JPH05158207A - Formation of relief pattern based on gradation image - Google Patents

Abstract

PURPOSE:To obtain the method for forming a relief pattern which can easily form the relief pattern having a smooth stereoscopic feel. CONSTITUTION:The gradation image consisting of the set of the picture elements defined in any of density values O to 255 is inputted to a computer. Plural reference lines parallel with each other apart prescribed intervals are defined on this image. The inputted gradation image is binarized and the contour lines of the designs included therein are extracted. The picture elements A to W on the reference line R6 are divided to the picture elements G to Q in the internal region of the designs and the picture elements A to F, R to W of the external region. As to the picture elements G to Q of the internal region, displacement points g to q are respectively defined in the scale position of the density value thereof. As to the external region of the designs, the reference line R6 is left as it is as a multiparallel line. As to the internal region, the connecting lines connecting the displacement points g to q are left as multiparallel lines. The relief pattern is constituted by the multiparallel lines formed in such a manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relief pattern producing method based on a gradation image, and more particularly to a relief pattern producing method used for security purposes such as stock certificates.

[0002]

2. Description of the Related Art For securities such as stock certificates, a fine pattern is usually printed on the surface of the securities in order to provide a visual anti-counterfeiting effect. A commonly used anti-counterfeit pattern is a relief pattern. This relief pattern is a pattern in which some three-dimensional motif is expressed in a two-dimensional plane. Conventionally, when creating such a relief pattern, an expert engraves a three-dimensional motif by hand engraving to create an engraving plate, or a resin letterpress plate that takes a three-dimensional motif pattern by a plate making process using resin. (Treasure version)
To create. Then, a relief engraving machine is used to convert the three-dimensional pattern formed on the engraving plate or the relief plate into a two-dimensional relief pattern.

[0003]

However, the above-mentioned method of making an engraving plate by hand engraving has a problem that it requires cost and time because an engraving plate needs to be made manually by a skilled craftsman. .. On the other hand, the above-described method of creating a relief plate requires less labor than hand engraving, but it is difficult to express a smooth three-dimensional effect. Further, in any of the above-mentioned methods, a relief engraving machine is required to convert a three-dimensional pattern into a two-dimensional relief pattern. This relief engraving machine is a device that creates a two-dimensional relief pattern by copying a three-dimensional pattern by mechanical operation, requires a considerable amount of installation space for the device, and requires time and labor for maintenance as the machine ages. Become.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a relief pattern creating method capable of easily creating a relief pattern having a smooth three-dimensional effect.

[0005]

[Means for Solving the Problems]

(1) The first invention of the present application is a method of creating a relief pattern based on a gradation image composed of a plurality of pixels each having a defined density value, and a step of preparing the gradation image as density value data, Binarizing the prepared gradation image by comparing the density value of each pixel with a predetermined threshold value, and the outline of the pattern included in the image based on the binary image. A step of extracting a line, a step of defining a plurality of reference lines at a predetermined interval in a predetermined direction on the gradation image, and a pixel on the reference line in the internal area of the pattern defined by the extracted contour line, The step of defining a displacement point at a position distant from the reference line by a distance related to the density value of the pixel, and the reference line for the outer area of the pattern defined by the contour line, and the connection for connecting the displacement point for the inner area Composed by lines, respectively The steps of defining a line to be drawn are performed, and a relief pattern is created by a plurality of lines.

(2) In the second invention of the present application, in the relief pattern creating method according to the first invention, thinning processing for leaving only the pixels on the reference line to be defined is applied to the input gradation image. The gradation image binarization process and the contour line extraction process are performed on the image subjected to the thinning process.

[0007]

[Operation] In the relief pattern creating method according to the present invention, a relief pattern having a gradation image composed of a plurality of pixels as a motif can be easily created using a computer. The gradation image serving as a motif may be prepared in a computer as array data of pixels whose density values are defined. A binary image is created based on this gradation image, and the contour line included in the image can be extracted based on this binary image. In addition, a plurality of reference lines are defined on the gradation image, and lines are created based on these reference lines. The created parallel line becomes a bent line in accordance with the density value of the pixel in the portion of the picture included in the gradation image that is the motif.
Therefore, if the relief pattern is formed by these lines, the original motif appears to be visually highlighted. After all, simply by inputting the two-dimensional gradation image data to the computer, a relief pattern having this image as a motif is automatically created.

[0008]

EXAMPLES The present invention will be described below with reference to illustrated examples. FIG. 1 is a flowchart showing a processing procedure in a computer for carrying out a relief pattern creating method according to an embodiment of the present invention. First, in step S1,
Input a gradation image. This gradation image is an image composed of a plurality of pixels whose density values are defined. In this embodiment, a gradation image in which one pixel is represented by 8-bit density value information is input to the computer as data. .. That is, the density value of any one of 0 to 255 is given to each pixel. Inputting such a gradation image
It may be performed using a scanner device or the like. In the present invention, the relief pattern is created using the pattern included in the gradation image as a motif. Here, in order to facilitate understanding of the invention, the following description will be given by taking a case where a gradation image as shown in FIG. 2 is input from a scanner device as an example. This gradation image is an image having a 23 × 23 pixel array, and has a pattern in which the density value increases toward the center. At the lower left of FIG. 2, the density value defined for each pixel is shown. It should be noted that this gradation image is shown as an extremely simple example for convenience of explanation, and in practice, a gradation image having a larger number of pixels and a higher resolution is generally used.

After the gradation image is loaded as data into the computer, the thinning process is performed in step S2. This thinning-out processing is not always necessary, but it is preferable to perform it in order to reduce the calculation load.
This thinning-out process is related to the reference line definition process performed in step S5 described later. That is, the pixels on the reference line defined in step S5 are left and the other pixels are thinned out. Let me explain this concretely. Now, as shown in FIG. 2, it is assumed that the reference lines R1 and R2 are defined in the horizontal direction at a predetermined interval d. This interval d corresponds to a pitch of exactly 2 pixels. Therefore, when a large number of reference lines are defined at this interval, each reference line will lie on pixels in even rows. In the present invention, it is sufficient to carry out all the processes subsequent to this on only the pixels on the reference line, so it is not necessary to perform the following processes on pixels that are not on the reference line, that is, on pixels in odd rows. Therefore, the thinning process of step S2 is performed to thin unnecessary pixels in advance, thereby reducing the calculation load of the subsequent steps. In the embodiment shown here, all the pixels in odd rows are thinned out, and the gradation image shown in FIG. 2 is converted into the gradation image shown in FIG. In other words, only the pixels on the reference line remain.

In the subsequent step S3, binarization processing is performed. This binarization processing is necessary to extract the contour line from the pattern included in the input gradation image. A predetermined threshold value is set for the density value, and the density value of each pixel is This is a process of defining a value of either "0" or "1" by comparing with a threshold value. For example, with respect to the gradation image shown in FIG. 3, threshold value = 128 is set and binarization is performed. Is processed, a binary image as shown in FIG. 4 (pixels not marked with "1" are all pixels with "0") is obtained. If an image including some pattern that serves as a relief pattern motif is used as the gradation image, the shape of this pattern is clearly highlighted by this binarization processing. On the contrary, the threshold value is set so that the shape of the underlying pattern is clearly highlighted.

After the binary image is obtained in this way, contour line extraction processing is performed in step S4. Various methods are known as a method for extracting a contour line from a binary image, and therefore, a description of this processing method is omitted in this specification. In this embodiment, the contour line information represented by the vector data shown in FIG. 5 is extracted based on the binary image shown in FIG. The contour information is not limited to such vector data and may be extracted in any format. As will be described later, the contour line information is used as a criterion for judging whether the area is the inside area or the outside area of the pattern, and in any format that can be used as the criterion for this judgment, any form of information can be used. May be. The binarization processing in step S3 and the contour line extraction processing in step S4 are both performed on the thinned images. Therefore, the contour line information obtained in step S4 indicates the contour line of the thinned image, and the contour line shown in FIG. 5 has a flattened shape with respect to the contour line existing in the image shown in FIG. It has been done.

Then, in step S5, a reference line is defined. However, in this embodiment, for convenience of explanation,
Although the reference line definition processing is performed in step S5, the reference line may be defined at any stage in practice. As shown in FIG. 2, the reference line is defined as a straight line having a predetermined distance d directed in a predetermined direction on the input gradation image. The reference line is a basic line of lines printed to form a relief pattern. In FIG. 2, the reference line R
Although the size of one pixel is considerably larger than those of 1 and R2, in reality, the thickness of a printed line and the size of one pixel are substantially the same. Therefore,
As shown in FIG. 2, when the distance d between the reference lines is set to 2 pixel pitch, the printed lines may actually be too dense. Therefore, in reality, the interval d between the reference lines is
Is generally set to about 5 to 20 pixel pitch (although the present invention is not limited to this numerical range). In the case of the present embodiment, considering an image subjected to thinning processing, as shown in FIG. 6, eleven reference lines R1
~ R11 will be defined.

Now, in the subsequent step S6, the displacement point is defined. This displacement point is a point for bending a part of the reference line. The process after that is roughly explained as follows.
It can be said that, of the reference lines R1 to R11 defined as shown in FIG. 6, the process of bending the portion corresponding to the internal area of the pattern surrounded by the contour line shown in FIG. The degree of bending is determined based on the density value of each pixel. Hereinafter, this process will be described with reference to a concrete example. Here, the process for the reference line R6 will be described.
FIG. 7 is a diagram in which only one row of pixels on the reference line R6 is extracted from the pixels forming the input gradation image. Now
Each pixel will be referred to as pixel A to pixel W as shown in the figure.
The density value of each pixel is 50 as shown in the figure below.
It is distributed to ~ 255. First of all, of these 23 pixels
The pixels in the internal area of the design are specified. This can be easily determined based on the contour line shown in FIG. That is, since the pixels G and Q are pixels on the contour line, if the pixels on the contour line are handled as the internal region, the pixels G to Q are the pixels in the internal region, the pixels A to F, and the pixels R to W. Are pixels in the external area. Such specific recognition of the internal area and the external area is logically performed by, for example, scanning pixels horizontally from left to right and counting how many times the vector indicating the contour line is crossed. Can be done. That is, if the number of intersections is an even number (including 0), the pixel currently being scanned is a pixel in the external region, and if the number of intersections is an odd number, the pixel currently being scanned is a pixel in the internal region. It can be recognized as something.

Then, for the pixel in the internal area, a displacement point is defined at a position separated from the reference line by a distance related to the density value of the pixel. In this embodiment, as shown in FIG. 8, the position of the reference line R6 is made to correspond to the density value 128, the scales of the density values 128 to 255 are arranged above the reference line R6 at equal intervals, and the density values 0 to 0 are arranged below. Displacement points are defined at graduation positions corresponding to respective density values above or below each pixel with 128 graduations at equal intervals. For example, since the density values of the pixels G and H are 150,
As shown in, the displacement points g and h are defined slightly above the reference line R6. Similarly, for pixels I to Q, displacement points i to q are defined as shown in the figure. If the intervals between the scales are widened, the positions of the displacement points are moved farther from the reference line, and a relief pattern having a strong three-dimensional effect can be created. On the contrary, if the interval between the scales is narrowed, the position of the displacement point comes closer to the reference line, and a relief pattern with a weak stereoscopic effect can be created. Therefore, the scale interval may be set arbitrarily according to the relief pattern to be created. Further, in this embodiment, the position of the reference line R6 corresponds to the density value 128, but the density value corresponding to the position of the reference line may be set arbitrarily. Furthermore, the scale intervals do not necessarily have to be even.

Finally, in step S7, lines are defined. The structure of the line differs between the outer area and the inner area of the pattern. That is, for the outer region of the pattern, the defined reference line is used as it is as a line. On the other hand, regarding the inner area of the pattern, the connecting line connecting the defined displacement points is defined as a parallel line. Specifically, as shown in FIG. 9, the reference line R6 is used as a straight line for the outer areas of the pixels A to G and the pixels Q to W, and the inner area of the pixels G to Q is used as it is. , A connecting line formed by connecting the displacement points g to q in order is used as a parallel line. Figure 10
A line created based on the reference lines R4 to R8 is shown. The portion where the ridge of the line is high corresponds to the portion where the density value is high in the gradation image that is the motif. Step S6
On the contrary, depending on how to set the scale of the density value in the above, it is possible to increase the ridge of the parallel line in the portion where the density value is low. Further, in the example of FIG. 10, the line is raised upward, but conversely, it is possible to make a depression downward. In the present invention, the relief pattern is created by the plurality of lines. In other words, the computer outputs the image data including only the lines as a relief pattern.

As described above, in reality, the size of each pixel and the thickness of the line are substantially the same, so the line created is smoother. 11
FIG. 6 is a diagram showing an example of a relief pattern actually created by the present invention. When the relief pattern creating method according to the present invention is carried out using a pattern having an outline as shown in FIG. 11 (a) as a motif, a relief pattern as shown in FIG. 11 (b) can be obtained, for example. It can be recognized that the motif shown in FIG. 11 (a) is three-dimensionally expressed in this relief pattern. The internal area and the external area of the pattern in this specification are relative concepts that depend on what part is considered to be the pattern, and do not indicate absolute inside and outside. For example, in Figure 1.
In the figure shown in FIG. 1 (a), if the figure in which the vertical band overlaps the center of the donut-shaped ring is regarded as a pattern, the area X becomes the outer area, the area Y becomes the inner area, and the area Z becomes the outer area.
However, if a figure in which the relationship between the negative and the positive is reversed is regarded as a pattern, it can be said that the region X is the inner region, the region Y is the outer region, and the region Z is the inner region.

Although the present invention has been described above based on several illustrated embodiments, the present invention is not limited to these embodiments and can be carried out in various modes other than this. .. For example, in the above-mentioned embodiments, the reference lines are all perfect straight lines, but it is also possible to use smooth curves or wavy lines. Further, when defining the reference line, if the reference lines in two or more directions are defined, it is possible to create a relief pattern having a more three-dimensional effect.

[0018]

As described above, according to the present invention, a plurality of reference lines are defined in a gradation image, the reference lines are used as they are for the outer area of the pattern, and the reference lines are used for the inner area. The lines bent according to the density value of the pixel are set as parallel lines, and the relief pattern is created by these parallel lines. Therefore, it is possible to easily create a relief pattern having a smooth three-dimensional effect. ..

[Brief description of drawings]

FIG. 1 is a flowchart showing a processing procedure in a computer for carrying out a relief pattern creating method according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a gradation image used as a motif in the relief pattern creating method according to the present invention.

FIG. 3 is a diagram showing an image obtained by thinning out the gradation image shown in FIG.

4 is a diagram showing a binary image obtained by binarizing the gradation image shown in FIG.

5 is a diagram showing a contour line extracted from the binary image shown in FIG.

FIG. 6 is a diagram showing reference lines defined for the gradation image shown in FIG.

FIG. 7 is a diagram showing pixel rows on one reference line.

8 is a diagram showing displacement points defined for the pixel shown in FIG. 7. FIG.

9 is a diagram showing a method of creating a parallel line based on the reference line and the displacement points shown in FIG.

10 is a diagram showing five lines created by the method shown in FIG. 9. FIG.

FIG. 11 is a diagram showing an example of an actual relief pattern created by the method according to the present invention.

[Explanation of symbols]

 A to W ... Pixels g to q ... Displacement points R1 to R11 ... Reference line

Claims (2)

[Claims] 1. A method of creating a relief pattern based on a gradation image composed of a plurality of pixels each having a defined density value, the method comprising: preparing a gradation image as density value data; Binarizing the gradation image by comparing a density value with a predetermined threshold value to obtain a binary image; and extracting a contour line of a pattern included in the image based on the binary image. A step of defining a plurality of reference lines at a predetermined interval in a predetermined direction on the gradation image; a pixel on the reference line in the internal region of the pattern defined by the contour line, the density of the pixel Defining a displacement point at a position distant from the reference line by a distance related to the value, and connecting the displacement point with the reference line for the outer region of the pattern defined by the contour line and with the inner region. By the line it A method for creating a relief pattern based on a gradation image, comprising: a step of defining each parallel line, and a step of creating a relief pattern by a plurality of lines. 2. The method according to claim 1, wherein a thinning process for leaving only pixels on a reference line to be defined is performed on an input gradation image, and the image subjected to the thinning process A relief pattern creating method based on a gradation image, characterized in that a tonal image binarization process and a contour line extraction process are performed.