JP2023089339A - Method for creating dot printed matter data - Google Patents

Abstract

To create dot printed matter data by seamless arrangement without a gap of individual dots as a dot printed matter having a complicated dot shape required for a security printed matter.SOLUTION: A method for creating a dot printed matter includes: disposing an object on a unit for forming dots; carrying out duplicate movement or split movement of the object if the entirety of the object is not included in the unit; and carrying out half tone screening by using the unit.SELECTED DRAWING: Figure 9

Description

The present invention relates to a method of creating halftone printed matter data having a function of preventing forgery and alteration in the field of security printed matter such as banknotes, passports, negotiable securities and certificates.

Security printed matter such as banknotes, passports, negotiable securities, and certificates must be protected against forgery and alteration. For example, as one of anti-counterfeiting measures, there is a geometric pattern composed of minute curved lines, which is used as background pattern, color pattern, and the like. Since it is difficult to extract the tint block, colored pattern, etc. by a color scanner or reproduce it by a copier, it has a function of preventing forgery.

However, when it is composed of lines such as background patterns or color patterns, it is not suitable for expression of continuous gradation (image line area ratio of 0% to 100%). Therefore, when continuous tone is used in a security print, a continuous tone image is applied to areas other than background and color patterns. In order to express a continuous tone image on a printed matter, as shown in FIG. must be halftone.

For example, Non-Patent Document 1 describes a method of halftone screening using a page description language called PostScript. In this method, as shown in FIG. 2, a rectangular array of cells [c] (hereinafter referred to as "unit [U]") containing a threshold value (hereinafter referred to as "threshold value [3]") written in hexadecimal as an 8-bit value is used. ) is used.

FIG. 3 shows the halftone screening process using unit [U]. This process compares the density value [4] of the gradation image [1] with the threshold value [3] of the unit [U] to generate the dot image [2].

However, halftone screening as described above is based on round, oval, rhombus, and square halftone dot shapes, which can be easily reproduced by using existing plate making technology or image processing technology, so counterfeit prevention is possible. It does not meet the required security printing requirements. Therefore, there has been a demand for halftone screening that generates complicated halftone dot shapes that make counterfeiting difficult.

Therefore, the applicant proposed that, as halftone screening for generating a complicated halftone dot shape, the unit [U], which is the minimum unit graphic area constituting the screen, is arranged in at least two different directions, as shown in FIG. a step of generating information for defining a halftone dot shape by combining graphics generated by a function in the subunit [5] by a computing means; An application has been filed for a technique for generating a complex halftone dot shape by performing halftone screening in a step of outputting information to be defined as screen definition data (see, for example, Patent Documents 1 and 2).

Patent No. 3855013 Patent No. 6651198

Adobe PostScript 3 "Halftones and Screens Technical Note #5602" (1997)

However, in the halftone screening of Patent Documents 1 and 2, as shown in FIG. 4, by deploying and arranging subunits [5] obtained by dividing the interior of the unit [U], a complex halftone dot shape can be obtained. , and since the halftone dot shape is completed with a single unit [U], halftone screening using such a unit [U] results in a halftone There was a problem that the continuity of the point shape was conspicuous and the complexity was insufficient.

The present invention has been made in view of the above-mentioned problems, and as a configuration for making the continuity of halftone dot shapes inconspicuous, halftone dots of a seamless design without joints as shown in FIG. The present invention relates to a method of creating dot print data. These seamless designs include, for example, Edo Komon, which is a traditional pattern. Edo Komon includes patterns with cherry blossom motifs that have been loved by Japanese people for a long time, such as falling cherry blossoms, and animals, vegetables, etc. Since there are more than several hundred types of design patterns such as patterns used as motifs, by utilizing various seamless designs, it is possible to realize halftone dot prints that are more complicated and in which the continuity of halftone dot shapes is less conspicuous. is possible.

A halftone print data creation method according to the present invention comprises halftone print data for halftone dot printing of a printing area having a gradation image using a unit formed by a plurality of objects on at least a portion of a base material. wherein M or more cells (M is an integer equal to or greater than 2) along a first direction, formed by a set of cells in a printing area, are arranged in a second direction different from the first direction A step of regularly arranging a plurality of units having N or more (N is an integer of 2 or more) arranged along a direction with a constant pitch and a constant shape, and forming a plurality of objects at positions on the unit that do not overlap each other confirming whether a plurality of objects are placed at positions straddling the boundaries between the adjacent units; When a plurality of objects are arranged in a straddling position, i) an object formed at a position straddling the boundary line in the first direction in each unit is moved from one end side to the other in the first direction. Copy to a position moved by the number of cells (M) to the end side and/or copy an object formed at a position straddling the boundary line in the second direction in each unit to one end in the second direction or ii) formed at a position straddling the boundary line in the first direction or the second direction in each unit The object formed outside the unit is divided along the boundary line of the unit, and the number of cells ( A step of moving an object formed outside the unit into the unit by moving by M or N), inputting an image that is the basis of the gradation image or reading an image that has been input in advance, and performing resampling processing. and creating halftone print data created by halftone screening the object formed by i) or ii). be.

Further, the method for creating data for halftone printed matter according to the present invention is a halftone printed matter in which a printing area having a gradation image is halftone-dotted using a unit formed by a plurality of objects on at least a part of a base material. A method for creating data for printing, wherein M or more (M is an integer equal to or greater than 2) cells along a first direction, which are formed by a set of cells in the printing area, are different from the first direction A step of regularly arranging a plurality of units in which N or more (N is an integer of 2 or more) arranged along a second direction with a constant pitch and a constant shape; determining whether a plurality of objects are placed at positions straddling boundaries between adjacent units; When a plurality of objects are arranged at positions straddling the line, iii) objects formed at positions straddling the boundary lines in the first direction and the second direction in each unit are placed at one end in the first direction Copy to a position shifted by the number of cells (M) from the side to the other end side, and a position shifted by the number of cells (N) from one end side to the other end side in the second direction , and moved from one end side to the other end side in the first direction and from one end side to the other end side in the second direction by the number of cells (M, N) or iv) objects formed outside the boundaries in each unit to regions formed within the unit and regions spanning only the first direction and regions spanning only the second direction. divided into a straddling region and a region straddling in the first direction and the second direction, and dividing the region straddling only in the first direction from one end side to the other end in the first direction the number of cells (M) in the second direction, and the region across only the second direction is moved from one end side to the other end side in the second direction by the number of cells (N); From one end side to the other end side with respect to the first direction and from one end side to the other end side with respect to the second direction in the region spanning the one direction and the second direction moving the object into the unit by moving the number of cells (M and N) to
inputting a base image for a grayscale image or reading a previously input image and performing a resampling process; and a step of creating dot print data.

Further, the step of forming an object on a unit in the halftone dot print data creating method of the present invention forms an object by a set of cells having density values of 8-bit values, m cells×n cells (m and where at least one of n is 2 or more, m is an integer that satisfies m≤M/2, and n is an integer that satisfies n≤N/2), and the gradation between cells in the object A method of generating halftone dot print data, comprising the step of setting the difference to be at least 1 or more in an 8-bit value.

Further, the halftone dot print data creation method of the present invention is characterized by having a step of optimizing the density value of each unit.

In the halftone dot print data creation method of the present invention, the concept of seamless design is incorporated into the definition of units, and halftone screening is performed in units in which objects straddling adjacent units are arranged, thereby making the halftone dot shapes continuous. Gender discrimination becomes difficult. As a result, a complex halftone dot shape required for security printed matter can be obtained.

In addition, the halftone dot print data creation method of the present invention is difficult to imitate due to the complicated halftone dot shape, and is expected to improve the anti-counterfeiting effect in the security printed matter.

FIG. 4 is a diagram showing an example of converting a gradation image into a halftone dot image; The figure which shows the structure of a unit. Schematic diagram showing halftone screening processing using a unit. FIG. 2 is a diagram showing the configuration of a unit in Patent Documents 1 and 2; FIG. 2 is a diagram showing an example of a halftone dot image in Patent Documents 1 and 2; FIG. 4 is a diagram showing an example of a seamless pattern; The figure which shows the structure of the unit in this invention. The figure which shows the structure of an object. Flowchart diagram for creating a unit. A diagram showing the creation of a unit. The figure which shows the structure of an object. A diagram showing the arrangement of objects in which cells with density values do not overlap The figure which shows the state which the object contains in the unit. The figure which shows the state where an object straddles the boundary line of a unit. FIG. 11 illustrates copy movement when an object straddles the left edge of a unit; The figure which shows a division|segmentation movement when an object straddles the left end of a unit. FIG. 10 is a diagram showing replication movement when an object straddles the left edge and top edge of a unit; A diagram showing quadrants where the object straddles the left and top edges of the unit. The figure which shows a division|segmentation movement when an object straddles the left end and upper end of a unit. FIG. 4 is a flow chart for creating a halftone dot image; Flowchart diagram of optimization. Flowchart diagram of halftone screening. FIG. 4 is a diagram showing an example of a halftone dot image according to the present invention;

Embodiments for carrying out the present invention will be described with reference to the drawings. Various other embodiments are included within the scope.

FIG. 7 shows the screen [6] used for halftone screening in the present invention. The structure of the screen [6] is described below.

Unit [U] is a basic unit that constitutes screen [6]. The screen [6] is formed by repeatedly arranging the units [U]. In FIG. 7, an example in which the unit [U] is square will be described. Other shapes are also possible.

As shown in FIG. 8, the object [o] is composed of a rectangular array of cells [c]. Each cell [c] of object [o] has a density value [4] which is an 8-bit value (0 to 255).

A unit [U] has at least two or more objects [o]. In addition, at least one or more objects [o] among them are arranged in a state straddling the boundary line between adjacent units [U], so that the boundary line between each unit [U] is inconspicuous Seamless design can be formed.

FIG. 9 shows a flow chart of the processing for creating a unit in the present invention. A method of creating a unit will be described according to this flowchart.

As S01, as shown in FIG. 10, a unit [U] along the virtual grid [7] is created. For example, the unit [U] is composed of a rectangular arrangement of M cells [c] in the horizontal direction and N cells [c] in the vertical direction, that is, M×N cells. Here, M and N are integers of 2 or more. Also, each cell [c] has the 8-bit value 255 as the density value [4].

As S02, an object [o] to be placed in the unit [U] is created. For example, as shown in FIG. 11, the object [o] is composed of a rectangular array of m cells [c] in the horizontal direction and n cells [c] in the vertical direction, that is, m×n cells.

Here, at least one of m and n is an integer of 2 or more, and as described above, since the condition that unit [U] has a plurality of objects [o] is satisfied, m≤M/2 or n. It is an integer that satisfies ≦N/2.

Further, each cell [c] of object [o] has a density value [4] from 0 to 254 out of 8-bit values. Of the 8-bit values, only 255 density values are treated as the transparency attribute [8]. At this time, one object [o] must have a density value [4] of at least two gradations.

As S03, the object [o] is placed in the unit [U]. As shown in FIG. 12, for each object [o], the cell [c] having the transparency attribute and the cell [c] having the density value may overlap, but the cells [c] having the density value may overlap each other. Place it so that it does not

As S04, it is determined whether or not the entire object [o] is contained within the unit [U]. If the entire object [o] is contained within the unit [U], the process proceeds to S06. Note that FIG. 13 shows a state in which the entire object [o] is contained within the unit [U].

If the entire object [o] is not contained within the unit [U], that is, if the object [o] straddles the boundary line in one or more of the upper, lower, left, and right directions of the unit [U], S05 Move to Note that FIG. 14 shows a state in which the object [o] straddles the leftmost boundary line of the unit [U].

As S05, the object placed in the unit is moved. There are two methods of moving an object: one is to duplicate the object and then move it (hereinafter referred to as "duplicate movement"), and the other is to move the object after dividing it at the boundary of the unit (hereinafter referred to as "split movement"). There are two ways.

The object moving methods of "copy move" and "split move" will be described below with reference to the drawings.

(When straddling the boundary line of one axis)
The processing under the condition that the object straddles the 1-axis boundary line of the unit will be described. The conditions for an object to straddle a boundary line on one axis of a unit include a first condition that the object straddles the boundary line to the left and right and a second condition that the boundary line is straddled vertically.

(duplicate move)
FIG. 15 shows copy movement when the object [o] straddles the leftmost boundary line of the unit [U] in the first condition. As a first process, the object [o] is duplicated at the same coordinates, and the duplicated object is called a first duplicate object [o']. As a second process, the first duplicate object [o'] is translated to the right of the M cell [c].

(split move)
FIG. 16 shows division movement when the object [o] straddles the leftmost boundary line of the unit [U] among the first conditions. As a first process, the object [o] is split at the left end of the unit [U]. At this time, the divided object [o] is divided into the first divided object [o1] from the left end of the unit [U], and the second divided object [o] from the left end of the unit [U]. Assume that the object is [o2]. As a second process, only the first divided object [o1] is translated to the right of the M cell [c].

In the above description, the left-to-right copy movement and division movement of the object under the first condition have been described, but the right-to-left copy movement and division movement are the same.

In addition, when the object straddles the boundary line of the unit vertically, which is the second condition, the movement direction of the object is changed to the vertical direction, and the number of cells to be moved is changed to N, but as in the first condition, This is the process of duplication movement and division movement of an object.

(When straddling the boundary between two axes)
Next, a description will be given of the processing under the condition that the object straddles the boundaries of the two axes of the unit.

(duplicate move)
FIG. 17 shows replication movement when the object [o] straddles the boundary line between the left end and the upper end of the unit [U]. As a first process, the object [o] is duplicated three times at the same coordinates, and the duplicated objects are respectively a first duplicated object [o'], a second duplicated object [o''], and a third duplicated object. Call it object [o'']. As a second process, the first duplicate object [o'] is translated to the right of the M cell [c]. As a third process, the second duplicate object [o''] is translated downward by N cells [c]. As a fourth process, the third duplicate object [o'''] is translated rightward by M cells[c] and downward by N cells[c].

(split move)
Next, a description will be given of division movement when the object [o] straddles the boundary line between the left end and the upper end of the unit [U]. As the first process, as shown in FIG. 18, the object [o] is divided into four parts by two extension lines, the left end of the unit [U] and its extension line and the upper end of the unit [U] and its extension line. . The four divided objects are divided counterclockwise from the upper right object into a third divided object [o3], a fourth divided object [o4], a fifth divided object [o5] and a sixth divided object [o5]. o6]. FIG. 19 shows how to move the third divided object [o3], the fourth divided object [o4], and the fifth divided object [o5]. As a second process, the third divided object [o3] is translated downward by N cells [c]. As a third process, the fourth divided object [o4] is translated to the right by M cells [c] and downward by N cells [c]. As a fourth process, the fifth divided object [o5] is translated to the right by M cells [c].

In the above description, the case of duplicating and moving an object that straddles the left end and the top end has been described. .

As S06, it is determined whether or not to add a new object. When adding a new object, the processing from S02 to S05 is repeated.

As S07, the created unit is saved.

(Creation of halftone dot image)
FIG. 20 shows a flow chart of the process of performing halftone screening with the unit created above and creating a halftone dot image. A method of creating a dot image will be described according to this flowchart.

As S1-01, the unit prepared above is read.

As S1-02, the optimization described later is performed on the unit.

In S1-03, an image that is the basis of the gradation image is acquired by a photographing device (not shown) or the like, or a gradation image input in advance is read. The gradation image here is 8-bit format bitmap data that is the basis for halftone screening, and if it is not 8-bit format bitmap data, it is converted into 8-bit format bitmap data.

At S1-04, the gradation image read at S1-03 is resampled according to the resolution of the halftone dot image to be output. Note that resampling is a technique widely used in image processing, and is arithmetic processing (for example, bilinear method or bicubic method) for increasing or decreasing the number of pixels, which are the minimum image units of a gradation image.

At S1-05, the unit optimized at S1-02 is used to perform halftone screening, which will be described later, on the gradation image resampled at S1-04.

In S1-06, the created halftone dot image is saved, and the creation of the halftone dot image ends.

(Unit optimization)
FIG. 21 is a flow chart of optimization processing for converting density values of units into threshold values. Unit optimization processing will be described according to this flowchart.

A histogram H is defined as S2-01. The histogram H is a one-dimensional array in the computer program storing the number of cells of each density value of the unit read in S1-01.

As S2-02, the processing of loop 1 is executed. Loop 1 is an iterative process starting from y=0 and adding 1 to y while y<N.

As S2-03, the processing of loop 2 is executed. Loop 2 is an iterative process starting from x=0 and adding 1 to x while x<M. After completing loop 2, return to loop 1.

As S2-04, values are substituted into the histogram H defined above. As a result of this processing, the histogram H takes the form shown in Table 1 below, for example.

As S2-05, a cumulative total array a is defined. Cumulative array a is a one-dimensional array in a computer program in which the number of cells of histogram H is accumulated.

In S2-06, "0" is substituted into the cumulative total array a(0).

As S2-07, the processing of loop 3 is executed. Loop 3 is an iterative process starting from i=1 and adding 1 to i while i<256. After the end of loop 3, the process proceeds to S2-09.

At S2-08, the following number 1 is executed to store the total number of cells in each index (i) of the total array a. As a result of this processing, the cumulative total array a takes the form shown in Table 2 below, for example.

As S2-09, the processing of loop 4 is executed. Loop 4 is an iterative process starting from y=0 and adding 1 to y while y<N.

As S2-10, the processing of loop 5 is executed. Loop 5 is an iterative process starting from x=0 and adding 1 to x while x<M. After loop 5 ends, return to loop 4.

As S2-11, the following Equation 2 is executed to store an 8-bit value (0 to 255) in the unit (U), which is a two-dimensional array. It should be noted that values below the decimal point generated in this arithmetic processing are rounded off to integer values.

As S2-12, the unit is overwritten and saved.

By the optimization process described above, the density value of the unit is converted into the threshold value.

(Halftone screening)
FIG. 22 is a flow chart showing the halftone screening process. Halftone screening for converting a gradation image into a halftone dot image will be described according to this flow chart.

In S3-01, the number of pixels in the horizontal direction of the gradation image subjected to the resampling process in S1-04 is substituted for the variable h. Also, the number of pixels in the vertical direction of the gradation image subjected to the resampling process is substituted for the variable v.

As S3-02, a dot image D(h, v) is created. This dot image D is a two-dimensional array in a computer program.

As S3-03, the processing of loop 1 is executed. Loop 1 is an iterative process starting from y=0 and adding 1 to y while y<v.

As S3-04, the processing of loop 2 is executed. Loop 2 is an iterative process starting from x=0 and adding 1 to x while x<h. After completing loop 2, return to loop 1.

In S3-05, the remainder obtained by dividing x by the number M of cells in the horizontal direction of the unit is assigned to variable dx, and the remainder obtained by dividing y by the number N of cells in the vertical direction of the unit is assigned to variable dy.

In S3-06, the density value of the gradation image resampled in S1-04 is compared with the value {255-U(dx, dy)} obtained by reversing the gradation of the threshold value of the unit described above. This process is a branching condition in computer programming that returns "true" if the former is less than the latter, and returns "false" otherwise.

In S3-07, "1" is substituted for the dot image D(x, y).

In S3-08, "0" is substituted for the dot image D(x, y).

By this halftone screening process, all pixels of the gradation image are converted to 2 gradation (black and white), and a seamless halftone dot image as shown in FIG. 23 can be generated.

1 Gradation image 2 Halftone dot image 3 Threshold value 4 Density value 5 Subunit 6 Screen 7 Virtual grid 8 Transparency attribute U Unit c Cell o Object o' First duplicated object o'' Second duplicated object o''' Third duplicate object o1 First divided object o2 Second divided object o3 Third divided object o4 Fourth divided object o5 Fifth divided object o6 Sixth divided object

Claims (4)

A method for creating data for halftone dot printed matter for halftone dot printing a printing area having a gradation image using a unit formed by a plurality of objects on at least a part of a base material, the method comprising:
In the printing area, formed by a set of cells, M or more (M is an integer equal to or greater than 2) cells along a first direction, along a second direction different from the first direction A step of regularly arranging a plurality of units in which N or more units (N is an integer of 2 or more) are arranged with a constant pitch and a constant shape;
forming a plurality of said objects in non-overlapping positions on said unit;
confirming whether a plurality of said objects are arranged at positions straddling a boundary line where each said unit is arranged adjacently;
When the plurality of objects are arranged at positions straddling the boundary line in the first direction or the second direction in the unit,
i) the number of cells ( M) copy the object to a position moved by 1 minute and/or copy the object formed at a position straddling the boundary line in the second direction in each of the units from one end side to the other end in the second direction copy to a position moved by the number (N) of the cells to the department side, or
ii) divide the object formed at a position straddling the boundary line in the first direction or the second direction in each unit with the boundary line in the unit as a boundary, and divide the object formed outside the unit The object is formed outside the unit by moving the number of cells (M or N) from one end side to the other end side in the first direction or the second direction. moving said object into said unit;
a step of inputting an image that is the basis of the gradation image or reading an image input in advance and performing a resampling process;
and creating the halftone dot print data created by halftone screening the object formed by the above i) or ii). A method for creating data for halftone dot printed matter for halftone dot printing a printing area having a gradation image using a unit formed by a plurality of objects on at least a part of a base material, the method comprising:
In the printing area, formed by a set of cells, M or more (M is an integer equal to or greater than 2) cells along a first direction, along a second direction different from the first direction A step of regularly arranging a plurality of units in which N or more units (N is an integer of 2 or more) are arranged with a constant pitch and a constant shape;
forming a plurality of said objects in non-overlapping positions on said unit;
confirming whether a plurality of said objects are arranged at positions straddling a boundary line where each said unit is arranged adjacently;
When the plurality of objects are arranged at positions straddling the boundary between the first direction and the second direction in the unit,
iii) moving the object formed at a position straddling the boundary lines in the first direction and the second direction in each of the units from one end side to the other end side in the first direction; copy to a position moved by the number (M) of cells, copy to a position moved by the number (N) of cells from one end side in the second direction to the other end side, and Copy to a position moved from one end side to the other end side in the direction of and from one end side to the other end side in the second direction by the number of cells (M, N) , or
iv) the object formed outside the boundary line in each of the units, the area formed in the unit, the area straddling only the first direction, and the area straddling only the second direction and a region straddling the first direction and the second direction, and the region straddling only the first direction is divided from one end side to the other end with respect to the first direction the number (M) of the cells to the part side, and the number (N) of the cells from one end side to the other end side with respect to the second direction in the area straddling only the second direction , and move the area straddling the first direction and the second direction from one end side to the other end side with respect to the first direction and one side with respect to the second direction moving the object into the unit by moving the number of cells (M and N) from one end side to the other end side;
a step of inputting an image that is the basis of the gradation image or reading an image input in advance and performing a resampling process;
and creating the halftone print data created by halftone screening the object formed in the above iii) or iv). The step of forming the object on the unit includes forming the object by a collection of cells having density values of 8-bit values, m cells×n cells (where at least one of m and n is 2 or more; m is an integer that satisfies m≤M/2 and n is an integer that satisfies n≤N/2), and the gradation difference between the cells in the object is at least 1 as an 8-bit value. 3. A method of creating halftone dot print data according to claim 1 or 2, comprising the steps described above. 4. The method of generating halftone dot print data according to claim 1, further comprising a step of optimizing the density values of said units.

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