JPH01253454A - Ink jet printer - Google Patents

Abstract

PURPOSE:To systematize color decomposing and gradation converting works theoretically and rationally so as to simplify them, by forming an image on recording paper that is composed of picture elements with the color density corresponding to the density of an original image in accordance with output signals which are converted from the image information signals gained from the original image by a gradation adjusting unit. CONSTITUTION:Transmitted or reflected light from each part in an original image is detected, and the voltage signals R, G, B, and USM at a detecting unit 1 are respectively converted to the density by a log amplifier 7. The black component (K) is separated from the density by a basic masking (BM) 8, and then Y, M, and C components are respectively separated. A proportion for expressing black component in the original image with K (black ink) and proportions for expressing other color components with three kinds of inks Y, M, and C are determined by UCR/UCA unit 10, Y, M, C, and K are converted to the picture element density in a picture element block, i.e. effective area proportions for each color component, by a gradation adjusting unit 11. And signals from a dot control unit 14 are applied to a ink jet head 4 for each color, and an image is recorded on recording paper 15.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention converts the image information signal obtained from the original image by using a new gradation adjustment method to form a recorded image with excellent gradation reproducibility. The present invention relates to an inkjet printer capable of printing.

More specifically, the present invention provides image processing methods that can be obtained from various original images (including all types of images to be reproduced on recording paper, such as continuous tone images such as monochrome or color photographs, and video images; the same shall apply hereinafter). The image information signal is converted using a new gradation adjustment mechanism, and an image consisting of pixels with a color density corresponding to the density of the original image is created on recording paper based on this gradation-converted output signal. The present invention relates to an inkjet printer that can be used to create an inkjet printer.

(Prior art) When copying an image from a continuous tone original image like a photograph onto a recording sheet using an image forming device such as a copying machine, analog processing (exposure) of the original using photosensitive paper as the recording sheet is necessary. ), an image having continuous gradations corresponding to the original is formed (silver halide photographic recording). On the other hand, inkjet printers that record images on plain paper rather than photosensitive paper cannot form images using analog processing, making it difficult to reproduce continuous gradation, and in the case of color image formation, color balance adjustment is required. etc. is not easy.

For this reason, efforts are being made to improve the gradation reproducibility of printer devices. Image formation in an inkjet printer is similar to the method of converting continuous gradation to halftone gradation in the case of photolithography in printing, in which an image is created by photoelectrically scanning a continuous gradation original image such as a photograph. The information signal is processed and, based on the signal, an image is formed on a recording sheet by pixel molecules fi having a color density corresponding to the original image.

However, in the printer devices currently in use, the gradation adjustment method that processes the image information signal obtained from the original image for gradation reproduction is unscientific, so it is not possible to achieve satisfactory gradation reproducibility. The current situation is that it has not been done.

As is well known, the gradation characteristics depend on the color density display performance of the pixel, and in the case of inkjet printers, there are two methods for displaying the color density of the pixel: one is a method of varying the pixel coverage rate depending on the size of the dot (size modulation method), , stipulated (same person) driver 1-
There is a method (density modulation method) in which the pixel coverage is changed by the number of arrays. However, when copying an original image to Infusiera 1 using a printer, the coverage rate of the corresponding pixel on the duplicated image by a dot, etc., for the color density value of a predetermined sample point on the original image, that is, the pixel Color density value (hereinafter,
It is simply called the density value (at) a pixel. ) should be, or how to obtain such a pixel'a degree value, etc., have not been studied in particular, and are based solely on the operator's experience, intuition, and the subjective judgment of the equipment designer. depends on. In particular, the characteristics of pixel density values, which are extremely important in reproducing gradations, are currently determined in advance by equipment manufacturers based on experience, intuition, and data based on a limited number of fixed conditions, and are stored in the printer's internal memory. Operators are using the data obtained. Therefore, in the case of non-standard color originals that were not anticipated by the device manufacturer, it is not easy to make adjustments to form the desired recorded image, and it is necessary to maintain the image quality level and stabilize the image quality. This is difficult to do, and it lacks the flexibility to change or modify the image quality as desired.

(Problem to be Solved by the Invention) The reason why the above-mentioned problems occur in conventional printer devices is that when forming an image based on the final pixel distribution from an original image such as a continuous tone image, The idea lies in the process of image gradation conversion, which is the first stage and plays an important 190% of the process. In other words, the conventional way of thinking about gradation conversion was not that ``it must be done based on scientifically rational gradation conversion means,'' but that it relied solely on experience and intuition. .

The present inventor has focused on this situation, and in order to ultimately streamline the image forming process and form recorded images of excellent quality, it is necessary to establish a rational image gradation conversion technology. Based on this basic understanding, we conducted extensive research.

(Means for Solving the Problems) If the present invention is described as tU, the present invention is an inkjet printer for forming a recorded image corresponding to a document image on recording paper based on an image information signal that is incremented by 1 from the document image. , the image information signal is converted to the basic density 1ig(1) of an arbitrary sample point on the original image (the difference between the density value at the sample point and the density value at the brightest part 1 of the same image),
An inkjet printer having a gradation adjustment mechanism that processes, for example, as defined by the following relational expression (1) so that pixel density values (Z) at positions corresponding to the sample points are correlated in a recorded image to be formed. It is related to.

・・・・・・(1) Hereinafter, the configuration of the present invention will be explained in detail.

In a recorded image formed by an inkjet printer, the basic component that makes up the recorded image is the density value of d5 (this is the number of dots in a pixel on the recorded image formed as described above) for each pixel. The opening degree (showing the surface reflection of the image forming process (ink)) and the opening degree (showing the 91 degrees covered by the cylindrical sheath) and the surface reflection of the image forming process (ink) are shown. Human story 1
As can be seen from the ability to easily identify a % difference as a density difference, as an image forming means, the pixel temperature value, which has the same relationship as the size of the vanishing point area, is extremely medium-wave. That is, how to set the pixel density value is very important.

In addition, in connection with the above, when attempting to form a recorded image using an inkjet printer, there are many problems such as the fact that the quality of the original image varies widely, and the image forming process has various characteristics. The background is that the evaluation standards for image quality are not uniform, and these complicated and unstable factors must be overcome.

For this reason, when converting a 13'A draft image such as a continuous tone image into an image with halftones using an inkjet printer, the density value (yh) of the pixel block in the brightest area (1'') must be and the density value (yS) of the pixel block in the darkest part (S) can be arbitrarily selected, and the gradation of the image from the brightest part (+1 > to the darkest part (S)) can be rationally and easily selected. It is absolutely necessary to have a means of coordinating and managing this.

The gradation adjustment method of the present invention described above was devised based on this idea, specifically, the gradation adjustment method determined by the above relational expression (1) (hereinafter referred to as "the present invention"). (Also referred to as “adjustment method.”)

The gradation adjustment method of the present invention is based on the values of the reflectance of the recording paper and the surface reflectance of the image forming material (ink), and the pixel desired to be placed in "1" and S of the recorded image to be formed) While arbitrarily selecting the temperature value, calculate the pixel density value of the struck pixel block (Y) at the corresponding position on the recorded image formed from the basic temperature value (D) of an arbitrary sample point (X) on the original image. This is done by finding (y).

In the above relational expression (1) of the present invention, the basic density value (1) is measured using a densitometer (for example, a density value of 0.2 to 2.70 for a portrait on a positive color film). ), and nh [the brightest part (
pixel temperature value 1 and 8 [pixel temperature value 1 set in the pixel block of the darkest part (S)] from percent 1 to a numerical value (for example, 5% or 95) %), the pixel density recorded in the pixel block (Y) relative to any sample point (X) on the original image is calculated as a percentage value. When applying the relational expression (1), it is possible to take this point into consideration and use it in a modified manner. When measuring the basic density value (1), the density may be measured by any density measuring means such as a color densitometer (transmissive type, reflective type, dedicated type, common type, etc.).

In the gradation adjustment method of the present invention, the basal temperature value (1) is not limited to the value determined by the concentration meter described above,
It goes without saying that the original image may be photoelectrically scanned to detect an electrical signal (current or voltage value) corresponding to the χ value, and ′j+direction may be determined based on this. That is, any value may be used as long as it correlates in some sense with the basic density value of the original image.

The relational expression (1) for calculating the pixel density value (y) described above is -
Density formula (photographic density, optical density) accepted for boat fishing, namely D = log■0/I =l○gl/T■o; Incident light amount ■2 Reflected light amount or transmitted light weight T-I/Io: Reflected or This is derived from the transmittance.

When this general formula regarding density is applied to image formation, it is as follows.

Density in image formation (Di=loq [4°, where, △: Median area dn: Area covered by dots etc. on the 0th and 1st pixels in the FLi area α: Area of the recording paper [reflection q] rate β: image formation +, i) 'II (ink) surface reflectance.

The present invention uses the density formula for image formation <Dl as a basic temperature value (1) at an arbitrary sample point on an original image such as the continuous tone image described above and the pixel density in a pixel block on a recorded image corresponding to this value. The relational expression (1) was derived in order to make the theoretical value and the measured value approximately match, taking into account the request for association with the value (y).

Therefore, according to the present invention, the tone adjustment from an original image such as a continuous tone image to a recorded image using the pixel division factor f5 is performed by correlating the basic temperature value (1) and the pixel temperature value (y). This applies to everything that needs to be adjusted.

The relational expression (1) 'correlation between the work of C and 7 () should be understood to be an example thereof, and the present invention is not limited thereto. That is, appropriate changes can be made without departing from the scope of the present invention.

The feature of the gradation adjustment of the present invention is that no matter what kind of crystalline content the original image, such as continuous or continuous gradation, has, γh and 8 and , or α
Since the values of I'll go.

"This conversion method" can be used by modifying this,
For example, by arbitrarily and appropriately selecting one shift between H and S, α and β, and in addition to the temperature range of the original image such as a continuous tone color photographic image and the distribution of pixels, If the range is different, a well-known gradation compression method is adopted, that is, the lunar surface that is the ratio of (recorded image density range)/(original image @ density IO,) is appropriately selected, and the "main adjustment" is performed. The image adjustment may be performed by calculating according to the "method".

That is, in the present invention, when forming a recorded image based on a pixel distribution based on an image information signal obtained by photoelectrically scanning an original image such as a continuous tone image, the above relational expression (1) is used.
It has extremely high flexibility and can perform image gradation conversion and gradation correction (or change) as defined by .

For details, when applying the "one-line adjustment method",
It must be noted that users (workers) have the following degrees of freedom.

Bad point 1: Use relational expression (1) for the purpose of forming an image that is faithful to the original image. In other words, the relational expression (■) should be applied with the primary consideration being to obtain exactly the same visual and sensory image when observed with the human eye. In the present invention, this attitude of tone adjustment is explained using the term "tone (of) conversion (of an image)."

Shit 2>: Using relational expression (1) to change or modify the original image due to the technical needs of image formation, artistic requirements, or the needs of the ordering party. In other words, applying relation 2) with the primary consideration being to obtain an image in which the visual sensory image itself is modified or changed when observed with the human eye. In the present invention, this attitude of tone adjustment is explained using the term "(image) tone (modification) (or change)."

The gradation adjustment work according to the present invention, specifically, the above-mentioned gradation conversion and gradation β positive (or change) can be performed using the above relational expression (1).
71. This can be easily done by appropriately changing the value of ε for the relationship S.

At that time, the above relational expression (1) or the terms, numerical values, and coefficients contained therein should be processed, transformed, derived, omitted, etc. as appropriate for image gradation conversion unless the rationality is 1 (4). Needless to say, it's good.

By the way, when forming a multicolor image, for example, when copying a color original using an inkjet printer, color separation, which is well known in the printing field, is used to separate the reflected light from the color original into 1 Lu (B) and green ( G), Red (R
) to obtain the amount of image information information, process the image information signal for each color using several gradation adjustments using the above relational expression α), and create the gradation characteristic curve (y value By calculating , and plotting the n value against the process value, a gradation characteristic curve similar to the halftone gradation characteristic curve in printing technology is increased by 1. The curve can be rationally determined by multiplying the seven values of the standard color components by appropriate adjustment values based on the gray balance ratio of each ink, so these image information can be used to create an image. All you have to do is form it.

The n value for each color component determined as described above,
That is, the gradation characteristic curve for each color component is expressed by the relational expression (1)
Of course, it is a reasonable characteristic curve because it is defined by
The correlation between these characteristic curves in terms of gradation and color tone is also reasonable and appropriate.

Gradation adjustment using the above relational expression (1)) Xl j, jl
, t. Depending on whether the gradation conversion (or correction, change, etc.) is direct or indirect, there are two ways to adjust the gradation of the image: One method is to directly convert a continuous-tone image with a characteristic curve into a gradation image based on pixel division A5, and the other is to convert a continuous-tone image into a gradation image by converting the continuous-tone image into a gradation image. The image is converted into a recorded image by pixel division lj (since gradation conversion, etc. have already been performed, the term conversion is used here to distinguish it).

). In addition, in any of the above-mentioned methods, there is a method in which the continuous tone temperature range is directly converted into a density region according to the pixel distribution without shrinking the temperature range by F "1", and a method in which the temperature range is directly converted into a density region according to the pixel distribution without shrinking the temperature range F "1". There is a method of converting the gradation of an image using a temperature range pressure 1 compressed original image corresponding to the density range of 1 h. You will need to use one that is appropriate for your work environment.

As a typical example, the basic density range of a continuous tone image (original image) with a linear deep tone characteristic curve (see Figure 1) is proportionally
An example of converting the remaining compressed original image into a recorded image by C1[77i element f+- is shown in the same figure (c) linearly) Continuously convert the gradation characteristic curves, read the gradation image (original image), compress the contrast area (at the same time), convert the gradation-adjusted density area compressed original image, and then convert this image. Figure 1 (2) shows an example of creating an image using IJ for each pixel by proportionally converting
, (c) 43, Do... Density value of the original image which is a continuous tone image.

DRo: Basic density range of the original image, which is a continuous tone image. The temperature value obtained by subtracting the temperature value at the brightest point (extreme point of the highlighted part: H) from the temperature value at the sample point (X) on the document in this DRo becomes the basic temperature value (1).

[] et al...Temperature value of a continuous tone original image whose density area is proportionally IJ compressed using the width value.

DR'o: Density range of the compressed original image.

D'o... The q value of a continuous tone image that has been converted to tone using the "single adjustment method" for a continuous tone image and compressed the temperature range.

D R”o...Continuous gradation document image is transformed into a continuous gradation image density area by gradation conversion () and density area compression using this adjustment method - J Gem.

Dρ: Pixel density value of a recorded image based on pixel distribution.

DRp: range of recorded images based on pixel distribution.

P: Tone characteristic value based on quality evaluation 11II standard of formed recorded image. The value of F) is compared with the value of N, and the consistency between the two is determined by a total of 1.

11 ...Brightest point on the original image (point to 1 of highlight 1 part) S ...Brightest point on the original image (water fish in the JiX/Do part) \・11 ...l' l! n draft image 1 ([point in the middle of the overflow of - (intermediate) point) ~・12 ... formed in the recorded image.
The density points at which the iI'ii' search depth value 50 solo is located are respectively shown, and there are 113 and C'' in the above embodiments and explanations.

[Example] Hereinafter, the ink sheller 1-printer of the present invention will be described as an example (
It goes without saying that the present invention is not limited to the following examples, unless a more detailed explanation is provided or the gist of the present invention is exceeded.

An embodiment of the Infusiera printer of the present invention will be explained in detail with reference to the drawings (FIGS. 2 and 3).

FIG. 2 is a block diagram of the infusier 1 to printer of the first embodiment of the present invention.

As shown in FIG.
, G (green), and B (blue).
An appropriate gradation image is formed from the color separation signal by using the color separation unit 2 that converts the color separation signal into color separation signals of (mapinta), C (cyan), and K (black), and the above-mentioned "main adjustment method" of the present invention. a gradation adjustment unit 3 that processes the gradation adjustment unit 3 so that the gradation adjustment unit 3
The infusier 1 is composed of four blocks, including an output section 4, which ejects ink droplets of each color from the infusiera 1 to the head based on output signals from the output section 4.

Here, the detection unit 1 includes a photomultiply, solid-state & afron element (C
Detects the transmitted light or reflected light of each part of the original 5 such as CD), outputs R, G, B, and tJSM signals as current values, and converts these signals into voltage signals in the A/V converter 6. do.

Color separation section 2t, in log amplifier 7, R of detection section 1
, G, B, and USM voltage signals are converted into density by logarithmic operation. In basic masking (BM) 8, the black (K) component is separated from this density, and roughly Y,
Separate the M and C components. Next, color
CC) In part 9, R, G, Bc15 and Y, M, C
Y component, M component, and C component for each original color in [ ]
- Roughly remove the black components of the original using LJCR (under color remove) in the UCR/UCA section 10.
al>, or UCA (under color
addition), determine the ratio expressed by three types of ink, Y, M, and C, and the ratio expressed by 1 ((black ink). These Y, M.

After the C and C components are obtained, the gradation adjustment section 11 obtains the Y and M components.

ye- indicates the pixel density value in the pixel block of each color component from C and K, that is, the effective area ratio of each color component.

Conversion to me-, ce-, and ke- is performed. Gradation adjustment section 1
1 has [this adjustment method-1 algorithm inside, Y
, M, and C, respectively, and the "ye-, me-, cc" are obtained.

Find ke-.

The gradation adjustment section 11 has the algorithm of "this adjustment method" as software, and the I/O of A/D and D/'A.
, a general-purpose computer with /F (interface), an electric circuit realized by a general-purpose IC using the algorithm as logic, and an RO that holds the calculation results of the algorithm.
It can take four different forms, such as an electric circuit including M, a PAt that embodies the algorithm as internal logic, a gate array, and a custom IC.

The effective area ratio corresponding to the color density information of each color component obtained by the gradation adjustment section 11 is determined by the color channel selector 12.
and the color channel selector 12 selects ye-,
Outputs me-, ce', and ke-. This output is Δ/D
The data is A/D converted by the converting section 13 and input to the dot control (D/C) section 14 for each color. Based on this input information, the inkjet head 4 (4
Driving voltages are applied to each pixel block (Y, 4), 4, 4C, 4K) corresponding to the number to be covered with dots, that is, corresponding to the color density. Then, each color ink is sequentially ejected onto the recording paper 15 while being controlled in sequence to form a recorded image with excellent gradation.

FIG. 3 is a diagram of an inkjet printer according to a second embodiment of the present invention. The one in Figure 3 uses the TV low signal as the image information signal of the original image, inputs it to the adjustment section with the "main adjustment method", converts it into a digital signal in the Δ/D conversion section, and charges it. The signal is input to the signal driver 13. The ink droplet 6 is charged by the charging unit 7 based on this input (ig).

Note that the amount of charge in a pixel block is 1'C-dot1-'
c corresponds to the amount of pixels covered, that is, the color density value. The ink droplets charged to an amount of charge corresponding to the color density are deflected by the deflection unit 8 and reach the recording paper 10 .

Infusiera 1 of the present invention - ``In forming an image using a printer, the coverage key (pixel density value) of a pixel may be changed by dot size modulation, such as a halftone dot in printing technology,'' or Dayzama 1~
It may also be possible to devise an arrangement of prescribed dots (dots of a certain size) as seen in the Rix method. (Density Modulation of Dots) Next, the usefulness of the "one-line adjustment method" applied to the gradation adjustment mechanism of the inkjet printer of the present invention will be supplementarily explained.

This is a supplementary explanation to facilitate understanding of the present invention. Operation of relational expression (1) and significance of its results)
I will mainly explain this in detail.

0) Operational experiment of "this adjustment method" The following two experiments were conducted as basic experiments for incorporating "this adjustment method" into the gradation adjustment mechanism.

a) First, use an ordinary simple calculator, namely Sharp Pythagoras EL509A (manufactured by Sharp Corporation), and apply the desired values to the "main adjustment method" while operating the simple calculator to calculate the following: Tone adjustment sections for the images shown in Table 1 O] ■■, Tables 2 and 3 were created.

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

b) The following experiment was also conducted.

Simple personal computer (NEC PC-98
01-M2>, input the desired software obtained separately as function data, and convert the basic density value (1) of the original image (continuous tone image) to the corresponding density value of the pixel on the recorded image (relational formula 〇) Adjustments were made to the following values:

As a matter of course, the result was the same value as the one obtained by manually calculating the above-mentioned simple calculator.

Moreover, in this experiment, the above software for adjusting the gradation of images input to the personal computer was created using the N88-BASIC that came with the personal computer, without using any special software. However, it only took one hour to complete.

In addition, it is also possible to convert the gradation of the target image by using software that allows you to directly input the measured values from a densitometer ranging from highlights (T1) to shadows (S) of the original image instead of the base W temperature value of the original image. It has been confirmed that modifications can be made.

Using these software 1~, set the desired density interval (for example, from 0.00 to 1.00 to 0.0
The target pixel 6 degree value (y) can be obtained by manually commanding the value to the personal computer. Ta.

Furthermore, by inputting density values at multiple locations from highlights to shadows on the original image, it was possible to obtain desired pixel temperature values (y) corresponding thereto.

The pixel temperature value (y) generated by the software mentioned above can be output as either a positive image or a negative image, either individually or simultaneously.

Next, the usefulness of Table 1 (3), Table 2, and Table 3 will be explained.

[About Table 1 ■■■] Table 1 shows that when creating a black and white image from an original image using an image forming device, the ideal In order to obtain a typical gradation characteristic curve, the pixel temperature value (y
) is what a wise man should do.

Also, even if the density of the ink is the same from this - Kento (
In other words, how the ideal halftone gradation characteristic curve changes when the usage range of pixel temperature values changes (even if the density range is the same) as shown in the leftmost column of Table 1. You can do whatever you need to do.

By the way, it is possible to create a black and white image with a 1:1 pixel distribution from a manuscript image such as a continuous tone image, and to master techniques and methods that can arbitrarily adjust the gradation of a black and white image. It is also the basis of multicolor image formation.

[About Table 2] Table 2 shows, as in Table 1, when the density of the image forming material (ink) changes when forming a black and white image from an original image (recorded image @changes in density range), Pixel density value (y)
While using 0% to 100%, the pixels at each sample point necessary to form an image with the same image tone and similar image quality to the human visual sense, apart from the overall pixel contrast. It is necessary to set the concentration value (y) to -sage.

In other words, in the ideal case, it is a list of pixel density values at each sample point on the ideal gradation characteristic curve corresponding to the maximum density value of the image forming material (ink) used. be.

[About Table 3] Table 3 has the same basic conditions as Table 2, but when using the range of pixel density values (5% to 95%), each value on the ideal gradation characteristic curve This is a table showing what percentage of pixel density values should be set at sample points.

Incidentally, it is unnecessary to explain that this list is the prototype of ``this adjustment method.''

Until today, for color separation work such as the creation of print image 1, color correction using masking techniques has been primarily done by hand, and image gradation adjustment work has basically been done by hand. relies exclusively on human experience and intuition, or on a limited number of fixed given materials.For this reason, it is based on the side of the image to be reproduced, such as a stamp, a single image, or an image recorded by a printer. Is it necessary to scientifically analyze image gradation adjustment?

[This adjustment method-1 performs gradation adjustment work during image formation in a rational manner17, and also calculates the correlation between the basic density value of the original image and the pixel density value of the image to be formed. The data in Tables 1 to 3, which show these relationships, will serve as useful basic data for scientific consideration of the basic divine matters in J-3 in the pre-color separation work during image formation. It is something.

From each of these people, what is the essence and principle that exists between the manuscript image and the color separation work, and what is the book? It is possible to extract what needs to be paid attention to and considered in order to rationally match -1, principles, and practice.

In addition, in creating Tables 1 to 3, all α-1oo
%, β-0%.

([1) Application of the ``r main adjustment method'' to gradation correction (or change) Next, ``the main adjustment method'' is used to convert the gradation of an image (i.e., to convert a continuous tone original image to a high-fidelity image). This shows that it is effective not only for converting to a gradation image based on pixel distribution, but also for modifying (or changing) the gradation of the original image itself. Fix (
(or change) is a necessary means, for example, when moving the position (M2) where the pixel density value is 50% depending on the size of the reduction/enlargement ratio, or when you want to strongly express the gradation of highlights or shadows. be.

For example, when the H and S pixel density values of the formed image are fixed at specific values of 5% and 95%, changes in the reflection density (based on yellow ink) of the image forming material (ink) or the original The pixel density value (y), which is an extremely important control point in image formation based on pixel distribution, changes to 50% due to changes in the reduction rate and enlargement rate of the recorded image formed from the image.
The problem is how to move the set point (M2) that is % to correct or change the gradation of the image.

Table 4 shows an example of basic materials that can be used to solve this type of problem.

Base li! i! By preparing multiple materials according to the actual work needs, you can reasonably move the position (M2) where the pixel opening value is 50%, thereby correcting the image gradation. (or change).

Temperature range of recorded images in Table 4 (corresponds to DRp in Figure 1)
is determined by the solid color of the ink used (and the value of β is determined based on this), and the value of
The number in parentheses at the top left of each space (frame) in the table is the basic density value (1) at that sample point, and the number at the bottom right is the pixel density value corresponding to each basic density value. (1) is shown.

However, the range of pixel density values used was 5% to 95%. The h1 values shown in Table 4 are pixel) flash intensity 1 straight (y)
This is extremely important when managing 50% location.

For example, "When creating an image with a reduction/enlargement ratio of 100% from a color 1 product using 71 film, when the recorded image @density range is 0.95 and the ε value is 1°12638, the image has the desired image quality. Next, based on the estimated values in Table 4, create a gradation characteristic curve to obtain a recorded image based on the pixel distribution (in other words, the horizontal axis is the basic density value of the original image ( (The pixel density value (y) is taken on the vertical axis to create a gradation characteristic curve.) Next, change the reduction/enlargement ratio for the reference color component, and when reducing it, change the pixel area ratio. For image formation, move the 50-6 position to the S side, and move the edge to the [-1 side when enlarging.

The test image obtained in this way is compared with an image 71 of the image tta<image of the reference component, in which the desired image quality is obtained. If you select a test image with the same image quality as the image quality of the latter pixel Ylj and reduce it to, for example, 1/2, the density range of the image formed will be 0.85 and the ε value will be 1.
．． 16449. Assume that when the image is enlarged to 200%, the density range of the image formed is 1.10 and the ε value is 1.05958. Then, create those gradation characteristic curves, and based on the intersection point with the straight line where the pixel density value (y) on the curve is 50%, sample points of that density value of the original image (in practice, the original image sample points on a working standard gray scale that is representative of the pixel density value (y, >50%
You can know what is good if you enter the . The reason why the density value corresponding to the pixel density value (y) of 50% was selected as the sample point is to facilitate inspection of the recorded image by pixel separation after color separation work. Therefore, another method is to select a sample point at 2/8° to 4/8 of the lt2 degree range of the original image, find out what percentage of the corresponding image temperature value should be from the gradation characteristic curve, and based on this, It is also a good idea to perform pre-color separation work. By using Table 4 in this way, it is possible to rationally modify (or change) the image at the same time as converting the gradation of the image.

Note that the correction (or change) of the gradation of this image depends not only on the reduction/enlargement ratio of the image formed by one person, but also on the intention of the orderer, the type of target image in the color manuscript, the purpose of use of the image to be formed, and the recording. White text on paper and image recording materials (ink)
There may be cases where it is necessary to perform color separation depending on the degree of C, etc., but in any case, it can be handled rationally using Table 4, and various color separation operations can be standardized.

Furthermore, according to the present invention, it is possible to correct (or change) the gradation of images in highlight areas and shadow areas in the same way, and furthermore, special measures can be taken to correct color fog in highlight areas of color originals. It can be automatically removed without any training.

(Margin below) (Effect of the invention〕 The present invention has the following excellent effects.

1) The correlation between the density of an original image such as a continuous tone image and the pixel temperature value of the formed recorded image (image recorded by pixel distribution), which is the most basic matter for image formation. In the past, the decision was made based solely on the experience and intuition of the worker, or based on data on a limited number of fixed forecasts, which was an irrational method, but with the present invention, Even if it is below, it can be replaced with a rational and easy decision method. Furthermore, when converting an original image such as a continuous-tone image into a recorded image based on pixel distribution, the most important requirement, gradation management (gradation conversion, modification, or change), is simply the image gradation. It is not limited to just the tone, but also has a direct and deep relationship with the color tone of the image.
According to the present invention, gradation and color tone can be managed rationally. In other words, Infusiera 1 to Plink, which incorporates "this adjustment method" in the gradation adjustment mechanism, can theoretically and rationally systematize color separation work, gradation conversion work, etc., and simplify the work. , the effect is extremely large.

2) By incorporating "this adjustment method" into the gradation adjustment mechanism of an inkjet printer, the printer device can be streamlined and simplified! ! In addition to reducing production costs, operations are also simplified and clearer, greatly reducing the need for rework, and greatly reducing the consumption of consumables, thereby improving the performance of inkjet printers. can be significantly improved.

3) By using a gradation adjustment mechanism using the "one line adjustment method", it is possible to rationally and simply specify the quality evaluation of recorded images using 15 pixels, separated from the image information of the original image. Can be done. In other words, "this adjustment method" can scientifically and objectively define the highlights, shadows, and density gradation characteristic curves from shadows to highlights of the original image, and can centrally adapt the mechanism of current printers. It can be streamlined.

4) By adopting "this adjustment method," it is possible to effectively educate and train technicians, which is required as printer equipment becomes more sophisticated, and eliminate unnecessary This saves labor and frees up time for new creative research and development.

[Brief explanation of the drawing]

Figure 1 (■) shows an example of converting a document image into a recorded image using a pixel distribution via a density-compressed document image, and FIG. FIG. 3 is a diagram showing an example of converting to a recorded image based on the distribution of . FIG. 2 is a block diagram showing a first embodiment of the inkjet printer of the present invention. FIG. 3 is a block diagram showing the second embodiment. Patent applicant Yamatoya Shokai Co., Ltd. Agent Patent attorney Yoshio Mizuno Figure 2

Claims (1)

[Scope of Claims] 1. In an inkjet printer that forms a recorded image having halftones of one color or multiple colors on recording paper based on an image information signal obtained from an original image, the image information signal is transmitted to the original image. The basic density value (x) of an arbitrary sample point on the image (the difference between the density value at the sample point and the density value at the brightest part on the same image) corresponds to the sample point of the recorded image to be formed. Pixel density value (y) at the position
An inkjet printer characterized in that it is equipped with a gradation adjustment mechanism that performs processing so that the 2. The gradation adjustment mechanism converts the image information signal into the basic density value (x) of an arbitrary sample point on the original image and the pixel density value (y) at the position corresponding to the sample point in the recorded image to be formed.
The inkjet printer according to claim 1, wherein the inkjet printer is processed as defined by the following relational expression (1). <Relational expression> y=yh+{α(1-10^-^k^x)/α-β}(
ys-yh)...(1) [However, x: Basic density value of an arbitrary sample point X on the original image. That is,
A density value obtained by subtracting the density value at the brightest part H of the same image from the density value at an arbitrary sample point X of the same image. y: pixel density value at position Y corresponding to X on the recorded image to be formed. yh: A density value of a desired size, which is set for the pixel of the brightest part H of the recorded image to be formed. ys: A density value of a desired size set for the pixel of the darkest part S of the recorded image to be formed. α: Reflectance of recording paper. β: Surface reflectance of ink. k: represents the ratio of (density range of the recorded image to be formed)/(density range of the original image). 3. The recording image according to claim 1 or 2, wherein the recorded image having halftones is a dot size modulation image formed by changing the recording dot diameter by controlling the amount of liquid ejected from the inkjet head. inkjet printer. 4. The inkjet printer according to claim 1 or 2, wherein the recorded image having halftones is a dot density modulation image formed by a dither matrix.