JP2000079751A - Method for forming screen for multicolor continuous tone image, and its printed matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To complicate a design by printing a continuous tone image by using screens of different shapes for respective color plates, thereby preventing a moire or a deviation or the like of a printed position. SOLUTION: In a multicolor printed matter, a screen S1 using concentric circle parallel lines for a screen representing separated colors A1, A2, A3 by separating a continuous tone image G1 into three color plates A1, A2, A3, a screen S2 using straight line group of a hook shape generated by taking offset at a predetermined pitch from straight lines of cross shape passing a center of the parallel lines S1, and a screen S3 using a set of dots disposed by a dither method are formed, the screens S1, S2, and S3 are printed by respective colors, thereby forming the printed matter representing multicolor continuous tone image G1.

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention creates a group of objects of different shapes and a set of dots by a dither method as a screen for expressing each color plate in all multicolor printing including process printing. And a printed material thereof.・

[0002]

2. Description of the Related Art Conventionally, in printed matter of multicolor printing,
When a multicolor continuous tone image is expressed by a process or a special color, as shown in FIG. 11, a halftone screen is used for all the plates as a means for expressing the gradation of each color plate. The only difference between screens is the angle and the number of lines.・

[0003] In addition to the screen using halftone dots,
Screens having an image configuration as shown in FIG. 12 such as a line screen, a concentric line screen, and a wave line screen are also used.・

[0004] The principle of generating a screen having the above-mentioned object configuration is as shown in FIG. 13, as shown in FIG. 13, when a set G4 of arbitrary objects and a continuous tone image G5 are superimposed on each other, By determining the image width of the G4 in accordance with the gradation of the G5 in the located portion, a printed matter G6 representing the G5 having the image shape of the G4 as a screen is generated.・

A set G6 of the screened objects
The method of determining the image width will be described in detail. FIG. 14A shows an object P1 constituting a group of objects G4 before the image width is determined, and a part of the continuous tone image G5, and FIG. The figure shows an object P1 that forms an aggregate G6 of objects that are screened with the object width determined. Like the object P1, the object width of the object P1 where the part M2 where the gradation of G5 is 100% is located is Wmax, and the object M3 where the part M3 where the gradation of G5 is 0% is located. Set the stroke width of P1 to Wmin
Is set, and the gradation of G5 is expressed in the range of the object width Wmax to Wmin of the object P1 constituting the object aggregate G4. That is, the object line width W1 of the object line P1 where the portion M1 of the continuous tone image G5 having the gradation α% is located is (Wmax−Wmin) × (α / 10
0) + Wmin. By reflecting the gradation of the continuous tone image G5 on the object width of all the objects constituting the object pattern G4 by the above-described method, the G5 having the object shape of the G4 as a screen is used. A printed matter G6 is generated.・

Further, as shown in FIG. 15, there is also used a screen generated by a dither method in which each color plate is divided into small arbitrary units and binarized, and one dot per unit is arranged in a portion of 100% density. ing.・

A method of generating a screen by the dither method will be described. As shown in FIG. 16A, the continuous tone image G8 is divided in fine units, and divided as shown in FIG. Average the density in the region. Further, a portion where the density of the averaged image G9 is 50% or more.
In M5, one dot is arranged in the area, and nothing is arranged in a portion M4 of less than 50%, and the area M4 is blanked.
A screen G10 representing the image G8 shown in (c) is generated. However, the size of the dots to be arranged must be all the same.・

[0008]

When a multi-color continuous tone image is created by a conventional screen-shape method such as a line screen, the image shape and arrangement of a screen used for each color plate. However, since all the printing plates are the same, there is a drawback that the printing position shift of printing is conspicuous, and as shown in FIG. 17, the printing position shift causes moire. Due to the above drawbacks, conventional image-shaped screens have usually been used to represent monochromatic continuous tone images. SUMMARY OF THE INVENTION An object of the present invention is to use a screen having a different shape for each color plate for a continuous tone image, thereby preventing moiré at the time of printing, a shift in a printing position, and the like, and attaining a complicated design.・

[0009]

[Means for Solving the Problems] A multi-color continuous tone image of 3
A hook-shaped straight line generated by offsetting at a fixed pitch from a concentric circle line and a cross-shaped straight line passing through the center of the concentric circle line as a screen that separates the colors and expresses the three separated colors. A multicolor continuous-tone image screen is created using a group and a set of dots arranged by the dither method.・

[0010] A multicolor continuous tone image is decomposed into three colors, and as a screen for expressing the decomposed three colors, a concentric circle line and a cross-shaped straight line passing through the center of the concentric circle line at a constant pitch. A printed matter characterized by using a group of hook-shaped straight lines generated by taking an offset and a set of dots arranged by a dither method, and superimposing and printing the multicolors.・

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as a screen for a continuous tone image printed in three colors, a plate using concentric circle lines and a cross-shaped straight line passing through the center of the concentric circle lines are used. A version using a group of hook-shaped straight lines generated by taking an offset at a pitch of and a version using a set of dots arranged by the dither method are created.・

Further, by printing using the three screens prepared above in each of the colors, it is possible to prevent moiré and displacement of the printing position at the time of printing, to complicate the design, and to prevent forgery. A printed matter of a continuous tone image having an effect of prevention can be produced.・

[0013]

Embodiments Embodiments of the present invention will be described below. In the present invention, as shown in FIG. 1, a plate using concentric circles is used as a screen of a multicolor continuous tone image G1 printed in three colors.
From S1 and a cross-shaped straight line passing through the center of the concentric circle line,
A plate S2 using a group of hook-shaped straight lines generated by offsetting at a fixed pitch and a plate S3 using a set of dots arranged by the dither method are created. The plate S1 using the concentric lines and the plate S2 using a hook-shaped line group generated by offsetting at a constant pitch from a cross line passing through the center of the concentric lines are used for printing. Even if the printing position shifts, moiré does not occur as in the conventional screen. Further, the plate S3 using the set of dots arranged by the dither method is the two plates S1 and S2.
Since the principle of screen generation is completely different from that described above, moire does not occur even if the printing position is shifted. In addition, the multi-color continuous tone image information is added to the printed matter of the securities, even though the object is composed, and the object composition on the printed matter is complicated. This makes it difficult for a scanner to forge.・

First, as shown in FIG. 2, the multicolor continuous tone image G1 is decomposed into three color plates A1, A2, and A3. Next, a method of creating a screen for expressing the color plates A1, A2, A3 of each of the three colors of the continuous tone image G1 will be described.
・

First, as shown in FIG. 3, a concentric line S4 is created as a screen for the color plate A1. However, the concentric circle line S4 is arranged in a square frame of one side W, and FIG.
As shown in the figure, the S4 is repeatedly arranged vertically and horizontally to cover the entire color plate A1. However, the value of one side W of the frame in which the concentric circle line is arranged is arbitrary,
It is assumed that the interval between the concentric circles constituting S4 is constant.
In addition, the center of the square frame on one side W and the position of the center of the concentric circle line must coincide.・

Further, the image width of the concentric line S4 is determined by the gradation of the color plate A1 in the same manner as the principle of the conventional line screen.
S1.・

Next, as shown in FIG. 6, the screen of the color plate A2 is generated by taking an offset P / 2 outward from a cross-shaped straight line passing through the center of the square of one side W. Create the four hooks Q1, Q2, Q3, Q4 to be performed. Further, by taking an offset P outward from the four hooks Q1, Q2, Q3, and Q4, four further hooks Q5, Q6, Q7, and Q8 are generated. A straight line group is generated by repeating the above-described operation, and a straight line group in which the center cross line is finally deleted is a hook-shaped straight line group S5 shown in FIG. Also, as shown in FIG. 8, the S5 is repeatedly arranged vertically and horizontally to cover the entire color plate A2.・

Further, the image width of the hook-shaped straight line group S5 is
Similar to the principle of the conventional line screen, the one determined by the gradation of the color plate A2 is the screen S2 of the A2 shown in FIG.・

Next, as shown in FIG. 10, the color plate A3
The screen S3 is generated by the arrangement of dots by the dither method as the screen.・

Finally, as shown in FIG.
1, A2, generated as a screen expressing the gradation of A3, by superimposing and printing the S1, S2, S3 in each color, while preventing moiré during printing, and to prevent the displacement of the printing position, etc. The printed matter G1 of the multicolor continuous tone image, which can complicate the design and has a forgery prevention effect, is reproduced. Note that there is no limitation on which screen to use for which of the three colors.・

[0021]

As described in detail above, according to the present invention, as a screen of a continuous tone image printed in multicolor, a plate using concentric circle lines and a cross-shaped line passing through the center of the concentric circle lines are used. From a straight line, a version using a group of hook-shaped straight lines generated by offsetting at a constant pitch, and a version using the concentric circle line to use a set of dots arranged by the dither method, The plate using the hook-shaped straight line group does not cause moire as in the conventional screen even if the printing position is shifted during printing. In addition, since a plate using a set of dots arranged by the dither method has a completely different screen generation principle from the two plates, moire does not occur even if the printing position is shifted.・

Further, according to the present invention, multicolor continuous tone image information can be added to the printed matter of the securities, even though the object has a streak structure, and the design can be complicated. Can be difficult.
・ ・

[Brief description of the drawings]

 ・

FIG. 1 is a diagram showing a printed matter using a screen for a multicolor continuous tone image of the present invention.

FIG. 2 is a diagram in which three color plates are generated from a multicolor continuous tone image.

FIG. 3 is a diagram showing a method of generating a concentric circle used as a screen.

FIG. 4 is a diagram showing a method of arranging concentric circle lines in a pattern.

FIG. 5 is a diagram showing one color plate of a continuous tone image with concentric circle lines as a screen.

FIG. 6 is a diagram showing a method of generating a hook-shaped straight line generated by offsetting a cross-shaped straight line passing through the center of the concentric circle line.

FIG. 7 is a diagram showing a method of generating a group of hook-shaped straight lines generated by offsetting at a fixed pitch from a cross-shaped straight line passing through the center of the concentric circle line.

8 is a diagram showing a method of arranging the straight line group of FIG. 7 in a pattern.

9 is a diagram showing one color plate of a continuous tone image using the straight line group of FIG. 8 as a screen.

FIG. 10 is a diagram showing one color plate of a continuous tone image using a halftone dot as a screen by the dither method.

FIG. 11 is a diagram showing a printed matter of a multicolor continuous tone image on a conventional halftone screen.

FIG. 12 is a diagram showing a printed matter of a single color continuous tone image on a conventional line screen.

FIG. 13 is a diagram showing a method of forming a screen by reflecting the gradation of a single-color continuous tone image on the line width of a line.

FIG. 14 is a diagram showing a method of determining the line width of a line generated as a screen for expressing a continuous tone image of a single color.

FIG. 15 is a diagram showing a printed matter by a halftone screen of the dither method.

FIG. 16 is a diagram showing a halftone dot generation method of the dither method.

FIG. 17 is a diagram showing moire.

[Description of sign]

G1 Multicolor continuous tone image printed by the screen of the present invention G2 Multicolor continuous tone image printed by the conventional halftone screen G3 Monochromatic continuous tone printed by the conventional line screen Tone image, G4 straight line, G5 Single color continuous tone image, G6 A screen that represents a single color continuous tone image G5 with straight line width, G7 Single color printed using a conventional dithered halftone screen Continuous tone image G8 Part of G7 G9 G8 averaged density for each minute unit G10 image G9 image expressed by gradation by arranging dots in areas where the gradation is 50% or more A1, A2, A3 Each color plate when the multicolor continuous tone image G1 is decomposed into three colors, P1 Strokes that compose a straight line G4, and M1 Monotone continuous tone image G5 where the gradation is α%・ M2 single-color continuous tone image G5 part where the tone is 100% ・ M3 single-color continuous tone image Part where the gradation of G5 is 0% ・ Part where the gradation of the M4 image G9 is 50% or less ・ Part where the gradation of the M5 image G9 is 50% or more ・ W One unit size of the concentric circle line ・ W1 Single color Image width of image line P1 determined corresponding to portion M1 of tone α% of continuous tone image G5, Wmax Determined corresponding to portion M2 of 100% tone of monochrome continuous tone image G5 Object width of object P1 ・ Wmin Object width of object P1 determined corresponding to 0% gradation M3 of monochrome continuous tone image G5 ・ S1, S2, S3 Continuous tone image G1 A screen that exhibits the effect of the present invention that expresses each color plate of S4 concentric circles S5 hook-shaped straight line group Q1, Q2, Q3, Q4 From a cross-shaped straight line passing through the center of a square with one side W to the outside Four hooks generated by taking an offset P / 2 toward the end ・ Q5 Hooks generated by taking an offset P toward the outside from Q1 ・ Off from Q6 Q2 toward the outside The hook shape generated by taking the offset P. The hook shape generated by taking the offset P outward from Q7 Q3.The hook shape generated by taking the offset P outward from Q8 Q4. P Offset width of hook-shaped straight line group

Claims (2)

[Claims] ・ 1. A multicolor continuous tone image is decomposed into three colors, and a screen that expresses the decomposed three colors includes a concentric circle line and a cross-shaped straight line passing through the center of the concentric circle line. A method for producing a multicolor continuous tone image screen, comprising using a group of hook-shaped straight lines generated by offsetting at pitches and dots arranged by a dither method.・ 2. A screen for decomposing a multicolor continuous tone image into three colors, and as a screen for expressing the decomposed three colors, a fixed line from a concentric circle line and a cross-shaped straight line passing through the center of the concentric circle line. Using a screen for a multicolor continuous tone image using a group of hook-shaped straight lines generated by offsetting at a pitch and a set of dots arranged by a dither method,
A multi-color continuous tone image printed matter, which is printed by overlapping colors.・