JP6692727B2 - Method of creating halftone screen, plate for plate making and printed matter - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention relates to a method for producing a halftone screen used in a printing technique for representing a grayscale or color image by a pattern of small dots having a limited number of colors (for example, black dots on white paper), a plate for plate making and a printed matter. Regarding

Conventionally, a dot screen (halftone screen) as shown in FIG. 14 can be exemplified as a method of expressing lightness and darkness on a printed matter. FIG. 14 is a general halftone screen.
Further, a halftone dot screen for preventing forgery and falsification of banknotes, passports, securities, cards, valuable printed matter and the like as shown in FIG. 15 is disclosed not only in the expression of light and dark (Patent Document 1). ). FIG. 15 shows a halftone screen for preventing forgery. The halftone screen shown in FIG. 15 has an anti-counterfeiting effect against copying by a copying machine or copying directly printed by a scanner.

Japanese Patent No. 5428086

  However, in the conventional technology, the shapes that are the basic halftone dots (the “round” shape in the upper part of FIG. 15 and the kanji “Ichi” in the middle part of FIG. 15) are easy to be identified, and after the print image data is once captured, it is analyzed and input. However, it was possible to make a copy corresponding to the halftone dot shape.

  Therefore, the present invention is directed to a method for creating a forgery-preventing halftone dot screen in which the changing halftone dot basic is changed for each halftone dot from dark to light (or from light to dark) so that the above-mentioned reproduction cannot be performed, and for plate making. Providing printing plates and printed matter.

In order to achieve the above object, the present invention uses the following means.
(Invention according to claim 1)
The invention according to claim 1 is a method for creating a halftone screen based on moving image data in which changes can be visually recognized, wherein the moving image data was taken in an environment in which the brightness of the moving image increases or decreases, or the brightness increases or decreases. The halftone dot screen is created by a change dividing means for dividing the time axis of the moving image data into first to nth (n is a natural number of 2 or more) change degrees. A lightness dividing means for dividing the increase or decrease of the lightness into first to nth lightness levels, and a halftone screen creating means for combining the first to nth changeability levels and the first to nth lightness levels respectively. The halftone dot screen creating means sets the first halftone dot to the first change degree stage and the first lightness stage, the second halftone dot to the second change degree stage and the second lightness stage, and the third halftone dot to the third change point. The degree of change and the third level of lightness are ... A halftone screen is obtained by setting one halftone dot as the (n-1) th degree of change and the (n-1) th degree of lightness, and the nth halftone dot as the (n) th degree of change and the nth lightness stage. ..
(Invention of Claim 2)
The invention according to claim 2 is the method for creating a halftone screen according to claim 1, wherein the increase or decrease in the brightness of the moving image data is from 0% to 5% in brightness depending on the start point to the end point of the time axis. It is characterized in that it increases from 95% to 100% or decreases from 100% to 95% in brightness to 5% to 0% in brightness.
(Invention of Claim 3)
According to a third aspect of the invention, in the method of creating a halftone screen according to the first or second aspect, the increase or decrease in the brightness is the moving image data in which the brightness increases according to an end point to an end point of the time axis, The dark area ratio of the first halftone dots is S, the dark area ratio of the nth halftone dot is F, and the dark area ratio of the halftone screen is the first halftone dot = S, the second halftone dot. = S-[(S-F) / (n-1)] * (2-1), the third halftone dot = S-[(S-F) / (n-1)] * (3-1). The n-1th halftone dot = S-[(S-F) / (n-1)] × (n-2), the nth halftone dot = S-[(S-F) / (N-1)] * (n-1) = F.

(Invention of Claim 4)
According to a fourth aspect of the present invention, in the method for creating a halftone screen according to the first or second aspect, the increase or decrease in the brightness is the moving image data in which the brightness decreases according to an end point to an end point of the time axis, The dark area ratio of the first halftone dots is S, the dark area ratio of the nth halftone dot is F, and the dark area ratio of the halftone screen is the first halftone dot = S, the second halftone dot. = S + [(F−S) / (n−1)] × (2-1), the third halftone dot = S + [(F−S) / (n−1)] × (3-1), ... the n-1th halftone dot = S + [(FS) / (n-1)] * (n-2), the nth halftone dot = S + [(FS) / (n-1) )] × (n−1) = F 2.
(Invention of Claim 5)
The invention according to claim 5 is the method for producing a halftone screen according to any one of claims 1 to 4, wherein the method for producing the halftone screen further comprises respective frame brightness adjusting means, and each frame brightness adjusting means. Is the moving image data (D) with vertical = Y dots, horizontal = X dots, and the number of frames = n frames, an arbitrary change rate constant is a, an arbitrary initial constant is b, and the halftone screen ( H ₁ , H ₂ , H ₃ ... H _n-1 , H _n )
The first halftone dot (H ₁ ) = [(1 / n) × a + b] × XY, the second halftone dot (H ₂ ) = [(2 / n) × a + b] × XY, the third halftone dot ( _{H 3) = [(3 /} n) × a + b] × XY, ···· the (n-1) th dot _{(H n-1) = [} {(n-1) / n} × a + b] × XY, The nth halftone dot (H _n ) = [(n / n) × a + b] × XY.
(Invention of Claim 6)
A sixth aspect of the present invention is characterized in that, in the halftone screen producing method according to any one of the first to fifth aspects, the moving image data is subjected to image quality adjustment processing.

(Invention according to claim 7)
According to a sixth aspect of the present invention, in the method of creating a halftone screen according to any of the first to sixth aspects, the moving image data is selected from a vertical inversion process, a horizontal inversion process, a black and white inversion process, and a time axis inversion process. It is characterized in that one or more inversion processes are performed.
(Invention of Claim 8)
The invention according to a seventh aspect is characterized by being produced by the method for producing a halftone screen according to any one of the first to seventh aspects.
(Invention of Claim 9)
The invention according to claim 9 is characterized in that it is produced using the plate for plate making according to claim 8.

According to the present invention, as shown in FIG. 6, at least two halftone dot basic shapes (the Buddha image and the mona Lisa in FIG. 6) are in a blackout or whiteout state. Then, it is difficult to derive the halftone dot basic shape from these intermediate images. FIG. 6 is a frame excerpt of the moving image data, and this moving image is processed so that the change from the Buddha image to the mona Lisa can be visually recognized and the brightness is increased or decreased.

1A and 1B are plan views showing two examples of halftone dot basics having light and dark. FIG. 2 is an explanatory diagram showing changes in halftone dot-based imaging in FIG. 1B. FIG. 3 is an explanatory diagram in which the first to nth halftone dots are entered in FIG. FIG. 4 is an explanatory diagram of the first halftone dot to the nth halftone dot when the time axis inversion process is performed. FIG. 5 is an explanatory diagram of the first halftone dot to the nth halftone dot when the left-right inversion process and the black-and-white inversion process are performed. FIG. 6 is a frame excerpt diagram of moving image data that changes from a Buddha image to a mona Lisa. FIG. 7 is a frame excerpt of moving image data that changes in the order of butterflies, flowers, and buds. FIG. 8 is a flowchart showing the computer processing of the halftone screen. FIG. 9 is a gradation diagram in which darkness is changed to light using the created halftone screen. FIG. 10: is a top view of the printed matter produced using the plate for platemaking. FIG. 11 is an example diagram of a tone jump that occurs in the process of FIG. FIG. 12 is a flowchart showing the computer processing of the halftone screen which does not cause the tone jump. FIG. 13 is an example diagram in which tone jump is suppressed by the processing of FIG. FIG. 14 is a gradation diagram of a conventional halftone screen (halftone screen). FIG. 15 is an explanatory diagram of a conventional halftone dot screen for the purpose of preventing forgery.

  Hereinafter, the method of forming a halftone screen, the plate for plate making and the printed matter of the present invention will be described with reference to the drawings showing examples.

(1. Overall flow of the present invention)
The present invention uses the first step of creating halftone screens H _{1 to} H _n from shooting and editing of moving image data D, and using the created halftone screens H _{1 to} H _n , photographs, illustrations, logo marks, etc. It can be divided into a second stage in which the target image is converted into a tone and output.
In the first stage, each frame of the moving image data D is converted into two-tone monochrome with a constant threshold value to create the halftone screens H _{1 to} H _n .

(2. About halftone dot basic shape H)
1 (a) and 1 (b) are plan views showing two examples of a halftone dot basic with light and dark.
In the case of converting into two-tone monochrome with a certain threshold value and converting to tone, it is preferable that the background is also colored, as shown in FIG. Here, for convenience of explanation, the background is fixed in white as shown in FIG. 1B, and an inverted “<”-shaped halftone dot basic shape H is illustrated.

(3. About time change of video data D and increase / decrease of brightness)
FIG. 2 is an explanatory diagram showing changes in halftone dot-based imaging in FIG. 1B.
In the case of the moving image data D obtained by photographing the above-mentioned inverted “U” -shaped halftone dot basic shape H that rotates counterclockwise, the time axis T of the moving image data D is the first to nth (n is a natural number of 2 or more). When divided into change stages T ₁ , T ₂ , T ₃ ... T _n-1 , T _n , the halftone dot basic shape H corresponds to the vertical axis of FIG.
In addition, the above-mentioned inverted "U" -shaped halftone dot basic shape H is a gradation in which the upper side is white and the lower side is black in FIG. 1B. With respect to such a halftone dot basic shape H, a light source is installed at a distance of 1 m, the diaphragm of the camera for photography is kept constant, and the light source is gradually changed from dark to bright (for example, 0.1 lux to 100,000 lux). .. When the halftone dot basic shape H is divided into the _first to nth lightness stages B ₁ , B ₂ , B ₃ ... B _n-1 , B _n in the situation where the lightness increases and decreases in this way, The halftone dot basic shape H corresponds to the horizontal axis of FIG.

(4. About halftone screen)
FIG. 3 is an explanatory diagram in which the first to nth halftone dots are entered in FIG.
The halftone dot basic shape H is set to the lightness B according to the first change degree step T ₁ which is the start point of the time axis T to the nth change degree step T _n which is the end point (that is, in correspondence with the passage of time). First to nth lightness levels B ₁ , B ₂ , B ₃ ... B _n-1 , B _n (light source is changed from dark to bright).
By doing so, as shown in FIG. 3, halftone dot screens (H ₁ , H ₂ , H ₃ ... H _{8) in which the} dark area decreases while rotating counterclockwise by 45 ° at n = 9. , H ₉ ) is created.

More specifically, in the case of a 360-second moving image in which 0 ° to 360 ° is photographed every second, the first halftone dot H ₁ is the 0 ° rotation at 0 second, that is, the first change step T ₁ and the time at 0 second. first and brightness step _{B 1,} the second halftone dots _{H 2} as a second lightness step _{B 2} when the second change degree phase _{T 2} and 45 seconds is 45 ° rotation of 45 second time point, 3rd dot _{H 3} Be a third degree of change level T ₃ that is 90 ° rotation at 90 seconds and a third brightness level B ₃ at 90 seconds, and the eighth halftone dot H ₈ is 315 ° rotation at 315 seconds. 8th change level T ₈ and 8th brightness level B ₈ at 315 seconds, and 9th halftone dot H ₉ is 360 ° rotation at 360 seconds, 9th change level T ₉ and 9th brightness at 360 seconds obtaining an image of color or gray scale and phase B _9. Then, binarization is performed using a predetermined threshold value (for example, median value, 50%, 128 in case of 8-bit 256-step gray scale), and simple black and white halftone screens (H ₁ , H ₂ , H shown in FIG. 3 are used. ₃ ... H ₈ and H ₉ ) are obtained.
The color or grayscale image before the simple black-and-white process is _{one in} which the brightness increases from 0% to 5% to 95% to 100% according to the start point T ₁ to the end point T ₉ of the time axis T. Is preferred. More preferably, the brightness B is increased from 0% to 100%.

(5. Adjusting the black and white area ratio)
The moving image data D is preferably photographed continuously from "darkness of light source to light". However, in the actual shooting, the dark area of the inverted V-shaped halftone dot basic shape H is decreased by 12.5% in the above-mentioned "dark to bright of the light source" and "simple black-and-white by threshold". Not something to do.
That is, the first halftone dot H ₁ is set to the first change degree stage T ₁ which is 0 ° rotation at 0 second and the first lightness stage B ₁ having a dark area ratio of 100% at 0 second, and the second halftone dot H ₂ Is defined as a second degree of change T ₂ that is a 45 ° rotation at the time of 45 seconds and a second lightness level B ₂ of a dark area ratio of 87.5% at the time of 45 seconds, and the third halftone dot H ₃ is 90 at the time of 90 seconds. ° a third variation of stage _{T 3} and third lightness step _{B 3} dark portion area ratio of 75% when 90 seconds which is rotating, a 315 ° rotation of the eighth time point halftone _{H 8} 315 seconds ... first 8 and change degree phase _{T 8} and the dark portion area ratio of 12.5% when 315 seconds eighth lightness step _{B 8,} 9 change degree phase _{T 9} the ninth dot _{H 9} is a 360 ° rotation of 360 second time point In addition, a color or gray scale image is obtained by setting the ninth lightness level B ₉ with a dark area ratio of 0% at 360 seconds. It is difficult to adjust the light source and the threshold. However, as a halftone screen, it is necessary to avoid a sudden increase / decrease in dark area (so-called tone jump).

Therefore, the following method is used to obtain the halftone screens H ₁ , H ₂ , H ₃ ... H _n-1 and H _{n based} on a constant increase or decrease of the dark area, not on the basis of a predetermined time interval. ..
The dark area ratio of the first halftone dot H ₁ is S and the dark area ratio of the nth halftone dot H _n is F, and the halftone screens H ₁ , H ₂ , H ₃ ... H _n-1 , H _n. The respective dark area ratios of the first halftone dot H ₁
= S, the second halftone _{H 2 = S - [(S} -F) / (n-1)] × (2-1), 3rd dot _{H 3 = S - [(S} -F) / (n −1)] × (3-1), ... N−1th halftone dot H _n−1 = S − [(S−F) / (n−1)] × (n−2), nth dot _{H n = S - [(S} -F) / (n-1)] × (n-1) = a F.
In the case of n = 9 shown in FIG. 3, since the first halftone dot H ₁ = S = 100% and the ninth halftone dot H ₉ = F = 0%, the halftone dot screens H ₁ , H ₂ , and H _{3 are shown.} The dark area ratios of H ₈ and H ₉ are respectively the first halftone dot H ₁ = 100 and the second halftone dot H ₂ = 100 − [(100) / (9-1)] × (2-1). = 87.5, the third halftone dot H ₃ = 100-[(100) / (9-1)] × (3-1) = 75, ... Eighth halftone dot H ₈ = 100-[(100 ) / (9-1)] × (8-1) = 12.5, and the ninth halftone dot H ₉ = 100 − [(100) / (9-1)] × (9-1) = 0.

Based on the above calculation results, in the case of a 360 second moving image in which 0 ° to 360 ° is photographed every second, it is created as follows based on a constant increase / decrease in the dark area. It is also possible to convert to black and white during shooting and check the dark area in real time.
The first halftone dot H ₁ is the first change step T ₁ that is 0 ° rotation at 0 second and the first lightness step B ₁ is 100% dark area ratio at 0 second, and the second halftone dot H ₂ is 38. The second change level stage T ₂ which is 38 ° rotation at the second time point and the second lightness stage B ₂ having a dark area ratio of 87.5% at 38 seconds, and the third halftone dot H ₃ is rotated at 98 ° point at the 98 ° time point. in a third variation of stage _{T 3} and a third lightness step _{B 3} dark portion area ratio of 75% of the time 98 seconds, the eighth variation is a 322 ° rotation of the eighth time point halftone _{H 8} 322 seconds ... and eighth brightness step _{B 8} dark portion area ratio of 12.5% of the time degree phase _{T 8} and 322 seconds, the ninth change degree phase _{T 9} and 360 of a ninth halftone _{H 9} is a 360 ° rotation of 360 second time point A color or gray scale image is obtained by setting the ninth lightness level B ₉ with a dark area ratio of 0% per second.

(6. Output of halftone screen)
Based on the color or gray scale image obtained in this way, if the gradation is converted into two-tone monochrome with a constant threshold, the change becomes irregular (in the case of FIG. 3, the rotation angle is irregular), and the duplication occurs. It is possible to obtain a halftone dot screen (H _{1 to} H _n ) that is difficult to achieve.
Specifically, the software of the computer causes the time axis T of the moving image data D to be the first to n-th (where n is a natural number of 2 or more) change degree stages T ₁ , T ₂ , T ₃ ... T _n−. Change division means for dividing into ₁ and T _n , and lightness division means for dividing the increase / decrease in the lightness B into first to nth lightness stages B ₁ , B ₂ , B ₃ ... B _n−1 , B _n. , The first to nth change levels T ₁ , T ₂ , T ₃ ... T _n-1 , T _n and the first to nth brightness levels B ₁ , B ₂ , B ₃ ... B _{n. -1,} by letting _{B n} and the comprises a halftone screen creating means for combining the respective video data by entering the D halftone screen _{H 1, H 2, H 3} ··· H n-1, H n outputs Can be made It is preferable that the halftone dot screens H _{1 to} H ₂₅₆ corresponding to 8-bit black and white shading are set with n = 256.

(7. About shooting from light to dark)
The moving image data D has been described as being photographed under dark to bright conditions, but it may be photographed from light to dark. When shooting from light to dark, the result is as follows.
The dark area ratio of the first halftone dot H ₁ is S, the dark area ratio of the nth halftone dot H _n is F, and the halftone screens H ₁ , H ₂ , H ₃ ... H _n−1 , H _n . For each dark area ratio, the first halftone dot H ₁ = S, the second halftone dot H ₂ = S + [(F−S) / (n−1)] × (2-1), and the third halftone dot H ₃ = S + [(F−S) / (n−1)] × (3-1), ... The n−1th halftone dot H _n−1 = S + [(F−S) / (n−1) ] (N−2), the nth halftone dot H _n = S + [(F−S) / (n−1)] × (n−1) = F.

(8. Pre-processing of video data)
Image quality adjustment processing such as sharpness processing and noise processing can be performed on the captured moving image to obtain moving image data D before input. In addition, upside down processing, horizontal inversion processing,
The moving image data D can be obtained by performing one or more inversion processes selected from the black and white inversion process and the time axis inversion process.
For example, FIG. 4 is an explanatory diagram of the first halftone dot to the nth halftone dot when the time axis inversion process is performed, and FIG. 5 is the first halftone dot when the horizontal inversion process and the black and white inversion process are performed. FIG. 6 is an explanatory diagram of n-th halftone dot.

(9. Regarding changes in video data)
The change content of the moving image data is not limited to the rotation of the arrow or the like, and a synthetic change of a photograph may be used. For example, FIG. 6 is a frame excerpt of moving image data that changes from a Buddha image to Mona Lisa, and FIG. 7 is a frame excerpt of moving image data that changes in the order of butterflies, flowers, and buds.
In FIG. 6, both the Buddha image at the start and the mona Lisa at the end are blacked out or whited out. Then, it is difficult to extract the Mona Lisa and the Buddha image as the original data from these intermediate images.

(10. About the first stage)
FIG. 8 is a flowchart showing the computer processing of the halftone screen. The first stage will be summarized based on the flowchart of FIG.
The moving image pre-edit is performed so that the change in the brightness H and the change in the moving image object H can be confirmed, and the moving image data D before input is obtained. With this editing, it is possible to perform image quality adjustment processing such as sharpness processing and noise processing, and one or more inversion processing selected from vertical inversion processing, horizontal inversion processing, black and white inversion processing, and time axis inversion processing. These processes are performed by Apple
Use MacPro (registered trademark), use Adobe Photoshop (registered trademark) for still image and moving image processing software, and use movie creating software Apple iMovie (registered trademark), and use Morph Exporter to blend still images into a moving image. Went by.
Next, the created moving image data D is input to the software.

The input moving image data D is set with a threshold value for conversion into two-tone monochrome by the halftone dot parameter setting means, and is decomposed into each frame of the moving image by the change dividing means and the lightness dividing means. The above-mentioned threshold is calculated so as to exclude the value of the dot gain curve of the printing machine so as to exclude the area that increases during printing. For example, “area of dark area−value of dot gain curve = area after conversion to 2 gradation monochrome”.
The halftone screen creating means determines that each frame of the decomposed moving image data D corresponds to the change level stages T _{1 to} T _n (that is, corresponds to the passage of time) or the brightness stages B _{1 to} B. _It is selected according to _n (that is, corresponding to the area after conversion to 2-tone monochrome). Further, the halftone screen creating means can also perform image sharpness processing and resolution conversion processing. Then, the halftone screen creating means outputs the halftone screens H _{1 to} H _n . These processings were performed by in-house programming of C ⁺⁺ .

(11. About the second stage)
Using the output halftone screens H _{1 to} H _n , the calculation means in the second stage halftone-converts (tone-converts) the original data for halftone dot processing, which is the target image such as a photograph, illustration, or logo mark. Output. The two-gradation monochrome halftone screens H _{1 to} H _n can be used in correspondence with the shades of the printing primary colors (process colors such as black, cyan, magenta, and yellow, and other colors), and the target image is monochrome half It can be a tone or a color halftone. These processes were performed by adding in-house programming of C ^{++ to} OpenSoft's GhostScript.
The target image that has become a monochrome halftone or a color halftone is output as halftoned data (BMP, JPEG, TIFF, GIF, etc.). Using the halftone dot data, it is possible to obtain a plate for plate making and a printed matter from a halftone dot output means (a plate exposing device, various printers, etc.). A printed matter may be prepared using the plate for plate making.

(12. Regarding printed materials)
FIG. 9 is a gradation diagram in which darkness is changed to light using the created halftone screen. FIG. 10: is a top view of the printed matter produced using the plate for platemaking.
More specifically, the printed matter is created in the manner as shown in FIG. 10 based on the gradation of the halftone screen as shown in FIG.
As shown in FIG. 9, two of the three basic dot shapes (buds, flowers, and butterflies in FIG. 9) at the left and right ends are blackout or whiteout. Then, it is difficult to derive the halftone dot basic shape from these intermediate images. Therefore, the printed matter is difficult to duplicate.

(13. About Example 2)
According to the invention described in the first embodiment, it can be dealt with that the change in the brightness B of the moving image data D is only increased or decreased. However, even if the lighting at the time of shooting changes from light to dark or dark to light, if there is a large change in the object to be shot (a white background is visible when the black door is opened, etc.), halftone dots will occur. The screens H _{1 to} H _n were uneven in tone or not continuous (so-called tone jump occurred). For example, FIG. 11 is a diagram of an example in which a tone jump has occurred in the processing of FIG.
In the second embodiment, based on the above-described first embodiment, the problem is solved by providing the tone jump determining means and the frame brightness adjusting means.

(14. Regarding tone jump discrimination means and frame brightness adjustment means)
FIG. 12 is a flowchart showing the computer processing of the halftone screen which does not cause the tone jump.
Similar to (10. First stage) in the first embodiment, the moving image data D is divided by the change dividing means and the lightness dividing means in the manner as shown in FIG.
The moving image data D that has been divided by change and divided by brightness is branched into YES (with tone jump) and NO (without tone jump) by the tone jump determination means as shown in FIG. The branch destination of NO (no tone jump) is the same as in the first embodiment.
When the flow branches to YES (there is a tone jump), it is output to each frame brightness adjusting means.

(15. Regarding each frame brightness adjustment means)
Each frame brightness adjusting means sets the moving image data D as a moving image in which vertical = Y dots, horizontal = X dots, and number of frames = n frames, and halftone screens H ₁ , H ₂ , H ₃ ... H _n-1. , An increase or decrease in the number of dots of H _n is an arbitrary rate constant, and an initial constant is b, and the number of dots of the halftone screens H ₁ , H ₂ , H ₃ ... H _n−1 , H _n The first halftone dot H ₁ = [(1 / n) × a + b] × XY, the second halftone dot H ₂ = [(2 / n) × a + b] × XY, and the third halftone dot H ₃ = [( 3 / n) × a + b ] × XY, ···· n-1 th dot _{H n-1 = [{(} n-1) / n} × a + b] × XY, = n-th dot _H n [( n / n) × a + b] × XY.
For example, when the moving image data D is a moving image with vertical = 16 dots, horizontal = 16 dots, and the number of frames = 256 frames, and an arbitrary change rate constant a = 1 and an arbitrary initial constant b = 0, a halftone screen _{H 1, H 2, H 3} ··· H n-1, H n is shown below in vertical × horizontal = 256 dots, and black dots are black and white as other white dots.
That is, the halftone dots H ₁ , H ₂ , H ₃ , H ₄ , ..., H ₂₅₃ , H ₂₅₄ , H ₂₅₅ , H ₂₅₆ are
First halftone dot H ₁ = [(1/256) × 1 + 0] × 256 = 1 dot (almost white),
Second halftone dot H ₂ = [(2/256) × 1 + 0] × 256 = 2 dots,
Third halftone dot H ₃ = [(3/256) × 1 + 0] × 256 = 3 dots,
Fourth halftone dot H ₄ = [(4/256) × 1 + 0] × 256 = 4 dots, ...
253rd halftone dot H ₂₅₃ = [(253/256) × 1 + 0] × 256 = 253 dots,
254th halftone dot H ₂₅₄ = [(254/256) × 1 + 0] × 256 = 254 dots,
255th halftone dot H ₂₅₅ = [(255/256) × 1 + 0] × 256 = 255 dots,
256th halftone dot H ₂₅₆ = [(256/256) × 1 + 0] × 256 = 256 dots (black)
It becomes.

(16. About arbitrary change rate constant a and arbitrary initial constant b)
By changing the arbitrary initial constant a, it is possible to adjust the speed of change of gradation in the same manner as adjusting the slope of the linear function. The arbitrary initial constant a is defined between 0.5 and 1.5, and is preferably in the range of 0.9 to 1.1.
For example, if a = 1.1, the 100th halftone dot H ₁₀₀ = [(100/256) × 1.1 + 0] × 256 = 110 dots, which is a gradation in which the change to black is 1.1 times larger than the direct proportion. ..
Then, by changing the arbitrary initial constant b, the start point of the gradation can be adjusted in the same manner as adjusting the Y-axis intercept of the linear function.
For example, if b = -1, the first halftone dot H ₁ = [(1/256) × 1-1] × 256 = 0 dots (white)
Can be

(17. About halftone screen output)
The output from each frame brightness adjusting means is again finely adjusted by the change dividing means and the brightness dividing means, and reaches the halftone screen creating means which is the branch destination of NO (no tone jump).

  The present invention relates to a method for producing a halftone dot screen of special halftone dots, which requires a delicate halftone dot structure, for plate making, in printed matters requiring forgery prevention and tampering prevention such as banknotes, passports, securities, cards and valuable printed matters. Available as a printing plate and print.

D video data B brightness _{B 1, B 2, B 3} ··· B n-1, B n lightness stage T time axis _{T 1, T 2, T 3} ··· T n-1, T n change degree phase H Halftone dot basic shape H ₁ , H ₂ , H ₃ ... H _n-1 , H _n halftone dot screen

Claims (9)

A method for creating a halftone screen based on moving image data (D) in which changes can be visually confirmed,
The moving image data (D) is captured in an environment where the brightness (B) of the moving image increases or decreases, or is processed so that the brightness (B) increases or decreases.
To create a halftone screen,
The time axis (T) of the moving image data (D) is the first to n-th (n is a natural number of 2 or more) change steps (T ₁ , T ₂ , T ₃ ... T _n-1 , T _n ). Change dividing means for dividing into
A lightness dividing means for dividing the increase / decrease in the lightness (B) into first to nth lightness stages (B ₁ , B ₂ , B ₃ ... B _n-1 , B _n ).
It said first to n change degree phase _{(T 1, T 2, T} 3 ··· T n-1, T n) and the first to n lightness Step _{(B 1, B 2, B} 3 ··· B _n−1 , B _n ) and halftone dot screen creating means for respectively combining
The halftone screen creating means,
The first halftone dot (H ₁ ) is the first change degree stage (T ₁ ) and the first lightness stage (B ₁ ),
The second halftone dot (H ₂ ) is the second degree of change level (T ₂ ) and the second lightness level (B ₂ ),
The third halftone dot (H ₃ ) is set to the third change degree stage (T ₃ ) and the third lightness stage (B ₃ ), ...
The ( _n-1 ) _th halftone dot (Hn _-1 ) is defined as the ( _n-1 ) _th degree of change stage ( _Tn-1 ) and the ( _n-1 ) _th brightness stage ( _Bn-1 ),
The nth halftone dot (H _n ) is _defined as the nth degree of change level (T _n ) and the nth lightness level (B _n ).
Halftone screen _{(H 1, H 2, H} 3 ··· H n-1, H n) halftone screen creation method of characterized in that to obtain. The increase / decrease in the brightness (B) of the moving image data (D) is
Depending on the start point to the end point of the time axis (T),
The halftone screen according to claim 1, wherein the lightness increases from 0% to 5% to 95% to 100% or decreases from 100% to 95% to 5% to 0%. Method. The increase / decrease in the brightness (B) is the moving image data (D) in which the brightness increases from the start point to the end point of the time axis (T),
Let S be the dark area ratio of the first halftone dots (H ₁ ),
The dark area ratio of the nth halftone dot (H _n ) is F,
The dark area ratios of the halftone screens (H ₁ , H ₂ , H ₃ ... H _n-1 , H _n ) are
The first halftone dot (H ₁ ) = S,
The second halftone dot (H ₂ ) = S − [(S−F) / (n−1)] × (2-1),
The third halftone dot (H ₃ ) = S − [(S−F) / (n−1)] × (3-1), ...
The ( _n-1 ) _th halftone dot (Hn _-1 ) = S-[(S-F) / (n-1)] * (n-2),
Wherein said n dot _{(H n) = S - [} (S-F) / (n-1)] × (n-1) = dot of claim 1 or 2, characterized in that the F How to create a screen. The increase / decrease in the brightness (B) is the moving image data (D) in which the brightness decreases from the start point to the end point of the time axis (T),
Let S be the dark area ratio of the first halftone dots (H ₁ ),
The dark area ratio of the nth halftone dot (H _n ) is F,
The dark area ratios of the halftone screens (H ₁ , H ₂ , H ₃ ... H _n-1 , H _n ) are
The first halftone dot (H ₁ ) = S,
The second halftone dot (H ₂ ) = S + [(F−S) / (n−1)] × (2-1),
The third halftone dot (H ₃ ) = S + [(F−S) / (n−1)] × (3-1), ...
The ( _n-1 ) _th halftone dot (Hn _-1 ) = S + [(FS) / (n-1)] * (n-2),
Wherein said n dot _{(H n) = S + [} (F-S) / (n-1)] × (n-1) = halftone screen according to claim 1 or 2, characterized in that the F How to create. The method of creating the halftone screen further comprises each frame brightness adjusting means,
Each frame brightness adjustment means,
The moving image data (D) is a moving image with vertical = Y dots, horizontal = X dots, and number of frames = n frames,
Let an arbitrary rate constant be a and an arbitrary initial constant b,
Each of the dot numbers of the halftone screens (H ₁ , H ₂ , H ₃ ... H _n-1 , H _n ) is represented by
The first halftone dot (H ₁ ) = [(1 / n) × a + b] × XY,
The second halftone dot (H ₂ ) = [(2 / n) × a + b] × XY,
The third halftone dot (H ₃ ) = [(3 / n) × a + b] × XY, ...
The ( _n-1 ) _th halftone dot (Hn _-1 ) = [{(n-1) / n} * a + b] * XY,
The method for producing a halftone screen according to claim 1, wherein the nth halftone dot (H _n ) = [(n / n) × a + b] × XY. 6. The halftone screen creating method according to claim 1, wherein the moving image data (D) has been subjected to an image quality adjustment process.   7. The moving image data (D) has been subjected to one or a plurality of inversion processes selected from a vertical inversion process, a horizontal inversion process, a black and white inversion process, and a time axis inversion process. The method for creating a halftone dot screen according to any one of 1.   A printing plate for plate making, which is produced by the method for producing a halftone screen according to any one of claims 1 to 7.   A printed matter produced using the plate for plate making according to claim 8.