KR930004061B1 - Ink-jet printer - Google Patents

Abstract

No content.

Description

Inkjet Printer

1 is a diagram showing the relationship between the r value and the shape change of the gradation characteristic curve.

2 is a correlation diagram of r _n and H _n .

3 is a view for explaining the principle of matching individual density characteristic curves with reference density characteristic curves of a color film original image.

4 is a diagram showing a gradation characteristic curve set for a non-standard document.

5 is a block diagram of the ink jet printer of the first embodiment of the present invention.

6 is a block diagram of the ink jet printer of the second embodiment of the present invention.

(Industrial use)

An ink jet printer capable of converting an image information signal obtained from an original image of the present invention by a novel gradation adjustment method to form a recording image having excellent gradation reproducibility.

More specifically, the present invention includes all kinds of target images to be copied on recording paper, such as various original images (continuous gradation images such as monochromatic or color photographs, and video images obtained from television or computer image signals). The image information signal obtained from the same) will be converted and processed according to the gradation adjustment mechanism using a new gradation conversion formula. It relates to an ink jet printer capable of forming.

(Prior Art)

When the image is reproduced on the recording sheet using an image forming apparatus such as a copying machine from an original image having a continuous gradation as shown in the photograph, the use of photosensitive paper as the recording sheet is applied to the original by analytical processing (exposure) of the original. An image having a corresponding continuous gradation is formed (silver leaf photograph recording).

On the other hand, in an ink jet printer apparatus for recording an image on plain paper rather than photosensitive paper, image formation cannot be performed by analytical processing, and density gradation (gradation) is difficult to reproduce, especially in the case of duplication of color images. In addition to the aforementioned density gradation, the adjustment of color tone (color balance) is not easy.

For this reason, efforts have been made to improve the reproducibility of gradation and color tone in printer apparatuses. Formation of a recording image in an ink jet printer is similar to the method of changing from continuous gradation to halftone gradation of a photographic panel in printing, and an image obtained by photoscanning of an original image having a continuous gradation such as a photograph The information signal is processed and an image formed from the distribution of pixels having gradation or color tone corresponding to the original image is formed on the recording paper by the signal.

However, in the current printer apparatus, the gradation adjustment method for processing the image information signal obtained from the original image for the reproduction of the gradation is unscientific, and therefore, satisfactory gradation reproducibility cannot be obtained.

As is well known, the density gradation of a recorded image depends on the density display method of the pixel. In the case of an ink jet printer, a method of displaying the density gradation of a pixel, which is a method of changing the coverage of a pixel by the size of a dot, and a method of changing the coverage of a pixel by the number of arrangement of dots of the same size ( Density modulation method). However, when an original image is reproduced by an ink jet printer, the coating of dots of pixels of the recording image corresponding to the density value of a predetermined sample point of the original image, i.e., the density gradation value of the pixel (hereinafter referred to as pixel) There is no scientific review of what should be done in terms of density processing, and how to obtain such pixel concentration values.

That is, no scientific correlation has been developed as to which pixel concentration values should be correlated with the density values of predetermined sample points of the original image to the pixels of the recording image corresponding to the sample points. There is no choice but to rely on the device manufacturer's decision on the basis of experience, feeling, or a fixed number of fixed conditions.

Therefore, in case of non-standard (e.g., overly bright originals, overly dark originals under exposure), or other color film originals, the desired recording image is excellent in gradation and color tone. Is difficult to get. Therefore, not only originals having standard image quality but also non-standard originals can be obtained with the desired image quality, and the quality of the originals can be arbitrarily changed or corrected (gradation or color tone). It was not possible to develop an ink jet printer with flexibility.

This means that the conventional ink jet printer could not scientifically correspond to the pixel concentration value with respect to the concentration value of a predetermined sample point of the original image.

(Problems Solved and Invented)

The above-mentioned problem in the conventional printer apparatus is caused by the formation of the recording image by the distribution of the final pixel from the original image such as the continuous gradation image, and also plays an important role in its first step. It is a method of thinking about the process of gray-scale conversion of the image.

In other words, when converting a density value of a predetermined sample point of an original image into a pixel concentration value of a pixel of a corresponding recording image, a conventional method of thinking about gray scale conversion is not performed based on a scientifically rational gray scale conversion means. It must be said that it depends on experience and feeling.

In view of such a situation, the present inventor has made intensive studies with the basic recognition that a rational image gradation conversion technique must be established for the ultimate rationalization of the image forming process and the formation of recording images having excellent quality. .

(Means to solve the task)

In the following, the present invention will be described in brief. The present invention provides an ink for processing an image information signal obtained from an original image with a gradation adjustment mechanism and forming a recording image corresponding to the original image on a recording sheet based on the processing signal. In a jet printer, the above-described gradation adjustment mechanism has a basic density value x of an arbitrary sample point in an original image based on an image information signal obtained from an original image (the density value and the same image at that sample point). The difference from the density value in the brightest part H of the image) is converted into a pixel concentration value y at a position corresponding to the electrosample point of the recording image to be formed by the following relational expression (1). The present invention relates to an ink jet printer.

<Relationship>

(y_S-y_H)…………………………………(1)y = y _H +

(y _S -y _H )... … … … … … … … … … … … … (One)

Where x is the basic concentration of any sample point X in the original image. Namely, the density value obtained by subtracting the concentration value in the sharpest part H of the moving image from the concentration value at any sample point X of the moving image.

y: pixel concentration value of position Y corresponding to electricity X in the recording image to be formed.

y _H : The pixel concentration value of the desired size, which is set for the pixel of the sharpest part H of the recording image to be formed.

y _s : The pixel concentration value of the desired size set for the pixel of the darkest part S of the recording image to be formed.

α: reflectance of recording paper

A value obtained from β: β = 10 ^-r .

A number obtained from h: r / (original image density range).

r: arbitrary coefficient

Respectively.

Hereinafter, the configuration of the present invention will be described in detail.

In a recording image formed by an ink jet printer, the basic component of the recording image is covered by the density value in the pixel (this is covered by the number and size of dots in the pixel of the recording image formed as described above). And the surface reflection density of the forming material (ink) of the image, of which human vision is easy, for example, by a difference in density of 1% of the size of the halftone area in a printed image. As can be seen from the fact that it has the ability to easily identify, the pixel concentration value having a relation such as the size of the halftone area plays an extremely important role as the image forming means. In other words, paying attention to a certain dot and examining the effect of the change in the amount of ink applied on the dot and the change in the dot size on the gradation, the latter is particularly large, and how should the pixel concentration value be set? Is an extremely important issue.

In relation to the foregoing, when a recorded image is formed by an ink jet printer, the quality of the original image varies widely, that the success level of image type has various characteristics, and that the evaluation criteria of image quality are uniform. Against this backdrop, they must overcome their complexity and instability.

For this reason, in converting an original image such as a continuous gradation image into a recording image having an intermediate tone by an ink jet printer, the pixel concentration value y _H of the pixel block of the brightest portion H and the pixel of the darkest portion S It is absolutely necessary to set a means for arbitrarily selecting the pixel concentration value y _S of the block, and furthermore, a means which can reasonably and easily adjust and manage the gradation of the image from the brightest part H to the darkest part S.

The method of adjusting the gradation of the present invention, specifically, the method of adjusting the gradation prescribed in the above-mentioned <Relational Expression (1)> is based on such a method of thinking.

First, the derivation process of the above relation (1) will be described.

The inventors of the present invention propose to convert the gradation (conversion of the continuous gradation to the halftone gradation) from the color film document of the continuous gradation so as to reasonably perform the conversion of the preceding <Relational Expression (1)>. We have already proposed the gray scale conversion formula. (Refer to special service small 62-1486912 special service small 63-2590)

The gray scale conversion formula (hereinafter referred to as &quot; Relational Expression (2) &quot;), which has been previously limited by the present inventors, is not only a preparation of a print image, but also a variety of reproduction images, such as a recording image by an ink jet printer according to the present invention. Although it can also be used, it is as shown below when it describes only the creation of a printed image.

〈Relationship (21)〉

(y_S-y_H)………………………………………(2)y = y _H +

(y _S -y _H )... … … … … … … … … … … … … … … (2)

Where x is the basic concentration of any sample point X in the original image. Namely, the difference between the concentration value at any sample point X of the moving image and the concentration value at the sharpest part H of the moving image.

y: Numerical value of the half-dot area of the halftone dot of Y corresponding to the electrical sample point X in a print image.

y _H : Numerical value of the half-area of halftone dots of halftones of desired size, which is set for the outermost portion H of the printed image.

y _S : Numerical value of the half-area area of halftones of a desired arbitrary size set for the outermost part S of the printed image.

α: reflectance of printing paper

β: surface reflectivity of printing ink

h: ratio of (printed image density range) / (original image density range)

Respectively.

When comparing <Relational Expression (1)> and <Relational Expression (2)>, the meanings of the β value and the h value are different, and there is no provision for the r value in <Relational Expression (2)>. These differences will be described later, and the derivation process of the relation (2) will be described to help the understanding of the present invention.

The relational formula (2), which obtains the numerical value y of the half-area area percentage used in the preparation of the above-described printed image, is a generally recognized density formula (photo density, optical density), that is,

D = log ¹⁰ / I = log ¹ / T

Io = incident light intensity

I = reflected or transmitted light

T = I / Io = reflectance or transmittance

Derived from.

The general formula for this concentration D is applied to plate making and printing as follows.

Concentration (D ') in plate making and printing = log

= log

= log

here,

A: unit area

d _n : area of each dot in the unit area

α: reflectance of printing paper

β: surface reflectivity of printing ink

to be.

The relational expression (2) makes it possible to arbitrarily set halftones having a predetermined size in the H and S portions of the print image in the density formula (D ') relating to the printing and printing thereof. A request is made to reasonably correlate the basic concentration value (x) at an arbitrary sample point with the numerical value (y) of the half-area area percentage of the halftone at the sample point of the halftone image. The observations were derived to approximate agreement.

When applying the above relation (2) to the gray scale conversion method of the image when creating a printed image, the reflectance (α) of the printing paper, the surface reflectivity (β) of the printing ink, and the print image density area / original image density Based on the numerical value of the inverse ratio (h), an arbitrary sample point (X) of the original image, while arbitrarily selecting the size (y _H , y _S ) of the desired halftone dots desired to be placed in the H and S portions of the printed image. It is operated to obtain a numerical value y of the half-area area of halftone dots at the corresponding sample points Y of the printed image from the basic concentration value x of the image.

As a result, the density gradation of the original image (continuous gradation image) can be faithfully reproduced 1: 1 on the print image (dotted gradation image). Furthermore, in the case of multicolor plates (generally considered to be one set of four plates of cyan (C), magenta (M), yellow (Y), ink (BL)), the reference plate (in the case of multicolor plates) As is well known, the work reference characteristic curve of the siam plate (C) becomes the reference plate, i.e., the halftone gradation characteristic curve (a basis for converting the density information of the original image into the halftone area value of the printed image). This is a curve obtained by graphing one x value and y value, and this is the standard for converting continuous gradation into halftone gradation.) When it is determined, the work reference characteristic curve of the other color plate is the value of y of the reference plate. It can always be reasonably determined by multiplying by the appropriate adjustment value based on the gray balance of the printing ink.

The work reference characteristic curves of the color plates thus determined are not only rational characteristic curves, but also the correlations related to the gradation and color tone between their characteristic curves are also reasonable and appropriate.

In other words, when a manganese gradation print image is created from a continuum gradation original image, if its gradation conversion is performed based on the foregoing <Relationship (2)>, it is free from the conventional gradation conversion method of an image depending only on the experience and feeling. In addition, it is possible to reasonably change the gradation of the image, and furthermore, it is possible to rationally adjust the hue which is closely related to the gradation. In this way, a printed image having a natural density gradient and color tone can be obtained as the human sense of sight. The present inventors have proposed the above.

In later studies, however, it was found that there were certain limitations in the operation of Equation (2).

The limit is

* If the original image is of standard quality, it is extremely effective, but the non-standard quality is particularly well suited to extremely poor quality contents (e.g., when the exposure is over or under). It is not.

If this is explained in terms of the operation of the relation (2),

* In case of standard quality (standard manuscript), when the gradation conversion is carried out using a molecule for determining the h value, using a pulverized printing concentration value (a typical concentration value of 0.9-1.0) of a yellow ink having a large stimulus value as a printing ink. (Furthermore, in the case of multicolor printing, plate C is manufactured using this value.) Although extremely effective, it may not be sufficiently satisfactory, especially for non-standard manuscripts with poor quality.

* For β values, the surface reflectance of the printing ink (yellow ink is used as a reference as described above) or other values may not be satisfactorily adopted. And so on.

In order to overcome the foregoing limitations, it is necessary to match the halftone gradation characteristic curve, which is the work criterion for the gradation conversion, to both standard and non-standard manuscripts, and the shape of the curve must be arbitrarily changed. As a result of the investigation, the inventors have found that satisfactory results can be obtained when the tone conversion is performed under the following conditions.

h = r / (original image density threshold)

r = positive or negative

* β value: A numerical value obtained by β = 10 ^−r from the r value that defines the h value.

By operating the above relation (2) under the above conditions, it is possible to produce a printed image excellent in reproducibility of density gradation from the standard and non-standard manuscripts, and the color tone which cannot be closely adhered thereto.

Although the above has been explained centering on the printing of the halftone gradation, it goes without saying that the theory supporting the above-described gradation conversion operation can be dedicated to the creation of the recording image by the ink jet printer.

It goes without saying that the gradation conversion equation suitable for the creation of the recording image by the ink jet printer can be referred to as &quot; relational expression (1) &quot;

Next, the meaning of each term of <the relational expression (1)> of this invention, the characteristic of an operating surface, etc. are demonstrated.

In the operation of the above relation (1), the basic concentration value x must be obtained from the image information signal of the original image. Any such concentration information value should be interpreted in the widest sense as long as it reflects the physical quantity of the concentration of each pixel of the original image. Synonyms include reflection concentration, transmission concentration, luminance, light amount, current, voltage value, and the like. These density information values may be acquired as photoconcentration as a density information signal. In addition, in the foregoing <Relational Expression (1)> of the present invention, there is a numerical value (for example, having a density value of 0.2-2.70 as a figure of a positive color film) for the measurement of the basic concentration value (x). ), And a percentage value (for example, 5%) for y _H [pixel concentration value set in the pixel block of the outermost part H] and y _S [pixel concentration value set in the pixel block of the darkest part S]. Or a value of 95%.), Y (a pixel concentration value recorded in the pixel block Y corresponding to an arbitrary sample point X of the original image) is calculated as a percentage value.

In the operation of the above-described <Relational Expression (1)> of the present invention, it is also possible to use it by modifying as follows and using it by any processing, deformation, induction, or the like.

y = y _H + E (1-10 ^-hx ) (y _S -y _H )

With E =

The former modification was made to be α = 1. This is a recording paper (the surface reflectance of the base material is 100%. The value of α may be 1.0 in practice.

In addition, according to the electric modification example (α = 1.0), y _H can be set as the predetermined portion _H and y _S as the darkest portion S of the recorded image by the ink jet printer as intended. This means that in the outermost part H of the recorded image, x = 0, or in the darkest part S, x = [original image concentration range], that is,

=r), 따라서 -hx=r로 되는 것으로부터 명백하다.(hx = r

r), and thus it is apparent from -hx = r.

In the operation of the above-described relation (1), the numerical values of α, β, and γ (which defines the β value by β-10 ^−r as described above) take various values. In the present invention, by appropriately selecting these numerical values, it is possible to reasonably perform the conversion processing of the gray level of an image even if the quality characteristics of the original image are any.

In other words, the conversion processing method of image gradation based on the above-described <Relational Expression (1)> of the present invention is extremely useful for reproducing gradation or color tone of an original image, that is, reproducing the quality of an original image 1: 1 in a recorded image. However, its usefulness is not limited thereto. The relation (1) of the present invention rationally changes or modifies the characteristics of the original image by appropriately selecting α, β, γ values, and further y _H , y _S values in addition to faithfully reproducing the characteristics of the original image. It is extremely useful to.

In detail, it will be noted that in the operation of the relation (1), the user (worker) has the following degrees of freedom.

In his use of <Relationship (1)> for the purpose of forming an image faithful to the original image, the primary goal is to obtain the same visual and sensory image as observed by the human eye. , Use the relational formula (1). This attitude of gray scale adjustment is described in the present invention in terms of &quot; (image) gray scale (conversion) &quot;.

〈His 2〉: When using the relational expression (1) to modify or modify the manuscript image by technical necessity of image shape, artistic request, or order of the ordering party, when observed with human eyes The first goal is to obtain a modified or changed visual and visual image by itself, and to operate the relational expression (1). This attitude of gray scale adjustment is described in the present invention by the term &quot; correction (or change) of (image) gray scale &quot;.

In the case of forming a multicolored image using the above relational expression (1), for example, when a color document is duplicated by an ink jet printer, color separation, which is well known in the field of printing and the like, is reflected. Spectral blue (B), green (G), and red (R) spectroscopy obtains density information signals for each color, and processes them in a gradation adjustment mechanism using the electric relation (1). What is necessary is just to form an image based on it. At this time, the y value of the reference color plate (e.g., C plate), that is, the gray scale characteristic curve (y value of the reference color plate) and the y value for the x value are plotted, The same gray scale characteristic curve is obtained.) The gray scale characteristic curves of the other color plates (M plate and Y plate) are appropriately adjusted by the gray balance ratio of each ink to the y value of the color plate as a reference thereof. Since it can be reasonably determined by multiplying by using, the image may be formed using these gray scale characteristic curves.

The gamma values for the color plates determined as described above, that is, the gray scale characteristic curves for the color plates are not only characteristic curves because they are defined in the relation (1). Relevant interrelations are also reasonable and appropriate.

As described above, when the recording image is formed by the ink jet printer, the gray scale is, of course, incorporated into the gray scale adjustment mechanism in the hard or soft to perform gradation conversion based on the electric relation (1). A recorded image excellent in reproducing a color tone or a recorded image arbitrarily corrected or changed in quality of an original image can be obtained.

Hereinafter, the present invention will be described in more detail based on examples. As long as the gist of the present invention is not exceeded, the present invention is not limited only to those of these examples.

As described above, the present invention has the greatest feature in that the gray scale adjustment mechanism of the ink jet printer allows the conversion of the gray scale by &quot; (1) &quot;. Thus, an aspect of perfecting the operation of relation (1), particularly the handling of r values, will be described.

EXAMPLE

(1) Regarding the determination method of the r value employed in <Relational Expression (1)>, the present invention relates to a process of converting a core tone in the process of creating a recording image when forming a recording image by an ink jet printer. It has the greatest characteristic in performing it based on the former <Relational formula (1)>.

In such a case, it is needless to say that even in an original image of which the contents of light, dark, etc. vary greatly, it is desirable that the quality image be formed of the same quality as the recorded image formed from a standard standard document. To do this, it is necessary to obtain a gradation characteristic curve that defines the relationship between x and y values that give the same quality as the recorded image obtained from the standard document without being influenced by the quality of the original image. In the relation (1) of the present invention, it is the r value that makes it possible to greatly change the shape of the gradation characteristic curve.

Hereinafter, the method of determining the r-value having an extremely important meaning in operation of the relational expression (1) will be described. The ink jet printer of the present invention can form a recording image excellent in reproducibility of gradation and hue as a ratio by reasonably determining this γ value.

The first table shows how the y value (that is, the pixel concentration value) changes for various gamma values.

The first table changes the gamma value (as shown in the first table, and employs gamma value = 2.00-0.20). The electrical relation (1) is represented by y _H = 3%, y _S = 95%, α = 1.00, β = 10 ^−γ , K = γ / (concentration threshold of original image) = γ / (2.8-0.2), and calculated under the conditions. The y value in each density step (the 1st table | surface divided | divided the density area of the original image into 9 steps) is shown.

[Table 1] <relationship between y value and y value>

(Note) (1) The elements in the table represent y values (pixel concentration values,%) at each concentration step.

The pixel concentration values set at (H) and (S) are all 3% and 95%.

According to the first table, when γ is changed, individual gradation characteristic curves corresponding to each can be obtained. Therefore, in the quality content of a given original image, the gray scale conversion may be performed by setting the optimal one. The results of the first table are shown in FIG.

Thus, when a manuscript image having a predetermined quality content is given, the problem is how to reasonably determine the optimal gamma value to be employed in the relation (1).

As an original image, in particular, a monochromatic or colored film that is faithful in reproduction of gradation and color tone is used as an original, and a determination method of gamma values to be employed is established in accordance with the image quality of the original. This is because it is considered to be useful for other original images if a method of determining the gamma value effective within the (image quality) range of a monochromatic or color film original having high gray scale reproducibility is established.

Analyzing the quality of the original color film in detail, his image quality such as High Key (Photographed with Exposure Overhead) or Low Key (Photographed with Exposure Under) is compared with standard color film documents taken with standard exposure. In comparison, it varies greatly. However, the difference in the image quality of the color film original can be objectively defined by paying attention to the advantages, since the difference in the exposure amount directly affects the maximum concentration value Hn of the original.

In the case of the standard manuscript (exposure is appropriate) as proposed above, the present inventors should find the correlation between Hn and γ in accordance with the idea that the value of γ is 0.9 to 1.0. The reason why Hn is selected is that the concentration region near the sharpest part is important in the reproduction of the gradation. Theoretically, it goes without saying that the darkest concentration value Sn of the original may be selected.

Thus, experiments were conducted using various color film originals to form a recording image with excellent image quality and to obtain the relationship between Hn and γ values. The experimental data are shown in Table 2. In addition, experiment No. 2 denotes a standard manuscript and 0.9 is adopted as the gamma value.

[Table 2]

(Note) Hn and Sn represent the sharpest part density | concentration value and the mudstone part concentration value of a predetermined | prescribed individual color film original.

In these experiments, the γ value can be reasonably determined by the following equation.

(Iii) When the relationship between γn and Hn in Table 2 is graphed as shown in Fig. 2 (epoch graph), γn is obtained by the following equation.

γn = γo ± | Dn | tanα

only,

γo = 0.90

Dn = Hn-Ho

Ho = maximum density of standard manuscripts.

0.2 for this experiment.

tanα represents the vertex gradient shown in FIG.

The sign of ± is +, when Hn> Ho

When hn <Ho-,

Shall be.

In addition to (ii), an experiment was performed in which a standard image (concentration range 0.20-2.80) was formed under? O = 1.00 and a recording image of the same quality was obtained from various color film originals. As a result, the relationship between γn and Hn could be defined as follows.

(A) γn = 1.70-2.2961 (log Hn + 1)

(Relational expression obtained when γn and Hn are expressed in logarithmic scale)

(B) γn = 1.70-2.3 (log Hn + 1)

(Relational expression obtained when γn is represented by normal scale and Hn by logarithmic scale)

As described above, in order to reproduce a recording image having excellent reproducibility of gradation by an ink jet printer from an original image having a quality difference only, first, γ n is determined from the Hn value of the original image, and then γ of <Relational Expression (1)> is obtained. It is only necessary to adopt a value and to perform the tone conversion process.

In the gradation adjusting mechanism of the ink jet printer, in order to operate on the basis of the γ value determined as described in the relation (1), the ink jet printer is a mechanism for measuring Hn of various original images, and Hn to γn. You can add a mechanism to calculate the value. Or you may leave these measurements and calculations to an operator.

(2) About method to fix (correction) of γ value to be employed in <relational expression (1)>

In operating the above-described <Relational Expression (1)>, the determination method of the above gamma value is complicated, and the recording image produced by this method is strictly different from the recording image obtained from the standard document. It is natural to say that the maximum density value Hn of the color film original is different from the maximum density value Ho of the standard document.

As described above, in <Relational Expression (2)>, which is useful for the gradation conversion of standard manuscripts, a value of γ = 0.9 (or a value between 0.9 and 1.0), and not only gradation but also excellent reproduction of hue reproduction. You can create an image. Therefore, in the operation of the relational expression (1), in order to purify the value of γ to γ = 0.9 or the like, the density gradation of the original image must be adjusted (corrected) to the standard gradation gradation. Hereinafter, the method of integerizing (gamma) value is demonstrated.

In the case of a color film document, the above-described density adjustment can be performed very reasonably. This will be described as FIG.

As is well known, the relationship between the exposure amount X of the color film sensitive material (note the difference from X described above as the sample point X) and the color film concentration D at that time is the basic concentration characteristic curve of FIG. It can be represented as.

The standard document and the non-standard document are based on whether or not the exposure dose is appropriate, and each density characteristic curve appears to have a specific range on the basic concentration characteristic curve. In FIG. 3, the former is shown as the reference concentration characteristic curve, and the latter is shown as the individual concentration characteristic curve (in FIG. 3, the non-standard manuscript and the under exposure are also shown).

Therefore, in order to adjust the density characteristic of the non-standard document to the density characteristic of the standard document, the basic density characteristic curve can be functioned very easily.

The basic concentration characteristic curve described above defines a function of D = f _D (X) as shown in the following third table (the third table also shows inverse irrigation water). In addition, the method of functionalizing the basic concentration characteristic curve in Table 3 will be understood as an example and a more simplified formula may be used.

[Table 3] (Example of Function Display of Basic Concentration Characteristic Curve)

I use color film made in F company

Note: In the basic concentration characteristic curve shown in Fig. 3,

A function f _D (X) that yields X → D,

The function f _X (D) to find D → X is shown.

(Note) To faithfully define the basic concentration characteristic curve

Formulated in each domain of X or D.

In order to match the individual density characteristic curves of the color document with the reference density characteristic curves, the following procedure can be used (see FIG. 3).

(Iii) From the density values of H and S of the color original image and the basic density characteristic curve (D = f _D (X)) of the color film-sensitive material of the color original, the individual density characteristic curve of the color original image is defined. Ii) Substituting the color values _DHn to D _Sn into X = f _X (D) to obtain the range of the color original image on the X axis, X _Hn to X _Sn , and (i) the density characteristics based on this. Match the band on the X axis of the curve, X _Ho to X _So. (Iii) Next, the range of D side of the reference concentration characteristic curve, D _Ho to D _So , is obtained.

As a matter of course, it is needless to say that when the individual density characteristic curves of the color documents coincide with the reference density characteristic curves, the matching of both is unnecessary. In addition, an arbitrary allowable range is defined in the reference concentration characteristic curve, and when it is within the allowable range, the image processing can be performed as regarded as the reference concentration characteristic curve.

In the matching procedure of the individual and reference density characteristic curves described above, XRn is usually not matched with XRn (the exposure range of the standard document) and XRn (the exposure range of the non-standard color-coded document). (Refer to the order of (ii) and (iii) above.) To match XRn to XRo, simple matching (attitude matching the highest concentration level to the same value) and proportional matching (The attitude of matching both the maximum concentration level and the darkest concentration level.) FIG. 3 shows a case where the proportional matching is mathematically performed.

As shown in FIG. 3, the concentration information value (Dinformation value between D _Hn and D _Sn , Dn) of the individual concentration characteristic curve is substituted into the basic concentration characteristic curve D = f _D (X) to obtain XRn. This means that the density information value (the density information value between D _Hn and D _Sn , Do) of the color originals adjusted by the X value adjusted to XRo is obtained, but the X value after adjusting XRn to XRo is obtained. The relational expression becomes as follows by simple calculation.

(1) In case of simple matching

X = f _x (Dn) ± | m |

(2) In case of proportional matching

X = f _X (D _Ho ) + [｛f _X (Dn) ± | m |｝ -f _X (D _Ho )] ×

only,

m: Parallel travel required

XRo: Exposure Range of Standard Density Characteristic Curve of Standard Document on X-axis

XRn: Exposure Range of Individual Concentration Characteristics of Non-Standard Individual Originals on X-axis

Color film originals of standard quality (D _Ho = 0.20, D _So = 2.80), of the high key (exposure over) (D _Hn = 0.10, D _Sn = 2.70), and of the low key (exposure under) Using D _Hn = 0.60 and D _Sn = 3.20), the matching data when the individual concentration characteristic curve is matched to the reference concentration characteristic curve under the basic concentration characteristic curve shown in Table 3 is shown in Table 4 below. Indicated.

[Table 4] Matching Data of Individual Concentration Characteristic Curves and Reference Concentration Characteristic Curves

In the above matching experiments, the density region (DR) of the three color film originals used was 2.60, so that one was simple matching and the other was proportional matching.

In the concentration values of D _n and D _{O in} the foregoing Table 4, the y value (pixel concentration value,%) was obtained by <Relational Expression (1)> based on D _o . The results are shown in Table 5. 4 shows the correlation between the y value in FIG. 5 and the D _n value. The curve shown in FIG. 4 is a gradation characteristic curve that defines the correlation between the x value and the y value for creating a recording image excellent in the reproducibility of the gradation from the non-standard image of the original image.

[Table 5] (Gradation Characteristic Curve Setting Data)

Integer of the relation (1): α = 1.00, γ = 0.90, y _H = 5%, y _S = 95%.

In the ink jet printer adjustment adjustment unit, in order to operate (fixed) the value of γ in relation (1), a mechanism for measuring the density of the original image in the ink jet printer (H, S, and HS) is used. In order to measure the density of the original image and to match the density of the original image to the individual concentration characteristic curves, soft or hard must be incorporated. This makes it possible to produce a recording image excellent in production and color tone for a document of any quality content.

(3) About the inkjet printer

The ink printer of this invention is demonstrated based on FIGS.

5 is a block diagram of an inkjet printer of the first embodiment of the present invention.

As shown in FIG. 5, the inkjet printer of the present invention has a detector 1 for spectroscopically reading out the transmitted or reflected light of an image into R (red), G (green), and B (blue), and the output of the detector 12. Proper production of the color separation signal using the color separation unit 2 for converting the signal into color separation signals of Y (yellow), M (magenta), C (cyan), and K (black), and the above-mentioned &quot; (1) &quot; And four blocks with a manufacturing adjustment mechanism 3 for processing an image to be formed, and an output portion 4 for escaping droplets of color ink from the ink head based on the output signal of the manufacturing adjustment mechanism 3.

The detection unit 1 detects transmitted light or reflected light of each part of the original 5, such as a photomultiplier or a solid state imaging device (CCD), and outputs signals of R, G, B, and USM as current values, and outputs these signals. Is converted into a voltage signal in the A / V converter 6.

In the Logarithmic Amplifier 7, the color separation unit 2 converts the voltage signals of the R, G, B, and USM signals of the detection unit 1 into logarithms and converts them into concentrations. In the basic masking (BM) 8 Black (K) component is isolate | separated from, and each component of Y, M, and C is isolate | separated again. Next, in the color correction (CC) section 9, the Y, M, and C components are controlled for each of the original colors of R, G, B, Y, M, and C, and the black component of the original is UCR. In the UCR (Under color removal) or UCA (Under color addition) of the / UCA section 10, the ratio expressed by three kinds of inks of Y, M, and C, and the ratio expressed by K (black ink) are determined. After these Y, M, C, and K components are obtained, in the gradation adjustment section 11, the pixel density values in the pixel blocks of the respective color components from Y, M, C, and K, that is, ye 'and me' representing the effective area ratios of the respective color components. to ce 'and ke'. The gradation adjusting unit 11 takes the rhythm of the relation (1) and applies the relation (1) to each of Y, M, C, and K to obtain the ye ', me', ce ', and ke's. .

As the gradation adjusting section 11, a general-purpose computer having an algorithm of &quot; Relational Expression (1) &quot; It can take various forms such as an embodied electric circuit, an electric electric circuit containing an RCM that holds the calculation result of an algorithm, a PAL embodied using an algorithm as an internal logic, a gate array, a custom IC, and the like.

The effective interview rate corresponding to the pixel concentration value of each color component obtained by the manufacturing adjustment unit 11 is input to the color channel selector 12, and the color channel selector 12 outputs ye ', me', ce ', and ke'. This output is subjected to A / D conversion by the A / D converter 13 and input to the dot control (D / C) unit 14 for each color. Based on this input information, a drive voltage corresponding to the amount of dots to be covered with each pixel block, i.e., a color density, is applied to the ink control head 4 (4Y, 4M, 4C, 4K). Each color ink is sequentially controlled on the recording paper 15, and is sequentially discharged to form a recording image following the gradation.

6 is a block diagram of an inkjet printer of a second embodiment of the present invention. In Fig. 6, a TV signal is used as an image information signal of an original image, which is input to a gray scale adjusting unit having an algorithm of relation (1) therein, converted into a digital signal by an A / D conversion unit, and charged. Input to signal driver 13. The ink room 6 is charged by the charging unit 7 based on this input signal. The charge amount corresponds to the pixel concentration value, that is, the color concentration value, which is covered with dots in the pixel block. It corresponds to the color density. Ink droplets charged to the amount of charge corresponding to the color concentration are deflected in the planar portion 8 to reach the recording paper 10.

In forming the image by the inkjet printer of the present invention, in order to change the coverage (pixel concentration value) of the pixel, the dot size may be the same as the dot in the printing technique (dimension modulation of dots), or dizer It is also possible to devise an array of specified dots (dots of constant size), such as those found in the matrix matrix method.

(4) About usability of <relationship (1)>,

Next, the usefulness of the relation (1) applied to the gradation adjustment mechanism of the inkjet printer of the present invention will be described. This is a supplementary explanation for better understanding of the present invention, and will be described in detail mainly with the significance of the ink ink printer of &quot; (1) &quot; applied to the gradation adjusting mechanism of the inkjet printer and its result.

(A) Operational experiment of 〈Relational formula (1)〉

The following two experiments were conducted as a basic experiment for incorporating &quot; (1) &quot; into the tone adjustment mechanism.

(a) First, using a conventional simple calculator, ie, the trade name, Shaaff P. Tyrathas EL509A (manufactured by Shaaf), fit the desired value into the relation (1), and then operate the simple calculator while The gradation adjustment table of the images shown in the sixth table (1), (2), (3), seventh table, and eighth table was prepared.

As a result, the time required for these operations was 3 hours, 2 hours and 2 hours, respectively, including the check time of the calculation results.

b) The following experiment was also performed.

The desired software obtained separately from the simplified personal computer (PC-9801-M2 manufactured by NMC) is inputted as a function data, and the basic density value (x) of the original image (continuous gradation image) is input to the density value of the pixel of the recording image corresponding thereto. The operation to adjust to (y) was performed.

His results are natural, but the same numerical values as the manual calculations using the simple calculator were obtained. In addition, in this experiment, there was no need to use any special software to create the above-mentioned software for use in the gradation adjustment of the image input to the personal computer, and the creation was performed using the N8-BASIC included with the personal computer. It only took an hour to complete him.

The gradation and correction of the target image can also be performed by software which can input the measured value by the density meter from the highlight (H) to the shadow (S) of the original image as it is instead of the basic density value of the original image. It was confirmed that there was.

Using these software, a desired density interval (e.g., 0.05 to 0.00 to 1.00 and 0.0 to 1.00 to 3.00) is created in the original image, and the value is inputted to the personal computer. By the command, the target pixel concentration value y was obtained.

In addition, by inputting a plurality of density values from the highlight of the original image to the shadow, a desired pixel concentration value y corresponding to them could be obtained.

The pixel concentration value y by the above software can output either a positive image or a negative image independently or simultaneously.

(B) About the calculation result and its usefulness obtained from the relational expression (1),

Next, the usefulness of the sixth table (1) (2) (3), the seventh table, and the eighth table described above will be described.

[About Table 6 (1) (2) (3)]

In Table 6, when a black and white image is formed from an original image by an image forming apparatus such as an inkjet printer, the density of the ink material (in the table, the density range of the recording image is indicated, which is represented by γ in the relation (1)). Value) and to obtain the ideal manufacturing characteristic curve when the range of use of the maximum concentration value is changed (the table shows three cases of 0 to 100%, 0 to 985 and 0 to 95%). Is a list of how the pixel concentration value t at each sample point should be set.

In addition, even if the concentration of the ink material in this table is constant (that is, even if the recorded image concentration range = gamma value in the leftmost column of the first table is the same), an ideal manufacturing characteristic and You can see how the line changes and how it must be changed.

In Table 6, the β value for determining the ε value is determined as β = 10 ^−γ . Incidentally, when the recording image concentration range = gamma value = 1.0, epsilon = 1 / (1-β) = 1.1111. The pixel concentration value (%) and the value of accompaniment are the theoretical values when β = 0 (ε = 1.0).

Further, it is necessary to acquire a technique and a method of forming a black and white image by the distribution of pixels corresponding to 1: 1 from an original image such as a continuous gray scale image, and to arbitrarily adjust the gray scale characteristics of the black and white image. It is also the basis of formation.

[Table 7]

Similarly to Table 6, in the case of Table 6, when the density of the ink material is changed when forming a black and white image from the original image (i.e., when the recording image concentration range) =? Is 0% to 100%, and the contrast of the entire image is different, and the pixel concentration value at each sample point necessary for forming an image having the same image quality and the same image quality with respect to the human visual sense ( y) is a list.

In other words, when the conditions are ideal, the pixel concentration values y of the respective sample points on the ideal gradation characteristic curve corresponding to the density values of the ink materials to be used are listed.

[Table 8]

In Table 8, the basic conditions are the same as in Table 7, but when the maximum concentration range (5% to 95%) is used, a percentage of pixel concentration (y) is obtained at each sample point on the ideal gray scale characteristic curve. Indicates if it should be set.

Until now, color separation in the production of printed images, etc., is primarily concerned with color correction by masking technology, and the adjustment of the gradation of the image is basically a human experience, a sense, Or they only relied on a limited number of fixed conditions. For this reason, it is necessary to make the conversion technology of manufacture at the time of creating a duplicate image scientifically based on the side of the image to be duplicated, such as a print image or a recording image by a printer.

Relational Expression (1) of the present invention is to perform gradation conversion in creating a duplicate image in a reasonable manner. In addition, the data of Tables 6 to 8 showing the correlation between the basic concentration value of the original image obtained by <Relationship (1)> and the pixel concentration value of the image to be formed are various basic elements in the color separation operation during image formation. This is a useful baseline for scientific review.

From each table, it is possible to extract what the essence or principle exists between the original image and the color separation work, and what must be paid attention to and consideration for rational matching of the essence, principle and practice. .

(C) Application to Examples of Modifications (or Changes) in Manufacturing of Formula (I)

The relational expression (1) is not only a conversion of the gradation of an image (that is, a conversion from an original image of a continuous production to a manufacturing image by distribution of pixels with high fidelity), but also of a so-called gradation that corrects the original image itself. It is also valid for modifications (or changes). Correction (or alteration) of the manufacture of the image includes a change in the reduction / enlargement ratio of the recording image to be formed, the intention of the client, the type of the target image in the color document, the purpose of using the image to be formed, and the wall paper or image of the recording paper. In this case, the concentration of the recording material (ink) or the like must be used. However, in any case, the operation of the relational expression (1) can be rationalized, and various color separation operations can be standardized and standardized.

In addition, according to the present invention, the correction (or change) of the gradation of the image of the highlight portion or the shadow portion can be performed in the same manner.

As shown in FIG. 1, it is apparent that the shape of the manufacturing characteristic curve (curve defining the correlation between the x value and the y value) can be arbitrarily changed by the adopted r value. On the other hand, it is confirmed by the gradation conversion according to the relation (1) of the present invention that the 훠 -Fog in the highlight portion of the color document can be automatically removed without taking special countermeasures. It became.

[Table 6]

Relationship between the recording image concentration value (r value), the use range of the maximum small concentration value, and the pixel concentration value (theoretical value)

^Calculated formula: y = y _H + ε (1-10 ^-hx ) (y _S -y _H ) X: Basic concentration value

α = 100%

y _H ~ t _S = 0 to 100%, 0 to 98%, 0 to 95% y: pixel concentration (%)

ε = 1 / (1-β) (theoretical value)

[Table 7]

Relationship between recorded image concentration range (r value) and pixel concentration value (y) (sample point of image selects 1/8 point of image) Range of pixel concentration value used: 0% to 100%

(Unit: o / o)

[Table 8]

Relationship between recorded image concentration range (r value) and pixel concentration value (y) (sample point of image selects 1/8 point of image) Range of used pixel concentration value: 5% to 95%

(Unit: o / o)

[Effects of the Invention]

The present invention achieves the following excellent effects.

1) In determining the correlation between the density value of an original image such as a continuous system image, which is the most basic matter for image formation, and the pixel concentration value of a recording image to be formed (image recorded by the distribution of pixels), It was based on irrational methods that were based solely on the experience and feelings of workers or on a limited number of fixed conditions. In the present invention, on the other hand, under any circumstances, this can be reasonably determined based on the relational expression (1). In addition, production management (conversion, modification or change), which is the most important requirement when converting an original image such as a continuous gradation image into a recording image by distribution of pixels, does not merely remain in the manufacture of the image. Since the image has a deep relationship directly to the color tone of the image, the present invention can reasonably manage manufacturing and color tone. In other words, the ink jet printer incorporating the algorithm of the relation (1) of the present invention into the adjustment mechanism of gradation can theoretically and rationalize the gradation conversion operation (color separation operation) and simplify its operation. The effect is very large.

2) By adopting the algorithm of the relation (1) into the manufacturing adjustment mechanism of the ink jet printer, the printer device can be rationalized and simplified, and manufacturing cost can be reduced. In addition, the operation is simplified and clarified, which greatly reduces the defective plate of work, greatly reduces the consumption of consumable materials, and can greatly improve the performance of the ink jet printer. In particular, in the performance of the ink jet printer, there is a large margin that a recording image that is poor in production or color tone can be formed, whatever the quality of the original image.

3) The gradation adjustment mechanism employing the algorithm of <Relational Expression (1)> can define a criterion for evaluating the quality of a recorded image by distribution of pixels reasonably and simply by separating the image information from the original image. . Therefore, it is possible to reasonably respond to the diversified needs of customers.

4) By adopting the relational expression (1), education and training of technicians required for the advancement of printer equipment can be effectively carried out through the operation of the relational expression (1). By eliminating one effort, you can free up time for new creative development.

Claims (3)

The detection unit that spectroscopically reads the transmitted and reflected light of the original image into red (R), green (G), and blue (B), and outputs signals from the detection unit to yellow (Y), magenta (M), and cyan (C). ), A color separation unit for converting to a black (K) color separation signal, a gradation adjustment mechanism for processing to form an appropriate gradation image from the chrominance signal, and a drop of various ink from the ink jet head based on the output of the gradation adjustment mechanism. An ink jet printer comprising an output section for forming a recording image having one color or a multi-color halftone on a recording paper in an emergency, wherein the gradation adjusting section of the gradation adjusting mechanism is based on an image information signal. The base concentration value x of the arbitrary sample point on the image (the difference between the concentration value at the sample point and the concentration value at the edge of the moving image) at a position corresponding to the electrosample point of the recording image to be formed. Of the pixel to the concentration values (Y) of the come <relational expression (1)> Ink jet printer characterized in that the conversion process by. <Relationship> y = y _H +

(Y _S -y _H ) X: Concentration value obtained by subtracting the concentration value at the outermost part H of the moving image from the basic concentration value of any sample point X of the original image, that is, the concentration value at any sample point X of the moving image. Y: The pixel concentration value of position Y corresponding to electricity X in the recording image to be formed. Y _H : Pixel concentration value of a desired size set for the pixel of the brightest part H of the recording image to be formed. Y _S : pixel concentration value of a desired size set for the pixel of the darkest part S of the recording image to be formed. α: reflectance of recording paper Number obtained by β: β = 10 ^-r Numerical value determined by k: γ / (concentration range of original image) γr: arbitrary coefficient Respectively. The ink jet printer according to claim 1, wherein the recording image having the intermediate tone is a modulated image of a dot dimension formed by controlling the amount of liquid discharged from the ink jet head to change the recording dot diameter. The ink jet printer according to claim 1, wherein the recording image having the halftone is a modulated image of dot density formed by Dither Matrix.

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