JP5071280B2 - Pseudo 3D printer and 3D original image pseudo printing method - Google Patents

Description

  The present invention relates to a pseudo three-dimensional printer and a pseudo three-dimensional original image printing method, and more particularly to a method of pseudo-printing a three-dimensional original image by transferring a diffraction grating onto a medium.

  Various types of printing machines and printers are used as apparatuses for printing a two-dimensional image on a medium. Printing using a general printing machine can produce a large number of copies using the same plate, but the plate making process is essential, so applications that require a small number of copies immediately Not suitable for. On the other hand, printing using a printer does not require a plate making process and is suitable for immediately producing a small number of printed materials.

  For example, Patent Documents 1 and 2 listed below disclose a face photo sticker making machine incorporating a video camera and a printer. This face photo sticker creation machine has a function to take a face photo of the user on the spot and immediately print the taken face photo on a sticker sheet to provide it, such as amusement facilities, tourist facilities, streets And is widely used.

On the other hand, a method using a diffraction grating has been put into practical use as a method of expressing a stereoscopic effect on a planar medium in a pseudo manner. For example, Patent Documents 3 and 4 below have a three-dimensional effect by preparing a transfer sheet on which a predetermined diffraction grating pattern is formed in advance and transferring the transfer sheet onto a flat medium. A method for generating a diffraction grating image is disclosed.
Utility Model Registration No. 3014733 Japanese Patent Laid-Open No. 10-307903 JP 2005-246893 A JP 2006-47721 A

  As disclosed in Patent Documents 3 and 4 described above, a method using a diffraction grating is known as a technique for expressing a three-dimensional original image on a flat medium. However, in this method, first, it is necessary to prepare a transfer sheet on which a diffraction grating pattern having a predetermined three-dimensional effect is formed, and to transfer the transfer sheet to a transfer object. Therefore, this method is unsuitable for an application for immediately printing an arbitrary three-dimensional original image. For example, the method is used for a face photo sticker making machine as disclosed in Patent Documents 1 and 2 described above. It cannot be used for creating a face photo sticker or the like having a three-dimensional effect.

  Therefore, the present invention provides a pseudo-stereoscopic printer and a pseudo-printing method capable of printing immediately on an image based on an arbitrary three-dimensional original image and capable of printing an image on which a stereoscopic effect can be obtained during observation. The purpose is to provide.

(1) A first aspect of the present invention is a pseudo-stereoscopic printer for pseudo-printing a stereoscopic original image having a three-dimensional structure on a two-dimensional surface of a medium to be printed.
An original image input unit for inputting the three-dimensional shape data of the stereoscopic original image;
An original image storage unit for storing the input three-dimensional shape data;
A two-dimensional image storage unit for storing two-dimensional image data composed of an array of pixels defined on a predetermined recording surface;
When a representative point P is determined for each pixel constituting the two-dimensional image, a reference line R orthogonal to the recording surface is drawn at the position of each representative point P, and a stereoscopic original image is arranged at an adjacent position on the recording surface An intersection calculation unit for obtaining an intersection point Q between each reference line R and the surface of the stereoscopic original image;
For each intersection Q obtained by the intersection computing unit, a normal vector computing unit for obtaining a normal vector N related to the surface of the original three-dimensional image,
Using a predetermined projection plane including the reference axis A, a projection vector N ^* obtained as an orthogonal projection of each normal vector N onto the projection plane is obtained, and each obtained projection vector N ^* or its extension line and the reference axis A are obtained. An intersection angle calculation unit for obtaining an intersection angle ξ with
The intersection obtained for each pixel constituting the two-dimensional image using a function f (ξ) that monotonously increases or decreases monotonically with respect to the intersection angle ξ and takes any one of 1 to n integers. A pixel value calculation unit that stores a function value f (ξ) for the angle ξ in the two-dimensional image storage unit as a pixel value of the pixel;
A transfer sheet supply unit that supplies a total of n types of transfer sheets from the first to the n-th each having a predetermined diffraction grating pattern;
A medium supply unit for supplying a medium to be printed;
On the surface of the medium, a unit region array corresponding to the pixel array constituting the two-dimensional image is defined, and the kth unit region corresponding to the pixel to which the pixel value k (k = 1 to n) is given A transfer processing unit for transferring the transfer sheet;
Provided,
The arrangement angle of the grating lines or the arrangement pitch of the grating lines of the diffraction grating pattern formed on the n types of transfer sheets is set so as to monotonously increase or monotonously decrease in the order of the first to nth transfer sheets,
For adjacent unit areas corresponding to adjacent pixels having the same pixel value, the transfer processing unit physically transfers a single transfer layer across the boundary line, and adjacent pixels having different pixel values. As for the adjacent unit area corresponding to the above, by performing transfer with securing a gap between the transfer layers of the adjacent unit area, different physically different transfer layers are transferred with a predetermined gap secured. It is.

(2) According to a second aspect of the present invention, in the pseudo-stereoscopic printer according to the first aspect described above,
The original image input unit is configured by a device that captures or scans an actual three-dimensional object and inputs the surface shape of the three-dimensional object as three-dimensional shape data.

(3) According to a third aspect of the present invention, in the pseudo-stereoscopic printer according to the first or second aspect described above,
Define a recording plane in the XY plane in the XYZ three-dimensional orthogonal coordinate system, define a projection plane in the YZ plane, define a reference axis A that is parallel to the Z axis,
The intersection angle calculation unit obtains a projection vector N ^* on the YZ plane by projecting the normal vector N in the X-axis direction, and intersects the angle between the obtained projection vector N ^* or its extension line and the reference axis A. The angle ξ is used.

(4) According to a fourth aspect of the present invention, in the pseudo-stereoscopic printer according to the third aspect described above,
An arrangement angle θk with respect to a predetermined angle reference line of a grid line formed on the kth (k = 1 to n) transfer sheet supplied by the transfer sheet supply unit is determined using predetermined angle values α and β. , Θk = α × (k−1) / (n−1) + β,
The pixel value calculation unit is f (ξ) = Int ((ξ + 90 °) / (180 ° / n)) + 1 (where Int (x) is a function indicating the integer part of x, and f (ξ)> n In this case, the pixel value is calculated using a function f (ξ) defined by the equation f (ξ) = n).

(5) According to a fifth aspect of the present invention, in the pseudo-stereoscopic printer according to the first to fourth aspects described above ,
Input a data of a two-dimensional captured image obtained by capturing a stereoscopic original image, and store this in the original image storage unit,
A photographed image printing unit for printing a two-dimensional photographed image on the surface of a medium to be printed;
Further provided,
The transfer sheet supply unit supplies a transfer sheet having a transparent transfer layer,
The transfer processing unit is configured to perform transfer processing of the transfer sheet onto the medium after the two-dimensional captured image is printed by the captured image printing unit.

(6) According to a sixth aspect of the present invention, in the pseudo-stereoscopic printer according to the first to fifth aspects described above ,
A dither processing unit that performs dither processing on the two-dimensional image stored in the two-dimensional image storage unit;
The transfer processing unit performs transfer processing based on pixel values of the two-dimensional image after dither processing.

(7) According to a seventh aspect of the present invention, in the pseudo print method of pseudo-printing a three-dimensional original image having a three-dimensional structure on a two-dimensional surface of a medium to be printed,
An original image input stage in which a computer inputs three-dimensional shape data of a stereoscopic original image;
A two-dimensional image storage location preparation stage in which a computer secures a storage location of a pixel value of a two-dimensional image consisting of a pixel array defined on a predetermined recording surface;
The computer determines a representative point P for each pixel constituting the two-dimensional image, draws a reference line R orthogonal to the recording surface at the position of each representative point P, and places the original three-dimensional image at an adjacent position on the recording surface An intersection calculation step for obtaining an intersection point Q between each reference line R and the surface of the original three-dimensional image,
A computer for calculating a normal vector N relating to the surface of the original three-dimensional image for each intersection Q determined by the intersection calculation step;
The computer defines a predetermined projection plane including the reference axis A, obtains a projection vector N ^* obtained as an orthogonal projection of each normal vector N onto the projection plane, and obtains each projection vector N ^* and the reference axis A A crossing angle calculation step for obtaining a crossing angle ξ of
A computer obtains individual pixels constituting a two-dimensional image based on a function f (ξ) that monotonously increases or decreases monotonously with respect to the intersection angle ξ and takes any one of n integers 1 to n. A pixel value calculation step of storing a function value f (ξ) for the obtained intersection angle ξ as a pixel value of the pixel in a storage location;
Defining a unit region array corresponding to the pixel array constituting the two-dimensional image on the surface of the medium to be printed, and transferring a transfer sheet having a predetermined diffraction grating pattern to each unit region; and
Have
In the transfer processing stage, a “grid line arrangement angle” or “grid line arrangement pitch” that monotonously increases or monotonously decreases in accordance with the pixel value k (k = 1 to n) of the corresponding pixel in each unit region. And a single transfer layer is physically transferred across the boundary for adjacent unit areas corresponding to adjacent pixels having the same pixel value. For adjacent unit areas corresponding to adjacent pixels having pixel values different from each other, separate transfer layers physically different from each other ensure predetermined gaps by performing transfer with gaps secured between the transfer layers of the adjacent unit areas. It is designed to be transferred in a state.

(8) According to an eighth aspect of the present invention, in the pseudo-printing method according to the seventh aspect described above ,
A photographed image input stage for inputting data of a two-dimensional photographed image obtained by photographing a stereoscopic original image,
A photographed image printing stage for printing a two-dimensional photographed image on the surface of the medium to be printed;
And further
In the transfer processing stage, a transparent transfer sheet is transferred onto the printing surface of the two-dimensional photographed image.

According to the present invention, information on the orientation of each part of the surface of a stereoscopic original image is extracted as a normal vector N, and a grid line arrangement corresponding to the orientation of the normal vector N is formed in a unit area constituting each pixel on the medium. Since a diffraction grating pattern with an angle or a grid line arrangement pitch is transferred, images can be printed immediately on the medium, and can be printed on the basis of an arbitrary three-dimensional original image. Can be printed on. In addition, at the time of transfer, for adjacent unit regions corresponding to adjacent pixels having the same pixel value, a single transfer layer is physically transferred across the boundary line, and corresponds to adjacent pixels having different pixel values. For adjacent unit areas, separate physically different transfer layers are transferred in a state where a predetermined gap is ensured, so even if a positional deviation occurs, there is a gap between adjacent transfer layers transferred from different transfer sheets. A physical void is secured. For this reason, it is possible to prevent adjacent transfer layers from partially overlapping and causing a transfer failure.

  Hereinafter, the present invention will be described based on the illustrated embodiments.

<<< §1. Basic Configuration of Printer According to the Present Invention >>
FIG. 1 is a block diagram showing a basic configuration of a pseudo three-dimensional printer according to the present invention. This printer has a function of pseudo-printing a three-dimensional original image 10 (here, an example of a human face) having a three-dimensional structure on a two-dimensional surface of a medium 20 to be printed. Yes.

  As shown in the figure, this printer is roughly composed of a data input unit 100, a data processing unit 200, and a print processing unit 300. Each of these units can be installed in a device casing that is almost the same size as a conventional general facial photo sticker making machine. It has a function to take a picture on the spot and immediately print and provide the photographed face photo. Therefore, it can be installed and used for amusement facilities, tourist facilities, streets, and the like. In addition, the face photograph provided to the user becomes an image in which a three-dimensional effect is obtained in spite of being formed on the two-dimensional surface of the medium.

  A data input unit 100 shown as a block in FIG. 1 is a unit that performs an operation of taking in three-dimensional shape data indicating a stereoscopic original image 10. In the case of the embodiment shown here, the data input unit 100 has a function of taking in three-dimensional shape data from a human face, and is configured by a stereoscopic camera or a three-dimensional scanner.

  The data processing unit 200 is a unit that performs processing for creating two-dimensional image data based on the three-dimensional shape data captured by the data input unit 100. In practice, a dedicated program is incorporated in the computer. It is realized by. Usually, the process of converting the three-dimensional shape data into the two-dimensional image data is performed by a geometric calculation process for projecting the three-dimensional structure onto a predetermined projection surface. In the present invention, however, the process is very unique. A process for generating a two-dimensional image is performed. The specific algorithm will be described in detail later.

  On the other hand, the print processing unit 300 is a unit that prints a two-dimensional image on the medium 20 based on the two-dimensional image data created by the data processing unit 200. However, the printing performed here is not a general two-dimensional image printing using ink, but is performed by transferring a transfer sheet on which a diffraction grating pattern is formed. As described above, the printer according to the present invention can print an image on which the three-dimensional effect is obtained on the medium 20 by transferring the transfer sheet on which the diffraction grating pattern is formed on the medium 20.

  FIG. 2 is an enlarged surface view of the printed matter created by the pseudo three-dimensional printer shown in FIG. 1, that is, the medium 20 on which the diffraction grating pattern is recorded. As shown in the figure, a large number of pixels are arranged on this printed matter, and a diffraction grating composed of grating lines each directed in a predetermined direction is arranged in each pixel.

  In FIG. 2, for convenience of explanation, individual grating lines are drawn as lines that can be observed with the naked eye. However, in actuality, the pitch of these grating lines is a dimension value (this value that can form a diffraction grating). In the case of the example, it is set to 1 μm), and individual lattice lines cannot be observed with the naked eye. In order to form a diffraction grating, it is usually necessary to set the grating line pitch to about 0.5 μm to 10 μm. On the other hand, the size of each pixel indicated by a square in the drawing is also set to a very small size (48 μm in this example) that does not cause graininess when observed with the naked eye. In FIG. 2, the boundaries between the pixels are indicated by lines, but these boundary lines are drawn for convenience in order to indicate the conceptually defined pixels.

  After all, the apparatus shown in FIG. 1 inputs 3D shape data from the user's face that is the stereoscopic original image 10, generates 2D image data based on the 3D shape data, and generates the 2D image data. Based on this, it has a function of printing a two-dimensional image on the surface of the medium 20. Then, on the surface of the medium 20 obtained after printing, as shown in FIG. 2, a diffraction grating composed of grating lines each having a predetermined arrangement angle is formed for each unit region corresponding to each pixel. The three-dimensional effect of the three-dimensional original image 10 is reproduced in a pseudo manner by the diffraction grating.

  A medium 20 shown in FIG. 2 is an example in which one of diffraction gratings having three kinds of grid line arrangement angles is transferred to each pixel. That is, on this medium 20, a pixel G1 in which a diffraction grating having a grating line having an arrangement angle of −45 ° (grating line from upper left to lower right) is arranged, and a grating line having an arrangement angle of 0 ° ( The pixel G2 having a diffraction grating having a horizontal grating line) and the pixel G3 having a diffraction grating having a grating line (grating line from the upper right to the lower left) having an arrangement angle of + 45 ° A dimensional image is formed.

  As described above, it is known that the medium 20 having the diffraction grating formed on the surface can obtain a pseudo-stereoscopic effect due to the diffraction phenomenon of illumination light generated during observation. However, since the example shown in FIG. 2 is an example using a diffraction grating having three kinds of grid line arrangement angles, a very large stereoscopic effect cannot be obtained. Therefore, in practice, it is preferable to use a diffraction grating having about 10 grating line arrangement angles as in the embodiments described later.

<<< §2. Printer according to a basic embodiment of the present invention >>
Next, the configuration of the pseudo-stereoscopic printer according to the basic embodiment of the present invention will be described based on the block diagram of FIG. In FIG. 3, constituent elements 100, 200, and 300 surrounded by a one-dot chain line are the data input unit 100, the data processing unit 200, and the print processing unit 300 shown in FIG. In addition, the solid line arrow shown in FIG. 3 shows the flow of an electric signal, and the broken line arrow shows other relations.

  As described above, the data input unit 100 is a unit that performs an operation of taking in the three-dimensional shape data indicating the three-dimensional original image 10, and includes the original image input unit 110. In the case of the embodiment shown here, the original image input unit 110 captures a user's face (stereoscopic original image 10) from various angles by an imaging system using a plurality of cameras, and uses based on these captured images. It is comprised by the apparatus which produces | generates the three-dimensional shape data which show the surface of a person's face. As described above, an apparatus that captures an actual three-dimensional object from various directions and generates three-dimensional shape data of the object is a known apparatus that has already been put into practical use. A description of the specific configuration 110 is omitted.

  Of course, the original image input unit 110 is not necessarily configured by an imaging system using a plurality of cameras. Various 3D scanners such as a range scanner device are also used as devices for capturing 3D shape data from an actual 3D object, and these devices may be used as the original image input unit 110. That is, the original image input unit 110 can be configured by an arbitrary device having a function of inputting a surface shape of a three-dimensional object as three-dimensional shape data by photographing or scanning an actual three-dimensional object. .

  In addition, the basic embodiment described here is intended for an apparatus having a function of performing printing immediately based on the three-dimensional shape data captured from the user's face. Although an apparatus having a function of photographing and scanning a user's face is used, the original image input unit 110 does not necessarily have a function of photographing and scanning.

  For example, if the user already has 3D shape data created by another system, the 3D shape data can be recorded on a data recording medium such as a CD-R or USB memory and brought in. The printer according to the present invention can be used. In this case, instead of capturing the three-dimensional shape data by photographing or scanning the user's face, a process of reading the three-dimensional shape data from a data recording medium such as a CD-R or USB memory brought in by the user. The original image input unit 110 can be configured by a CD drive device, a USB memory reading device, or the like.

  Of course, the user can also transmit the three-dimensional shape data through a network such as the Internet. In this case, since the original image input unit 110 only needs to perform the function of receiving the transmitted three-dimensional shape data, it can be configured by a data receiving device having a communication function.

  In the basic embodiment described here, an actual object “user's face” is used as the stereoscopic original image 10. However, the stereoscopic original image 10 used in the present invention is not necessarily an actual object. It doesn't have to be an image. For example, it is possible to artificially create the three-dimensional original image 10 using CG or the like. When the three-dimensional original image 10 is artificially created, since the three-dimensional shape data is already prepared, the original image input unit 110 has a function of simply inputting the three-dimensional shape data. If it is enough.

  In short, the original image input unit 110 according to the present invention inputs the three-dimensional shape data of any stereoscopic original image 10 by any method regardless of whether it is a real object or a virtual object created by CG or the like. Any device may be used as long as it has a function.

  On the other hand, the data processing unit 200 is a unit that performs processing for creating two-dimensional image data based on the three-dimensional shape data thus captured, and is actually realized by incorporating a dedicated program into the computer. It is a component. As shown in FIG. 3, the data processing unit 200 includes an original image storage unit 210, an intersection calculation unit 220, a normal vector calculation unit 230, an intersection angle calculation unit 240, a pixel value calculation unit 250, and a two-dimensional image storage unit 260. It is configured. Hereinafter, functions of these components will be described.

  First, the original image storage unit 210 is a component that stores the three-dimensional shape data D1 input by the original image input unit 110, and includes a storage device such as a hard disk for a computer. As described above, the three-dimensional shape data D1 is data for representing the real or virtual three-dimensional original image 10, and is usually given as data defining the surface shape of the three-dimensional structure on the XYZ three-dimensional coordinate system. It is done. Specifically, the surface of the three-dimensional original image 10 is replaced with a large number of polygons, and three-dimensional shape data D1 is prepared as coordinate data indicating the vertex coordinates of each polygon, or the surface of the three-dimensional original image 10 is expressed by a mathematical expression. A method is known in which three-dimensional shape data D1 is prepared as data indicating parameters that define individual parametric curved surfaces, replacing with possible parametric curved surfaces.

  The purpose of data processing by the data processing unit 200 is to create two-dimensional image data D2 based on the three-dimensional shape data D1 stored in the original image storage unit 210. The intersection calculation unit 220, the normal vector calculation unit 230, the intersection angle calculation unit 240, and the pixel value calculation unit 250 are components that perform processing for creating the two-dimensional image data D2. Is executed by a dedicated program incorporated in the computer. A specific method for determining individual pixel values constituting the two-dimensional image data D2 will be described in detail in Section 3. On the other hand, the two-dimensional image storage unit 260 is a component that stores the two-dimensional image data D2 created in this way, and includes a storage device such as a hard disk for a computer.

  Like the general two-dimensional image data, the two-dimensional image data D2 created here is data composed of an array of a large number of pixels each having a predetermined pixel value. It does not indicate a projected image, but indicates the direction of a normal line set on each minute surface constituting the three-dimensional original image 10.

  In the two-dimensional image storage unit 260 shown in FIG. 3, two-dimensional image data D2 having a pixel array of 6 rows and 8 columns is exemplified, and a pixel G (i, j) in the i-th row and j-th column is exemplified. In practice, however, a larger number of pixels will be defined. However, in the following description, for the sake of convenience, description will be made using two-dimensional image data D2 having a pixel array of 6 rows and 8 columns. The pixel array defined as the two-dimensional image data D2 corresponds to the pixel array (unit area array) formed on the medium 20 shown in FIG.

  Since the diffraction grating is transferred in the pixel (unit region) on the medium 20, each pixel forms a diffraction grating (a collection of grating lines capable of causing a diffraction phenomenon). In order to achieve this, it is necessary to use a square having a side dimension of 10 μm or more, or an arbitrarily shaped cell having a size equivalent thereto. However, if the size of the pixel becomes too large, the resolution when observed with the naked eye will be reduced, and smooth representation will not be possible. Therefore, in practice, each pixel is a square with a side dimension of 500 μm or less or It is preferable to use an arbitrarily shaped cell having a size according to this.

  After all, it is preferable that each pixel (unit region) on the medium 20 is composed of a square cell having a side dimension of 10 μm to 500 μm or an arbitrarily shaped cell having a size equivalent thereto. Although an example in which one pixel is formed by a square cell will be described here, of course, the shape of each pixel is not limited to a square, but may be any other shape such as a square or a circle. It doesn't matter. However, since the diffraction grating is formed only inside each pixel, it is preferable to use a rectangular pixel in which no gap is generated between adjacent pixels in order to improve diffraction efficiency and obtain a brighter reproduced image.

  In this way, the two-dimensional image data D2 obtained in the two-dimensional image storage unit 260 is the general two-dimensional image data in terms of “data indicating a pixel array defined on the two-dimensional plane”. There is no change. However, the meaning of the pixel value of each pixel is slightly different from general two-dimensional image data. That is, in the case of general two-dimensional image data, the pixel value of each pixel indicates the gradation value of the image at the pixel position. In the present invention, the pixel value of each pixel is This is a value indicating the number of the transfer sheet used in the printing process (transfer process) by the print processing unit 300.

  For example, the example shown in FIG. 2 is an example of printing using three types of diffraction gratings as described above. In order to perform such printing, the pixel value “1” is given to the pixel G1, the pixel value “2” is given to the pixel G2, and the pixel value “3” is given to the pixel G3. D2 is created, and the first transfer sheet (sheet having a diffraction grating pattern with an arrangement angle of −45 °) is transferred into the pixel having the pixel value “1”, and the pixel value “2” is set. The second transfer sheet (sheet having a diffraction grating pattern with an arrangement angle of 0 °) is transferred into pixels having the third transfer sheet (positioning angle with pixels having a pixel value “3”). A sheet having a diffraction grating pattern having + 45 ° may be transferred.

  The print processing unit 300 has a function of performing a process of transferring the transfer sheet onto the medium 20 based on the two-dimensional image data D2 stored in the two-dimensional image storage unit 260. A supply unit 310, a transfer processing unit 320, and a medium supply unit 330 are configured.

  The transfer sheet supply unit 310 is a component that supplies a total of n types of transfer sheets from the first to the nth, each having a predetermined diffraction grating pattern. A specific structure of the transfer sheet will be described in detail in Section 5. FIG. 3 shows a state in which the transfer sheet supply unit 310 holds n types of transfer sheets T1 to Tn and supplies the kth transfer sheet Tk from among them.

  On the other hand, the medium supply unit 330 is a component that supplies the medium 20 to be printed. Here, an example in which sticker paper is used as the medium 20 will be described. This sticker paper is a paper in which a backing sheet is attached to the back surface of the paper body via an adhesive layer. After printing (transfer of a transfer sheet having a diffraction grating pattern) is performed on the front surface of the paper body, the back surface By peeling off the mount, the paper body can be attached to an arbitrary object. Such a sticker sheet is used in a conventional general face photo sticker making machine.

  Of course, the medium 20 supplied by the medium supply unit 330 may be any medium. The material is not limited to paper, and synthetic resin or cloth can be used as the medium 20. Further, the surface of the medium 20 does not necessarily need to be a flat surface, and may be a curved surface. For example, if a beverage mug or the like is used as the medium 20, the medium supply unit 330 functions to supply the mug, and the transfer seal is transferred to the surface of the mug.

  The transfer processing unit 320 defines, on the surface of the medium 20 supplied from the medium supply unit 330, a unit region array corresponding to the pixel array constituting the two-dimensional image indicated by the two-dimensional image data D2, and the k th The k-th transfer sheet Tk is transferred to the unit area corresponding to the pixel to which the pixel value k (k = 1 to n) is given. A specific transfer processing method will be described in detail in Section 5.

  For example, in order to obtain a printed matter as shown in FIG. 2, n = 3 is set, and three types of transfer sheets T1 (lattice line arrangement angle −45 °) and T2 (lattice lines) are set in the transfer sheet supply unit 310. Arrangement angle 0 °) and T3 (grid line arrangement angle + 45 °) may be prepared. First, the first transfer sheet T1 is supplied from the transfer sheet supply unit 310, and the transfer processing by the transfer processing unit 320 is performed. That is, with reference to the two-dimensional image data D2, the transfer sheet T1 is transferred only to the unit area on the medium 20 corresponding to the pixel G1 having the pixel value “1”. Subsequently, the second transfer sheet T2 is supplied from the transfer sheet supply unit 310, and the transfer processing by the transfer processing unit 320 is performed. This time, the transfer sheet T2 is transferred only to the unit area on the medium 20 corresponding to the pixel G2 having the pixel value “2”. Finally, the third transfer sheet T3 is supplied from the transfer sheet supply unit 310, and the transfer processing by the transfer processing unit 320 is performed. As a result, the transfer sheet T3 is transferred only to the unit area on the medium 20 corresponding to the pixel G3 having the pixel value “3”.

<<< §3. Pixel value determination algorithm >>>
As already described, the two-dimensional image data D2 stored in the two-dimensional image storage unit 260 shown in FIG. 3 is data indicating the pixel value of each pixel G (i, j). It is determined by the intersection calculation unit 220, the normal vector calculation unit 230, the intersection angle calculation unit 240, and the pixel value calculation unit 250. Here, this pixel value indicates the direction of the normal line set up on each minute surface constituting the stereoscopic original image 10, and the number of the transfer sheet used in the printing process (transfer process) by the print processing unit 300. It is used as a value indicating Hereinafter, the algorithm of the pixel value determination process will be described, and the reason why the three-dimensional structure of the three-dimensional original image 10 is expressed in a pseudo manner on the printed matter on which the diffraction grating pattern is transferred will be described.

  FIG. 4 is a perspective view showing the basic principle of the pixel value determination process of the two-dimensional image in the pseudo-stereoscopic printer shown in FIG. Here, for convenience of explanation, as illustrated, an XYZ three-dimensional orthogonal coordinate system is defined, a recording surface Sxy is defined on the XY plane, a projection surface Syz is defined on the YZ plane, and a reference axis A is defined on the Z axis. (For the sake of convenience, the direction of the reference axis A is opposite to the Z axis).

  The recording surface Sxy is a surface corresponding to the printing surface of the medium 20, and a two-dimensional pixel array composed of pixels G (i, j) is defined on the recording surface Sxy as illustrated. As described above, an array of pixels (unit areas) corresponding to the two-dimensional pixel array is defined on the actual medium 20. FIG. 4 shows an example in which a simple pixel array of 6 rows and 8 columns is defined for convenience of explanation. In practice, however, the definition of a pixel array having a resolution sufficient to express the stereoscopic original image 10 is shown. Done.

  As illustrated, the three-dimensional original image 10 is arranged at a position adjacent to the recording surface Sxy. As already described, the three-dimensional original image 10 is taken into the original image storage unit 210 as the three-dimensional shape data D1, and this three-dimensional shape data D1 is data in a format in which the shape can be defined in the XYZ three-dimensional coordinate system. If so, the stereoscopic original image 10 can be defined at a position adjacent to the recording surface Sxy. The pixel value of the pixel G (i, j) in the i-th row and j-th column of the two-dimensional pixel array defined on the recording surface Sxy is as follows using the information on the surface of the stereoscopic original image 10. It is determined by a simple method.

  First, a representative point P is determined for the pixel G (i, j). The representative point P may be determined at any position as long as it is a point in the pixel G (i, j) (may be a point on the contour line of the pixel). For example, the upper left corner point of each pixel may be set as the representative point P. However, in the embodiment described here, the center point of each pixel is set as the representative point P. The representative point P shown in FIG. 4 is the center point of the pixel G (i, j).

  Subsequently, a reference line R orthogonal to the recording surface Sxy is drawn at the position of the representative point P. In the case of the embodiment shown here, since the recording surface Sxy is a surface defined on the XY plane, the reference line R becomes a line parallel to the Z-axis as shown by a one-dot chain line in the figure. Then, an intersection point Q between the reference line R and the surface of the stereoscopic original image 10 is obtained, and a normal vector N related to the surface of the stereoscopic original image 10 is obtained for the intersection point Q (indicated by arrows in the figure). . This normal vector N is a unit vector that starts from the intersection point Q and goes vertically outward with respect to the minute surface of the stereoscopic original image 10 including the intersection point Q, and the direction of the surface of the stereoscopic original image 10 at the position of the intersection point Q It has information indicating.

  Depending on the shape of the three-dimensional original image 10, a plurality of intersections may be obtained for one reference line R. For example, FIG. 5 is a side view showing an example in which four intersection points Q1 to Q4 are obtained for the reference line R extending from the representative point P. In this case, normal vectors N1 to N4 are obtained for each of the intersections Q1 to Q4, as shown in the figure. Among them, the intersection point Q1 and the normal vector N1 closest to the recording surface Sxy are represented by the representative point. What is necessary is just to employ | adopt as the intersection Q about P, and the normal vector N. This is because, when the three-dimensional original image 10 is observed from the recording surface Sxy side, the intersection points Q2 to Q4 are points on the hidden surface, and therefore it is not necessary to record information on the normal vectors N2 to N4 on the recording surface Sxy. Because.

  Further, as shown by the representative point P ′ shown in FIG. 5, even if the reference line R ′ is extended, the stereoscopic original image 10 may not be crossed. For a pixel having such a representative point P ′, no intersection point is defined and no normal vector is defined, and therefore no pixel value is defined. In this way, for the pixel in which the pixel value is not defined, the transfer of the diffraction grating pattern by the print processing unit 300 is not performed finally, but it is an area corresponding to the background portion where the stereoscopic original image 10 does not exist originally. There is no problem if the diffraction grating pattern is not transferred.

  However, if it is preferable to transfer a diffraction grating pattern to such a background portion as well, as illustrated in FIG. 5, the background surface 11 (as a part of the stereoscopic original image) is located behind the stereoscopic original image 10. Should be handled). In the case of the illustrated example, a surface parallel to the recording surface Sxy is defined as the background surface 11. In this case, for the pixel having the representative point P ′, the intersection point Q ′ is obtained, and the normal vector N ′ parallel to the reference axis A is obtained.

Next, a projection vector N ^* is obtained as an orthographic projection obtained by projecting the normal vector N thus obtained onto the projection plane Syz. That is, as shown in FIG. 4, when the normal vector N is projected in the X-axis direction, the projection image obtained on the projection plane Syz (YZ plane) becomes the projection vector N ^* . In the embodiment shown here, the projection surface Syz is defined as a surface orthogonal to the recording surface Sxy, but the projection surface does not necessarily have to be a surface orthogonal to the recording surface. Further, the projection vector N ^* is not necessarily an orthogonal projection image of the normal vector N, and may be a projection image in an arbitrary direction. However, in order to reproduce the three-dimensional structure of the original three-dimensional image 10 as faithfully as possible, in practice, a projection plane Syz orthogonal to the recording plane Sxy is defined as in the embodiment described herein, and a normal vector is defined. Preferably, N orthogonal projection images are used as the projection vector N ^* .

Subsequently, the intersection angle ξ between the projection vector N ^* or its extension line and the reference axis A is obtained. In the embodiment shown here, since the reference axis A is on the Z axis, the intersection angle ξ is obtained as an angle formed by the projection vector N ^* or its extension line and the Z axis. In Figure 4, for convenience of explanation, the projected image on the projection plane Syz the intersection Q and the projected point Q ^*, and the projection vector N ^* to the start point of the projection point Q ^*, is obtained by translating the reference axis A An example in which the intersection angle ξ is defined as an angle formed with the axis A ^* is shown. This is equivalent to setting the angle formed between the projection vector N ^* or its extension line and the reference axis A as the intersection angle ξ. It is.

  In the embodiment shown here, since the direction of the reference axis A is defined in the direction opposite to the Z-axis, the crossing angle ξ is −90 ° to + 90 ° as shown in FIG. Defined as an acute angle in range. In addition, as for the normal vectors N2 and N4 shown in FIG. 5, the crossing angle ξ is an obtuse angle, but these are normals for the intersections Q2 and Q4 located on the hidden surface, and are adopted as described above. There is nothing. However, the reference axis A does not necessarily need to be set to an axis parallel to the Z axis, and any axis may be set as the reference axis as long as it is an axis included in the projection plane Syz. For example, if an axis parallel to the Y axis is set as the reference axis, the crossing angle ξ is defined as an angle in the range of 0 ° to 180 °.

  The thus obtained intersection angle ξ is a value indicating the degree of inclination in the Y-axis direction (vertical direction in FIG. 4) of the minute surface of the stereoscopic original image 10 at the position of the intersection point Q. That is, when the direction of the reference axis A is defined in the direction opposite to the Z axis, the plane near the intersection Q where the crossing angle ξ = 0 ° is obtained is a minute surface parallel to the XY plane, and the crossing angle ξ is As the angle increases toward + 90 °, the minute surface inclines in the positive Y-axis direction (upward in FIG. 4), and when the crossing angle ξ decreases toward −90 °, the minute surface becomes smaller. The surface is inclined in the Y-axis negative direction (downward in FIG. 4).

  The basic concept of the present invention is to express the information on the inclination of the individual microsurfaces constituting such a stereoscopic original image 10 as a variation in the arrangement angle of the grating lines of the diffraction grating pattern formed on the medium 20. is there. For this purpose, an arrangement angle θ that monotonously increases or monotonously decreases with respect to the intersection angle ξ is defined, and a unit region on the medium 20 corresponding to the pixel from which the intersection angle ξ is obtained is set to the intersection angle ξ. A diffraction grating pattern having a corresponding arrangement angle θ may be transferred.

  For example, when using n diffraction grating patterns having an arrangement angle θ distributed in a range of −45 ° to + 45 °, the crossing angle ξ shown in FIG. 6A is changed to the arrangement angle shown in FIG. 6B. It may be associated with θ. The crossing angle ξ shown in FIG. 6 (a) is an angle distributed in the range of −90 ° to + 90 ° as described above, whereas the arrangement angle θ shown in FIG. 6 (b) is −45 °. Since the angle is distributed in a range of ˜ + 45 °, for example, if a linear relational expression such as θ = ξ / 2 is defined, the arrangement angle θ can be uniquely determined based on the crossing angle ξ. The arrangement angle θ of the grid line L is defined as an angle formed by the grid line L with respect to a predetermined angle reference line B defined on the medium 20 (for example, the horizontal outline of the medium 20 shown in FIG. 2). ing.

  However, in practice, the grating line arrangement angle θ of the diffraction grating pattern is not a value that can be defined as an arbitrary continuous quantity, but must be defined as a discrete value that takes any one of n ways. For example, the example shown in FIG. 2 is an example in the case of n = 3, and each pixel (unit region) on the medium 20 has one of three arrangement angles of −45 °, 0 °, and + 45 °. It is necessary to selectively transfer the diffraction grating pattern. Therefore, in practice, even if the arrangement angle θ is calculated based on a linear relational expression such as θ = ξ / 2, the diffraction grating pattern having the arrangement angle closest to the calculated value is selected and transferred. become.

  For example, in a unit region corresponding to a pixel having an intersection angle ξ within a range of −90 ° ≦ ξ <−30 °, a diffraction grating pattern in which grating lines L are arranged at an arrangement angle θ = −45 ° is used. The diffraction grating pattern in which the grating line L is arranged at the arrangement angle θ = 0 ° is transferred to the unit region corresponding to the pixel that has been transferred and the intersection angle ξ within the range of −30 ° ≦ ξ ≦ + 30 ° is obtained. Then, the diffraction grating pattern in which the grating line L is arranged at the arrangement angle θ = + 45 ° is transferred to the unit region corresponding to the pixel where the crossing angle ξ within the range of + 30 ° <ξ ≦ + 90 ° is obtained. A selection rule like this should be established.

  Of course, as in the example shown in FIG. 2, when a diffraction grating having three lattice line arrangement angles is used, a practically sufficient stereoscopic effect cannot be obtained. Therefore, hereinafter, a specific example (example of n = 10) using a diffraction grating having 10 kinds of grid line arrangement angles distributed in a range of −45 ° to + 45 ° will be described.

  FIG. 7 is a plan view of ten transfer sheets T1 to T10 used in the pseudo three-dimensional printer shown in FIG. These transfer sheets T1 to T10 are all rectangular sheets having the same size as the medium 20, and the lattice lines L are formed at different arrangement angles θ. Of course, since each grating line L is actually a grating line constituting a diffraction grating, its pitch is on the order of the wavelength of light and cannot be observed with the naked eye. The grid lines L shown in the figure are drawn for convenience of explanation. Here, when the lower side of each sheet is the angle reference line B, a value indicating the angle formed by the lattice line L and the angle reference line B with a signed acute angle is defined as the arrangement angle θ.

  As shown in the figure, the first transfer sheet T1 has a grid line L having an arrangement angle θ = −45 °, and the second transfer sheet T2 has an arrangement angle θ = −35 °. Lattice lines L having are formed. Hereinafter, the arrangement angle θ of the lattice lines L formed on the third transfer sheet T3, the fourth transfer sheet T4,..., The tenth transfer sheet T10 increases in order by 10 °. Go. As shown in FIG. 6 (a), the arrangement angles of the diffraction gratings to be transferred to the unit region corresponding to the pixel where the crossing angle ξ within the range of −90 ° ≦ ξ ≦ + 90 ° is obtained are these 10 types. A value closest to ξ / 2 may be selected from the angles.

  Of course, variations of the diffraction grating pattern are not limited to ten, and n can be set to an arbitrary value. Further, the range that the arrangement angle θ should take is not limited to the range of −45 ° to + 45 ° as in the above-described example. In the first place, the definition of the arrangement angle θ varies depending on the definition of the angle reference line B, and the angle distribution range is not limited to 90 °. However, it is preferable that the angular distribution range does not exceed 90 °. For example, the angle reference line B is set on the right side of each transfer sheet, and the arrangement angle θ can be set as n angles distributed in a range of −15 ° to + 70 °.

If the arrangement angle θ is defined as n angles distributed at equal intervals, the kth arrangement angle θk is, as shown in FIG.
θk = α · (k−1) / (n−1) + β Equation (1)
Can be expressed as Here, α is an angle value indicating the distribution range, and β is an angle value indicating the offset. For example, when α = 90 °, β = −45 °, and n = 10, this equation (1) is expressed as shown in FIG.
θk = 10 ° · (k−1) −45 ° Formula (2)
become that way. The arrangement angles −45 °, −35 °, −25 °,..., + 45 ° of the lattice lines L formed on the ten types of transfer sheets T1 to T10 shown in FIG. , K = 1, 2, 3,..., 10 are obtained.

  Thus, in the present invention, the n lattice line arrangement angles θ can be set as arbitrary angles distributed in an arbitrary angle range. However, the important point in the present invention is to define a relationship such that the arrangement angle θ monotonously increases or monotonously decreases with respect to the crossing angle ξ. In the case of the above-described example, when the crossing angle ξ increases from −90 ° to + 90 °, the corresponding arrangement angle θ also increases monotonously from −45 ° to + 45 °. Of course, as the crossing angle ξ increases from −90 ° to + 90 °, a corresponding relationship may be defined in which the corresponding arrangement angle θ decreases monotonously from + 45 ° to −45 °. .

  When the intersection angle ξ (i, j) for a specific pixel G (i, j) is obtained by the method shown in FIG. 4, the unit region U (i) on the medium 20 corresponding to the pixel G (i, j) is obtained. , J) is transferred with a diffraction grating pattern having an arrangement angle θ corresponding to the crossing angle ξ (i, j) by the above correspondence. In this way, when the diffraction grating pattern having the arrangement angle θ corresponding to the crossing angle ξ obtained for each pixel is transferred to the unit area corresponding to each pixel, the stereoscopic original image 10 having a stereoscopic effect is observed. It can be done.

  Of course, since the original three-dimensional image 10 is not recorded as a hologram on the medium 20 printed by the pseudo-stereoscopic printer according to the present invention, the observed image is not an original three-dimensional image. However, it is possible to observe a pseudo stereoscopic image that visually creates a stereoscopic effect. Although the theoretical analysis of the phenomenon in which such pseudo stereoscopic vision occurs is not sufficiently performed at present, the inventor of the present application has applied the inclination distribution (inclination distribution in the Y-axis direction) of each part of the surface of the stereoscopic original image 10. This information is expressed as an arrangement angle distribution of the grating lines of the diffraction grating formed on the medium 20. It is closely related to this reason that it is necessary to define a correspondence relationship in which the arrangement angle θ monotonously increases or monotonously decreases with respect to the change in the intersection angle ξ.

  Note that the intersection angle ξ determined by the method shown in FIG. 4 includes only information on the inclination distribution of each surface portion of the stereoscopic original image 10 in the Y-axis direction. This is because the projection plane Syz is defined on the YZ plane. Therefore, the stereoscopic view obtained when observing the medium 20 is only the depth change in the vertical direction of the stereoscopic original image 10. If it is desired to generate a stereoscopic view in which the depth change in the left-right direction of the stereoscopic original image 10 is felt, the projection plane may be defined on the XZ plane.

  As described above, in the present invention, it is important to determine a specific grid line arrangement angle θ based on the intersection angle ξ obtained for each pixel. However, since the lattice line arrangement angle θ takes n discrete values, the process of selecting one of the n arrangement angles θ is eventually prepared in the transfer sheet supply unit 310. This is equivalent to the process of selecting one of the various transfer sheets T1 to Tn. Therefore, as the pixel value of each pixel constituting the two-dimensional image data D2 prepared in the two-dimensional image storage unit 260, a value indicating the grating line arrangement angle θ of the diffraction grating to be transferred to the pixel is used. However, in the embodiment shown here, a value indicating the number of the transfer sheet to be transferred to the pixel is used instead.

  Specifically, the pixel value “1” is set for the pixel to which the first transfer sheet T1 shown in FIG. 7 (the diffraction grating pattern on which the grating line L having the arrangement angle θ = −45 ° is formed) is to be transferred. A pixel value “2” is given to a pixel to which the second transfer sheet T2 (diffraction grating pattern on which the grating line L having the arrangement angle θ = −35 ° is formed) is given, and so on. The pixel value “10” is given to the pixel to which the tenth transfer sheet T10 (diffraction grating pattern on which the grating line L having the arrangement angle θ = + 45 ° is formed) is to be transferred.

In order to determine the pixel value indicating the number of the transfer sheet to be transferred to each pixel (unit area) based on the intersection angle ξ, the equation of the pixel value f (ξ) can be defined as a function of the intersection angle ξ. That's fine. FIG. 9 is a diagram showing an example of such an expression. That is, the pixel value f (ξ) is
f (ξ) = Int ((ξ + 90 °) / (180 ° / n)) + 1 Formula (3)
(However, if f (ξ)> n, f (ξ) = n)
Is defined by the expression Here, Int (x) is a function indicating the integer part of x. In the case of the embodiment shown in FIG. 4, −90 ° ≦ ξ ≦ + 90 °, so the pixel value f (ξ) defined by the above equation (3) is any one of n integers 1 to n. It becomes a function that takes Therefore, if the function value f (ξ) with respect to the crossing angle ξ obtained for each pixel is the pixel value of the pixel, this pixel value is transferred in n ways in the transfer sheet supply unit 310. The value indicates one of the sheets T1 to Tn.

For example, when n = 10, ten transfer sheets T1 to T10 as shown in FIG. 7 are prepared in the transfer sheet supply unit 310.
f (ξ) = Int ((ξ + 90 °) / 18 °) +1 Formula (4)
(However, if f (ξ)> 10, f (ξ) = 10)
become that way. As shown in FIG. 6A, the crossing angle ξ takes a value within the range of −90 ° to + 90 °. According to the equation (4), when ξ = −90 °, f (ξ) = 1. When ξ = + 90 °, f (ξ) = 10. Therefore, when the crossing angle ξ increases from −90 ° to + 90 °, the pixel value f (ξ) increases monotonously from 1 to 10. Will do.

  FIG. 10 is a graph of the function f (ξ) defined by the equation (4) shown in FIG. It is clearly shown that when the crossing angle ξ shown on the horizontal axis increases from −90 ° to + 90 °, the value of the function f (ξ) increases monotonically from 1 to 10 in steps. The vertical axis on the right side of the graph indicates the value of the grid line arrangement angle θ corresponding to the value of the function f (ξ). As the crossing angle ξ increases from −90 ° to + 90 °, the arrangement angle θ increases monotonically from −45 ° to + 45 °.

  Conversely, when the crossing angle ξ increases from −90 ° to + 90 °, the pixel value f (ξ) decreases monotonously from 10 to 1 (the arrangement angle θ changes from + 45 ° to −45 °). May be used. Even when such a monotonically decreasing function f (ξ) is used, information on the inclination distribution of each part of the surface of the stereoscopic original image 10 is expressed as an arrangement angle distribution of the grating lines of the diffraction grating formed on the medium 20. Therefore, pseudo stereoscopic vision can be generated.

  In short, as a function for determining the pixel value f (ξ), a function that monotonously increases or monotonously decreases with respect to the intersection angle ξ and takes any one of n integers 1 to n may be defined. As described in §2, the transfer processing unit 320 defines a unit region array corresponding to the pixel array constituting the two-dimensional image on the surface of the medium 20, and gives a pixel value k (k = 1 to n). A process of transferring the kth transfer sheet is performed on the unit area corresponding to the pixel. Accordingly, the arrangement angle of the grating lines of the diffraction grating pattern formed on the n types of transfer sheets prepared in the transfer sheet supply unit 310 is monotonously increased or decreased in the order of the first to nth transfer sheets. As a result, it is possible to obtain a correspondence relationship in which the arrangement angle θ is monotonously increased or monotonously decreased with respect to the change in the crossing angle ξ. The image can be observed.

<<< §4. Components that determine pixel values >>>
In §3, the basic algorithm for determining the pixel value of each pixel G (i, j) constituting the two-dimensional image data D2 is described. This pixel value determination process is actually executed by the intersection calculation unit 220, normal vector calculation unit 230, intersection angle calculation unit 240, and pixel value calculation unit 250 shown in FIG. Hereinafter, specific functions of these components will be described.

  As shown in FIG. 3, a two-dimensional image consisting of an aggregate of pixels G (i, j) is defined by the two-dimensional image data D2 stored in the two-dimensional image storage unit 260. At this time, The individual pixels G (i, j) do not yet have pixel values, and the two-dimensional image data D2 is so-called empty data. The pixel value determination process described here is a process for giving a pixel value to each pixel G (i, j).

  The vertical and horizontal dimensions of the individual pixels G (i, j) constituting the two-dimensional image may be set to appropriate values in consideration of the resolution when the three-dimensional original image 10 is recorded. Further, the size of the two-dimensional pixel array (the number of pixels in the vertical and horizontal directions) may be set to a size sufficient to define the intersection point Q over the entire stereoscopic original image 10 arranged on the XYZ three-dimensional coordinate system. . Note that the vertical and horizontal dimensions of the individual pixels G (i, j) constituting the two-dimensional image and the vertical and horizontal dimensions of the unit area on the medium 20 do not necessarily need to be matched. It is possible to print on the medium 20 at an arbitrary magnification.

  First, the intersection calculation unit 220 determines a representative point P for each pixel G (i, j) constituting the two-dimensional image. As described above, in the case of the example described here, each pixel G (i, j) is constituted by a square cell, and the center point is defined as the representative point P. Since the representative point P is a point representing the pixel, it may be determined at any position as long as it is a point inside the cell including the outline of the cell constituting the pixel. The position of the representative point P of each pixel can be easily calculated by calculation based on the pitch of the pixel in the X-axis and Y-axis directions, and is expressed as a coordinate value P (x, y, 0) on the XYZ three-dimensional coordinate system. Given.

  Next, as shown in FIG. 4, the intersection calculation unit 220 draws a reference line R orthogonal to the recording surface Sxy at the position of the representative point P of each pixel G (i, j), and positions adjacent to the recording surface Sxy. A process for obtaining an intersection point Q between each reference line R and the surface of the stereoscopic original image 10 when the stereoscopic original image 10 is arranged on the surface is performed. In the case of the example described here, since the recording surface Sxy is defined on the XY plane, the reference line R is a line parallel to the Z axis. Since the information of the three-dimensional original image 10 is already prepared as the three-dimensional shape data D1 in the original image storage unit 210, the intersection calculation unit 220 refers to the three-dimensional shape data D1 to obtain the reference line R and The coordinate value Q (x, y, z) of the intersection point Q can be obtained.

  Next, the normal vector calculation unit 230 obtains a normal vector N related to the surface of the stereoscopic original image 10 for each intersection Q. The normal vector N is a unit vector that starts from the intersection point Q and goes vertically outward with respect to the minute surface of the stereoscopic original image 10 including the intersection point Q. The three-dimensional shape data D1 in the original image storage unit 210 is also used as the normal vector N. It can be determined by referring to it. Such a calculation method of the normal vector N is a method widely known in the field of CG, and therefore the specific method will not be described here.

Subsequently, a projection vector N ^* obtained as an orthogonal projection of the normal vector N onto the projection plane Syz is obtained by the intersection angle calculation unit 240. That is, the projection vector N ^* is obtained on the YZ plane by projecting the normal vector N in the X-axis direction. This projection vector N ^* is a vector on the projection surface Syz starting from the projection point Q ^* on the projection surface Syz. Here, the projection point Q ^* is a point indicated by a coordinate value Q ^* (0, y, z). Then, an arbitrary reference axis A (in this embodiment, an axis positioned on the Z axis and opposite to the Z axis) included in the projection plane Syz is determined, and the obtained projection vector N ^* or its extension line and the reference Processing for obtaining the crossing angle ξ with the axis A is performed. Such processing can also be performed by a known geometric calculation.

Finally, a process of storing the function value f (ξ) with respect to the intersection angle ξ obtained for each pixel constituting the two-dimensional image by the pixel value calculation unit 250 in the two-dimensional image storage unit 260 as the pixel value of the pixel. Is done. Here, as described above, the function f (ξ) is a function that monotonously increases or monotonously decreases with respect to the crossing angle ξ and takes any one of n integers 1 to n. Specifically, for example, as described in §3,
f (ξ) = Int ((ξ + 90 °) / (180 ° / n)) + 1 Formula (3)
(However, if f (ξ)> n, f (ξ) = n)
It is sufficient to define a function f (ξ) as follows.

<<< §5. Specific steps of the transfer process >>>
Next, a specific procedure of the transfer process by the pseudo three-dimensional printer according to the present invention will be described. Here, as an example, the transfer sheet supply unit 310 in the pseudo three-dimensional printer shown in FIG. 3 has a function of supplying ten transfer sheets T1 to T10 as shown in FIG. A specific procedure of the transfer process executed by the transfer processing unit 320 when the two-dimensional image data D2 as shown in FIG. 11 is prepared in the unit 260 will be described.

  As already described, the pixel value of each pixel indicated by the two-dimensional image data D2 indicates the number of the transfer sheet to be transferred in the unit area corresponding to the pixel on the medium 20, as shown in FIG. In the pixel array, the pixel values “1 to 10” of the pixel G (i, j) in the i row and j column correspond to the transfer sheets “T1 to T10”, respectively. Therefore, for example, the unit region U (1,1) corresponding to the pixel G (1,1) in the first row and the first column (the upper left pixel in FIG. 11) has the first corresponding to the pixel value “1”. The transfer sheet T1 may be transferred, and in the unit region U (6, 8) corresponding to the pixel G (6, 8) in the sixth row and the eighth column (lower right pixel in FIG. 11), the pixel value “ The sixth transfer sheet T6 corresponding to “6” may be transferred.

  FIG. 12A shows a state in which the first transfer sheet T1 is transferred to a unit region array (array corresponding to the pixel array) having 6 rows and 8 columns defined on the surface of the medium 20. FIG. The oblique lines in the unit area indicate the transferred diffraction grating pattern. In the example shown in FIG. 12A, the transfer sheet T1 is transferred to three locations of the unit areas U (1, 1), U (1, 2), and U (2, 1). This is because in the pixel array shown in FIG. 11, the three pixels G (1,1), G (1,2), G (2,1) are pixels having the pixel value “1”.

  FIG. 12B is a plan view showing a state where the second transfer sheet T2 is transferred following the state shown in FIG. 12A, and a new unit region U (1, 3) is shown. , U (1, 8), U (2, 2), U (3, 1), the transfer sheet T2 is transferred. This is because the four pixels G (1,3), G (1,8), G (2,2), G (3,1) have a pixel value “2” in the pixel array shown in FIG. This is because it is a pixel.

  FIG. 12C is a plan view showing a state where the third transfer sheet T3 has been transferred following the state shown in FIG. 12B, and a new unit region U (1, 4) is shown. , U (1,7), U (2,3), U (2,8), U (3,2), U (4,1), U (5,1) are placed on the transfer sheet T3. Transcription is taking place. This is because the seven pixels G (1,4), G (1,7), G (2,3), G (2,8), G (3,2), G in the pixel array shown in FIG. This is because (4, 1) and G (5, 1) are pixels having the pixel value “3”.

  Thereafter, the transfer from the fourth transfer sheet T4 to the tenth transfer sheet T10 is sequentially performed in the same manner. FIG. 13 is a plan view showing a state in which all of the ten types of transfer sheets T1 to T10 have been transferred, that is, a state in which printing has been completed based on the two-dimensional image data D2 illustrated in FIG. Any one of the transfer sheets T1 to T10 is transferred to all the unit areas.

  In the case where the reference line R ′ is extended and does not intersect the stereoscopic original image 10 like the representative point P ′ shown in FIG. 5, no pixel value is defined for the pixel having the representative point P ′. As described above, the transfer sheet is not transferred for the unit area corresponding to the pixel in which the pixel value is not defined. From such a unit area, no diffracted light is generated during observation, so that it is recognized as a dark background portion. In the case where it is preferable to generate some diffracted light for such a background portion, as described in the explanation of FIG. 5, the background surface 11 is defined behind the stereoscopic original image 10 to form a pixel array. Any pixel value may be defined for all the pixels to be processed.

  As described above, the example in which the transfer process is performed in the order of the unit sheets T1 to T10 has been described. Of course, the order of the transfer process is not necessarily performed in the order of the unit sheets T1 to T10, and the transfer can be performed in an arbitrary order. It is. An important point in the present invention is that an arrangement angle θ that monotonously increases or monotonously decreases with respect to the crossing angle ξ obtained for each pixel is defined, and on the medium 20 corresponding to the pixel from which the crossing angle ξ is obtained. The unit area is to transfer a diffraction grating pattern having an arrangement angle θ corresponding to the crossing angle ξ.

If n transfer sheets T1 to Tn are prepared in the transfer sheet supply unit 310 and n angles distributed at equal intervals are defined as the grating line arrangement angle θ of the diffraction grating formed on these transfer sheets. , The k-th arrangement angle θk is as described above.
θk = α · (k−1) / (n−1) + β Equation (1)
Can be expressed as Here, α is an angle value indicating the distribution range, and β is an angle value indicating the offset. With such a setting, the arrangement angle θ of the grating lines of the diffraction grating pattern formed on the n types of transfer sheets T1 to Tn increases monotonously in the order of the first to nth transfer sheets T1 to Tn. (Alternatively, α may be set to a negative value and monotonously decreased), so that the transfer processing unit 320 applies a unit area corresponding to a pixel to which a pixel value k (k = 1 to n) is given. What is necessary is just to perform the process which transfers the kth transfer sheet Tn. Then, it is possible to transfer a diffraction grating pattern having an arrangement angle θ that monotonously increases or monotonously decreases with respect to the intersection angle ξ.

  Various methods are known as a method for transferring a diffraction grating pattern onto a medium. However, the most practical method for carrying out the present invention uses a thermal transfer sheet on which a diffraction grating is formed. Is the method.

  FIG. 14 is a side sectional view showing a specific configuration example of the print processing unit 300 of the pseudo three-dimensional printer shown in FIG. 3 (hatching indicates a cross section). In the figure, the medium 20 is a medium (for example, paper) supplied from the medium supply unit 330, and the transfer sheet 30 is a transfer sheet (any one of T1 to Tn) supplied from the transfer sheet supply unit 310. It is. On the other hand, the thermal head 40 (illustration of the internal structure is omitted) is a component of the transfer processing unit 320 and has a function of applying heat to the transfer sheet 30 as necessary.

  In the case of the example shown here, the transfer sheet 30 has a structure in which a mount 31, an adhesive layer 32, an aluminum layer 33, a support carrier layer 34, and an adhesive layer 35 are laminated as illustrated. The mount 31 functions as a support layer for the entire transfer sheet 30. Each of the adhesive layers 32 and 35 is made of a thermoplastic resin and maintains a solidified state at room temperature, but has a property of melting when heat is applied from the thermal head 40. The support carrier layer 34 is made of an ultraviolet curable resin, and an uneven structure is formed on the upper surface thereof. The aluminum layer 33 is a reflective layer formed on the surface of this uneven structure.

  In the transfer sheet 30, the portion that is actually transferred to the medium 20 side is a three-layer portion including an aluminum layer 33, a support carrier layer 34, and an adhesive layer 35. That is, the transfer sheet 30 is placed in contact with the upper surface of the medium 20, the thermal head 40 is brought into contact with the upper surface of the transfer sheet 30 and pressed downward in the figure, and heating is performed by energizing the thermal head 40. Then, the adhesive layers 32 and 35 having thermoplasticity are in a molten state. Here, if the adhesive force of the adhesive layer 35 to the medium 20 is larger than the adhesive force of the adhesive layer 32 to the mount 31, the aluminum layer 33 and the support carrier layer can be heated and pressed. 34, the three-layer portion of the adhesive layer 35 is transferred to the medium 20 side. The mount 31 and the adhesive layer 32 remain without being transferred to the medium 20 side. Therefore, the original “transfer sheet” in the present invention is a three-layer portion of the aluminum layer 33, the support carrier layer 34, and the adhesive layer 35. Here, for convenience, the illustrated five-layer structure 30 is also illustrated. This will be referred to as a “transfer sheet”.

  Due to the concavo-convex structure formed in the support carrier layer 34, convex portions 33 a and concave portions 33 b are formed in the aluminum layer 33. The convex portion 33a and the concave portion 33b are arranged at positions that constitute a diffraction grating when viewed from above. Since the support carrier layer 34 is made of an ultraviolet curable resin, a necessary concavo-convex structure is formed on the upper surface of the support carrier layer 34 before curing, cured by irradiating ultraviolet rays, and aluminum is deposited on the upper surface. If it adheres by this method, the aluminum layer 33 with the uneven structure which comprises the grating | lattice line of a diffraction grating can be obtained. The side sectional view of FIG. 14 shows a cross section orthogonal to the grating lines of this diffraction grating, and each grating line extends in a direction perpendicular to the drawing sheet.

  FIG. 14 shows the structure of one type of transfer sheet 30, but the basic structures of the n transfer sheets T1 to Tn prepared in the transfer sheet supply unit 310 are all shown in FIG. Make. However, the arrangement angle θ of the lattice lines differs for each individual transfer sheet.

  FIG. 15 is a perspective view showing transfer processing by the print processing unit 300 shown in FIG. In the figure, a medium 20 is a medium such as paper supplied from a medium supply unit 330, and a transfer sheet 30 is a transfer sheet (any one of T1 to Tn) supplied from a transfer sheet supply unit 310. . In the embodiment shown here, as shown, the width of the medium 20 and the width of the transfer sheet 30 are substantially equal, but the length of the transfer sheet 30 is extremely longer than the length of the medium 20. This is because the transfer sheet 30 takes the form of a transfer ribbon and is accommodated in a wound state in a ribbon cassette (not shown). The transfer sheet supply unit 310 has a function of drawing the transfer sheet 30 from such a ribbon cassette in the conveyance direction C in the drawing and holding the transfer sheet 30 at a position in contact with the upper surface of the medium 20.

  On the other hand, at the lower end of the thermal head 40, a large number of heating elements are arranged in a row in a direction orthogonal to the transport direction C. The arrangement pitch of the individual heat generating elements corresponds to the pitch of the unit areas defined on the medium 20. Further, the transfer processing unit 320 has the thermal head 40 with its lower end in contact with the upper surface of the transfer sheet 30 and pressing the contact portion toward the medium 20 toward the conveyance direction C in the figure. A scanning mechanism (not shown) for scanning a distance corresponding to a length of 20 is provided. This scanning pitch also corresponds to the pitch of the unit area defined on the medium 20.

  Therefore, in the process of scanning the thermal head 40 in the conveyance direction C in the figure, energization is performed to any heating element formed at the lower end of the thermal head 40 at each position for each scanning pitch, and the energized heat generation is performed. If the transfer sheet 30 is heated by the element, the diffraction grating can be transferred only for the heated portion. If the size and amount of heat generation of each heating element are set to be suitable for transferring a diffraction grating for one unit region, for each unit region (that is, for each pixel in a two-dimensional image), Transfer / non-transfer can be controlled.

  After all, the transfer sheet T1 shown in FIG. 7 is supplied as the transfer sheet 30 so that the transfer is performed only in the unit area corresponding to the pixel having the pixel value “1” in the two-dimensional image shown in FIG. When the energization control 40 is performed, the diffraction grating as shown in FIG. 12A is transferred onto the medium 20 by the process of scanning the thermal head 40 once in the conveyance direction C in the figure. . Subsequently, when the thermal head 40 is returned to the original scanning start position, the transfer sheet to be supplied is switched to the transfer sheet T2 shown in FIG. 7, and the same scanning process is performed, the medium 20 is shown in FIG. As shown, the diffraction grating is transferred. If this scanning process is repeated 10 times, the diffraction grating as shown in FIG. 13 is transferred onto the medium 20, and the printing process is completed.

  In the embodiment shown here, since a long transfer ribbon is used as the transfer sheet 30, when printing on one medium 20 is completed, the transfer sheet 30 is moved in the transport direction C in the figure. By sending only the amount corresponding to the length, the second medium 20 can be used for printing. In the present invention, in order to perform the printing process for one medium 20, a total of n transfer processes using n types of transfer sheets T1 to Tn are required. Therefore, if a long transfer ribbon is used as the transfer sheet, n ribbon cassettes RC1 to RCn are prepared in the transfer sheet supply unit 310 as shown in FIG. The ribbon-shaped transfer sheets T1 to Tn may be pulled out and supplied.

  However, in order to prepare n ribbon cassettes RC1 to RCn in this way, an accommodation space is required, and the transfer sheet T1 drawn from each ribbon cassette RC1 to RCn with respect to the same medium 20 is used. A mechanism for sequentially switching to Tn is required. In order to omit such a mechanism and simplify the configuration, as shown in FIG. 17, a single ribbon cassette RC containing transfer ribbons in which transfer sheets T1 to Tn are repeatedly connected in order is used. That's fine. The transfer ribbon shown in FIG. 17 is used by being pulled out from the ribbon cassette RC in the conveyance direction C in the figure. The transfer sheets T1, T2,..., Tn shown in the figure each constitute one area of the one transfer ribbon, and each area is set to be approximately equal to the area of the medium 20 to be printed. .

  In FIG. 15, if the transfer ribbon drawn from the ribbon cassette RC shown in FIG. 17 is used as the transfer sheet 30, first, the region constituting the transfer sheet T1 in the transfer ribbon is brought into contact with the medium 20. The first scanning by the thermal head 40 is performed, and the transfer to the unit area corresponding to the pixel having the pixel value “1” is performed. Subsequently, the thermal head 40 is returned to the scanning start position, the transfer ribbon is sent in the conveyance direction C, the region constituting the transfer sheet T2 is brought into contact with the medium 20, and the second scanning by the thermal head 40 is performed, whereby the pixel value Transfer to the unit area corresponding to the pixel having “2” is performed. If such processing is repeated n times in total, printing on one medium 20 is completed. Thereafter, if the transfer ribbon is again fed in the conveyance direction C and the area of the new transfer sheet T1 is brought into contact with the medium 20, printing on the second medium 20 can be performed.

  The transfer / non-transfer control with respect to the medium 20 can be controlled by energization / non-energization of individual heating elements as described above, but in actuality, each position of a preset unit area is controlled. It is difficult to perform accurate transfer / non-transfer control. This is because misalignment occurs when the transfer process is repeated a total of n times. Although the thermal head 40 performs scanning a total of n times, it is difficult to accurately match the scanning positions of each time, and it is inevitable that a positional shift will occur to some extent. If such a positional shift occurs, there is a possibility that the transfer layer partially overlaps and transfers at the boundary part between adjacent unit areas, and there is a problem such as a transfer failure from this part, which is not preferable. .

  Therefore, practically, when performing the transfer process by the transfer processing unit 320, for adjacent unit areas corresponding to adjacent pixels having different pixel values, transfer with a gap between the transfer layers of the adjacent unit areas is performed. Preferably. FIG. 18 is a plan view showing an embodiment for ensuring a gap between the transfer layers as described above. Based on the two-dimensional image data D2 shown in FIG. 11, diffraction is performed on each unit region U (i, j) on the medium. The transfer layer having a lattice is transferred.

  The numbers in each unit area in FIG. 18 indicate the numbers (1 to 10) of the transfer sheets transferred to the unit area, and correspond to the pixel values of the two-dimensional image shown in FIG. In addition, among the boundary lines of each unit region, the portion drawn in bold lines indicates that a gap is secured between the transfer layers transferred to the adjacent unit regions. On the other hand, the boundary line drawn by the thin line indicates the boundary of the conceptual unit region, and in reality, a physically continuous transfer layer is formed across the thin line.

  For example, three unit regions U (1,1), U (1,2), U (2,1) located in the upper left corner of the figure are actually physically continuous in an L shape. One transfer layer (transfer layer formed by the transfer sheet T1) is transferred, and the boundary lines indicated by thin lines in the drawing, that is, the unit areas U (1,1) and U (1,2) And the boundary line between the unit areas U (1,1) and U (2,1) are not physical boundary lines that divide the transfer layer. On the other hand, for example, the unit region U (2, 2) has four sides drawn with thick lines, and between the adjacent unit regions arranged on the top, bottom, left, and right, a transfer layer (transfer sheet T2). A physical boundary line is formed to divide the transfer layer formed by the above.

  In short, for adjacent unit regions corresponding to adjacent pixels having the same pixel value, adjacent unit regions corresponding to adjacent pixels having different pixel values from which a single transfer layer is physically transferred across the boundary line. With regard to the above, it is only necessary that different physically different transfer layers are transferred in a state where a predetermined gap is secured. Then, in the process of sequentially transferring the n transfer sheets T1 to Tn, a physical gap is secured between the adjacent transfer layers transferred from different transfer sheets even when a positional deviation occurs. Therefore, it is possible to prevent adjacent transfer layers from partially overlapping and causing a transfer failure.

  As described above, in order to secure a physical gap between adjacent unit areas corresponding to adjacent pixels having different pixel values, for example, the energization time for the heating element corresponding to the corresponding pixel is shortened, and the amount of heat applied. Should be reduced. The dot size of one pixel can be increased or decreased by about 10 to 20% by increasing or decreasing the amount of heat applied in the transfer process. Therefore, if the pixels in the boundary region are extracted by predetermined image processing and the energization amount for these pixels is reduced, the boundary line can be moved backward.

  Next, another method of transfer processing performed by the transfer processing unit 320 will be described. The feature of this method is that a specific one of the n types of transfer sheets T1 to Tn is defined as a background transfer sheet, the transfer process for the background transfer sheet is first executed, and all the transfer values are obtained regardless of pixel values. The background transfer sheet is transferred to the unit area corresponding to the pixel, and then the transfer process using the remaining transfer sheet is performed on the upper surface of the transfer layer by the background transfer sheet. is there.

  For example, let us consider a case where the sixth transfer sheet T6 is set as the background transfer sheet when ten transfer sheets T1 to T10 as shown in FIG. 7 are prepared. In this case, first, the background transfer sheet T6 is transferred to all unit areas on the medium 20. FIG. 19 is a plan view showing a state where the background transfer sheet T6 has been transferred in this way (hatched lines indicate grid lines L). Subsequently, the transfer processes for the remaining transfer sheets T1 to T5 and T7 to T10 are sequentially performed. These transfer processes are performed on the transfer layer after the transfer of the background transfer sheet T6 is completed as shown in FIG. Lamination is performed on the upper surface.

  FIG. 20 is a side cross-sectional view showing a state in which the transfer layer t1, the transfer sheet T2, the transfer layer t2, and the transfer sheet T3, the transfer layer T3 are transferred onto the upper surface of the transfer layer t6. (Hatching indicates a cross section). As shown in the drawing, a transfer layer t6 formed of a background transfer sheet T6 is formed as a lower layer on the entire upper surface of the medium 20, and the transfer layers t1, t2, and t3 are formed as upper layers by being laminated thereon. Although the lower transfer layer t6 is formed in all unit regions, it is gradually covered by the upper layers such as the transfer layers t1, t2, and t3 by the subsequent transfer process. When the transfer process for the transfer sheet is completed, only an exposed portion that is not covered by another transfer layer (upper layer) is observed during observation. Therefore, for example, when printing is performed based on the two-dimensional image data D2 shown in FIG. 11, the transfer layer t6 is exposed only in the unit region corresponding to the pixel having the pixel value “6”, and finally The result obtained is the same as that obtained when the above-described normal transfer processing method is executed.

  As described above, an advantage of the embodiment in which one transfer sheet is used as the background transfer sheet is that a space is easily secured between the upper transfer layers. For example, in the example shown in FIG. 20, the transfer layers t1, t2, and t3 constituting the upper layer are not directly adjacent to each other. That is, since there is no upper transfer layer in the unit area where the transfer layer t6 should be exposed, a space can be secured in this portion for the upper layer. For this reason, even when a positional shift occurs, it is possible to prevent adjacent transfer layers from partially overlapping and causing a transfer failure.

  Of course, since a space is not always secured between the upper transfer layers, there may be a portion where the upper transfer layer is directly adjacent, but a transfer sheet corresponding to a pixel value having a high appearance frequency. Is set as the background sheet, it becomes possible to secure more space in the upper layer portion, and the effect of suppressing the harmful effects caused by the positional deviation can be obtained.

<<< §6. Basic procedure of pseudo print method >>
The configuration and operation of the pseudo three-dimensional printer according to the present invention have been described based on the illustrated embodiment. Here, the procedure of the pseudo print method according to the basic embodiment of the present invention is described with reference to FIG. This will be described with reference to a flowchart.

  In the flowchart of FIG. 21, steps S10 to S60 are actually steps executed by a computer. First, in the original image input stage of step S10, the three-dimensional shape data of the stereoscopic original image to be printed is input and stored in the computer. In the case of the embodiment shown in FIG. 3, the three-dimensional shape data D <b> 1 is stored in the original image storage unit 210. In the subsequent two-dimensional image storage location preparation stage of step S20, a storage location for a pixel value of a two-dimensional image composed of a pixel array defined on a predetermined recording surface is secured. In the case of the embodiment shown in FIG. 3, a storage location for the pixel values of the two-dimensional image is secured in the two-dimensional image storage unit 260.

  Next, at the intersection calculation stage of step S30, a representative point P is determined for each pixel constituting this two-dimensional image, a reference line R orthogonal to the recording surface is drawn at the position of each representative point P, and the recording surface The process of obtaining the intersection point Q between each reference line R and the surface of the stereoscopic original image when the stereoscopic original image is arranged at the adjacent position of is performed. The specific contents of this processing are as already described as the function of the intersection calculation unit 220.

  Then, in the normal vector calculation stage of step S40, a process for obtaining a normal vector N related to the surface of the stereoscopic original image is performed for each intersection Q obtained in the intersection calculation stage. The specific contents of this processing are as already described as the function of the normal vector calculation unit 230.

Subsequently, in the intersection angle calculation stage of step S50, a predetermined projection plane including the reference axis A is defined, and a projection vector N ^* obtained as an orthogonal projection of each normal vector N onto the projection plane is obtained and each obtained A process for obtaining the intersection angle ξ between the projection vector N ^* and the reference axis A is performed. The specific contents of this processing are as already described as the function of the intersection angle calculation unit 240.

  Further, in the pixel value calculation stage of step S60, the two-dimensional image is based on a function f (ξ) that monotonously increases or decreases monotonously with respect to the intersection angle ξ and takes any one of n integers 1 to n. A function value f (ξ) with respect to the intersection angle ξ obtained for each pixel constituting the pixel is obtained as a pixel value of the pixel, and stored in the storage location prepared in step S20. The specific contents of this processing are as already described as the function of the pixel value calculation unit 250.

  Finally, the transfer processing stage of step S70 is performed. In this transfer processing stage, a unit region array corresponding to the pixel array constituting the two-dimensional image is defined on the surface of the medium to be printed, and a transfer sheet having a predetermined diffraction grating pattern is transferred to each unit region. Processing is performed. As a result, a diffraction grating pattern having a “grid line arrangement angle” that monotonously increases or monotonously decreases in accordance with the pixel value k (k = 1 to n) of each corresponding pixel is transferred to each unit region. It will be. The specific method of this transfer process is as described in §5.

  Thus, according to this printing method, a three-dimensional original image having a three-dimensional structure can be pseudo printed on the two-dimensional surface of the medium to be printed. That is, information on the orientation of each part of the surface of the stereoscopic original image is extracted as a normal vector N, and a diffraction grating pattern having a grid line arrangement angle corresponding to the direction of the normal vector N is transferred to each unit area on the medium. Therefore, based on an arbitrary three-dimensional original image, printing can be performed immediately, and an image that provides a three-dimensional effect during observation can be printed on the medium.

<<< §7. Modified example >>>
Finally, a modification of the present invention will be described. FIG. 22 is a block diagram showing a configuration of a pseudo three-dimensional printer according to this modification. In this modification, a photographic image input unit 120, a dither processing unit 270, and a photographic image printing unit 340 are further added to the pseudo-stereoscopic printer according to the basic embodiment shown in FIG.

  The photographed image input unit 120 has a function of inputting two-dimensional photographed image data D3 obtained by photographing the stereoscopic original image 10 and storing it in the original image storage unit 210. Actually, the captured image input unit 120 can be configured by a digital camera, a video camera, or the like. After all, in this modified example, the data input unit 100 includes the original image input unit 110 and the captured image input unit 120.

  Both the original image input unit 110 and the captured image input unit 120 have a function of inputting data based on the three-dimensional original image 10, but the data input by the original image input unit 110 is a three-dimensional shape of the three-dimensional original image 10. The data input by the captured image input unit 120 is the two-dimensional captured image data D3 obtained by capturing the three-dimensional original image 10 on a two-dimensional plane. .

  The two-dimensional photographed image data D3 is stored in the original image storage unit 210 and then used by the photographed image printing unit 340. The photographed image printing unit 340 is a component added in the print processing unit 300 and functions to print a two-dimensional photographed image on the surface of the medium 20 to be printed. The captured image printing unit 340 is a so-called general printer that prints a two-dimensional image on the two-dimensional surface of the medium 20. Therefore, a general printer (for example, an ink jet printer) that has been conventionally used can be used as the captured image printing unit 340 as it is.

  Specifically, the captured image input unit 120 captures the three-dimensional original image 10 as a color image composed of three primary colors of RGB, and then converts the color image into a color image composed of four colors of CMYK suitable for printing. The photographed image printing unit 340 may perform printing using four color inks of C, M, Y, and K.

  In the pseudo-stereoscopic printer according to this modified example, after the surface of the medium 20 supplied from the medium supply unit 330 is printed by the captured image printing unit 340, the two-dimensional captured image is printed. A transfer process by the transfer processing unit 320 is performed on the printing surface of the medium 20. Therefore, the two-dimensional captured image printed on the surface of the medium 20 is in a state of being covered with the transfer layer when the transfer process is completed.

  Even in such a covered state, a transfer sheet having a transparent transfer layer is used as the transfer sheet supplied by the transfer sheet supply unit 310 so that the two-dimensional captured image can be observed. Specifically, when the transfer sheet 30 having the structure shown in FIG. 14 is used, the aluminum layer 33 is removed, and transparent materials are used for the support carrier layer 34 and the adhesive layer 35. Then, the observer observes the two-dimensional photographed image printed on the medium 20 through the transparent transfer layer (layers 34 and 35), and diffracted light by the diffraction grating formed on the surface of the transfer layer. Can be observed simultaneously. Of course, since the aluminum layer 33 is removed, the intensity of the diffracted light is reduced, but the diffraction phenomenon still occurs due to the uneven structure on the upper surface of the support carrier layer 34.

  After all, in this modified example, printing of the two-dimensional photographed image and transfer of the diffraction grating pattern are performed on the same medium. Of course, in this case, each part of the stereoscopic original image 10 indicated by the two-dimensional photographed image and each part of the stereoscopic original image 10 indicated by the diffraction grating are aligned at the same position on the medium 20. To. Then, the printing surface of the two-dimensional photographed image and the transfer layer of the diffraction grating pattern play a complementary role, and a clear image with a three-dimensional effect can be observed. That is, the transfer layer of the diffraction grating pattern can present a stereoscopic effect in a pseudo manner, but cannot present a clear image showing the original three-dimensional image 10 because it is an assembly of diffraction gratings. On the other hand, the printing surface of the two-dimensional captured image cannot give a stereoscopic effect, but can present a clear image that accurately represents the characteristics of the original stereoscopic image 10.

  FIG. 23 is a flowchart showing the procedure of the pseudo printing method according to this modification. The difference from the procedure of the basic embodiment shown in FIG. 21 is that a photographed image input stage S15 and a photographed image printing stage S65 are newly added. The photographed image input step S15 is a step of performing processing for inputting two-dimensional photographed image data obtained by photographing a stereoscopic original image. The photographed image printing step 65 is performed on the surface of the medium to be printed. This is a step of printing a dimension photographed image. In the transfer processing step S70, a transparent transfer sheet is transferred onto the printing surface of the two-dimensional photographed image.

  Another feature of this modification is that a dither processing unit 270 is added to the data processing unit 200 shown in FIG. The dither processing unit 270 is to perform dither processing on the two-dimensional image stored in the original image storage unit 260. Dither processing is image processing that is widely used in the field of DTP, and performs a function of correcting this rapid change to a more gradual change for a portion where the pixel value changes spatially abruptly. . In general halftone dot printing, it is used to simulate gray with a collection of fine black dots, but it can also be applied to a technique for forming a diffraction grating pattern in a pixel.

  For example, Japanese Patent Laid-Open No. 2007-240838 discloses a technique for performing dither processing on two-dimensional image data in order to smoothly recognize the transition of anisotropic reflection due to a diffraction grating. Since various methods are known for dithering the image data having a general two-dimensional pixel arrangement in which pixels are arranged vertically and horizontally, detailed description thereof is omitted here.

  In the pseudo-stereoscopic printer according to this modification, when the pixel value is given to each pixel by the pixel value calculation unit 250 and the two-dimensional image data D2 is obtained in the two-dimensional image storage unit 260, the dither processing unit 270 Dither processing is executed on the two-dimensional image data D2. The transfer processing unit 320 performs transfer processing based on the pixel values of the two-dimensional image after the dither processing.

  Originally, the inclination of the minute surface of the three-dimensional original image 10 (that is, the angle of the normal vector N) is a continuously changing value. However, in the present invention, the inclination of the minute surface is simulated by the n number of diffraction gratings formed on the medium 20, so that information on the inclination of the minute surface, which is a continuous amount, is forcibly n stages. Will be quantized. When such quantization is performed, there is a possibility that a pseudo contour that should not exist originally is observed. The above-described dither processing has an effect of suppressing such an adverse effect, and by adding the dither processing, an image with a smoother three-dimensional feeling can be observed.

  Further, in the embodiments described so far, a plurality of n types of transfer sheets T1 to Tn are prepared by changing the arrangement angle θ of the grid lines to n ways, but according to experiments conducted by the present inventor, It is confirmed that substantially the same effect can be obtained even if a plurality of n types of transfer sheets T1 to Tn are prepared by changing the arrangement pitch of the lattice lines to n types instead of changing the arrangement angle θ of the n. did it.

  For example, in the case of the example shown in FIG. 7, the ten transfer sheets T1 to T10 are obtained by gradually changing the grid line arrangement angle θ in the range of θ = −45 ° to + 45 °. In this case, the pitch of the lattice lines is set to a common value (for example, 1 μm) for any of the transfer sheets T1 to T10. On the other hand, it is possible to prepare 10 transfer sheets by changing the arrangement pitch of the grid lines. However, in order to form a diffraction grating, it is usually necessary to set the grating line pitch in the range of 0.5 μm to 10 μm, and therefore the variation in the arrangement pitch of the grating lines is set to be within the above range. For example, if 10 arrangement pitches are set in increments of 0.1 μm such as 0.8 μm, 0.9 μm, 1.0 μm,..., 1.7 μm, 10 transfer sheets T1 to T10 are prepared. can do. In this case, the grid line arrangement angle θ may be set to a common value (for example, 0 °) for any of the transfer sheets T1 to T10.

  In general, when n types of transfer sheets are prepared, the arrangement pitch of the grating lines of the diffraction grating pattern formed on the n types of transfer sheets increases monotonously or monotonically in the order of the first to nth transfer sheets. You can set it to decrease.

1 is a block diagram showing a basic configuration of a pseudo three-dimensional printer according to the present invention. FIG. 2 is an enlarged surface view of a printed matter (medium on which a diffraction grating pattern is recorded) created by the pseudo three-dimensional printer shown in FIG. 1 (lines in pixels indicate lattice lines L). 1 is a block diagram illustrating a configuration of a pseudo three-dimensional printer according to a basic embodiment of the present invention. FIG. 4 is a perspective view illustrating a basic principle of pixel value determination processing of a two-dimensional image in the pseudo stereoscopic printer illustrated in FIG. 3. FIG. 4 is a side view showing a normal vector defining method in the pseudo-stereoscopic printer shown in FIG. 3. FIG. 4 is a diagram illustrating a relationship between an intersection angle ξ and a grating line arrangement angle θ of a diffraction grating in the pseudo three-dimensional printer illustrated in FIG. 3. FIG. 4 is a plan view of ten transfer sheets T1 to T10 used in the pseudo three-dimensional printer shown in FIG. 3 (hatched lines indicate lattice lines L). It is a figure which shows the type | formula which calculates the grid line arrangement | positioning angle (theta) of the diffraction grating currently formed on the transfer sheets T1-T10 shown in FIG. FIG. 4 is a diagram illustrating an expression of a pixel value f (ξ) defined as a function of an intersection angle ξ in the pseudo-stereoscopic printer illustrated in FIG. 3. 10 is a graph of a function f (ξ) defined by the equation shown in FIG. It is a top view which shows an example of the two-dimensional image D2 produced in the two-dimensional image storage part 260 of the pseudo | stereoscopic printer shown in FIG. FIG. 13 is a plan view illustrating a process in which the pseudo-stereoscopic printer illustrated in FIG. 3 performs printing based on the two-dimensional image data D2 illustrated in FIG. 11 (hatched lines indicate grid lines L). FIG. 13 is a plan view showing a state in which the pseudo three-dimensional printer shown in FIG. 3 has completed printing based on the two-dimensional image data D2 illustrated in FIG. 11 (hatched lines indicate grid lines L). FIG. 4 is a side sectional view showing a specific configuration example of a print processing unit 300 of the pseudo three-dimensional printer shown in FIG. 3 (hatching indicates a section). FIG. 15 is a perspective view illustrating a transfer process by the print processing unit 300 illustrated in FIG. 14. FIG. 15 is a top view illustrating a configuration example of a transfer ribbon cassette used in the print processing unit 300 illustrated in FIG. 14. FIG. 15 is a top view illustrating another configuration example of a transfer ribbon cassette used in the print processing unit 300 illustrated in FIG. 14. In this invention, it is a top view which shows the Example which ensures a space | gap between transfer layers. FIG. 4 is a plan view showing an embodiment in which one transfer sheet is used as a background transfer sheet in the present invention (the oblique lines indicate lattice lines L). FIG. 20 is a side sectional view showing a transfer state in the embodiment shown in FIG. 19 (hatching indicates a cross section). It is a flowchart which shows the procedure of the pseudo printing method which concerns on basic embodiment of this invention. It is a block diagram which shows the structure of the pseudo | simulation stereoscopic printer which concerns on the modification of this invention. It is a flowchart which shows the procedure of the pseudo printing method which concerns on the modification of this invention.

Explanation of symbols

10: Three-dimensional original image 11: Background surface 20: Medium to be printed 30: Transfer sheet 31: Mount 32: Adhesive layer (thermoplastic resin)
33: Aluminum layer 33a: Convex part 33b: Concave part 34: Support carrier layer (ultraviolet curable resin)
35: Adhesive layer (thermoplastic resin)
40: Thermal head 100: Data input unit 110: Original image input unit 120: Captured image input unit 200: Data processing unit 210: Original image storage unit 220: Intersection calculation unit 230: Normal vector calculation unit 240: Crossing angle calculation unit 250: Pixel value calculation unit 260: Two-dimensional image storage unit 270: Dither processing unit 300: Print processing unit 310: Transfer sheet supply unit 320: Transfer processing unit 330: Medium supply unit 340: Captured image printing unit A: Reference axis A ^* : Translated reference axis B: Angle reference line C: Conveying direction D1: Three-dimensional shape data D2: Two-dimensional image data D3: Two-dimensional photographed image data f (ξ): Pixel value (function of ξ)
G1 to G3: Pixel G (i, j) on the medium: Pixel i in the i-th row and j-th column, j: Integer k indicating the row and column of the pixel array and unit area array: an integer L in the range of 1 to n : Grid lines N, N ′, N1 to N4: Normal vector N ^* : Projection vector n: Integer indicating the type of transfer sheet to be used O: Origin P, P ′: representative point (center of pixel) of three-dimensional orthogonal coordinate system point)
Q, Q ′, Q1 to Q4: Intersection Q ^* : Projection point R, R ′: Reference line RC, RC1 to RCn: Ribbon cassettes S10 to S70: Steps Sxy in the flowchart: Recording surface (XY plane)
Syz: Projection plane (YZ plane)
T1 to T10, Tk, Tn: transfer sheet t1 to t6: transfer layer U (i, j) of transfer sheet: unit region X, Y, Z corresponding to pixel: coordinate axes x, y, z: Each coordinate value of the three-dimensional orthogonal coordinate system α: Distribution angle β: Offset angle θ: Grid line placement angle ξ: Crossing angle

Claims (8)

A printer that artificially prints a three-dimensional original image having a three-dimensional structure on a two-dimensional surface of a medium to be printed,
An original image input unit for inputting three-dimensional shape data of the stereoscopic original image;
An original image storage unit for storing the input three-dimensional shape data;
A two-dimensional image storage unit for storing two-dimensional image data composed of an array of pixels defined on a predetermined recording surface;
A representative point P is determined for each pixel constituting the two-dimensional image, a reference line R orthogonal to the recording surface is drawn at the position of each representative point P, and the three-dimensional original image is placed at a position adjacent to the recording surface. An intersection calculation unit for obtaining an intersection Q between each reference line R when placed and the surface of the original three-dimensional image;
For each intersection Q obtained by the intersection computing unit, a normal vector computing unit for obtaining a normal vector N related to the surface of the original three-dimensional image,
Using a predetermined projection plane including the reference axis A, a projection vector N ^* obtained as an orthogonal projection of each normal vector N onto the projection plane is obtained, and each obtained projection vector N ^* or its extension line and the A crossing angle calculation unit for obtaining a crossing angle ξ with the reference axis A;
A function f (ξ) monotonically increasing or monotonically decreasing with respect to the intersection angle ξ and taking any one of n integers 1 to n is obtained for each pixel constituting the two-dimensional image. A pixel value calculation unit that stores the value f (ξ) of the function with respect to the intersecting angle ξ as a pixel value of the pixel in the two-dimensional image storage unit;
A transfer sheet supply unit that supplies a total of n types of transfer sheets from the first to the n-th each having a predetermined diffraction grating pattern;
A medium supply unit for supplying a medium to be printed;
A unit region array corresponding to a pixel array constituting the two-dimensional image is defined on the surface of the medium, and a unit region corresponding to a pixel to which a pixel value k (k = 1 to n) is given A transfer processing section for transferring the second transfer sheet;
With
The arrangement angle or the arrangement pitch of the grating lines of the diffraction grating pattern formed on the n types of transfer sheets is set so as to monotonously increase or monotonically decrease in the order of the first to nth transfer sheets. And
For the adjacent unit regions corresponding to adjacent pixels having the same pixel value, the transfer processing unit physically transfers a single transfer layer across the boundary line, and has adjacent pixel regions having different pixel values. For the adjacent unit area corresponding to the pixel, by performing transfer with a gap between the transfer layers of the adjacent unit area, separate physically different transfer layers are transferred with a predetermined gap secured. A pseudo-stereoscopic printer characterized by that. The pseudo-stereoscopic printer according to claim 1,
A pseudo three-dimensional printer, wherein the original image input unit is configured by a device that inputs or captures a surface shape of a three-dimensional object as a three-dimensional shape data by photographing or scanning an actual three-dimensional object. The pseudo-stereoscopic printer according to claim 1 or 2,
Define a recording plane in the XY plane in the XYZ three-dimensional orthogonal coordinate system, define a projection plane in the YZ plane, define a reference axis A that is parallel to the Z axis,
The intersection angle calculation unit obtains a projection vector N ^* on the YZ plane by projecting the normal vector N in the X-axis direction, and intersects the angle between the obtained projection vector N ^* or its extension line and the reference axis A. A pseudo three-dimensional printer characterized by an angle ξ. The pseudo-stereoscopic printer according to claim 3,
An arrangement angle θk with respect to a predetermined angle reference line of a grid line formed on the kth (k = 1 to n) transfer sheet supplied by the transfer sheet supply unit is determined using predetermined angle values α and β. , Θk = α × (k−1) / (n−1) + β,
The pixel value calculation unit is f (ξ) = Int ((ξ + 90 °) / (180 ° / n)) + 1 (where Int (x) is a function indicating the integer part of x, and f (ξ)> n In this case, the pseudo-stereoscopic printer is characterized in that the pixel value is calculated using a function f (ξ) defined by an expression of f (ξ) = n). In the pseudo three-dimensional printer according to any one of claims 1 to 4 ,
Input a data of a two-dimensional captured image obtained by capturing a stereoscopic original image, and store this in the original image storage unit,
A photographed image printing unit for printing the two-dimensional photographed image on the surface of the medium to be printed;
Further comprising
The transfer sheet supply unit supplies a transfer sheet having a transparent transfer layer,
A pseudo-stereoscopic printer, wherein the transfer processing unit performs transfer processing of a transfer sheet on the medium after the two-dimensional captured image is printed by the captured image printing unit. In the pseudo three-dimensional printer according to any one of claims 1 to 5 ,
A dither processing unit that performs dither processing on the two-dimensional image stored in the two-dimensional image storage unit;
A pseudostereoscopic printer, wherein a transfer processing unit performs a transfer process based on a pixel value of the two-dimensional image after the dither process. A printing method for printing a three-dimensional original image having a three-dimensional structure on a two-dimensional surface of a medium to be printed,
An original image input step in which a computer inputs three-dimensional shape data of the stereoscopic original image;
A two-dimensional image storage location preparation stage in which a computer secures a storage location of a pixel value of a two-dimensional image consisting of a pixel array defined on a predetermined recording surface;
A computer determines a representative point P for each pixel constituting the two-dimensional image, draws a reference line R orthogonal to the recording surface at the position of each representative point P, and places the three-dimensional image at a position adjacent to the recording surface. An intersection calculation step for obtaining an intersection point Q between each reference line R when the original image is arranged and the surface of the stereoscopic original image;
A computer for calculating a normal vector N for the surface of the original three-dimensional image for each intersection Q determined by the intersection calculation step;
A computer defines a predetermined projection plane including a reference axis A, obtains a projection vector N ^* obtained as an orthogonal projection of each normal vector N onto the projection plane, and obtains each projection vector N ^* and the reference A crossing angle calculation step for obtaining a crossing angle ξ with the axis A;
The individual pixels constituting the two-dimensional image based on a function f (ξ) that monotonously increases or decreases monotonously with respect to the intersection angle ξ and takes any one of all n integers 1 to n. A pixel value calculation step of storing the value f (ξ) of the function with respect to the crossing angle ξ obtained with respect to the storage location as the pixel value of the pixel;
Defining a unit region array corresponding to the pixel array constituting the two-dimensional image on the surface of the medium to be printed, and transferring a transfer sheet having a predetermined diffraction grating pattern to each unit region; ,
Have
In the transfer processing stage, “unit angle of grid lines” or “arrangement pitch of grid lines” that monotonously increases or decreases monotonously according to the pixel value k (k = 1 to n) of each corresponding pixel in each unit region And a single transfer layer is physically transferred across the boundary line for adjacent unit regions corresponding to adjacent pixels having the same pixel value. For adjacent unit areas corresponding to adjacent pixels having different pixel values, separate transfer layers that are physically different from each other secure a predetermined gap by performing transfer with a gap secured between the transfer layers of the adjacent unit area. A method for pseudo-printing a stereoscopic original image, wherein the three-dimensional original image is transferred in a transferred state . The pseudo printing method according to claim 7 ,
A photographed image input stage for inputting data of a two-dimensional photographed image obtained by photographing a stereoscopic original image,
A photographed image printing step for printing the two-dimensional photographed image on the surface of the medium to be printed;
Further comprising
A pseudo-printing method of a three-dimensional original image, wherein a transparent transfer sheet is transferred onto a printing surface of the two-dimensional photographed image in the transfer processing step.