JPS5919164A - Image-forming method - Google Patents

Abstract

PURPOSE:To enable to form an image free from roughness or glaring feeling, by expressing a tone through a modulation of an arranging pitch of image-forming elements under non-quantization and a modulation of areas of the image-forming elements. CONSTITUTION:An image is formed by operating image-forming elements (e.g., dot pins or ink dots) by an image-forming signal (b) corresponding to a density signal (a) for the image to be formed. Pulse signals S1-S10 contained in the signal (b) have the same width, but the level thereof is varied to be L1-L3. The pulse intervals are non-quantized, that is, they are not made to be multiples of the minimum interval. The areas of the image-forming elements E for forming the image on a paper in accordance with the image-forming signal (b) are also modulated in a manner of E(1)=E(2)=E(3)=E(4)>E(5)=E(6)=E(7)>E(8)=E(9)= E(10) in accordance with the levels of the pulse signals S1-S10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming method for expressing so-called image information in a visually perceivable state, which has two-dimensional flooring such as characters, graphics, graphs, images, etc. This invention relates to an image forming method that expresses image information with tonality.

In the field of image information recording, for example, methods for expressing image information with gradation, that is, image information including intermediate R11()1-ftone) information in a visually perceivable state, include: The number of image forming elements having a certain optical density and a certain area, which are provided within a desired certain minute area (unit area: hereinafter referred to as a cell) constituting one pixel, and the arrangement within the pixel. Conventional examples include controlling the state and expressing it through traps.

That is, in the conventional example, for example, one pixel is subdivided into a plurality of cells that can be occupied by only one of the image forming elements in the form of a matrix (hereinafter referred to as a cell matrix), and the cells constituting the cell matrix are A desired level of gradation is expressed depending on the number of cells occupied by the image forming elements and the arrangement state of the image forming cords occupying the cells.

The image-forming elements are arranged so that the arrangement pitch is an integral multiple of the minimum arrangement pitch determined by the cell size (hereinafter referred to as standard arrangement pitch Ps) (hereinafter, this is referred to as quantized (expressed as image forming elements arranged below the arrangement pitch).

According to this method, if you want to improve the gradation, you can either increase the area of one pixel itself (pixel area) or reduce the area of the image forming element as much as possible to reduce the size of the cells that make up one pixel. It is necessary to increase the number.

In the former case, it is an undeniable fact that the larger the pixel area is, the further the sharpness and resolution will be reduced and the image will become rougher, so this is not desirable from a practical standpoint.

Even in the latter case, if you try to increase the number of hills constituting one pixel while maintaining a certain degree of sharpness and resolution, you will realize that there is a limit to reducing the area of the image forming element. There is a limit.

Therefore, when trying to express a wide range of gradations from gradation levels with higher optical density to gradation levels with lower optical density, the gradation expression becomes finer due to the lack of the number of gradation levels that can be expressed. The image lacks grain and has a ``grainy'' or ``rough'' feel to it. Furthermore, if you try to express the gradation in fine wood grain, the range of gradation expression cannot be wide enough, so either the highlights or the dark areas cannot be fully expressed, and the resulting image will not be able to fully express the dark areas, for example. If you try to express the gradation well enough, you should give a 1-glare feeling to the light and illumination areas, which is stimulating to the eyes, and try to express the gradation of the light and light areas sufficiently well. Otherwise, the overall tone will be low and lack sharpness. In any case, if you try to express fine grain gradation, the gradation expression area will become uneven, resulting in an unnatural image.

The present invention has been made in view of the above points, and it is possible to achieve fine gradation in a wide gradation expression range from a gradation level with a higher optical density to a gradation level with a lower optical density. The main purpose is to propose an image formation method that can express sexuality.

Another object of the present invention is to propose an image forming method that provides images with excellent sharpness and resolution.

The image forming method of the present invention is an image forming method in which an image is formed by arranging image forming elements. By configuring a gradation expression area that can be expressed by a gradation expression area by modulation under quantization and a gradation expression area by modulating the area of the image forming element, the gradation can be improved. It is characterized by forming a sexual image. According to the image forming method of the present invention having such characteristics, it is possible to easily produce a non-irritating image that is free from roughness, roughness, and glare in highlighted areas. You can.

Furthermore, since it is possible to express fine gradation in a wide range of expression, it is possible to obtain images with excellent naturalness. Furthermore, the images obtained by the image forming method of the present invention are excellent in sharpness and resolution.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory diagram for explaining the basic concept of the present invention. For example, the change in optical reflection density (of course, it may also be expressed as optical transmission density) on one scanning line of the image to be expressed is shown by the density signal sequence (&) in diagram m1. shall be.

W indicates the lowest gradation level, that is, the level with the lowest optical reflection density, for example, the white level, and B indicates the highest level of the gradation level, that is, the level with the highest optical reflection density, for example, black. Indicates the level, FT+, L, TI, (It,
(b) shown in FIG. 1 shows the optical reflection density at an intermediate level between them. In the figure, the shape of the image forming element is circular, which is generally used. Pulse signals S, ˜S1°, which vary in level as , L□l L3, are arranged in time series under a non-quantized arrangement pitch. The image forming element Eli for forming an image, the above-mentioned expression signal (b) K, is therefore arranged under a non-quantized arrangement pitch on a recording medium such as paper, and the image forming element E is arranged on the recording medium such as paper. In this state, the gradation with the density change shown by the density signal (a) is expressed.

That is, in the first image, the image forming elements E are arranged in a one-to-one correspondence with the pulse signals S and 5IOK [2].

The arrangement pitch between each image forming element of ~Eln is P, = P2
= Ps < Pg = P-< P4 < Pt
The relationship is <Pg<Pl, and it is not an integral multiple of Pl, which is the minimum arrangement pitch. Clogging, arrangement pitch P
, for each array pitch h, is not childified. Then, the area of the image forming element E also changes according to the level of the pulse signal (b) as E(+l = E(t+ = ID(31
> E(u)=E (I11= E+71> E(i
= E(, 1 = E(,.), respectively.

In this way, according to the present invention, the array pitch P and area of the image forming elements E are continuously modulated according to the gradation level expressing the area, thereby creating an image having a desired gradation property. It is something that is fully expressed.

In the invention, the arrangement pitch P is 0 (a state in which the two image forming elements are completely overlapped; if the image forming element E is circular as shown in FIG. 1, the center point of the circle is It is continuously modulated within a range of values that can be arbitrarily determined depending on the desired image quality of the image to be formed. Assuming that the area of two successively arranged image forming elements is 5II82, the upper limit of the array pitch modulation area is the image forming element E.
Duty ratio D in the array = (f tile + (L > /
Determined by the values of C, II'ma and P) (however,
P is the array pitch). That is, as the duty ratio {circle around (2)} becomes smaller, the naturalness of the image formed by °C1 is gradually lost, and when the duty ratio becomes smaller than a certain value, the naturalness is rapidly lost.

This tendency becomes more pronounced as the optical reflection density of the image forming element increases.

In the present invention, when the optical reflection density of the image forming element E is high, in order to achieve the objective more effectively, the arrangement pitch is adjusted under the condition that the duty ratio is 0.5 or more. is preferably modulated.

In the present invention, the arrangement pitch P of the image forming element E is continuously changed by 1.1 from 0 to a value suitably calculated as desired without quantization. teeth,
They can be arranged with continuity from a completely overlapping state to a completely separated state. Further, the area of the image forming element E can also be continuously modulated from the minimum area value to the maximum area value.

That is, to explain with reference to FIG. 1, at density level B,
Image forming element E(II, E(2)t E +
81 *E(4) is the same arrangement pitch (P + = Pt”
Ps) and are arranged so that a partially overlapping region is formed in the occupied region. At the density level H1, the image forming element E (51
p”, +61 + E(7)° are arranged below the arrangement pitch (Ps=P6) such that they are circumscribed with the adjacent image forming elements. Between the density level B and the density level H, teeth,
It is switched by the arrangement pitch P4 and the area modulation of the image forming element body E. The density level ■■ is such that the image forming elements E(81tE(9)) having a smaller area than the image forming element E(6) are arranged at an arrangement pitch P such that they are spaced apart from each other by a desired distance. At density level HI, one image forming element Ea
It is expressed as i. - and dark IA; - level H, and density level Il, , 6 degree level 11. and the density level are switched at the arrangement pitch pt + P, respectively.

In this way, in the image forming method of the present invention, the image forming element E
Analog modulation of two factors, the array pitch and area, enables smooth gradation expression over a wide range of expression.

FIG. 2 shows the on-demand (on-demand) image forming method of the present invention.
A block diagram when applied to an inkjet monochrome printer is shown.

An input signal Sla+ having gradations such as a video signal is amplified by an amplifier AMP, and a frequency modulation section FM
Input to OD. The amplified gradation signal S+bl is frequency modulated by the frequency modulation unit FMOD according to the gradation characteristics, and the signal S (as el, the filter part FI
It is input to L. Frequency modulated grayscale signal S (c)
is part of the filter FIL, and is controlled by the controller C0NT.
The frequency modulation signal exceeding the highest response frequency of the inkjet head IJH is cut and the dot pitch is reduced.
It is input to the diameter control section DCON.

Signal S input to dot pitch/diameter control unit DCON
A control signal outputted from the controller C0NT to ldl provides a voltage according to the gradation characteristics, and a dot pitch is given based on the density threshold given by the controller C0NT. Inkjet head I output from dot pitch/diameter control unit DCON
The JH applied voltage signal is input to the head drive voltage control unit VOL to set the head drive voltage, and is supplied to the image forming pulse generation unit PGEN. Image forming pulse generator PGEN
Here, a pulse signal from the controller DCON switches the signal from the head drive voltage control unit VOL to generate a drive signal for driving the inkjet head J)l. In response to this drive signal, the inkjet head IJfI repeats the ON-OFF operation so that the inkjet head 1.
Ink liquid is ejected from the ejection orifice provided in J'HK to form flying ink droplets. In synchronization with the ejection of the ink liquid, the controller C0NT sends a control signal 5 (CR) to the key It, ridge control section CR, and paper feed control section PF, respectively.
).

5 (PF) is supplied, and the inkjet head JH scans the recording paper in accordance with these signals, thereby forming an image having the grade R1, 5 on the recording paper.

[FIG. 3 shows a time series of signals at each part in the embodiment shown in FIG. 2 and an example of the arrangement of dots on the recording paper.

In Figure 3, (C) is the inkjet head IJ1
It is a timing pulse for generating the drive signal of 1,
The voltage applied to the head at this time is given by (1)). The above timing pulse (C),! : Head applied voltage ([
)) generates an inkjet head drive signal fE), and this drive signal (1ε) repeatedly drives the inkjet head IJH from ON to OFF to produce a dot (
The image forming elements E) are arranged as shown in IF). (F)
As shown in the figure, the pitch between the dots (arrangement pitch) and the dot diameter change depending on the gradation level, and in the high optical density area, the dots overlap each other, thereby widening the range of gradation expression.

In the example shown in Fig. 3, the pitch modulation is performed in the entire expression region, but the dot diameter (dot area) modulation region is performed only in the high optical density region. It is also possible to perform pitch modulation and dot area modulation simultaneously.

That is, in the present invention, the gradation expression area by dot array pitch modulation and the gradation expression area by dot area modulation only need to be continuous; for example, the entire gradation expression area is A]3C.
If it is divided into four areas D, (I) gradation expression area AB
is pitch modulation.

The gradation expression area CD has area modulation; (2) the gradation expression area A has pitch modulation; the gradation expression area BC has simultaneous pitch and area modulation; the gradation expression area has area modulation nLW; 1
Table > r (areas A and C are pitch modulation 1ul1 expression areas B and I) are area modulation, (4) In the above gradation ■ expression method, if the modulation factors of the gradation expression area are swapped, etc. A large number of gradations can be expressed by combining pitch modulation and area modulation.

FIG. 4 shows a second embodiment of the present invention, which is applied to a color printer that performs color printing using on-demand inkjet type ink using three colors of yellow, magenta, and cyan ink.

First, a color video signal or 1ζ, G, and H color signals are sent to amplifiers RAMP and GAMP, respectively.

The signal is input to the color signal generating section CGEN via IIAMP. The controller CONT performs image processing on these input signals and outputs output signals corresponding to each input signal. The output signal is a color frequency modulation section YFM,
The signals are input to MFM and CFM, respectively. Frequency modulation section YFM
, M.F.M.

In CFM, after frequency modulating the input signals of the respective colors, the output signals are passed through filters YFIL and MFIL.
, CFIL respectively.

The signals of each color modulated with the same wave number in the filters YFIL, MFIL, and CFIL are controlled by the control signals output from the controllers Co and NT to cut frequency modulation components higher than the maximum response frequency of the inkjet head, and the dot pitch/diameter control units YCON and MC0N ,CC0N
are input into each. Dot pitch/diameter control MI+YC
From the signals input to ON, MC0N, and CC0N, the controller C0NT obtains a dot timing signal and a head applied voltage signal according to the change in gradation.

Dot pitch/diameter control unit YCON.

The dot timing signals outputted from MC0N and CC0N are transmitted to image forming pulse generators YGEN and MGEN, respectively.
, CGEN, respectively.

Also, dot pitch/diameter control parts YCON and MC0N.

On each of the head drive voltage signals outputted from CC0N,
Head drive riih voltage control section YVOL, MVOL.

The 11'c pressure value of the drive signal input to the CVOL and applied to the corresponding head is set.

1-image forming pulse generator, YGEN, MGEN.

In CGEN, the dot pitch/diameter control section YCON.

The input signals from MC0N and CC0N switch the head voltage control (if current from #YVOL, MVOL, and CVOL, and the inkjet head IJY,
Generates drive pulses for IJM and IJC. By this driving pulse, the inkjet head, YI JI (
, MI J.H.

CZ J fI\'i 0 N -OF' F is repeatedly driven to form flying ink droplets on the driven surface.

In synchronization with the ejection of the ink liquid, the controller CONT outputs a control signal to the key), ridge control section CR, and paper feed control section 13F, and the inkjet head scans the recording paper.

FIG. 5 is a block diagram for explaining the third embodiment of the present invention, which is a color printer that prints in color using four colors of ink: yellow, magenta, cyan, and black using an on-demand inkjet method. This is an example of application.

The circuit block shown in FIG. 5 is a black signal processing circuit section, that is, a frequency modulation section B, in the three-color printer shown in FIG.
FM, filter 13FIL.

The basic signal processing is the same as the color printer shown in FIG. 4, with the addition of dot pitch/diameter control BCON, head voltage control ftIBVOL, image forming pulse emitting section BGEN, and inkjet head 11 IJH.

FIG. 6 is a block diagram for explaining the fourth embodiment of the present invention, which is an example applied to an on-demand inkjet type monochrome printing device equipped with a reading section RIN for reading an original image. It is.

The reading main scanning control section RCR and the reading sub-scanning control section RPF are controlled by a control signal from the controller C0NT, and the reading section RIN scans the original image, thereby obtaining gradation number 44. The process subsequent to the processing of the gradation signal is the same as the embodiment example shown in FIG.

Also, the symbols used in the figures indicate the same ones as in FIG. 2.

FIG. 7 is a block diagram for explaining the fifth embodiment of the present invention, which is an on-demand inkjet system equipped with an original image reading unit and uses three colors of ink: yellow, magenta, and cyan. This is an example of application to a color printing device.

The reading main scanning control section RCR and the reading sub-scanning control section RPF are controlled by a control signal U from the controller CON i'', and the reading section RIN scans the original image to obtain a gradation signal of the original image. The process subsequent to the processing of the gradation signal is the same as in the embodiment shown in FIG. 4. Also, the symbols used in the drawings indicate the same ones as in FIG. 2.

FIG. 8 is a block diagram illustrating a sixth embodiment of the present invention, which is an on-demand inkjet system equipped with a reading section for reading original images, and uses four colors of ink: yellow, magenta, cyan, and black. This is an example in which the present invention is applied to a color printing device.

Controls the reading main scanning control section RCR and the reading sub-scanning control section RPF by a control signal from the controller C0NT,
The reading unit RIN scans the original image and obtains a gradation signal. The processing after the gradation signal processing is the same as the embodiment example shown in FIG.

4. The symbols used in the drawings are the same as in FIG. 5.

Although the above embodiments have been described with respect to on-demand inkjet printers, the present invention is not limited thereto, and can be applied to other printers, such as thermal transfer printers, wire tod printers, and electrophotographic printers. It can also be applied.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram for explaining the basic concept of the present invention, and FIGS. 2 to 8 are block diagrams of devices embodying the present invention. The first embodiment, FIG. 3 shows the second embodiment, FIG. 4 shows the third embodiment, FIG. 5 shows the fourth embodiment, and FIG. 6 shows the fifth embodiment. For example, FIG. 7 shows a sixth embodiment, and FIG. 8 shows a seventh embodiment. -e-eCcl-e--

Claims (1)

[Claims] In an image forming method of forming an image by arranging image forming elements, under non-quantization of the arrangement pitch of the image forming elements in at least one arrangement direction of the image forming elements. An image with gradation can be created by configuring a gradation expression area that can be expressed by a gradation expression area by modulation of the area of the image forming element and a gradation expression area by modulation pressure of the area of the image forming element. An image forming method characterized by forming.