation processing for two or more colors independently,
A method is disclosed in which the output value is modified by the sum of the input values and a similar improvement is made.

In particular, in order to reduce the graininess in the medium density area of a color image, a cyan component (C) and a magenta component (M) are used.
It is known that it is effective to form an image so that the dots do not overlap each other, and the following method is used as a method therefor. FIG. 16 is a diagram for explaining image formation control according to the conventional inkjet method.

Here, in the image data, each density component (Y, M, C, K) of each pixel is 8 bits (gradation value is 0 to 255).
Will be described as being represented by multi-valued data.

If the density values of the C and M components of the target pixel of the multi-valued color image are Ct and Mt, and the density values of the C and M components of the original image are C and M, respectively, then Ct = C + Cerr Mt = It is expressed as M + Merr. Here, Cerr and Merr are the values obtained by error diffusion for the pixel of interest for each of the C component and the M component.

Regarding the C and M image formation shown in FIG. 16, four types of image formation control are performed according to the densities of the C and M components of the pixel of interest. 1. The sum of (Ct + Mt) is less than or equal to a threshold value (Threshold 1),
That is, in the case of belonging to the region R1 in FIG. 16, dot recording using C (cyan) ink and M (magenta) ink is not performed. 2. The sum of (Ct + Mt) exceeds the threshold (Threshold 1), and the sum of (Ct + Mt) exceeds another threshold (Threshol).
d 2) and Ct> Mt, that is,
If it belongs to the region R2 in FIG. 16, dot recording is performed using only C ink. 3. The sum of (Ct + Mt) exceeds the threshold (Threshold 1), and the sum of (Ct + Mt) exceeds another threshold (Threshol).
d 2) and Ct ≦ Mt, that is,
If it belongs to the region R3 in FIG. 16, dot recording is performed using only M ink. 4. If the sum of (Ct + Mt) is greater than or equal to another threshold value (Threshold 2), that is, if it belongs to the region R4 in FIG. 16, dot recording is performed using C ink and M ink.

It should be noted that here, between the above threshold values,
It is assumed that the relational expression of hold 1 <Threshold 2 holds.

[0012]

However, in the conventional method, the determination formula becomes more complicated and the processing time becomes longer as the number of gradations in the case of performing quantization increases.

Here, an example of the case where cyan and magenta are quantized into three values by the conventional method is shown below.

[0014] As described above, the process of quantizing into three values is a complicated process, and the process of quantizing into more gradations is more complicated.

When the multi-valued error diffusion process is performed and two or more colors are controlled so as not to overlap each other, the dot landing position shift when actually outputting by the printer will be described as follows. There is a problem to be solved on the image. This problem will be described with reference to FIGS. 17 and 18. FIG. 17 is a diagram showing an output image of a highlight part for explaining a conventional problem to be solved, and FIG. 18 is a diagram showing an output image of a halftone part for explaining a conventional problem to be solved.

Here, FIG. 17A shows an example of the result of the two-color simultaneous error diffusion in the highlighted portion on the printer output paper surface, and in the figure, dots (dots) 6 are filled in with dots.
01 represents a cyan ink dot, and a circle 602 (dot) filled with a diagonal line represents a magenta ink dot.
In the result example shown in FIG. 17A, the paper surface is almost evenly filled with cyan ink dots 601 and magenta ink dots 602, and this result example is a good image. On the other hand, FIG. 17 (b) shows FIG. 17 (a).
The case where the entire cyan ink dot group in is shifted to the left with a width substantially the same as the ink diameter. In this case, the cyan ink dots 601 are still present even if there is a slight layout difference on the paper surface.
Since the magenta ink dots 602 and the magenta ink dots 602 do not overlap each other, there is no change in the area factor, which is the coverage of the ink on the paper surface.

FIG. 18A shows an example of the result of simultaneous two-color error diffusion in the halftone part on the printer output paper surface. In the figure, dots 701 filled with dots are cyan ink. Circles (dots) 702 filled with diagonal lines represent magenta ink dots. In the result example shown in FIG. 18A, the paper surface is almost evenly filled with the cyan ink dots 701 and the magenta ink dots 702. Therefore, the result example is a good image. On the other hand, FIG. 18B shows FIG.
The case where the entire cyan ink dot group is shifted to the left with a width substantially equal to the ink diameter. In this case,
Unlike the transition from FIG. 17A to FIG. 17B, the cyan ink dot 701 and the magenta ink dot 702 overlap with high probability. In this case, the area factor, which is the coverage of the ink on the paper, changes greatly.

Changes in the area factor are easily perceived as a large difference by the human eye. Further, as the factors causing the positions of the cyan ink dot and the magenta ink dot to shift, for example, vibration of the carriage motor, deflection of the output target medium in the main scanning direction, and expansion of the medium caused by the output target medium absorbing ink -There is a change over time, there is a difference in ejection speed for each color ink, etc.In addition, unevenness in paper feeding due to eccentricity of the paper feeding roller and gear in the sub-scanning direction, and instability of paper behavior at the upper and lower edges of the paper, etc. is there.

Many of these factors vary depending on the position of the medium to be output. Therefore, when the area factor changes depending on the position, the change of the area factor is recognized by human eyes as a large image unevenness.

The present invention has been made in view of the above problems, and can perform high-speed processing with a simple configuration even in an image processing mode having a larger number of gradations, and is also effective for dot landing position deviation. It is an object of the present invention to provide an image processing device, an image processing method, a program, and a storage medium that can function as described above.

[0021]

In order to achieve the above object, the present invention provides an image processing apparatus for performing error diffusion processing on multi-valued image data composed of a plurality of density components and outputting the result of the error diffusion processing. Of the plurality of concentration components,
First error diffusion means for performing error diffusion based on the density value of the first density component, and error based on the density value of the first density component and the density value of at least one of the other density components A second error diffusion unit that performs diffusion and a determination unit that determines which of the first error diffusion unit and the second error diffusion unit is used according to a predetermined condition are provided. It is characterized by

In the above image processing apparatus, the predetermined condition is that when the density value of the first density component is in a predetermined area, the first error diffusion means is averaged in the predetermined area. The condition is characterized in that the probability of use is higher than the probability of using the second error diffusion means.

In the above image processing, the predetermined area is an area in which the density value of the first density component is equal to or smaller than the minimum value of the quantized representative value larger than 0, and is equal to or larger than the second largest quantized representative value. It is a region included in at least one of the above regions.

In the image processing apparatus, the predetermined area is an area in which the density value of the first density component is equal to or smaller than the minimum value of the quantized representative value larger than 0, and the second largest quantized representative value. It is characterized in that it is an area including at least one of the above areas.

In order to achieve the above-mentioned object, the present invention is an image processing apparatus which performs error diffusion processing on multi-valued image data composed of a plurality of density components and outputs the result of the error diffusion processing, Of the plurality of density components, at least one of a first quantization unit that performs quantization based on a first density component and outputs the quantization result as a first quantization result, and at least other density components A determining unit that determines a threshold value based on a concentration value of one concentration component; a comparing unit that compares the threshold value determined by the determining unit with the first concentration component and outputs the comparison result; Second quantizing means for outputting a second quantizing result based on the first quantizing means output from the quantizing means and the comparing result output from the comparing means; For the concentration component, the second quantum Characterized in that it comprises the error diffusion execution means for executing the error diffusion processing based on the results.

Further, in order to achieve the above object, the present invention is an image processing apparatus which performs error diffusion processing on multi-valued image data composed of a plurality of density components and outputs the result of the error diffusion processing, Of the plurality of density components, quantization is performed based on the first density component, and the first quantization means for outputting the quantization result as the first quantization result, and at least one of the other density components. Deciding means for deciding a threshold value based on the density value of one density component, quantization is performed based on the threshold value decided by the deciding means and the first density component, and the quantized result is a second quantized result. Second quantizing means for outputting as the first quantizing means, the first quantizing means outputted from the first quantizing means according to a predetermined condition, and the second quantizing means outputted from the second quantizing means. Quantization result of any of Selection means for selecting whether to use the fruit, characterized by comprising the error diffusion execution means for executing the error diffusion processing based on the quantization result selected by said selection means.

In the image processing apparatus, the predetermined condition is that when the density value of the first density component is in a predetermined area, the first quantization result is averaged in the predetermined area. The condition is characterized in that the probability of use is higher than the probability of using the second quantization result.

In the above image processing apparatus, the predetermined area is an area in which the density value of the first density component is equal to or less than the minimum value of the quantization representative value larger than 0, and the second largest quantization representative value. It is a region included in at least one of the above regions.

In the above image processing apparatus, the predetermined area is an area in which the density value of the first density component is equal to or less than the minimum value of the quantized representative value larger than 0, and the second largest quantized representative value. It is characterized in that it is an area including at least one of the above areas.

In order to achieve the above object, the present invention is an image processing method for performing error diffusion processing on multi-valued image data composed of a plurality of density components, and outputting the result of the error diffusion processing, Out of the plurality of density components, a first error diffusion means for performing error diffusion based on a density value of a first density component, a density value of the first density component and a density value of at least one other density component It is characterized by further comprising a determining step of determining which of the second error diffusion means to perform the error diffusion based on and the error diffusion means to be used according to a predetermined condition.

In order to achieve the above object, the present invention is an image processing method for applying error diffusion processing to multi-valued image data composed of a plurality of density components and outputting the result of the error diffusion processing, Of the plurality of density components, a first quantization step of performing quantization based on a first density component and outputting the quantization result as a first quantization result, and at least one other density component From a determination step of determining a threshold value based on a density value, a comparison step of comparing the threshold value determined by the determination step with the first concentration component, and outputting the comparison result, and a first quantization step. A second quantization step of outputting a second quantization result based on the output first quantization result and the comparison result output from the comparison step; and based on the second quantization result False for the first concentration component Characterized in that it comprises the error diffusion execution step of executing spreading processing.

In order to achieve the above object, the present invention is an image processing method for performing error diffusion processing on multi-valued image data composed of a plurality of density components and outputting the result of the error diffusion processing. Of the plurality of density components, a first quantization step of performing quantization based on a first density component and outputting the quantization result as a first quantization result, and at least one other density component A determination step of determining a threshold value based on a density value; quantization performed based on the threshold value determined by the determination step and the first density component; and outputting the quantization result as a second quantization result. 2 quantization step, a selection step of selecting which of the first quantization result and the second quantization result is to be used according to a predetermined condition, and a selection step performed by the selection step. Based on the quantized result Characterized in that it comprises the error diffusion execution step of executing the error diffusion processing.

In order to achieve the above object, the present invention performs error diffusion processing on multi-valued image data composed of a plurality of density components and outputs the result of the error diffusion processing.
A program executable by a computer, comprising: a first error diffusion step of performing error diffusion based on a density value of a first density component among the plurality of density components; and a density value of the first density component. Secondly, error diffusion is performed based on a density value of at least one density component of other density components.
Error diffusion step and the step of determining which of the first error diffusion step and the second error diffusion step is to be executed according to a predetermined condition.

In order to achieve the above object, the present invention performs error diffusion processing on multi-valued image data composed of a plurality of density components and outputs the result of the error diffusion processing.
A program executable by a computer, the first quantization step of performing quantization based on a first density component of the plurality of density components and outputting the quantization result as a first quantization result. And, among other concentration components,
A determination step of determining a threshold value based on the density value of at least one concentration component; a comparison step of comparing the threshold value determined by the determination step with the first concentration component and outputting the comparison result; A second quantization step that outputs a second quantization result based on the first quantization result output from the first quantization step and the comparison result output from the comparison step; Error diffusion executing step for executing the error diffusion process on the density component of the above-mentioned second quantization result.

In order to achieve the above object, the present invention performs error diffusion processing on multi-valued image data composed of a plurality of density components and outputs the result of the error diffusion processing.
A program executable by a computer, the first quantization step of performing quantization based on a first density component of the plurality of density components and outputting the quantization result as a first quantization result. A determination step of determining a threshold value based on the density value of at least one density component of the other density components, and quantization based on the threshold value determined by the determination step and the first density component,
The second quantizing result is output as the second quantizing result.
Of the first quantization result output from the first quantization step and the second quantization result output from the second quantization step according to a predetermined condition. Of the quantization result to be used, and an error diffusion executing step of executing an error diffusion process based on the quantization result selected by the selecting step.

Further, in order to achieve the above object, the present invention is characterized in that the program according to any one of claims 19 to 21 is stored.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing the schematic arrangement of an information processing system for forming an image processing apparatus according to the first embodiment of the present invention.

As shown in FIG. 1, an information processing system for configuring an image processing apparatus includes a host device 51 including a personal computer and an image output device 52 including an ink jet printer (IJRA). The host device 51 and the image output device 52 are connected to each other via the bidirectional interface 53. Then, the driver software 54 for performing image processing is loaded in the memory (not shown) of the host device 51.

Next, the hardware configurations of the host device 51 and the image output device 52 will be described with reference to FIG. FIG. 2 is a block diagram showing an outline of the hardware configuration of the host device 51 and the image output device 52 which form the information processing system of FIG.

As shown in FIG. 2, the host device 51 comprises a processing unit 1000 and peripheral devices connected thereto. The processing unit 1000 of the host device 51 is an MPU 10 that performs overall control of the host device according to a control program.
01 and a bus 100 for connecting system components to each other
2, a DRAM 1003 for temporarily storing programs and data executed by the MPU 1001, and a bridge 1004 for connecting the bus 1002 to the DRAM 1003 and the MPU 1001. The bus 1002 includes a graphic adapter 1005 and an HDD controller 10.
06, keyboard controller 1007, communication I / F1
008 is connected respectively.

The graphic adapter 1005 has a control function for displaying graphic information on a display device 2001 such as a CRT. The HDD controller 1006 is a HDD (hard disk device) 2002.
Controls the interface with the keyboard controller 1
Reference numeral 007 controls the interface with the keyboard 2003. The communication I / F 1008 is a parallel interface that controls communication with the image output device 52 according to the IEEE1284 standard.

The image output device 52 includes a recording head 301.
0, a carrier (CR) motor 3011 that drives a carrier that conveys the recording head 3010, a conveyance motor (LF motor) 3012 that conveys a sheet, and the like, and a controller 3003. The control unit 3003 has both a control program execution function and a peripheral device control function, and is an MCU that controls the entire image output device main body 52.
3001, a system bus 3013 for connecting each component inside the control unit 3003, and a recording head 3 for recording data
010, a gate array (GA) 3002 in which a supply mechanism for memory address decoding, a control pulse generation mechanism for the carrier motor 3011, and the like are housed.

Further, the control unit 3003 uses the MCU 3001.
Between a ROM 3004 that stores a control program executed by the computer, host print information, and the like, a DRAM 3005 that saves various types of data (image recording information, print data supplied to the print head 3010, and the like), and a host device 51 according to the IEEE1284 standard. A communication I / F 3006, which is a parallel interface that controls communication, and a gate array 3002
The head recording signal output from the recording head 3010
Driver 3007 for converting into an electric signal for driving
Have and.

Further, the control unit 3003 converts the carrier motor control pulse output from the gate array 3002 into an electric signal for actually driving the carrier (CR) motor 3011, and the MCU 3 and the MCU 3.
LF motor driver 3009 that converts the carry motor control pulse output from 001 into an electric signal that actually drives the carry motor (LF motor) 3012.

Next, a specific structure of the image output device 52 will be described with reference to FIG. FIG. 3 is a perspective view specifically showing the configuration of the image output device 52 of FIG.

The image output device 52, as shown in FIG.
It has a carriage HC. The carriage HC is engaged with the spiral groove 5004 of the lead screw 5005, and the lead screw 5005 rotates via the driving force transmission gears 5011 and 5009 in conjunction with the forward / reverse rotation of the drive motor 5013. As a result, the carriage HC is reciprocated in the directions of arrows a and b. On this carriage HC, an integrated ink jet cartridge IJC having a printhead IJH (corresponding to the printhead 3010 in FIG. 2) and an ink tank IT is mounted. Further, a paper pressing plate 5002 is provided, and the paper pressing plate 5002 is
The sheet P is placed on the platen 50 in the moving direction of the carriage HC.
Press against 00.

Further, the carriage HC is provided with a lever 5006 for detecting the home position. When the carriage HC is at the home position, the lever 5006 is detected by the photocouplers 5007 and 5008. The detection of the lever 5006 by the photocouplers 5007 and 5008 functions as home position detection means for detecting that the carriage HC is at the home position and switching the rotation direction of the drive motor 5013.

When the ink jet cartridge IJC is at the home position, the front surface of the recording head IJH has a cap member 502 supported by a member 5016.
Covered with 2. In addition, the inkjet cartridge IJ
The suction recovery of the recording head IJH of C is performed by the suction unit 5.
015 through the in-cap opening 5023. A cleaning blade 5017 that is movable in the front-rear direction is provided by the member 5019, and the cleaning blade 5017 and the member 5019 are supported by the main body support plate 5018. Further, a lever 5012 for starting suction for suction recovery is provided.
The lever 5012 moves along with the movement of the cam 5020 that engages with the carriage HC, and the driving force is transmitted from the drive motor 5013 to the cam 5020 via a known transmission means such as a clutch.

The capping, cleaning, and absorption recovery are configured so that when the carriage HC enters the home position side area, the desired processing can be performed at the corresponding positions by the action of the lead screw 5005. However, the configuration is not limited as long as it is a configuration capable of performing a desired operation at a known timing.

As described above, the ink cartridge IJC has a replaceable structure in which the ink tank IT and the print head IJH are integrated, but the ink tank IT and the print head IJH are separable from each other. Alternatively, only the ink tank IT may be replaceable when the ink is used up.

The recording head IJH has Y, M, C,
A color image can be recorded on the paper P using at least four inks of yellow (Y), magenta (M), cyan (C), and black (K) based on the multivalued density data of each K component.

Next, the software configuration of the information processing system will be described with reference to FIG. Figure 4
2 is a block diagram showing a software configuration used in the information processing system of FIG. 1. FIG.

In the host device 51, as shown in FIG. 4, in order to output the print data to the image output device 52, the three layers of application software, operating system, and driver software cooperate with each other. Perform image processing.

In the present embodiment, the parts that are individually dependent on the image output device 52 are designated by the device-specific drawing function 31-
, 31-n, and separates the program components that depend on the individual implementation of the image processing apparatus from the programs that can perform common processing, and separates the basic processing part of the driver software. The image output device 52 of FIG.

Here, the application software 11 is provided in the layer of application software, and the drawing processing interface 21 that receives a drawing command from the application software 11 and the generated image data are provided in the layer of the OS (operating system). A spooler 22 for delivering to an image output device 52 such as an inkjet printer is provided.

A device-specific drawing function 3 in which an expression format peculiar to the image output device is stored in the layer of the driver software.
, 1-, 31-2, ..., 31-n, and a color characteristic conversion unit 33 that receives line-segmented image information from the OS and performs conversion from a color system inside the driver to a device-specific color system. A halftone processing unit 34 that performs conversion into a quantization amount that represents the state of each pixel of the device, and a print command that outputs the halftoned image data to the spooler 22 by adding a command to the image output device 52. And a generation unit 35.

Image processing such as color conversion characteristics by the color characteristic conversion unit 33 and intermediate processing by the halftone processing unit 34 is applied to the line-divided image converted into the quantization amount, and further the print command generation unit. In 35, the data created by adding the data compression / command is passed to the image output device 52 through the spooler 22 prepared in the OS (operating system).

Next, the image processing in this embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing the procedure of image processing by the software configuration of the information processing system of FIG. Here, a case where the application software 11 outputs an image to the image output device 52 will be specifically described.

When the application software 11 outputs an image to the image output device 52, first, as shown in FIG. 5, the application software 11 sends a character, line segment, figure, bitmap, etc. through the drawing processing interface 21 of the OS. A drawing command is issued (step S1). When the drawing command forming the screen / paper surface is completed (step S2), the OS causes the device-specific drawing functions 31-1, 31-2, ..., 3 inside the driver software.
While calling 1-n, each drawing command is converted from the internal format of the OS into an expression format unique to the apparatus (one in which each drawing unit is divided into lines) (step S3), and then the screen / paper surface is divided into lines. The image information is transferred to the driver software (step S4).

Inside the driver software, the color characteristic conversion unit 33 corrects the color characteristic of the device, and
Conversion from the color system in the driver software to the color system unique to the device is performed (step S5), and further converted by the halftone processing unit 34 into a quantization amount representing the state of each pixel of the device (halftoning). Is performed (step S6). The conversion into the quantization amount here corresponds to the form of data processed by the image output device 52, and for example,
When the image output device 52 prints on the basis of binary data, the data is binarized, and the image output device 52 prints on the basis of multi-valued data (for printing with dark and light inks and printing with large and small inks). If so, it is a multi-valued data. The details of the halftone processing (halftoning) will be described later.

The print command generator 35 receives the quantized (binarized and multivalued) image data (step S7). The print command generation unit 35 processes the quantized image information according to the characteristics of the image output device by different methods. Further, the printer command generator 35 compresses data and adds a command header (step S8).

After that, the print command generator 35
The generated data is passed to the spooler 22 provided inside the OS (step S9), and data is output from the spooler 22 to the image output device 52 (step S10).

In the present embodiment, the control method described above can be realized by storing the program according to the flowchart of FIG. 5 in the storage device in the host device 51 and reading and executing the program. Becomes

As described above, since the basic processing portion of the driver software has a structure independent of the individual image output device 52, the driver software and the image output device 5
It becomes possible to flexibly change the sharing of data processing between the two, without impairing the configuration of the driver software.
This is advantageous in terms of software maintenance and management.

Next, the halftone processing unit 3 in the present embodiment.
The details of the error diffusion processing executed by No. 4 will be described. In the error diffusion processing described below, each pixel has a yellow (Y) component, a magenta (M) component, and a cyan (C) component.
Concentration data consisting of black component (K),
For each component, multi-valued image data composed of 8 bits (256 gradation expression) is used. In order to simplify the description, a case will be described in which the error diffusion process is performed using an error diffusion method that controls inks of two or more colors so that they do not overlap each other.

First, an error diffusion method for controlling inks of two or more colors so as not to overlap each other will be described. Here, the image data includes density components (Y, M, C,
It is assumed that K) is represented by multi-valued data of 8 bits (gradation value is 0 to 255) and the output is binary.

If the densities of the C and M components of the target pixel of the multi-valued color image are Ct and Mt, and the densities of the C and M components of the original image are C and M, then Ct = C + Cerr Mt = M + Merr Is expressed as Here, Cerr and Merr are the values obtained by error diffusion for the pixel of interest for each of the C component and the M component.

As shown in FIG. 16, regarding the image formation of C and M, the image formation control is performed in the following procedure according to the densities of the C and M components of the pixel of interest.

First, the threshold value Cthreshold used in the error diffusion of the C component is calculated based on the density value Mt of the M component. Then, the density value Ct of the C component is compared with the threshold value Cthreshold,
When the density value Ct is larger than the threshold value Cthreshold, C ink is output.

Next, the threshold value Mthreshold used in the error diffusion of the M component is calculated based on the density value Ct of the C component. Then, the density value Mt of the M component is compared with the threshold value Mthreshold,
When the density value Mt is larger than the threshold value Mthreshold, output is performed with M ink.

However, even in the above-mentioned method, similar to the problem of the conventional example, when the quantized gradation values of C and M increase, the processing tends to become more complicated. Specifically, one threshold value table is referred to when output is performed in binary, two threshold value tables are referred to when output is performed in three values, and n−1 number of values are used when output is performed in n value. Since the threshold value table is required, the number of tables to be prepared becomes larger for multi-valued processing having a larger number of gradations.

Further, since the density value is compared with the threshold value by the number of threshold value tables, it is necessary to refer to the threshold value table stored in the memory each time, and the processing speed is inevitably slowed down. Specifically, in the case of five-value quantization, four threshold tables are required, and the following processing is required.

Ct = C + Cerr Mt = M + Merr Cout = 0 if (Ct> Threshold_Table1 [Mt]) Cout = 1 if (Ct> Threshold_Table2 [Mt]) Cout = 2 if (Ct> Threshold_Table3 [Mt]) Cout = 3 if (Ct> Threshold_Table4 [Mt]) Cout = 4 Mout = 0 if (Mt> Threshold_Table1 [Ct]) Mout = 1 if (Mt> Threshold_Table2 [Ct]) Mout = 2 if (Mt> Threshold_Table3 [Ct]) Mout = 3 if (Mt> Threshold_Table4 [Ct]) Mout = 4 Therefore, the above method is used to improve the above problems. In this embodiment, the target of the error diffusion processing is multi-valued image data of C component and M component, and the case of multi-valued conversion into three or more values is handled.

Image formation control in this case will be described with reference to FIGS. 6 is a flowchart showing a procedure of image forming control in the information processing system of FIG. 1, FIG. 7 is a diagram showing threshold conditions and output examples used in the image forming control of FIG. 6, and FIG. 8 is a diagram showing image forming control of FIG. It is a figure which shows the example of an output image of a halftone part.

In the image forming control, as shown in FIG. 6, first in step S901, the total density values Ct and Mt are obtained from the input pixel density values C and M and the cumulative error values Cerr and Merr. Then, in step S902, the density components C and M are quantized. The quantization performed here may be based on the conventionally known monochromatic error diffusion method. In this embodiment, the error diffusion method for cyan is f
(C), the error diffusion method for magenta is described as g (M), but different error diffusion methods do not necessarily have to be applied to cyan and magenta, and the same method is used for simplicity. May be.

Next, in step S903, the total density value Mt is referred to by referring to the threshold table Table1 for magenta.
The threshold value Table1 [Mt] corresponding to is read, and the threshold value Table1 [Mt] corresponding to the total density value Mt is compared with the total density value Ct. Here, when the total density value Ct is larger than the threshold value Table1 [Mt], the quantized value is set to 1 in step S904 when the quantized value Cout obtained in step S902 is 0. In the present embodiment, for simplicity, the quantized value C obtained in step S902 is used.
Compare out with the numerical value 1, and set the larger value to new Cout
I am trying to. Then, the process proceeds to step S905. When the total density value Ct is not larger than the threshold value Table1 [Mt], the step S904 is skipped and the step S904 is performed.
Proceed to 905.

In step S905, the threshold table Tabl
Threshold value corresponding to the total concentration value Ct by referring to e2 Table2 [Ct]
Is read out and the threshold value corresponding to this total density value Ct
[Ct] is compared with the total density value Mt. Here, when the total density value Mt is larger than the threshold value Table2 [Ct], the quantized value is set to 1 in step S906 when the quantized value Mout obtained in step S902 is 0. In the present embodiment, for simplicity, the above step S
The quantized value Mout obtained in 902 is compared with the numerical value 1, and the larger value is set as a new Mout. Then, the process proceeds to step S907. Total concentration value Mt
If is not larger than the threshold value Table2 [Ct], the above step S906 is skipped and the process proceeds to step S907.

In step S907, the above step S9 is performed.
The error amount is calculated based on the output quantized values Cout and Mout determined from 01 to step S906, and the error is diffused to peripheral pixels. Then, this process ends.

In the above image forming control, the relationship between the input density value and the output value of cyan and magenta in the case of, for example, quaternarization is represented by the graph of FIG. 7A.
0), (C: 0, M: 1), C <6
The area of 4 and M <64 is steps S904 and S90.
This is the part where the process of 6 is performed. As an example of the threshold table Table1 for magenta used at this time, FIG.
There is a table represented by the graph of (b).

In this embodiment, Table 1 and Table 2 for magenta and cyan are used as the threshold table, but it is not always necessary to have independent tables.
The same table may be used for simplicity. In practice, if the same table is used, the possibility that the values of Cout and Mout will be the same under the condition of Ct = Mt increases, so a table with different contents for magenta and cyan may be used. Preference is given to using. This allows
The scattering effect of C and M is improved, and improvement in image quality can be expected. Even when the same table is used, the same effect can be expected if one of the comparisons in step S903 and step S905 is a comparison including an equal sign (≧).

Further, in this embodiment, only the threshold condition on the most highlight side is modulated based on the other color information. Therefore, in the present embodiment, the image quality is improved only for the pixels having quantized values of 0 and 1, and the error diffusion is performed independently for each color for the halftone portion.
This makes it possible to suppress the variation of the area factor in the halftone part for the following reason.

For example, FIG. 8A shows an example of the result on the printer output paper surface of each color independent error diffusion in the halftone part. In the figure, dots 801 filled with dots are cyan ink. Circles (dots) 802 filled with diagonal lines represent magenta ink dots. In FIG. 8B, the landing position shift occurs and
The result on the printer output paper surface in the case where the entire cyan ink dot group in (a) is shifted to the left with a width substantially equal to the ink diameter is shown. In the case of each color independent error diffusion that originally has no correlation between cyan and magenta, no large difference occurs in the area factor in the results on the printer output paper surface of either of FIGS. 8A and 8B.

As described above, even in the system in which the landing position shift occurs, the image quality of the highlight portion can be improved while reducing the adverse effect on the image. Furthermore, since the number of required threshold tables can be set to one while simplifying the process by adopting the threshold table, the size of the threshold table can be made compact.

The independent quantization processing for each color performed in step S902 is performed in steps S903 to S90.
If the processing speed is faster than the two-color simultaneous error diffusion processing performed in step 6, the processing speed is improved by the smaller number of two-color simultaneous error diffusion processing.

As described above, according to the present embodiment, even in the image processing mode having a larger number of gradations, high-speed processing can be performed with a simple structure, and an error that effectively acts on the dot landing position deviation can be obtained. It becomes possible to perform diffusion processing.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 9 to 12. FIG. 9 is a diagram showing a result example on the printer output paper surface of two-color simultaneous error diffusion in the dark portion, and FIG. 10 is a diagram showing a result example on the printer output paper surface of two-color simultaneous error diffusion in the halftone portion from dark, FIG. 11 is a flowchart showing a procedure of image forming control according to the second embodiment of the present invention, and FIG. 12 is a diagram showing a threshold condition used in the image forming control of FIG. 11 and an output example. Note that this embodiment has the same configuration as the first embodiment, and a description of that configuration is omitted.

In the first embodiment, the two-color simultaneous error diffusion is assigned only to the highlight portion. However, in the present embodiment, an application example of a portion having a higher density will be described.

In order to reduce the change of the area factor, it is necessary to consider not only the highlight portion but also the portion having the highest density.

For example, FIG. 9A shows an example of the result on the printer output paper surface of the two-color simultaneous error diffusion in the dark portion.
Consider a case where a blue region 1100 is formed on the paper surface by both cyan and magenta as shown in FIG. Here, circles (dots) 1101 filled with dots represent portions where no magenta ink is recorded, and circles (dots) 1102 filled with diagonal lines represent portions where cyan ink is not recorded. The output result of FIG. 9A is
The area 1100 on the paper surface is almost evenly filled with blue, and the portions 1101 and 1102 on which one of the cyan ink and the magenta ink is not printed are evenly distributed, so that it can be said that the image is a good image. On the other hand, FIG.
The output result on the printer output sheet shown in FIG.
In the output result in (a), the entire subgroup on which no magenta ink is printed is shifted to the left by a width substantially equal to the ink diameter. A portion 1102 where cyan dots are not recorded yet, although there is a slight difference in the arrangement on the paper surface.
Since the areas 1101 where the magenta dots are not printed do not overlap with each other, the area factor, which is the ink coverage on the paper surface, does not change.

Next, 2 in the halftone part from dark
FIG. 10 shows an example of the result of simultaneous color error diffusion on the printer output paper.
It shows in (a). In this example, a blue area 1200 is formed on the paper surface with both cyan and magenta. Here, dots (dots) 12 filled with dots
01 represents a portion where no magenta ink is recorded,
Circles (dots) 1202 filled with diagonal lines represent portions where cyan ink is not recorded. In the present example, the portion 120 in which the paper surface is almost evenly filled with blue and one of the cyan ink and the magenta ink is not recorded is shown.
Since 1, 1202 are evenly scattered, it can be said that it is a good image. On the other hand, in the example of the output result shown in FIG. 10B, the entire subgroup on which magenta ink is not printed is shifted to the left with a width substantially the same as the ink diameter with respect to the output result of FIG. 10A. Is. In the example shown in FIG. 9B, unlike the transition from FIG. 9A to FIG. 9B,
A portion 1202 where cyan dots are not printed and a portion 1201 where magenta dots are not printed overlap with each other with a high probability. In such a case, the overlapping portion is not recorded with either cyan or magenta ink, and the area factor, which is the coverage of the ink on the paper surface, changes greatly.

Therefore, the present embodiment enables high-speed processing with a simple configuration, as in the first embodiment, and
The error diffusion processing is performed so as to reduce the variation of the area factor in the dark portion and the variation of the halftone area factor from dark.

Next, the image forming control in this embodiment will be described with reference to FIG.

In the image forming control of this embodiment, as shown in FIG. 11, first, in step S1301, the total density values Ct and Mt are obtained from the input pixel density values C and M and the accumulated error values Cerr and Merr. Then, step S1302
At, quantization is performed based on the total density values Ct and Mt. The quantization performed here may be based on the conventionally known single-color error diffusion method as in the first embodiment. The cyan error diffusion method is f (Ct), and the magenta error is The diffusion method is represented by g (Mt). Also,
It is not necessary to apply different error diffusion methods to cyan and magenta, and the same method may be used for simplicity.

Next, in step S1303, the threshold Ta corresponding to the total density value Mt is read from the threshold table Table1.
ble1 [Mt] is read, the threshold value Table1 [Mt] corresponding to this total density value Mt is compared with the total density value Ct, and if the total density value Ct is smaller than the threshold value Table1 [Mt], step S
In 1304, the quantized value Cout obtained in step S1302 is “n−” which is the maximum value of the n-valued quantization.
If it is “1”, the quantization value is set to “n−2”, which is the second largest value. In the present embodiment, for the sake of simplicity, the quantization value Cou obtained in step S1302 above is set.
t is compared with the numerical value n-2, and the smaller value is used as a new Co value.
I'm trying to ut. Then, in step S1305
Proceed to. On the other hand, if the total density value Ct is not smaller than the threshold value Table1 [Mt] in step S1303, step S1304 is skipped and step S130 is performed.
Go to 5.

In step S1305, the threshold table Ta
The threshold value Table2 [Ct] corresponding to the total density value Ct is read from ble2, and the threshold value Table2 [Ct] corresponding to this total density value Ct.
And the total density value Mt are compared, and the total density value Mt is the threshold Tabl.
If it is smaller than e2 [Ct], in step S1306, the quantized value Mou obtained in step S1302 is calculated.
When t is "n-1" which is the maximum value of the n-value quantization, the quantization value is set to "n-2" which is the second largest value. In the present embodiment, for simplicity, the quantized value Mout obtained in step S1302 is compared with the numerical value n−2, and the smaller value is set as the new Mout. Then, the process proceeds to step S1307. On the other hand, in step S1305, the total density value Mt is equal to the threshold value Tab.
If it is not smaller than le2 [Ct], then step S13 is performed.
06 is skipped and the process proceeds to step S1307.

In step S1307, the above step S
An error amount is calculated based on the output quantized values Cout and Mout determined from 1302 to step S1306, and the error is diffused to the surroundings. Then, this process ends.

In the above image forming control, the relationship between the input density value and the output value of cyan and magenta in the case of, for example, quaternarization is represented by the graph of FIG.
2), of the two areas (C: 2, M: 3), C> 1
The area of 92 and M> 102 is the portion subjected to the processing of steps S1304 and S1306. In addition, here, as the threshold table Table1, for example, FIG.
The table shown in the graph is used.

In this embodiment, Table 1 and Table 2 for magenta and cyan are used as the threshold table, but it is not always necessary to have independent tables.
The same table may be used for simplicity. In practice, if the same table is used, the possibility that the values of Cout and Mout will be the same under the condition of Ct = Mt increases, so a table with different contents for magenta and cyan may be used. Preference is given to using. This allows
The scattering effect of C and M is improved, and improvement in image quality can be expected. Even when the same table is used, the same effect can be expected if one of the comparisons in step S1303 and step S1305 is a comparison including an equal sign (≧).

As described above, according to the present embodiment, high-speed processing is possible with a simple structure, the variation of the area factor of the dark portion is reduced, and the variation of the area factor of halftones from the dark is reduced. be able to.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. Figure 1
FIG. 3 is a diagram showing a threshold value condition and an output example used for image formation control according to the second embodiment of the present invention. Note that this embodiment has the same configuration as the first embodiment, and a description of that configuration is omitted.

In the present embodiment, the two-color simultaneous error diffusion method focused on the highlight portion described in the first embodiment and the two-color simultaneous error diffusion method focused on the dark portion described in the second embodiment. Image forming control is performed by combining and. The actual processing flow when performing this image formation control proceeds from immediately before step S907 in the flowchart of FIG. 6 to step S1303 in the flowchart of FIG. 11, and again immediately before step S1307 to step S907 of the flowchart in FIG. It becomes a form to go. The processing of each step is based on the first and second embodiments.

FIG. 13A shows the relationship between the input density value and the output value of cyan and magenta in the case of, for example, quaternarization in the image forming control of the present embodiment. As the threshold table Table1, for example, a table shown in the graph of FIG. 13B is used. That is, in this embodiment, two threshold value tables are used for at least one color in order to suppress the variation in the area factor of the highlight portion and the dark portion.

As described above, according to the present embodiment, the two-color simultaneous error diffusion is mainly applied to the highlight portion and the dark portion to enable high-speed processing with a simple structure and to achieve the entire density region. A well-balanced image can be formed.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIGS. 14 and 15. FIG. 14 is a flowchart showing the procedure of image forming control according to the fourth embodiment of the present invention, and FIG. 15 is a flowchart showing the procedure of switching the error diffusion processing including the error diffusion method in the image forming control of FIG.

In each of the first, second and third embodiments described above, the final quantized value is determined based on the comparison between the quantized result and the threshold value, but it is not always judged from both results. No need. Therefore, in the present embodiment, which error diffusion method is used is determined according to the total density value.

Specifically, the image forming control of this embodiment is executed according to the flowchart of FIG. The program code for this flowchart is as follows. Here, step numbers in FIG. 14 corresponding to each code are added to the right side.

Ct = C + Cerr (S1601) Mt = M + Merr (S1601) if (Ct> threshold1) (S1602) Cout = f (Ct) (S1603) else if (Ct> Threshold_table [Mt] (S1604) Cout = 1 (S1606) else Cout = 0 (S1605) Duffuse C Error (S1607) if (Mt> threshold2) (S1608) Mout = g (Mt) (S1609) else if (Mt> Threshold_table [Ct] (S1610) Mout = 1 (S1612) else Mout = 0 (S1611) Duffuse M Error (S1613) Further, which method is to be used may be determined according to the input density value as follows.

[0109] Further speaking, it is possible to expect the same effect by switching the error diffusion processing method for each pixel, including the error diffusion portion, without being limited to selectively using only the quantization portion, Further, it is possible to employ an error diffusion method suitable for each error diffusion method.

The processing procedure in this case is shown in the flowchart of FIG. The program code for this flowchart is as follows. Here, step numbers in FIG. 15 corresponding to each code are added to the right side.

Ct = C + Cerr (S1701) Mt = M + Merr (S1701) if (Ct <threshold1) (S1702) Cout = f (Ct) (S1703) Diffuse C Error1 (S1705) else if (Ct> Threshold_table [ Mt] (S1704) Cout = 1 (S1706) else Cout = 0 (S1707) Diffuse C Error2 (S1708) if (Mt <threshold2) (S1709) Mout = g (Mt) (S1710) Diffuse M Error1 (S1714) else if (Mt> Threshold_table [Ct] (S1711) Mout = 1 (S1713) else Mout = 0 (S1712) Diffuse M Error2 (S1715) where Diffuse C Error1 is the error diffusion means corresponding to the quantized Cout = f (Ct). Diffuse C Error2 is an error diffusing means corresponding to two-color simultaneous error diffusion, and similarly, Diffuse M Error1 is an error diffusing means corresponding to quantization Mout = g (Mt), and Diffuse M Error2. Is two-color simultaneous error expansion The corresponding error diffusion means.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described.

In the first embodiment, a simpler error diffusion method has been described, but in the present embodiment, an example in which the first embodiment is applied to the conventional example will be described.

[0114] As described above, the processing can be extremely simplified.

The above f (Ct) and g (Mt) are the same as those in the first embodiment. Similarly, the second to third embodiments can also be applied to the conventional example.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described.

In each of the first to fifth embodiments described above, only two colors, cyan and magenta, are handled, but in the present embodiment,
Handle more density values. Specifically, cyan large droplet dark ink, large droplet light ink, small droplet dark ink, small droplet light ink, and magenta large droplet dark ink, large droplet light ink, and small droplet dark ink. Multi-valued error diffusion is performed to reduce the overlap of ink and small droplet light ink dots.

Hereinafter, Cl is a cyan large droplet dark ink, Cs is a cyan small droplet dark ink, cl is a cyan large droplet light ink, cs is a cyan small droplet light ink, and Ml is a magenta large ink. Droplet dark ink, Ms is magenta small drop dark ink, ml is magenta large drop light ink, ms is magenta small drop light ink, and the respective density values are the cumulative error of each density value. The word err will be added to the end of the word.

In this embodiment,     Clt = Cl + Clerr     Cst = Cs + Cserr     clt = cl + clerr     cst = cs + cserr     Mlt = Ml + Mlerr     Mst = Ms + Mserr     mlt = ml + mlerr     mst = ms + mserr     Clout = d (Clt)     Csout = e (Cst)     clout = f (clt)     csout = g (cst)     Mlout = h (Mlt)     Msout = i (Mst)     mlout = j (mlt)     msout = k (mst)     if (Clt> Threshold_Table [Cst + clt + cst + Mlt + Mst + mlt + mst])         Clout = max (1, Clout)     if (Cst> Threshold_Table [Clt + clt + cst + Mlt + Mst + mlt + mst])         Csout = max (1, Csout)     if (clt> Threshold_Table [Clt + Cst + cst + Mlt + Mst + mlt + mst])         clout = max (1, clout)     if (cst> Threshold_Table [Clt + Cst + clt + Mlt + Mst + mlt + mst])         clout = max (1, clout)     if (Mlt> Threshold_Table [Clt + Cst + clt + cst + Mst + mlt + mst])         Mlout = max (1, Mlout)     if (Mst> Threshold_Table [Clt + Cst + clt + cst + Mlt + mlt + mst])         Msout = max (1, Msout)     if (mlt> Threshold_Table [Clt + Cst + clt + cst + Mlt + Mst + mst])         mlout = max (1, mlout)     if (mst> Threshold_Table [Clt + Cst + clt + cst + Mlt + Mst + mlt])         msout = max (1, msout) Take the procedure.

By the method described above, it is possible to reduce the overlap between ink groups having different dye concentrations of a plurality of colors and different ejection amounts. Furthermore, it becomes possible to perform quantization at a higher number of gradations at high speed.

As described above, in the examples described in each of the first to sixth embodiments, the ink colors are cyan and magenta, the dye density is two levels, dark and light, and the ejection amount is large and small. Although there are two levels, the effect of the present invention is not particularly limited to the above case, and a larger number of colors, a larger number of quantization gradations,
It goes without saying that the same effect can be obtained even in the case of the number of gradations of the dye concentration and the number of gradations of the ejection amount.

In each of the above-described embodiments, the liquid droplets ejected from the recording head have been described as ink, and the liquid contained in the ink tank has been described as ink. However, the content is limited to ink. It is not something that will be done. For example, an ink tank may contain a treatment liquid such as a treatment liquid ejected onto a recording medium in order to improve the fixability and water resistance of a recorded image or to improve the image quality.

Further, in each of the embodiments, particularly in the ink jet recording system, means for generating thermal energy as energy used for ejecting ink is provided (for example, an electrothermal converter or laser light). By using a method in which the state of the ink is changed by thermal energy, it is possible to achieve high density and high definition recording.

Regarding its typical structure and principle, see, for example, US Pat. Nos. 4,723,129 and 4740.
What is done using the basic principles disclosed in 796 is preferred. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, liquid (ink)
By applying at least one drive signal to the electrothermal transducer arranged corresponding to the sheet or liquid path in which is stored, which corresponds to the recorded information and gives a rapid temperature rise exceeding nucleate boiling. Since the electrothermal converter is caused to generate heat energy to cause film boiling on the heat-acting surface of the recording head, as a result, bubbles in the liquid (ink) corresponding to the drive signal in a one-to-one relationship can be formed. It is valid. The liquid (ink) is ejected through the ejection openings by the growth and contraction of the bubbles to form at least one droplet. More preferably, when the drive signal has a pulse shape, the growth and contraction of the bubbles are immediately and appropriately performed, so that the ejection of the liquid (ink) with excellent responsiveness is achieved.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications, The present invention also includes configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose configurations in which the heat-acting surface is arranged in a bending region. In addition, for multiple electrothermal converters,
Japanese Unexamined Patent Publication No. 59-123670, which discloses a structure in which a common slot is used as a discharge portion of an electrothermal converter, and Japanese Patent Laid-Open No. 59-63, which discloses a structure in which an opening for absorbing a pressure wave of thermal energy is associated with the discharge portion. A configuration based on Japanese Patent No. 138461 may be adopted.

Further, as a full line type recording head having a length corresponding to the width of the maximum recording medium which can be recorded by the recording device, a combination of a plurality of recording heads as disclosed in the above-mentioned specification is used. Either the structure that satisfies the length or the structure as one recording head integrally formed may be used.

In addition to the recording head of the cartridge type in which the ink tank is integrally provided in the recording head itself described in the above-mentioned embodiment, the recording head is electrically attached to the apparatus main body by being attached to the apparatus main body. A replaceable chip-type recording head that enables various connections and supply of ink from the apparatus main body may be used.

Further, it is preferable to add recovery means for the recording head, preliminary means, etc. to the structure of the recording apparatus described above, because the recording operation can be made more stable. Specific examples thereof include capping means for the recording head, cleaning means, pressurizing or sucking means, electrothermal converters or heating elements other than these, or preheating means by a combination thereof. Further, provision of a preliminary ejection mode for performing ejection different from recording is also effective for performing stable recording.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but the recording head may be integrally formed or a combination of plural recording heads may be used. The device may include at least one of full-color by color mixing or color mixing.

Further, in each of the above-described embodiments, the explanation is made on the assumption that the ink is a liquid. However, even if the ink is solidified at room temperature or lower, one that is softened or liquefied at room temperature is used. Or, in the inkjet method, it is common to adjust the temperature of the ink itself within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that the viscosity of the ink is in a stable ejection range. Any ink can be used as long as the ink is in a liquid state when a recording signal is applied.

In addition, in order to positively prevent the temperature rise due to the thermal energy from being used as the energy for changing the state of the ink from the solid state to the liquid state,
Alternatively, in order to prevent the evaporation of the ink, an ink that solidifies in a standing state and liquefies by heating may be used. In any case, by applying heat energy such as ink that is liquefied by applying heat energy according to the recording signal and liquid ink is ejected, or that starts to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In such a case, the ink in a state of being held as a liquid or a solid in the recesses or through holes of the porous sheet as described in JP-A-54-56847 or JP-A-60-71260. Alternatively, it may be configured to face the electrothermal converter. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as the form of the image processing apparatus according to the present invention, in addition to one provided integrally or separately as an image output terminal of information processing equipment such as a computer, a copying apparatus combined with a reader or the like, and It may take the form of a facsimile machine having a transmission / reception function.

Even if the present invention is applied to a system composed of a plurality of devices (for example, host computer, interface device, reader, printer, etc.), a device composed of one device (for example, a copying machine, a facsimile device) Etc.)

Further, an object of the present invention is to supply a storage medium (or recording medium) recording a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply a computer of the system or apparatus ( Alternatively, by the CPU or MPU) reading and executing the program code stored in the storage medium,
It goes without saying that it will be achieved. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.
Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also based on the instruction of the program code,
An operating system (OS) running on the computer does some or all of the actual processing,
It goes without saying that the processing includes the case where the functions of the above-described embodiments are realized.

Further, after the program code read from the storage medium is written in the memory provided in the function expansion card inserted into the computer or the function expansion unit connected to the computer, based on the instruction of the program code, , The CPU provided in the function expansion card or the function expansion unit performs some or all of the actual processing,
It goes without saying that the case where the processing realizes the functions of the above-described embodiments is also included.

[0137]

As described above, according to the present invention,
Even in the image processing mode having a larger number of gradations, it is possible to perform high-speed processing with a simple configuration, and it is possible to perform error diffusion processing that effectively acts on dot landing position deviation.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an information processing system for configuring an image processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an outline of a hardware configuration of a host device 51 and an image output device 52 which form the information processing system of FIG.

3 is a perspective view specifically showing a configuration of an image output device 52 of FIG.

4 is a block diagram showing a software configuration used in the information processing system of FIG. 1. FIG.

5 is a flowchart showing the procedure of image processing by the software configuration of the information processing system of FIG.

6 is a flowchart showing a procedure of image formation control in the information processing system of FIG.

7 is a diagram showing a threshold value condition used for the image formation control of FIG. 6 and an output example.

FIG. 8 is a diagram showing an example of an output image of a halftone portion by the image formation control of FIG.

FIG. 9 is a diagram showing an example of a result of simultaneous error diffusion of two colors in a dark portion on a paper output from a printer.

FIG. 10 is a diagram showing an example of a result of simultaneous error diffusion of two colors in a halftone portion from dark on a printer output paper surface.

FIG. 11 is a flowchart showing a procedure of image formation control according to the second embodiment of the present invention.

12 is a diagram showing a threshold value condition and an output example used for the image formation control of FIG.

FIG. 13 is a diagram showing a threshold value condition and an output example used for image formation control according to the second embodiment of the present invention.

FIG. 14 is a flowchart showing the procedure of image forming control according to the fourth embodiment of the present invention.

FIG. 15 is a flowchart showing a procedure for switching error diffusion processing including an error diffusion method in the image forming control of FIG.

FIG. 16 is a diagram showing image forming control according to a conventional inkjet method.

FIG. 17 is a diagram showing an output image of a highlight portion for explaining a conventional problem to be solved.

FIG. 18 is a diagram showing an output image of a halftone portion for explaining a conventional problem to be solved.

[Explanation of symbols]

11 Application software 21 Drawing processing interface 22 Spooler 31-1, 31-2, ..., 31-n Device-specific drawing function 33 color characteristics converter 34 Halftone Processing Section (Half Toning Section) 35 Print command generator 51 Host device 52 image output device 53 bidirectional interface 54 driver software 1000 processing unit 1001 MPU 1005 graphic adapter 1006 HDD controller 1007 Keyboard controller 1008 Communication I / F 2001 display device 2002 HDD 2003 keyboard

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G06T 5/00 200 B41J 3/00 A 5C079 H04N 1/46 3/04 103X 1/60 101Z (72) Invention Kentaro Yano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F-term (reference) 2C056 EA01 EA04 EA11 ED01 ED05 EE18 2C057 AF05 AF39 AF91 AM15 CA01 CA05 2C262 AA02 BB02 AC17 AB22 BB07 AC17 AB22 BB02 AC19 5B057 AA11 CA01 CA08 CA12 CA16 CB01 CB08 CB12 CB16 CC01 CE13 CE16 CH07 CH08 5C077 LL19 MP08 NN11 PP33 PQ08 PQ12 PQ20 PQ23 RR08 TT02 TT05 5C079 HB03 LA31 LC09 MA04 MA11 NA11 PA03

Claims (24)

[Claims] 1. An image processing apparatus for performing error diffusion processing on multi-valued image data composed of a plurality of density components and outputting the result of the error diffusion processing, wherein the first density of the plurality of density components is used. A first error diffusion means for performing error diffusion based on the density value of the component; and a first error diffusion means for performing error diffusion based on the density value of the first density component and the density value of at least one of the other density components. Error diffusion means, and the first error diffusion means and the second error diffusion means according to a predetermined condition.
And an deciding unit for deciding which error diffusing unit to use. 2. The predetermined condition is that, when the density value of the first density component is in a predetermined region, the probability of using the first error diffusion means is the average in the predetermined region. The image processing apparatus according to claim 1, wherein the condition is such that the probability is higher than the probability of using the second error diffusion means. 3. The predetermined region is a region in which the density value of the first density component is less than or equal to the minimum quantized representative value greater than 0, and a region in which the density value is greater than or equal to the second quantized representative value. The image processing apparatus according to claim 2, wherein the image processing apparatus is an area included in at least one of the areas. 4. The predetermined region is a region in which the density value of the first density component is equal to or smaller than a minimum value of a quantized representative value larger than 0, and a region in which the density value is equal to or larger than a second largest quantized representative value. The image processing apparatus according to claim 2, wherein the image processing apparatus is an area including at least one of the areas. 5. An image processing apparatus which performs error diffusion processing on multi-valued image data composed of a plurality of density components and outputs a result of the error diffusion processing, wherein a first density of the plurality of density components is output. Quantization is performed based on the component, and the first quantization means that outputs the quantization result as the first quantization result, and the threshold value is determined based on the density value of at least one density component among other density components. Determining means, comparing means for comparing the threshold value determined by the determining means with the first concentration component, and outputting the comparison result, and the first quantizing means for outputting the first density component. Second quantizing means for outputting a second quantizing result based on the quantizing result and the comparing result outputted from the comparing means; and the second quantizing result for the first density component. Error when performing error diffusion processing based on The image processing apparatus characterized by comprising a diffusion execution means. 6. An image processing apparatus for performing error diffusion processing on multi-valued image data composed of a plurality of density components and outputting a result of the error diffusion processing, wherein a first density of the plurality of density components is used. Quantization is performed based on the component, and the threshold value is determined based on the first quantization means that outputs the quantization result as the first quantization result and the density value of at least one density component of the other density components. A deciding means, a second quantizing means for performing quantization based on the threshold value decided by the deciding means and the first density component, and outputting the quantized result as a second quantized result; Which of the first quantization result output from the first quantization means and the second quantization result output from the second quantization means according to the condition The selection means to select whether to use, The image processing apparatus characterized by comprising error diffusion execution means for executing the error diffusion processing based on the selected quantization result by the selecting means. 7. The predetermined condition is that, when the density value of the first density component is in a predetermined region, the probability of using the first quantization result is the average in the predetermined region. 7. The image processing apparatus according to claim 6, wherein the condition is that the probability is higher than the probability of using the second quantization result. 8. The predetermined area is an area in which the density value of the first density component is equal to or smaller than a minimum value of a quantized representative value larger than 0, and an area in which the density value is equal to or larger than a second largest quantized representative value. The image processing apparatus according to claim 7, wherein the image processing apparatus is an area included in at least one of the areas. 9. The predetermined region is a region in which the density value of the first density component is equal to or smaller than a minimum value of a quantized representative value larger than 0, and a region in which the density value is equal to or larger than a second largest quantized representative value. The image processing apparatus according to claim 7, wherein the image processing apparatus is an area including at least one of the areas. 10. An image processing method for performing error diffusion processing on multi-valued image data composed of a plurality of density components and outputting the result of the error diffusion processing, wherein the first density of the plurality of density components is used. First error diffusion means for performing error diffusion based on the density value of the component;
Of the second error diffusion means for performing error diffusion based on the density value of the density component and the density value of at least one other density component, which is determined according to a predetermined condition. An image processing method comprising steps. 11. The predetermined condition is that, when the density value of the first density component is in a predetermined region, the probability of using the first error diffusion means is the average in the predetermined region. 11. The image processing method according to claim 10, wherein the condition is that the probability is higher than the probability of using the second error diffusion means. 12. The predetermined region is a region in which the density value of the first density component is equal to or smaller than a minimum value of a quantized representative value larger than 0, and a region in which the density value is equal to or larger than a second largest quantized representative value. The image processing method according to claim 11, wherein the area is included in at least one of the areas. 13. The predetermined region is a region where the density value of the first density component is equal to or smaller than a minimum value of a quantized representative value larger than 0, and a region which is equal to or larger than a second largest quantized representative value. The image processing method according to claim 11, which is an area including at least one of the above. 14. An image processing method for performing error diffusion processing on multi-valued image data composed of a plurality of density components and outputting a result of the error diffusion processing, wherein a first density of the plurality of density components is used. A first quantization step of performing quantization on the basis of a component and outputting the quantization result as a first quantization result; and a determination step of determining a threshold value based on the concentration value of at least one other concentration component, A comparison step of comparing the threshold value determined by the determination step with the first density component and outputting the comparison result; and the first quantization result output from the first quantization step and the A second quantization step of outputting a second quantization result based on the comparison result output from the comparison step; and an error diffusion process for the first density component based on the second quantization result. Error diffusion execution process Image processing method, characterized in that it comprises a. 15. An image processing method for performing error diffusion processing on multi-valued image data composed of a plurality of density components, and outputting the result of the error diffusion processing, wherein the first density of the plurality of density components is used. A first quantization step of performing quantization on the basis of a component and outputting the quantization result as a first quantization result; and a determination step of determining a threshold value based on the concentration value of at least one other concentration component, A second quantization step of performing quantization on the basis of the threshold value determined by the determination step and the first density component, and outputting the quantization result as a second quantization result; A selection step of selecting which of the first and second quantization results to use, and performing error diffusion processing based on the quantization result selected by the selection step. Error diffusion An image processing method characterized by comprising a degree. 16. The predetermined condition is that, when the density value of the first density component is in a predetermined region, the probability of using the first quantization result is the average in the predetermined region. 16. The image processing method according to claim 15, wherein the condition is that the probability is higher than the probability of using the second quantization result. 17. The predetermined region is a region where a density value of the first density component is equal to or smaller than a minimum value of a quantized representative value larger than 0, and a region which is equal to or larger than a second largest quantized representative value. The image processing method according to claim 16, wherein the area is included in at least one of the areas. 18. The predetermined region is a region in which the density value of the first density component is equal to or smaller than a minimum value of a quantized representative value larger than 0, and a region in which the density value is equal to or larger than a second largest quantized representative value. The image processing method according to claim 16, wherein the image processing area is an area including at least one of the areas. 19. A computer-executable program for performing error diffusion processing on multi-valued image data composed of a plurality of density components and outputting the result of the error diffusion processing. A first error diffusion step of performing error diffusion based on the density value of the first density component; a density value of the first density component and a density value of at least one of the other density components; A second error diffusion step for performing error diffusion based on a predetermined error condition; and a determination step for determining which of the first error diffusion step and the second error diffusion step is to be executed according to a predetermined condition. A program having: 20. A computer-executable program for performing error diffusion processing on multi-valued image data composed of a plurality of density components, and outputting the result of the error diffusion processing. Of these, the first quantization step of performing quantization based on the first density component and outputting the quantization result as the first quantization result, and the density of at least one density component of other density components A determination step of determining a threshold value based on a value; a comparison step of comparing the threshold value determined by the determination step with the first density component and outputting the comparison result; and an output from the first quantization step. A second quantization step of outputting a second quantization result based on the first quantization result obtained and the comparison result outputted from the comparison step; Min to a program and having an error diffusion execution step of executing the error diffusion processing based on the second quantization result. 21. A computer-executable program for performing error diffusion processing on multi-valued image data composed of a plurality of density components and outputting the result of the error diffusion processing. A first quantization step of performing quantization based on the first density component and outputting the quantization result as the first quantization result; and a density value of at least one density component of the other density components. A determination step of determining a threshold value based on the above, and a second quantization step of performing quantization on the basis of the threshold value determined by the determination step and the first density component, and outputting the quantization result as a second quantization result. A quantization step, and the first quantization result output from the first quantization step and the second quantization output from the second quantization step according to a predetermined condition. A program having a selection step of selecting which quantization result to use, and an error diffusion execution step of executing an error diffusion process based on the quantization result selected by the selection step. . 22. A computer-readable storage medium having the program according to claim 19 stored therein. 23. A computer-readable storage medium storing the program according to claim 20. 24. A computer-readable storage medium storing the program according to claim 21.