JP4698229B2 - Embossed sheet manufacturing method and manufacturing apparatus expressing anisotropic reflection surface of grain - Google Patents

Description

  The present invention relates to a method and an apparatus for manufacturing an embossed sheet expressing an anisotropic reflective surface of a grain, and particularly expresses a gloss pattern called “shine” or “moku” that appears on the surface of natural wood. Therefore, the present invention relates to a technique for manufacturing a wood-like texture embossed sheet used by being laminated on a printed surface of a wood grain pattern.

  Wood grain patterns are the most popular motifs used as surface decorations for building materials such as wallpaper and flooring, and furniture surface decorations. When creating a printed matter having such a wood grain pattern, a method is usually employed in which the surface of the natural wood is photographed with a camera or the like and the wood grain pattern of the natural wood is used as it is. In recent years, since image processing technology using computers has become widespread in the printing field, a natural wood grain pattern is captured as image data by a CCD camera or the like, and this image data is required using a computer. There has also been a widespread method of performing simple image processing and printing based on the processed image data.

  In general, the grain pattern found in natural wood is mainly composed of annual ring patterns, conduit groove patterns, shimmering patterns, and the like. The annual ring pattern is a dense and dense pattern of cellular tissue formed in accordance with the annual growth of natural wood based on the annual temperature difference. The conduit groove pattern is a cross-sectional pattern obtained by cutting a fibrous conduit used as a passage for moisture and nutrients necessary for growth of natural wood, and usually has a slightly distorted elliptical pattern. On the other hand, the shimmering pattern is a glossy pattern generally called “shining” or “moku”, and is a pattern generated based on the reflected light from the material surface. On the natural wood material surface (cut surface), the orientation of the fiber is different for each part, and this orientation distribution is observed as a shimmering pattern. In other words, since the pattern is generated based on the reflection of light on the anisotropic reflection surface, different illumination patterns appear depending on the incident direction of light from the light source and the observation direction by the observer even on the same material surface. It will be.

  In this way, the shimmering pattern has a unique property of changing depending on the optical observation conditions. Therefore, in the case of an artificial building material in which a wood grain pattern is printed on a sheet of vinyl chloride or the like, normal printing is performed. It is difficult to express only by layer. In view of this, a technique has been proposed in which a laminated structure in which an embossed sheet is formed on a printed sheet is employed, and a shimmering pattern is expressed by the uneven structure on the surface of the embossed sheet.

For example, in the following Patent Documents 1 to 8, a technique for expressing an anisotropic reflective surface of a grain by an embossed sheet in which a large number of ridge grooves (a large number of fine linear grooves) are formed on the surface. Is disclosed. In any case, the anisotropic reflection of light caused by the fiber of natural wood is expressed in a pseudo manner by the reflection of light caused by the ridges. For this reason, for example, Patent Documents 3, 4, 6, 8 and the like were obtained by photographing an actual natural wood cut surface and measuring the angle of each individual fiber (fiber submerged angle) relative to the cut surface A method for forming a multi-row groove according to the distribution of fiber dive angles is disclosed.
Japanese Patent Laid-Open No. 10-287033 Japanese Patent Laid-Open No. 11-180027 JP-A-11-295052 JP 2000-057310 A JP 2000-090278 A Japanese Patent Laid-Open No. 2000-230817 JP 2001-0909907 A JP 2002-071329 A

  As described above, in each of the above-mentioned patent documents, there is a method of obtaining a fiber diving angle distribution from a photographed image of a cut surface of a natural tree and forming a linear groove having an orientation according to the obtained distribution. It is disclosed. In this way, if the ridge groove is formed according to the distribution of the fiber diving angle on the actual cut surface of natural wood, it is possible to reproduce the anisotropic reflection surface using the natural texture as it is. However, in reality, the work of analyzing the photographed image of the cut surface of natural wood to accurately determine the fiber submerged angle distribution is a considerably heavy work.

  In particular, in order to estimate the fiber diving angle from the photographed image, it is necessary to prepare a large number of images photographed under various illumination environments, and a large burden is imposed on the photographing work. For example, in the technique disclosed in the above-mentioned Patent Document 3, it is necessary to capture a large number of images by finely changing the illumination light irradiation angle in several stages. In order to solve such a problem, Japanese Patent Application Laid-Open No. H10-228867 discloses that photographing is performed only under some typical irradiation angles, and photographing results for other irradiation angles are obtained by interpolation processing. A technique for reducing the work burden is disclosed. However, even if such a method is adopted, it is necessary to perform about eight types of shooting as typical irradiation angles in practice. In addition, in order to accurately obtain the fiber submerged angle distribution from the photographed image, a correction calculation that takes into consideration the light distribution characteristics of the light source is required, as disclosed in Patent Documents 6 and 8 described above. The burden for calculation is also quite large.

  Therefore, an object of the present invention is to provide a technique capable of reducing the burden of work and processing when manufacturing an embossed sheet expressing an anisotropic reflective surface of wood grain.

(1) A first aspect of the present invention is a manufacturing method for manufacturing an embossed sheet expressing an anisotropic reflective surface of wood grain.
A step of obtaining a first basic image by photographing a cut surface of a natural tree as a sample in a state in which illumination light is irradiated from a first direction;
A step of obtaining a second basic image by photographing the cut surface in a state in which illumination light is irradiated from the second direction;
Obtaining a difference image having a pixel value as a pixel value difference between a pair of pixels at corresponding positions for each pixel constituting the first basic image and each pixel constituting the second basic image; ,
Define a correspondence relationship for associating the pixel value range of the pixels constituting the difference image with a predetermined angle range, and set the pixel value of each pixel constituting the difference image to a predetermined angle based on the defined correspondence relationship Obtaining an angle image by transforming; and
Defining an angle distribution on a two-dimensional plane based on the angle image, and generating a line having an orientation corresponding to the angle defined at each position;
Creating an embossed sheet expressing the generated lines as a concavo-convex pattern;
Is to do.

(2) According to a second aspect of the present invention, in the manufacturing method for manufacturing an embossed sheet expressing an anisotropic reflective surface of grain,
A step of obtaining a first basic image by photographing a cut surface of a natural tree as a sample in a state in which illumination light is irradiated from a first direction;
A step of obtaining a second basic image by photographing the cut surface in a state in which illumination light is irradiated from the second direction;
Obtaining a contrast image having a pixel value as a pixel value ratio of a pair of pixels at corresponding positions for each pixel constituting the first basic image and each pixel constituting the second basic image; ,
Define a correspondence relationship for associating the pixel value range of the pixels constituting the contrast image with a predetermined angle range, and set the pixel value of each pixel constituting the contrast image to a predetermined angle based on the defined correspondence relationship Obtaining an angle image by transforming; and
Defining an angle distribution on a two-dimensional plane based on the angle image, and generating a line having an orientation corresponding to the angle defined at each position;
Creating an embossed sheet expressing the generated lines as a concavo-convex pattern;
Is to do.

(3) A third aspect of the present invention is a manufacturing method for manufacturing an embossed sheet expressing an anisotropic reflective surface of wood,
A step of obtaining a first basic image by photographing a cut surface of a natural tree as a sample in a state in which illumination light is irradiated from a first direction;
A step of obtaining a second basic image by photographing the cut surface in a state in which illumination light is irradiated from the second direction;
Obtaining a difference image having a pixel value as a pixel value difference between a pair of pixels at corresponding positions for each pixel constituting the first basic image and each pixel constituting the second basic image; ,
For each pixel constituting the difference image, the rank value indicating the magnitude order of the pixel values in the difference image is determined so as not to overlap, and the pixel value of each pixel constituting the difference image is converted into a rank value. To obtain a ranking image,
By defining the correspondence for associating the range of the rank value with a predetermined angle range, and converting the pixel value of each pixel constituting the rank image into a predetermined angle based on the defined correspondence, the angle Seeking an image,
Defining an angle distribution on a two-dimensional plane based on the angle image, and generating a line having an orientation corresponding to the angle defined at each position;
Creating an embossed sheet expressing the generated lines as a concavo-convex pattern;
Is to do.

(4) A fourth aspect of the present invention is a manufacturing method for manufacturing an embossed sheet expressing an anisotropic reflective surface of wood,
A step of obtaining a first basic image by photographing a cut surface of a natural tree as a sample in a state in which illumination light is irradiated from a first direction;
A step of obtaining a second basic image by photographing the cut surface in a state in which illumination light is irradiated from the second direction;
Obtaining a contrast image having a pixel value as a pixel value ratio of a pair of pixels at corresponding positions for each pixel constituting the first basic image and each pixel constituting the second basic image; ,
For each pixel constituting the contrast image, a rank value indicating the magnitude order of the pixel values in the contrast image is obtained so as not to overlap, and the pixel value of each pixel constituting the contrast image is converted into a rank value. To obtain a ranking image,
By defining the correspondence for associating the range of the rank value with a predetermined angle range, and converting the pixel value of each pixel constituting the rank image into a predetermined angle based on the defined correspondence, the angle Seeking an image,
Defining an angle distribution on a two-dimensional plane based on the angle image, and generating a line having an orientation corresponding to the angle defined at each position;
Creating an embossed sheet expressing the generated lines as a concavo-convex pattern;
Is to do.

(5) According to a fifth aspect of the present invention, in the method for manufacturing an embossed sheet according to the first to fourth aspects described above,
As the first basic image and the second basic image, images having pixel values indicating luminance are used.

(6) According to a sixth aspect of the present invention, in the method for manufacturing an embossed sheet according to the first to fifth aspects described above,
When defining the angle distribution on the two-dimensional plane, a representative point indicating the position of each pixel constituting the angle image is defined, and the angle defined as the pixel value of the pixel at the position of the representative point of each pixel A value is given, and an arbitrary point other than the representative point is given a predetermined angle value by interpolation based on the angle values of a plurality of adjacent representative points.

(7) According to a seventh aspect of the present invention, in the method for manufacturing an embossed sheet according to the sixth aspect described above,
When generating a parallel line, a starting point is set on a two-dimensional plane in which an angular distribution is defined, a reference point with the initial position on this starting point is defined, and this reference point is defined as `` current position defined. The process of moving a predetermined length in a direction corresponding to a certain angle value ”is repeated, and the process of forming a single line from the movement locus of the reference point is performed for a number of origins defined at predetermined intervals. Thus, a large number of lines are formed.

(8) According to an eighth aspect of the present invention, in the method for manufacturing an embossed sheet according to the first to seventh aspects described above,
When obtaining the angle image, the width of the angle range is set to 90 °.

(9) According to a ninth aspect of the present invention, in the method for manufacturing an embossed sheet according to the first to eighth aspects described above,
When obtaining the first basic image, a cut surface of a natural tree is arranged on the XY plane, and a line sensor is arranged above the cut surface so as to be parallel to the Y axis, and on the Y axis on the cut surface. An image of a parallel linear region can be captured, and an image of the cut surface is obtained by the line sensor while moving the cut surface in the X-axis direction while illuminating the linear region with illumination light from the first direction. To do the importing work,
When obtaining the second basic image, a cut surface of a natural tree is arranged on the XY plane, and a line sensor is arranged above the cut surface so as to be parallel to the Y axis, and on the Y axis on the cut surface. An image of a parallel linear region can be captured, and the line sensor is used to capture the image of the cut surface while moving the cut surface in the X-axis direction while illuminating the linear region with illumination light from the second direction. It is intended to perform the importing work.

(10) According to a tenth aspect of the present invention, in the method for manufacturing an embossed sheet according to the ninth aspect described above,
When the line sensor is arranged directly above the Y axis and the first basic image is obtained, illumination light is irradiated from the negative region of the X axis, and when the second basic image is obtained, the X axis The illumination light is irradiated from the positive region.

(11) An eleventh aspect of the present invention is the method for manufacturing an embossed sheet according to the ninth or tenth aspect described above,
A linear light source parallel to the Y axis is used as illumination light.

(12) In a twelfth aspect of the present invention, in the method for producing an embossed sheet according to the first to eleventh aspects described above,
A correction image is obtained by photographing a white diffuser in the same photographing environment as that of a natural tree, and the basic image is corrected using the correction image.

(13) A thirteenth aspect of the present invention, in a manufacturing apparatus for manufacturing an embossed sheet expressing an anisotropic reflective surface of wood,
Photographing a cut surface of a natural wood sample as a first basic image obtained by photographing with illumination light from the first direction and illumination light from the second direction. An image input means for inputting a second basic image obtained by
A difference image for obtaining a difference image having a pixel value as a pixel value difference between a pair of pixels at corresponding positions for each pixel constituting the first basic image and each pixel constituting the second basic image. Computing means;
By converting the pixel value of each pixel constituting the difference image into a predetermined angle based on a correspondence relationship defined in advance in order to associate the pixel value range of the pixels constituting the difference image with a predetermined angle range. Angle image calculation means for obtaining an angle image;
A line generating means for defining an angle distribution on a two-dimensional plane based on the angle image and generating a line having an orientation corresponding to the angle defined at each position;
An embossed sheet creating means for creating an embossed sheet expressing the generated lines as a concavo-convex pattern;
Is provided.

(14) According to a fourteenth aspect of the present invention, in a manufacturing apparatus for manufacturing an embossed sheet expressing an anisotropic reflecting surface of wood grain,
Photographing a cut surface of a natural wood sample as a first basic image obtained by photographing with illumination light from the first direction and illumination light from the second direction. An image input means for inputting a second basic image obtained by
A contrast image for obtaining a contrast image having a pixel value of a pixel value ratio of a pair of pixels at corresponding positions for each pixel constituting the first basic image and each pixel constituting the second basic image Computing means;
By converting the pixel value of each pixel constituting the contrast image into a predetermined angle based on a correspondence relationship defined in advance to associate the pixel value range of the pixels constituting the contrast image with a predetermined angle range. Angle image calculation means for obtaining an angle image;
A line generating means for defining an angle distribution on a two-dimensional plane based on the angle image and generating a line having an orientation corresponding to the angle defined at each position;
An embossed sheet creating means for creating an embossed sheet expressing the generated lines as a concavo-convex pattern;
Is provided.

(15) According to a fifteenth aspect of the present invention, in a manufacturing apparatus for manufacturing an embossed sheet expressing an anisotropic reflecting surface of wood grain,
Photographing a cut surface of a natural wood sample as a first basic image obtained by photographing with illumination light from the first direction and illumination light from the second direction. An image input means for inputting a second basic image obtained by
A difference image for obtaining a difference image having a pixel value as a pixel value difference between a pair of pixels at corresponding positions for each pixel constituting the first basic image and each pixel constituting the second basic image. Computing means;
For each pixel constituting the difference image, the rank value indicating the magnitude order of the pixel values in the difference image is determined so as not to overlap, and the pixel value of each pixel constituting the difference image is converted into a rank value. A ranking image calculation means for obtaining a ranking image;
By converting the pixel value of each pixel constituting the ranking image into a predetermined angle based on a correspondence relationship defined in advance to associate the pixel value range of the pixels constituting the ranking image with a predetermined angle range. Angle image calculation means for obtaining an angle image;
A line generating means for defining an angle distribution on a two-dimensional plane based on the angle image and generating a line having an orientation corresponding to the angle defined at each position;
An embossed sheet creating means for creating an embossed sheet expressing a line as an uneven pattern;
Is provided.

(16) According to a sixteenth aspect of the present invention, in a manufacturing apparatus for manufacturing an embossed sheet expressing an anisotropic reflective surface of wood grain,
Photographing a cut surface of a natural wood sample as a first basic image obtained by photographing with illumination light from the first direction and illumination light from the second direction. An image input means for inputting a second basic image obtained by
A contrast image for obtaining a contrast image having a pixel value of a pixel value ratio of a pair of pixels at corresponding positions for each pixel constituting the first basic image and each pixel constituting the second basic image Computing means;
For each pixel constituting the contrast image, a rank value indicating the magnitude order of the pixel values in the contrast image is obtained so as not to overlap, and the pixel value of each pixel constituting the contrast image is converted into a rank value. A ranking image calculation means for obtaining a ranking image;
By converting the pixel value of each pixel constituting the ranking image into a predetermined angle based on a correspondence relationship defined in advance to associate the pixel value range of the pixels constituting the ranking image with a predetermined angle range. Angle image calculation means for obtaining an angle image;
A line generating means for defining an angle distribution on a two-dimensional plane based on the angle image and generating a line having an orientation corresponding to the angle defined at each position;
An embossed sheet creating means for creating an embossed sheet expressing the generated lines as a concavo-convex pattern;
Is provided.

  In the present invention, the basic principle of actually photographing a cut surface of natural wood and forming a linear groove for expressing the anisotropic reflecting surface based on the photographed image is common to the conventional method. To do. However, the technique of obtaining an accurate distribution of the fiber diving angle from the photographed image is not adopted, and two basic images photographed in two illumination environments are selected according to the difference or ratio of the corresponding pixel values. Since the orientation of the groove is determined, the burden of photographing work and the burden of calculation processing are greatly reduced.

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

<<< §1. Simulated reproduction of shimmering patterns appearing on the surface of natural wood >>>
The main point of the present invention is to artificially reproduce the natural shimmering pattern that appears on the surface (cut surface) of natural wood using an embossed sheet. Therefore, here is a brief description of the essence of the shimmering pattern that appears on the surface of natural wood and the principle of reproducing this shimmering pattern in an embossed sheet.

  As already mentioned, there are annual ring patterns, conduit groove patterns, and shimmer patterns on the surface of general natural wood. Here, the shining pattern is a peculiar pattern that varies depending on the angle of the incident light and the observation direction, and is generally called “shining” or “moku”. For example, when a timber board cut out from natural wood is observed from a certain direction, the area shown in gray tone in FIG. 1 (a) appears to be whitish, and if the observation direction is slightly changed, this time, FIG. As shown, another area appears whitish. In this way, the reason why the pattern of the shining pattern changes depending on the observation angle is that the orientation of the fiber is different for each part on the surface of the natural wood. The natural tree contains various elements such as cells, conduits, fibers, etc. in order to operate as a plant, and these elements are generally oriented in the growth direction of the tree. Here, the axial element along the growth direction of the tree is generally called fiber.

  Thus, although the orientation of the natural wood fiber is generally oriented in the growth direction of the tree, the orientation often varies partially. Such orientation is generally called “wood”, and it is called by the names of wavy wood, spiral wood, cross wood, etc., depending on the state of orientation. For example, if the growth direction of an actual natural tree is vertically upward, the fibers inside the natural tree extend in the direction along the vertical upward direction as a whole, but the orientation of the fibers partially varies. Will be. Such variation in partial orientation is recognized as a shimmering pattern on the material surface.

  For example, consider a fiber bundle model as shown in FIG. The model shown here shows the orientation of axial elements such as conduits and fibers in a tree as a bundle of a large number of elongated cylindrical fibers 11 and shows the direction of the flow of fibers constituting the tree. Is. Of course, actual natural wood is not composed of such simple bundles of cylindrical fibers, but includes many elements such as cells, conduits, and fibers. The model shown in FIG. 2 is a model generally called a waved wood, and each reference fiber bundle extends vertically upward as a whole, but each of them is wavy. When such natural wood is cut along a predetermined cut surface, the orientation of fibers appearing on the cut surface varies.

  FIG. 3 is an enlarged cross-sectional view showing a model in the vicinity of the surface of the natural wood board 10. In FIG. 3, only one cylindrical fiber 11 is shown for convenience of explanation, but in reality, a large number of fibers are cut at the position of the material surface 12. Here, if the angle formed by the longitudinal axis of the cylindrical fiber 11 and the material surface 12 is defined as a fiber dive angle ξ, the fiber dive angle ξ differs for each individual fiber, and the natural wood board 10 has Depending on the wood texture, the material surface 12 has a specific distribution. The illumination light applied to the material surface 12 is reflected by the inner wall of the cylindrical fiber 11, and the reflection characteristic depends on the fiber dive angle ξ. Therefore, if a fiber dive angle ξ distribution is generated on the material surface 12, an anisotropic reflection surface is formed according to this distribution.

  FIG. 4 is a perspective view showing an anisotropic reflecting surface formed on the natural wood board 10. On the surface of the natural woodcut 10, a shimmering pattern 14 appears in a hatched area in the figure, together with a wood grain pattern 13 based on annual rings and conduit grooves. Here, the grain pattern 13 is basically the same pattern when observed from any direction, but the shimmering pattern 14 varies greatly depending on the observation direction. The reason why the shine pattern 14 is observed only in the hatched region is that the distribution of the fiber dive angle ξ in this region satisfies a predetermined condition for causing anisotropic reflection. In the example shown in the figure, the illumination light L is reflected by the hatching area and is directed toward the viewpoint 15. In such an environment, as long as the observation area 15 is observed, the hatching area is illuminated 14. Will be grasped as. However, if the lighting environment and the position of the viewpoint 15 are different, the position and size of the illuminated pattern 14 are also different. Thus, the shimmering pattern 14 is a pattern that changes depending on the observation environment, and the woodgrain pattern 13 is recognized as a picture pattern, whereas the shimmering pattern 14 is literally recognized as “shining” on the material surface.

  After all, the essence of the shimmering pattern that appears on the surface of natural wood is the distribution of fiber dive angle ξ based on wood, and the region where fiber dive angle ξ is almost the same appears to shine simultaneously under certain observation conditions. Become. Therefore, in order to reproduce the shimmering pattern of natural wood according to the same principle, it is necessary to physically reproduce the fiber structure having various fiber dive angles ξ on the surface of the embossed sheet. However, with current embossing technology, it is not practical to incorporate complex steps to reproduce such an actual fibrous structure in a commercial building material manufacturing process. Currently, the embossing plate manufacturing method that is generally used is a method called the direct etching method. On the embossing plate created by this method, a two-step step structure of a concave portion and a convex portion is formed. It is only done. If this direct etching method is repeated several times, a multi-stage structure can be obtained, but it is impossible to physically reproduce fiber structures having various fiber dive angles ξ.

  Therefore, in the method disclosed in each of the above-mentioned patent publications, an element called fiber submerged angle ξ that appears on the surface of an actual natural wood is changed into a single line groove (a large number of fine linear shapes formed on the embossed sheet). It is replaced with the direction of the groove), and the shimmering pattern is expressed as a large number of striped grooves.

  FIG. 5 is a perspective view showing the basic structure of the multi-row groove G formed on the embossed sheet E. FIG. In this example, a large number of strips G having a width W1 are formed while maintaining a spacing W2. With respect to the total thickness D1 of the embossed sheet E, the single-line groove G forms a groove with a depth D2, and a large number of single-line grooves G are arranged substantially in parallel. Generally, W1 = W2 = about 10 to 100 μm and D2 = about 5 to 30 μm are often set. Such a pattern consisting of the line grooves G has a two-step structure of a concave portion having a width W1 and a convex portion having a width W2, and can be easily performed using a conventional general direct etching method. Can be configured.

  In the embossed sheet E on which such a multi-row groove G is formed, the intensity of reflected light obtained from the surface varies depending on the observation direction. A cross section of the embossed sheet E cut along a plane parallel to the ridge groove G is shown in FIG. 6A, and a cross section cut along a plane perpendicular to the lane groove G is shown in FIG. As shown in FIG. 6 (a), light incident from a direction parallel to the ridge groove G is reflected from the bottom surface of the ridge groove G and is directly directed along the ridge groove G. And emitted as specular reflection light. On the other hand, as shown in FIG. 6 (b), the light incident from the direction perpendicular to the line groove G is reflected many times on the wall surface and bottom surface of the line groove G, and finally The light is emitted as diffusely reflected light in different directions. For this reason, strong specular reflected light is obtained when observed from a direction parallel to the ridge groove G. However, when observed from a direction perpendicular to the ridge groove G, the specular reflected light becomes weak.

  If such a property of the line groove G is utilized, it becomes possible to express a shimmering pattern in a pseudo manner. For example, as shown in the plan view of FIG. 7, a line groove G is formed over the entire surface of the embossed sheet E, and the direction of the line groove G in a certain partial region is changed. In this case, the intensity of the specular reflection light obtained from this partial area is different from the intensity of the specular reflection light obtained from other partial areas (whether it becomes stronger or weaker depends on the observation direction). A so-called shimmering pattern will be observed. Therefore, such an embossed sheet E is made of a transparent material, and as shown in FIG. 8, the embossed sheet E is laminated on a printed sheet T on which a wood grain pattern is printed. If a building material is comprised, the wood grain pattern building material with a shimmering pattern can be obtained. The wood grain pattern 13 shown in FIG. 4 is reproduced by the wood grain printed sheet T, and the shimmering pattern 14 is reproduced by the embossed sheet E. It is also possible to reproduce the shimmering pattern 14 by directly embossing the upper surface of the woodgrain printed sheet T.

<<< §2. Manufacturing method of embossed sheet according to the present invention >>
In the above-mentioned §1, the technique for expressing the shimmering pattern using the embossed sheet E having the ridges G has been described. Here, the shimmering pattern 14 appearing on the surface of the natural wood as shown in FIG. 4 is based on the distribution of the fiber dive angle ξ on the surface of the material, whereas the striped groove as shown in FIG. The shimmering pattern appearing on the embossed sheet E having the shape is based on the distribution of the direction (direction vector) on the plane of the ridges. And in the former, it can be seen that the region where the fiber dive angle ξ is approximately equal is simultaneously whitish in a certain state, whereas in the latter, the region where the direction vectors of the ridges are approximately equal in a certain state At the same time, you can see a white glow.

  In the first place, the fiber dive angle ξ is defined as the intersection angle between the cylindrical fiber 11 and the material surface 12, as shown in FIG. This indicates the direction of the line groove. Therefore, theoretically, the fiber dive angle ξ and the direction vector of the line groove are completely different physical quantities. However, both have the common feature that they function as parameters that govern the reflected light intensity during observation. Therefore, in the techniques disclosed in the above-mentioned patent documents, paying attention to this common point, the distribution of fiber submerged angles ξ appearing on the actual natural wood surface is measured as accurately as possible, and the distribution is The method of reproducing the image on the embossed sheet E in the form of a direction vector is used. However, in order to accurately determine the fiber submerged angle distribution from the photographed image of the cut surface of natural wood, it is necessary to prepare a large number of images photographed under various lighting environments and to perform various correction processes. Therefore, as described above, there is a problem that the burden of photographing work and arithmetic processing increases.

  In order to solve such problems, in the present invention, the conventional idea of “measuring an accurate fiber dive angle from natural wood” is first discarded. Certainly, it is necessary to measure the fiber submerged angle accurately from the viewpoint of "reproducing the shine on the natural wood surface of the sample faithfully with the embossed sheet". However, from the viewpoint of the industrial purpose of “manufacturing a building material having a grain pattern”, it is not always necessary to accurately measure the fiber dive angle. In producing building materials such as wallpaper and flooring, it is certain that building materials with a natural texture can be obtained if the “shine” found in actual natural wood can be faithfully reproduced. However, even if the shine of natural wood is not faithfully reproduced, it is sufficient as a building material to be used as an industrial mass-produced product if it can feel the shine of natural wood at least when viewed by humans. It is.

  However, in order to express the “shine of natural wood”, it is preferable to determine the direction of the ridges based on the information of the actual natural wood. Therefore, the inventor of the present application abandoned the conventional technique of “accurately measuring the distribution of fiber dive angle from natural wood”, while stating that “the image of the wood surface when the natural wood is placed in two lighting environments. We decided to take the method of “measuring differences”. Of course, this method can only extract information about the difference between images under two specific lighting environments, but when we actually created a sample using this method, we compared it with the building materials created by the conventional method. But the result was almost inferior. That is, even with the embossed sheet manufactured by the method of the present invention, as long as it is observed with human eyes, it is possible to sufficiently feel the shimmer of natural wood. Hereinafter, the procedure of this method will be described in detail.

  FIG. 9 is a flowchart showing a procedure of the embossed sheet manufacturing method according to the basic embodiment of the present invention. In this procedure, first, a natural wood board serving as a sample is prepared, and a first basic image is taken in step S1 and a second basic image is taken in step S2. Here, in step S1 and step S2, the same natural wood board is photographed from the same direction at the same magnification, but only the direction of illumination is changed.

  FIG. 10 is a perspective view showing the arrangement of members necessary to perform such shooting. The imaging device 20 is disposed immediately above the natural wood board 10, and a first light source 31 and a second light source 32 are disposed on both sides thereof. The first light source 31 is arranged at a position suitable for illuminating the material surface of the natural wood board 10 from the upper left, and the second light source 32 is suitable for illuminating the material surface of the natural wood board 10 from the upper right. It is arranged at the position. FIG. 11 is a front view showing an illumination state on the material surface of the natural wood board 10 by these two light sources. FIG. 11A shows the illumination state by the first light source 31, and FIG. 11B shows the illumination state by the second light source 32.

  In step S1 in the flowchart of FIG. 9, only the first light source 31 is turned on, and imaging by the imaging device 20 is performed in an illumination state as shown in FIG. In other words, a cut surface of a natural wood sample is photographed in a state where illumination light is irradiated from a first direction (upper left direction in the illustrated example). Here, an image obtained by such shooting is referred to as a first basic image P1.

  On the other hand, in step S2 in the flowchart of FIG. 9, only the second light source 32 is turned on, and imaging by the imaging device 20 is performed in an illumination state as shown in FIG. In other words, a cut surface of a natural wood sample is photographed in a state where illumination light is irradiated from the second direction (upper right direction in the illustrated example). Here, an image obtained by such shooting is referred to as a second basic image P2.

When a monochrome imaging device is used as the imaging device 20, the pixel values of the individual pixels constituting the first basic image P1 and the second basic image P2 indicate the luminance value at the corresponding position of the shooting target. become. On the other hand, when a color imaging device is used as the imaging device 20, pixel values of individual pixels are given as RGB three primary color components. In this case, as the pixel value of the pixels constituting each basic image, any one color component value may be selected and used, or the average value of the three primary color components may be used. Alternatively, an image photographed with the three primary colors of RGB can be converted into the L ^* a ^* b ^* color system, and only the L ^* value indicating luminance can be extracted and used as a basic image. In short, it is sufficient that the pixel values of the individual pixels constituting the basic image used in the present invention reflect the luminance of the corresponding position of the photographing target in some form, and indicate the luminance of a specific color component. It may be present or may indicate the total luminance of all color components.

  FIG. 12 is a plan view showing a comparison between the first basic image P1 and the second basic image P2 thus obtained. Here, for convenience of explanation, a two-dimensional XY coordinate system is defined on the material surface (upper surface) of the natural wood board 10, and the basic images P1 and P2 are composed of a set of a large number of pixels arranged two-dimensionally on the XY plane. And Since the shooting in step S1 and the shooting in step S2 differ only in the illumination environment, the same area to be imaged is recorded at the same resolution in the first basic image P1 and the second basic image P2. Each pixel of the basic image corresponds to a pixel at the same coordinate position of the other basic image. Therefore, the pixel on the first basic image P1 located at the coordinates (x, y) on the XY plane is represented as a pixel P1 (x, y), and the second basic image located at the coordinates (x, y). If the pixel on P2 is represented as a pixel P2 (x, y), the pixel P1 (x, y) and the pixel P2 (x, y) are pixels in which the same point to be photographed is recorded.

  Here, the pixel value of the pixel P1 (x, y) (for convenience, this pixel value will also be represented by the same symbol P1 (x, y)) and the pixel value of the pixel P2 (x, y) (for convenience, this pixel If the value is also represented by the same symbol P2 (x, y)), the difference is that the illumination environment at the time of photographing is different from the anisotropic reflection on the surface of the natural wood board 10. This is based on the existence of the surface. In step S3, the “difference image” is calculated. The “difference image” in the present application means “a pixel value of a pair of pixels at corresponding positions for each pixel constituting the first basic image P1 and each pixel constituting the second basic image P2. It can be defined as “an image having a difference as a pixel value”. In step S3, a “contrast image” may be calculated instead of the “difference image”. The “contrast image” in the present application means “a pixel value of a pair of pixels at corresponding positions for each pixel constituting the first basic image P1 and each pixel constituting the second basic image P2. It can be defined as “an image having a ratio as a pixel value”.

FIG. 13 is a plan view for explaining the principle of calculation for obtaining a difference image or a contrast image based on the first basic image P1 and the second basic image P2. The first basic image P1, the second basic image P2, the difference image D, and the contrast image Q are all images having a pixel arrangement of the same size. The pixel value D (x, y) of the pixel located at an arbitrary coordinate (x, y) of the difference image D is the pixel value P1 (x, y) of the pixel at the same position on the first basic image P1. And the pixel value P2 (x, y) of the pixel at the same position on the second basic image P2. That is,
D (x, y) = P1 (x, y) -P2 (x, y)
Thus, the pixel value of each pixel constituting the difference image D can be obtained. Similarly, the pixel value Q (x, y) of the pixel located at an arbitrary coordinate (x, y) of the contrast image Q is the pixel value P1 (x, y) of the pixel at the same position on the first basic image P1. ) And the pixel value P2 (x, y) of the pixel at the same position on the second basic image P2. That is,
Q (x, y) = P1 (x, y) / P2 (x, y)
Thus, the pixel value of each pixel constituting the contrast image Q can be obtained.

  As described above, in step S3, calculation for obtaining either the difference image D or the contrast image Q is performed. As described above, the basic concept of the present invention is to employ a technique of “measuring the difference in the material image when the material surface of the natural wood is placed in two lighting environments”. The above-described difference image D is an image showing the absolute magnitude of the difference in how much the pixel value is different, and the contrast image Q is a difference in how many times the pixel value is increased. This is an image showing a relative size. Since both are images showing the difference between two basic images taken under different illumination environments, either the difference image D or the contrast image Q may be used in carrying out the present invention.

  Subsequently, in step S4, an angle image is calculated. This angle image defines the correspondence for associating the pixel value range of the pixels constituting the difference image D or contrast image Q obtained in step S3 with a predetermined angle range, and constitutes the difference image D or contrast image Q This is an image obtained by converting pixel values of individual pixels to a predetermined angle based on this correspondence.

  FIG. 14 is a graph showing an example of the correspondence relationship between the pixel value of the difference image D and the angle range. In this example, it is assumed that the pixel values (indicated by the same symbol D) of the difference image D are distributed within the range of −255 to +255, and this range of the pixel value D is set to −45 of the angle value θ. Corresponding to a range of ° to + 45 °. In order to execute the calculation of step S3 by the computer, it is necessary to capture the basic images P1 and P2 as digital data. If these basic images P1 and P2 are captured as 8-bit digital data, each pixel is , Data having pixel values in the range of 0 to 255. Therefore, the minimum value of the pixel value D of each pixel constituting the difference image D is −255, and the maximum value is +255. Therefore, in the illustrated example, the minimum pixel value D = −255 corresponds to the minimum angle value θ = −45 °, the maximum pixel value D = + 255 corresponds to the maximum angle value θ = + 45 °, and the pixel value D increases. Then, a monotonically increasing function f (D → θ) is defined such that the angle value θ also increases.

  In the example shown in the figure, the function f (D → θ) is a linear function, but it is not always necessary to use a linear function in implementing the present invention. In other words, the correspondence between the pixel value D of the difference image D and the angle value θ is not necessarily a linear relationship. However, a relationship of monotonic increase (or monotonous decrease) is set such that as the pixel value D increases, the angle value θ also increases (or decreases). Actually, some pattern is formed on the finally obtained embossed sheet even if it is not monotonously increasing or monotonically decreasing, but in order to realize reflection similar to the appearance of the grain of wood, it is monotonously increasing or A monotonic decrease is very preferable.

  On the other hand, FIG. 15 is a graph showing an example of the correspondence between the pixel value of the contrast image Q and the angle range. In this example, it is assumed that the pixel values (indicated by the same symbol Q) of the contrast image Q are distributed within the range of 1/255 to 255, and this range of the pixel value Q is set to −− of the angle value θ. It corresponds to the range of 45 ° to + 45 °. As described above, if the basic images P1 and P2 are captured as 8-bit digital data, each pixel has data having a pixel value within a range of 0 to 255. However, when the ratio of pixel values is obtained, calculation becomes impossible if the denominator becomes 0. In this example, for convenience, processing for replacing the pixel value 0 with the pixel value 1 is performed. As a result, the range of the pixel values of the basic images P1 and P2 is 1 to 255, and the minimum value of the pixel value Q obtained as the ratio between them is 1/255, and the maximum value is 255/1. Here, the minimum pixel value Q = 1/255 corresponds to the minimum angle value θ = −45 °, the maximum pixel value Q = 255 corresponds to the maximum angle value θ = + 45 °, and the angle value increases as the pixel value Q increases. A monotonically increasing function f (Q → θ) is defined such that θ also increases.

  In FIG. 15, for convenience, the function f (Q → θ) is shown as a linear function. However, since the horizontal axis (the axis of the pixel value Q) of this graph is not a linear axis, the function f (Q → θ) is shown. θ) is not a linear function, but is a monotonically increasing function such that the angle value θ increases as the pixel value Q increases (a monotonically decreasing function may be used).

  FIG. 16 is a plan view showing the angle image θ calculated in step S4. The angle image θ is obtained by replacing each pixel value of the difference image D or the contrast image Q shown in FIG. 13 with an angle value based on a predetermined correspondence relationship. The arrangement is the same as the pixel arrangement of the difference image D or the contrast image Q, and is represented by the pixel value (the same symbol θ (x, y)) of the pixel θ (x, y) located at an arbitrary coordinate (x, y). ) Is an angle in the range of −45 ° to + 45 °. Eventually, this angle image θ is an image showing the angular distribution on the XY two-dimensional plane, and is an image showing the angular distribution on the material surface of the natural wood board 10 used as the original image.

  In the next step S5, based on the angular distribution obtained in this way, a process of generating all lines (a number of fine lines and hairlines) on the two-dimensional region corresponding to the material surface of the natural wood board 10 is performed. The main point of this line generation processing is that a line having a direction corresponding to the angle defined at each position on the two-dimensional plane is generated based on the angle image θ obtained in step S4. .

  For example, assume that an angle indicating the direction of the line is defined as shown in FIG. In this example, as shown in the lower part of the figure, a single line is drawn from the left to the right of the figure, and the orientation of the horizontal line facing the horizontal direction is defined as 0 ° as a reference. Then, a positive angle is defined counterclockwise and a negative angle is defined clockwise. Therefore, an angle value of −45 ° is given to a line that faces 45 ° obliquely downward, and + 45 ° is given to a line that faces 45 ° obliquely upward. In the above example, since the angle value defined on the angle image θ is in the range of −45 ° to + 45 °, the direction of the line is any one in the range of 45 ° diagonally downward to 45 ° diagonally upward. become.

  The upper part of FIG. 17 is a plan view showing an example of a line generated on the XY plane. In this example, a line having an orientation of + 45 ° is formed in the area A1, a line having an orientation of 0 ° is formed in the area A2, and a line of −45 ° is formed in the area A3. A line with a direction is formed. As a result, in the angle image θ shown in FIG. 16, the pixel value of the pixel corresponding to the region A1 is + 45 °, the pixel value of the pixel corresponding to the region A2 is 0 °, and the region It is obtained when the pixel value of the pixel corresponding to A3 is −45 °.

  In the embodiment shown here, the width of the angle range that the pixel value of the angle image θ should take is set to 90 °, and an angle value of −45 ° to + 45 ° is obtained. This is because the angle is in the range of 45 ° diagonally downward to 45 ° diagonally upward. Of course, it is also possible to set the width of the angle range to 180 ° and obtain an angle value of −90 ° to + 90 °. However, in this case, the value is different in the difference image D or the contrast image Q. The two most distant regions are −90 ° and + 90 ° on the angle image, resulting in the result that the angles of the lines are almost the same. This is not preferable because two areas where the expression of the shine is most different from each other will develop a similar shine on the embossed sheet. Therefore, in order to give the most different angle values to these two regions, it is preferable to set the angle range to −45 ° to + 45 ° as in the present embodiment.

  However, there is no physical basis for the correspondence between the pixel value of the difference image D or the contrast image Q and the pixel value of the angle image θ (the angle value θ is a value directly related to the fiber dive angle ξ). Therefore, it is not always necessary to set the angle range within the range of −45 ° to + 45 °.

  For convenience of explanation, FIG. 17 shows only the lines formed in the three regions A1, A2, and A3. However, in actuality, not only the regions A1, A2, and A3 but also the angle image θ. Since a predetermined angle value is defined for all the regions, if the line generation processing in step S5 is performed, a line facing a predetermined direction is formed in the entire image region. Moreover, the formed lines need to be continuous lines having a certain length due to their properties. Therefore, a specific method for generating such a line will be described below.

  As described above, the line generation processing in step S5 is performed based on the angle image θ obtained in step S4. Here, as shown in FIG. 16, the angle image θ is an image that defines some angle value θ (x, y) at the position of the coordinates (x, y). The coordinates (x, y) are The position of a certain pixel is shown. That is, since the angle image θ is composed of a finite set of pixels, a predetermined angle value θ (x, y) is defined for each discrete pixel position defined on the two-dimensional plane. I'm just there. However, in practice, it is possible to obtain the angle value θ at an arbitrary position on the two-dimensional plane by performing an interpolation calculation.

  FIG. 18 is an enlarged view of pixels constituting a part of the angle image θ. Although six pixels are drawn in the figure, a representative point R indicating the position of each pixel is defined, and an angle value defined as the pixel value of the pixel is given to the position of the representative point R of each pixel. . For example, the pixel value of the pixel θ (x, y) is given to the representative point R (x, y). As described above, the angle image θ is information in which a predetermined pixel value is discretely defined at each representative point R defined at a predetermined pitch on a two-dimensional plane, and interpolation based on the discrete value is performed. If calculation is performed, an angle value at an arbitrary position on the two-dimensional plane can be obtained.

  For example, for an arbitrary point Z shown in the figure (a point other than the representative point), a plurality of adjacent representative points R (x, y), R (x + 1, y), R (x, y + 1), R (x + 1, y + 1) ) To calculate a predetermined angle value by an interpolation calculation based on the angle values θ (x, y), θ (x + 1, y), θ (x, y + 1), and θ (x + 1, y + 1) respectively defined for Can do. Since such an interpolation operation is already a well-known technique, a detailed description is omitted here. However, if it is assumed that this interpolation operation is performed, an arbitrary position on the two-dimensional plane is determined by the angle image θ. An angle value will be given.

  Therefore, consider a procedure for defining a single line on a two-dimensional plane in which the distribution of angle values is defined. FIG. 19 is a plan view showing an example of a procedure for defining such a line. First, a starting point K1 is set on a two-dimensional plane in which the angular distribution is defined, and a reference point having the initial position on the starting point K1 is defined. Here, the coordinates of the starting point K1 are (x1, y1), and this starting point is expressed as K1 (x1, y1) in order to clearly indicate the coordinates. Then, the process of moving the reference point by a predetermined length in the direction corresponding to the angle value defined at the current position is repeatedly performed to form a single line from the movement locus of the reference point.

  For example, in the illustrated example, the initial position of the reference point is the starting point K1 (x1, y1), so this reference point is illustrated based on the angle value θ (x1, y1) defined at this position. As shown in the figure, it is moved by a predetermined length δ in the direction corresponding to the angle value θ (x1, y1). In the illustrated example, the horizontal right direction is set to a reference angle of 0 °, and the angle is defined. As described above, the angle value θ (x1, y1) at the position of the coordinates (x1, y1) can be obtained by performing an interpolation calculation as necessary based on the angle image θ. The predetermined length δ may be set arbitrarily. As the value of δ is set smaller, more accurate lines can be defined. However, in practice, it is sufficient to set δ = 10 to 100 μm when converted to the actual size.

  As shown in the figure, when the reference point is moved from the starting point K1 (x1, y1) by a predetermined length δ in the direction corresponding to the angle θ (x1, y1), the relay point K2 (x2, y2) is reached. Let's say. In this case, since the angle value defined at the new position of this reference point is θ (x2, y2), this time, the reference point is moved from the relay point K2 (x2, y2) to the angle θ (x2, y2). It is moved by a predetermined length δ in the direction according to y2). As a result, if the relay point K3 (x3, y3) is reached, the reference point is moved from the relay point K3 (x3, y3) by a predetermined length δ in the direction corresponding to the angle θ (x3, y3). And move to the relay point K4 (x4, y4). In this way, the process of moving the reference point from the start point K1 → the relay point K2 → the relay point K3 → the relay point K4 →... Until the predetermined condition is satisfied (for example, the distance between the start point K1 and the reference point is predetermined). Repeat until the value is reached. And if the movement locus of this reference point is a single line, at least as far as the starting point and each relay point are concerned, the direction in which the line extends will match the angle value defined for that point, A line having a direction corresponding to the angle defined at each position of the angle image θ can be generated. In the illustrated example, a line is defined as a polygonal line connecting the starting point and each relay point. However, a line may be defined as a curve smoothly connecting each point.

  When one line has been generated in this way, the second starting point K11 (x11, y11) is subsequently defined at a position separated from the first starting point K1 (x1, y1) by a predetermined distance d. Here, the predetermined interval d is the interval of all lines at the starting position. In the illustrated example, the second starting point K11 (x11, y11) is defined at a position separated by a predetermined distance d in the Y direction. Then, using the second starting point K11 (x11, y11) as a starting point, a procedure equivalent to the procedure described above is executed to generate a second line. In this way, a large number of lines can be formed by performing the above-described line generation process for a large number of starting points defined at predetermined intervals. In practice, if the starting points are arranged at predetermined intervals not only in the Y direction but also in the X direction, many lines are arranged at substantially uniform intervals in both the X and Y directions. In this case, the distance between the starting points in the X direction and the distance in the Y direction are not necessarily the same.

  The interval between the lines at the starting position is a set value d, but the direction in which each line extends is determined according to the angle value defined at each position, so any position on the line The interval at is not necessarily the value d. Therefore, in some cases, adjacent lines may cross each other, but there is no practical problem.

  If a line can be generated in this way, an embossed sheet is created in the final step S6. That is, an embossed sheet expressing the lines generated in step S5 as a concavo-convex pattern is created. The line generated in step S5 is a geometrical line, but on the actual embossed sheet, a wide line groove having a width is formed in order to express the line as an uneven pattern. It will be. For this purpose, a single line as shown in FIG. 19 may be formed on the embossed sheet as a single-line groove having a width d, for example. Such a method for forming a line groove is a known technique as disclosed in, for example, each of the above-mentioned patent documents, and a detailed description thereof will be omitted here.

  The line groove on the embossed sheet produced by such a method does not directly represent the fiber dive angle on the surface of the natural wood board used as a sample. That is, in the present invention, it is not possible to faithfully form a line having a direction corresponding to the fiber dive angle of a natural wood board. However, the orientation of the lines on the embossed sheet created by the process according to the present invention includes information on the difference in images when the natural wood board used as a sample is photographed in two different lighting environments, and at least human , You can feel the shine of natural wood, and you can realize building materials with a natural texture. Moreover, in the process of the present invention, it is only necessary to take two images with different illumination environments and perform a relatively simple calculation process, so that the work burden and the processing burden are greatly reduced compared to the conventional method. The

<<< §3. More preferred embodiment of the present invention >>>
Next, a more preferred embodiment of the present invention will be described based on the flowchart of FIG. The difference between the procedure shown in the flowchart of FIG. 20 and the procedure of the flowchart shown in FIG. 9 described above is that a ranking image calculation process is added as step S7, and the angle image calculation in step S4 is performed based on the ranking image. It is only the point that I tried to do. Therefore, this difference will be described below.

  In step S4 in the procedure of the flowchart shown in FIG. 9, the angle image θ is obtained by converting the pixel value of the difference image D or the contrast image Q into an angle value based on a predetermined correspondence relationship. Specifically, in order to convert the pixel value D of the difference image into the angle value θ, a function f (D → θ) as shown in FIG. 14 is defined, and the pixel value Q of the contrast image is converted into the angle value θ. Therefore, a function f (Q → θ) as shown in FIG. 15 is defined. However, when conversion to the angle value θ is performed based on such a correspondence relationship, the appearance frequency of the angle value θ is not uniform within the range of −45 ° to + 45 °, and the appearance frequency is biased. There are many cases.

  According to experiments conducted by the inventors of the present application, the appearance frequency of the pixel values (angle values) of each pixel constituting the angle image θ should be as uniformly distributed as possible within an angle range of −45 ° to + 45 °. It was confirmed that the “shine” generated on the finally obtained embossed sheet looks more natural. In other words, more favorable results can be obtained when the orientation of the line grooves formed on the embossed sheet is uniformly distributed over the entire range of −45 ° to + 45 °. become. Therefore, in the embodiment described here, instead of directly converting the difference image D or the contrast image Q into the angle image θ, the difference image D or the contrast image Q is once converted into the order image S, and the order image S is converted into the angle image θ. Take the method.

  FIG. 21 is a plan view for explaining the principle of converting the difference image D or the contrast image Q into the order image S and then converting it into the angle image θ. Here, the difference image D, the contrast image Q, the ranking image S, and the angle image θ are all images having the same size pixel array. The rank image S is obtained for each pixel constituting the difference image D or the contrast image Q so that a rank value indicating the magnitude order of the pixel value in the image is determined so as not to overlap, and the individual images constituting the image are determined. It is an image obtained by converting the pixel value of a pixel into the obtained rank value. The process of step S7 is a process of calculating the ranking image S by such a method.

  For example, consider a case where the ranking image S is obtained based on the difference image D. The pixel values of the individual pixels constituting the difference image D are distributed within the range of −255 to +255 in the above example. However, a pixel having a specific pixel value does not always exist. Further, the number of pixels having the same pixel value is not limited to one. Therefore, for example, there is no pixel having the pixel value D = 255 to 244, one pixel having the pixel value D = 243, and three pixels having the pixel value D = 242. Consider the case where there are 16 pixels with D = 241.

  In this case, a rank value S = 1 may be given to a pixel having a pixel value D = 243. Subsequently, the rank value S = 2 can be given to any of the three pixels having the pixel value D = 242. However, in the embodiment described here, the rank value is obtained so as not to overlap. Therefore, the order values S = 2, 3, and 4 are respectively given. In short, an ordering that does not allow the same order is performed. The superiority or inferiority regarding three pixels having the same pixel value D = 242 may be determined in any way. For example, an arbitrary superiority or inferiority determination method may be determined in advance, such as determining randomly superiority or inferiority using random numbers, or determining based on the value of coordinates (x, y). Subsequently, the rank value S = 5 to 20 is similarly given to the 16 pixels having the pixel value D = 241.

  As described above, the process of giving each pixel a rank value corresponding to the pixel value can be easily performed as a sort process by a computer. Eventually, if the total number of pixels constituting the difference image D is M, the rank value S (x, y) of the pixel located at an arbitrary coordinate (x, y) on the rank image S is 1 ≦ S (x, y) A value that satisfies the condition of ≦ M. The same applies to the case where the ranking image S is obtained based on the contrast image Q. The appearance frequency of the rank value of the rank image S thus obtained is uniform within a range of 1 to M.

  A feature of the embodiment described here is that the angle image calculation process in step S4 is performed based on the ranking image S, not the difference image D or the contrast image Q. That is, a correspondence relationship for associating the range of the rank value S with the predetermined angle range θ is defined, and the pixel value S of each pixel constituting the rank image is determined based on this correspondence relationship. By converting to θ, an angle image is obtained. FIG. 22 is a graph illustrating an example of a correspondence relationship between the pixel value S of the ranking image and the angle value θ. The horizontal axis of the figure is the rank value S, and a range of 1 to M is shown. The vertical axis represents the angle value θ, and a range of −45 ° to + 45 ° is shown.

  In the illustrated example, the minimum rank value S = 1 corresponds to the minimum angle value θ = −45 °, the maximum rank value S = M corresponds to the maximum angle value θ = + 45 °, and the angle value increases as the rank value S increases. A monotonically increasing function f (S → θ) is defined such that θ also increases. In the illustrated example, the function f (S → θ) is a linear function, but it is not always necessary to use a linear function in carrying out the present invention. In other words, the correspondence between the ranking value S of the ranking image S and the angle value θ does not necessarily have to be a linear relationship. However, a relationship of monotonic increase (or monotonous decrease) is set such that as the rank value S increases, the angle value θ also increases (or decreases).

  When the function f (D → θ) shown in FIG. 14 or the function f (Q → θ) shown in FIG. 15 is used for conversion to the angle value θ, as described above, the angle value θ The frequency of occurrence is not uniform within the range of −45 ° to + 45 °, and is often biased. On the other hand, when the conversion to the angle value θ is performed using the function f (S → θ) shown in FIG. 22, the appearance frequency of the rank value S is completely in the range of 1 to M. Thus, the appearance frequency of the angle value θ is substantially uniform within a range of −45 ° to + 45 °. In particular, if a linear function as shown in the figure is used as the function f (S → θ), theoretically, the appearance frequency of the angle value θ is also completely uniform.

  Thus, based on the angle image obtained in step S4, a line is generated in step S5 and an embossed sheet is created in step S6, which is exactly the same as in the basic embodiment described above. The line-shaped grooves on the embossed sheet thus prepared include directions in an angle range of −45 ° to + 45 ° almost uniformly, which is preferable for reproducing natural “shine”. Results are obtained.

<<< §4. Embossed sheet manufacturing apparatus according to the present invention >>
As mentioned above, although the manufacturing method of the embossed sheet which concerns on this invention was described, the structure of the apparatus used for implementation of this manufacturing method is described here.

  FIG. 23 is a block diagram showing a basic configuration of an embossed sheet manufacturing apparatus according to the present invention. This device has the function of executing the procedure shown in the flowchart of FIG. 20, and each component shown in the block can execute a specific step of the flowchart of FIG. First, the image input means 110 is a component for performing the basic image photographing process in steps S1 and S2. Specifically, as shown in FIG. 10, the imaging device 20 and the light sources 31 and 32 are configured to illuminate the material surface (cut surface) of the natural wood board 10 serving as a sample from the first direction. The first basic image P1 obtained by photographing with the first and the second basic image P2 obtained by photographing with illumination light from the second direction are input.

  On the other hand, the difference image calculation means 120 is a component for performing the calculation process of the difference image in step S3, and each pixel constituting the first basic image P1 and each pixel constituting the second basic image P2. The pixel has a function of calculating a difference image using a difference between pixel values of a pair of pixels at corresponding positions as a pixel value. When a contrast image is used instead of the difference image, the contrast image calculation means 120 may be used. In this case, the ratio of the pixel value of a pair of pixels at the corresponding positions is used as the pixel value for each pixel constituting the first basic image P1 and each pixel constituting the second basic image P2. A function for obtaining a contrast image by calculation is executed.

  The rank image calculation means 130 is a component for performing the rank image calculation process in step S7, and for each pixel constituting the difference image D or the contrast image Q, the pixel value of the pixel value in the corresponding image Is obtained so that there is no overlap, and the pixel value of each pixel constituting the image is converted into the obtained rank value, thereby performing a calculation for obtaining the rank image S. Such a calculation process is nothing but a process of sorting individual pixels constituting the difference image D or the contrast image Q based on the pixel values. However, as described above, in order to perform ordering so that the same order does not overlap, when there are a plurality of pixels having the same pixel value, superiority or inferiority is determined by some method.

  The angle image calculation means 140 is a component for performing the angle image calculation processing in step S4, and is a predefined response for associating the pixel value range of the pixels constituting the ranking image S with a predetermined angle range. Based on the relationship (for example, the correspondence relationship shown in FIG. 22), it has a function of performing an operation for obtaining an angle image by converting the pixel value of each pixel constituting the rank image into a predetermined angle.

  The line generating means 150 is a component for performing the line generation processing in step S5, and defines an angle distribution on a two-dimensional plane based on the angle image θ and is defined at each position. It has a function of performing processing for generating a line having a direction corresponding to an angle. An example of the specific processing is as described with reference to FIG.

  The difference image calculation means (contrast image calculation means) 120, the rank image calculation means 130, the angle image calculation means 140, and the line generation means 150 are practically realized by incorporating a dedicated program into the computer. The image input means 110 serves to input the first basic image P1 and the second basic image P2 as digital data to the computer.

The last embossed sheet creating means 160 is a component that performs the process of step S6.
It has a function of creating an embossed sheet expressing the lines generated by the line generating means 150 as an uneven pattern. Specifically, for example, a drawing apparatus that draws a predetermined exposure pattern based on digital data indicating a line output from a computer, and an apparatus that creates an embossing plate by etching processing based on the exposure pattern The embossed sheet creating means 160 can be configured by an apparatus for mass-producing embossed sheets by performing embossing using this plate.

  Note that, as described in §2, the rank image calculation means 130 may be omitted when executing a procedure that does not create a rank image. In this case, the angle image calculation unit 140 calculates the angle image θ based on the difference image D or the contrast image Q.

  Finally, a configuration example of an apparatus that is optimal for use as the image input unit 110 will be described with reference to a perspective view of FIG. As shown in the figure, the image input means 110 includes a first line light source 111, a second line light source 112, a line sensor 113, and a conveyance device (not shown). Surface) 12 is photographed in two different lighting environments.

  Here, for convenience of explanation, an XY plane is defined on the material surface 12 of the natural wood board 10, and the natural wood board 10 is configured to be conveyed in the X-axis positive direction by a conveyance device (not shown). The line sensor 113 is disposed above the material surface 12 of the natural wood board 10 so as to be parallel to the Y axis, and is a linear region 16 (an example shown in the drawing) parallel to the Y axis on the material surface 12. Then, an image of a hatching area on the Y axis can be captured as a one-dimensional pixel array. On the other hand, the first line light source 111 and the second line light source 112 are both arranged so as to be parallel to the Y axis, and can illuminate the linear region 16. In the case of the illustrated example, the first linear light source 111 and the second linear light source 112 are disposed at positions that are plane-symmetric with respect to the YZ plane (a plane perpendicular to the material surface 12) and have the same illumination function. It has become.

  FIG. 25 is a front view showing an operation of inputting the first basic image P1 and the second basic image P2 using the image input means shown in FIG. First, when inputting the first basic image P1, only the first linear light source 111 is turned on, and the linear region 16 is illuminated with the illumination light L1. Under such an illumination environment, the linear region 16 is read by the line sensor 113 while conveying the natural wood board 10 from the left direction to the right direction (the positive direction of the X axis). By doing so, the entire surface of the material surface 12 can be scanned by the linear region 16, and by collecting the pixel value information of the one-dimensional pixel array output as time-series data from the line sensor 113, the first The basic image P1 can be obtained as digital data.

  When the second basic image P2 is input, the above-described scanning process may be performed with only the second line light source 112 turned on. That is, the linear sensor 16 may be read by the line sensor 113 while conveying the natural wood board 10 in the positive direction of the X axis in an environment where the linear sensor 16 is illuminated with the illumination light L2.

  Eventually, the first basic image P1 is moved in the X-axis direction while moving the material surface 12 in the X-axis direction in a state in which the illumination light L1 is irradiated obliquely from the upper left to the linear region 16 by the first line light source 111. The second basic image P2 is obtained by performing the image capturing operation by the line sensor 113. The second linear light source 112 irradiates the illumination light L2 obliquely from the upper right with respect to the linear region 16. In this state, the image is acquired by the line sensor 113 while moving the material surface 12 in the X-axis direction. In the case of the illustrated example, the line sensor 113 is disposed immediately above the Y axis. Therefore, when obtaining the first basic image P1, the illumination light L1 is irradiated from the negative region of the X axis, and the first When the second basic image P2 is obtained, the illumination light L2 is irradiated from the positive region of the X axis.

  As described above, when the basic image is captured by scanning the linear region 16 using the line sensor 113 and the transport device, the image is captured in a common illumination environment at any position on the material surface 12. The merit that it becomes possible is obtained. This can solve, for example, a problem that occurs in the imaging system as shown in FIG. Let me explain this advantage in a little more detail.

  The imaging system shown in FIG. 10 can capture the entire material surface as a two-dimensional image at once by an imaging device 20 (for example, a digital camera) provided above the natural wood board 10. However, when a basic image is captured by such an imaging system, an illumination environment as shown in FIG. 11 (a) or (b) is obtained, so that the amount of illumination light and the irradiation angle are different for each part of the material surface. It will be different. For example, in the lighting environment shown in FIG. 11 (a), the natural wood board 10 is illuminated by the first light source 31, but the left side portion of the natural wood board 10 is closer to the light source than the right side portion. Is greater in the left side of the natural wood board 10 than in the right side. When attention is paid to the illumination angle of the illumination light, the left side portion of the natural wood board 10 is illuminated with the illumination light from a near-perpendicular angle, whereas the right side portion is illuminated with the illumination light from a considerably oblique angle. It will be. Such a relationship is completely opposite in the illumination environment shown in FIG.

  In the present invention, the first basic image P1 and the second basic image P2 are photographed under two illumination environments in order to obtain information on the anisotropic reflection surface of the grain. Therefore, originally, it is desirable that the two illumination environments differ only in the direction of the illumination light, and the light amount and the irradiation angle are the same. For example, under a first illumination environment, all portions on the material surface are illuminated with a predetermined amount of light at an angle of 45 ° diagonally to the upper left, and under the second illumination environment, the same material is used. In an ideal environment, all parts on the surface should be illuminated with the same amount of light from obliquely upward 45 °.

  Unfortunately, such an ideal illumination environment cannot be realized with the imaging system shown in FIG. 10, but this is possible with the imaging system shown in FIG. If the first line light source 111 and the second line light source 112 are arranged at positions symmetrical with respect to the YZ plane, the irradiation direction of the illumination light L1 on the linear region 16 as shown in the front view of FIG. Since the illumination direction of the illumination light L2 is plane-symmetric, the light amount and the illumination angle are the same. Moreover, since the method of scanning the linear area | region 16 is taken, such an illumination environment is common regarding the whole material surface of the natural wood board 10. FIG.

  It is possible to use a point light source instead of the line light sources 111 and 112. In this case, the X-axis direction can obtain an imaging result under a common illumination environment by scanning, but the Y-axis direction can be obtained. Will cause the same problem as the imaging system shown in FIG. That is, in FIG. 24, when a point light source is used instead of the line light sources 111 and 112, a phenomenon in which the light amount and the irradiation angle differ depending on the position of the natural wood board 10 on the Y axis occurs. Therefore, in practice, it is preferable to use a linear light source parallel to the Y axis as illumination light, as in the illustrated example.

  However, a line light source such as a fluorescent tube that can be prepared in practice is not an ideal line light source because it is a light source having a finite length. Of course, if a line light source having a sufficiently large length with respect to the width of the natural wood board 10 in the Y-axis direction can be prepared, such a line light source is substantially an ideal infinite length. An illumination environment equivalent to that of a line light source can be realized. However, in designing in consideration of the size of the apparatus, it is realistic to set the length of the line light sources 111 and 112 to be approximately the same as or slightly longer than the width of the natural wood board 10 in the Y-axis direction. is there. In such a case, it cannot be denied that a phenomenon in which the amount of light and the irradiation angle are slightly different depending on the position of the natural wood board 10 on the Y-axis is unavoidable. For example, in the example shown in FIG. 24, the lengths of the line light sources 111 and 112 are approximately the same as the width of the natural wooden board 10 in the Y-axis direction. There is a difference in the lighting environment between the center portion and the back portion.

  In order to cope with such a difference, a correction image is obtained by photographing a white diffuser plate in the same photographing environment as that for a natural wood board, and the basic image is corrected using the correction image. What should I do? FIG. 26 is a perspective view of the natural wood board 10 to which a white diffuser plate 50 for photographing such a correction image is connected. The white diffuser plate 50 is a plate having a function of diffusing illumination light under the same conditions at any location. As shown in FIG. 25, the white diffuser plate 50 conveys the natural wood board 10 and performs a work for capturing a basic image. Further, the image is continuously captured even for the portion of the white diffusion plate 50. Then, correction is performed using the image captured for the white diffuser plate 50 as a correction image.

  When the linear light source used for illumination is an ideal linear light source having an infinite length, the luminance of the correction image should be the same at any position. However, since the actually used line light sources 111 and 112 are light sources of finite length, as described above, the light amount and the irradiation angle are slightly different depending on the position on the Y axis. As described above, the change in the illumination environment according to the position on the Y axis appears as a change in luminance on the correction image. Accordingly, a function B (y) indicating the luminance distribution in the Y-axis direction is obtained based on the actually captured correction image, and the pixel values of the individual pixels constituting the obtained basic image are determined as the Y-axis of the pixel. By performing a correction process that divides by the value of the function B (y) corresponding to the upper position y, it is possible to obtain an accurate result that offsets the influence of using a finite-length linear light source.

It is a top view which shows the shimmering pattern which appears on the surface of a natural wood. It is a perspective view which shows the fiber bundle model of a wavy grain. 2 is an enlarged cross-sectional view showing a model in the vicinity of the surface of a natural wood board 10. FIG. 2 is a perspective view showing an anisotropic reflecting surface formed on a natural wood board 10. FIG. 3 is a perspective view showing a basic structure of a multi-row groove G formed on an embossed sheet E. FIG. It is sectional drawing which shows the state which cut | disconnected the embossing sheet E shown in FIG. 4 is a plan view showing an example in which a shimmering pattern is expressed by forming multi-row grooves G in different directions on the surface of the embossed sheet E. FIG. It is a perspective view which shows the state which laminated | stacked the embossed sheet E on the printing sheet T of a wood grain pattern. It is a flowchart which shows the procedure of the manufacturing method of the embossed sheet which concerns on basic embodiment of this invention. It is a perspective view which shows arrangement | positioning of a member required in order to image | photograph step S1, S2 of the flowchart shown in FIG. It is a front view which shows the illumination state on the material surface of the natural wood board 10 by the two light sources 31 and 32 shown in FIG. FIG. 10 is a plan view showing a comparison between a first basic image P1 and a second basic image P2 obtained by photographing in steps S1 and S2 of the flowchart shown in FIG. It is a top view explaining the principle of the calculation which calculates | requires a difference image or a contrast image based on the 1st basic image P1 and the 2nd basic image P2. It is a graph which shows an example of the correspondence of the pixel value of difference image D, and an angle range. It is a graph which shows an example of the correspondence of the pixel value of contrast image Q, and an angle range. It is a top view which shows angle image (theta) calculated by step S4 of the flowchart shown in FIG. It is a figure which shows an example of a parallel line produced | generated on XY plane, and the correspondence of the direction and angle of a parallel line. It is an enlarged view of the pixel which comprises a part of angle image (theta). It is a top view which shows an example of the specific procedure of the production | generation process of a line performed at step S5 of the flowchart shown in FIG. It is a flowchart which shows the procedure of the manufacturing method of the embossed sheet which concerns on more preferable embodiment of this invention. It is a top view explaining the principle which converts the difference image D or the contrast image Q once into the order image S, and converts this into the angle image (theta). It is a graph which shows an example of the correspondence of the pixel value of the order image S, and an angle range. It is a block diagram which shows the basic composition of the manufacturing apparatus of the embossed sheet which concerns on this invention. FIG. 24 is a perspective view showing a configuration example of an apparatus optimal for use as the image input means 110 in the embossed sheet manufacturing apparatus shown in FIG. 23. FIG. 25 is a front view showing an operation of inputting a first basic image P1 and a second basic image P2 using the image input means shown in FIG. It is a perspective view of the natural wood board 10 which connected the white diffuser plate 50 for image | photographing the image for correction | amendment.

Explanation of symbols

10 ... Natural wood board 11 ... Cylindrical fiber 12 ... Material surface (cut surface of natural wood)
DESCRIPTION OF SYMBOLS 13 ... Wood grain pattern 14 ... Shining pattern 15 ... Viewpoint 16 ... Linear area | region 20 used as the reading object of a line sensor ... Imaging device 31 ... 1st light source 32 ... 2nd light source 50 ... White diffuser plate 110 ... Image input means 111 ... first line light source 112 ... second line light source 113 ... line sensor 120 ... difference image calculation means (contrast image calculation means)
130 ... Rank image calculation means 140 ... Angle image calculation means 150 ... Line generation means 160 ... Embossed sheet creation means A1, A2, A3 ... Each region D on the XY plane D ... Difference image or its pixel value D (x, y) ... Pixel on the difference image or its pixel value D1 ... Thickness D2 of embossed sheet ... Depth of line groove d ... Space between line E ... Embossed sheet G ... Line groove L, L1, L2 ... Illumination light M ... Total number of pixels P1 ... First basic image P1 (x, y) ... Pixel on the first basic image or its pixel value P2 ... Second basic image P2 (x, y) ... Second Pixel on the basic image or its pixel value Q ... contrast image Q (x, y) ... pixel on the contrast image or pixel value R (x, y) ... representative point S ... ranking image or pixel value S (x, y) y)... pixel on the ranking image or its pixel values S1 to S7 Each step T in the flowchart: a woodgrain printed sheet W1 ... a width W2 of the linear stripes ... an interval Z between the linear stripes Z ... an arbitrary point δ on the XY plane ... a predetermined length ξ used in the procedure for generating the parallel lines ξ ... Fiber dive angle θ ... Angle image θ (x, y) ... Pixel on the angle image or its pixel value

Claims (16)

A method of manufacturing an embossed sheet expressing an anisotropic reflective surface of wood,
A step of obtaining a first basic image by photographing a cut surface of a natural tree as a sample in a state in which illumination light is irradiated from a first direction;
Obtaining the second basic image by photographing the cut surface in a state of illuminating illumination light from the second direction;
For each pixel constituting the first basic image and each pixel constituting the second basic image, a difference image having a pixel value as a pixel value difference between a pair of pixels at corresponding positions is obtained. Stages,
A correspondence relationship for associating a pixel value range of pixels constituting the difference image with a predetermined angle range is defined, and pixel values of individual pixels constituting the difference image are set to a predetermined angle based on the correspondence relationship. Obtaining an angle image by transforming; and
Defining an angle distribution on a two-dimensional plane based on the angle image, and generating a line having an orientation corresponding to the angle defined at each position;
Creating an embossed sheet expressing the lines as an uneven pattern;
A method for producing an embossed sheet expressing an anisotropic reflective surface of wood, characterized by comprising: A method of manufacturing an embossed sheet expressing an anisotropic reflective surface of wood,
A step of obtaining a first basic image by photographing a cut surface of a natural tree as a sample in a state in which illumination light is irradiated from a first direction;
Obtaining the second basic image by photographing the cut surface in a state of illuminating illumination light from the second direction;
For each pixel constituting the first basic image and each pixel constituting the second basic image, a comparison image having a pixel value ratio of a pair of pixels at corresponding positions is obtained. Stages,
Define a correspondence relationship for associating a pixel value range of pixels constituting the contrast image with a predetermined angle range, and set a pixel value of each pixel constituting the contrast image to a predetermined angle based on the correspondence relationship Obtaining an angle image by transforming; and
Defining an angle distribution on a two-dimensional plane based on the angle image, and generating a line having an orientation corresponding to the angle defined at each position;
Creating an embossed sheet expressing the lines as an uneven pattern;
A method for producing an embossed sheet expressing an anisotropic reflective surface of wood, characterized by comprising: A method of manufacturing an embossed sheet expressing an anisotropic reflective surface of wood,
A step of obtaining a first basic image by photographing a cut surface of a natural tree as a sample in a state in which illumination light is irradiated from a first direction;
Obtaining the second basic image by photographing the cut surface in a state of illuminating illumination light from the second direction;
For each pixel constituting the first basic image and each pixel constituting the second basic image, a difference image having a pixel value as a pixel value difference between a pair of pixels at corresponding positions is obtained. Stages,
For each pixel constituting the difference image, a rank value indicating the magnitude order of the pixel value in the difference image is determined so as not to overlap, and the pixel value of each pixel constituting the difference image is determined as the rank. Obtaining a ranking image by converting to a value;
By defining a correspondence relationship for associating the range of the rank value with a predetermined angle range, and converting the pixel value of each pixel constituting the rank image into a predetermined angle based on the correspondence relationship, Seeking an image,
Defining an angle distribution on a two-dimensional plane based on the angle image, and generating a line having an orientation corresponding to the angle defined at each position;
Creating an embossed sheet expressing the lines as an uneven pattern;
A method for producing an embossed sheet expressing an anisotropic reflecting surface of wood, characterized by comprising: A method of manufacturing an embossed sheet expressing an anisotropic reflective surface of wood,
A step of obtaining a first basic image by photographing a cut surface of a natural tree as a sample in a state in which illumination light is irradiated from a first direction;
Obtaining the second basic image by photographing the cut surface in a state of illuminating illumination light from the second direction;
For each pixel constituting the first basic image and each pixel constituting the second basic image, a comparison image having a pixel value ratio of a pair of pixels at corresponding positions is obtained. Stages,
For each pixel constituting the contrast image, a rank value indicating the magnitude order of the pixel values in the contrast image is determined so as not to overlap, and the pixel value of each pixel constituting the contrast image is determined as the rank Obtaining a ranking image by converting to a value;
By defining a correspondence relationship for associating the range of the rank value with a predetermined angle range, and converting the pixel value of each pixel constituting the rank image into a predetermined angle based on the correspondence relationship, Seeking an image,
Defining an angle distribution on a two-dimensional plane based on the angle image, and generating a line having an orientation corresponding to the angle defined at each position;
Creating an embossed sheet expressing the lines as an uneven pattern;
A method for producing an embossed sheet expressing an anisotropic reflective surface of wood, characterized by comprising: In the manufacturing method in any one of Claims 1-4,
An embossed sheet manufacturing method expressing an anisotropic reflecting surface of wood, wherein images having pixel values indicating luminance are used as the first basic image and the second basic image. In the manufacturing method in any one of Claims 1-5,
When defining the angle distribution on the two-dimensional plane, a representative point indicating the position of each pixel constituting the angle image is defined, and the angle defined as the pixel value of the pixel at the position of the representative point of each pixel Embossing expressing an anisotropic reflective surface of a grain, wherein a predetermined angle value is given by interpolation based on the angle values of a plurality of adjacent representative points for any point other than the representative point Sheet manufacturing method. The manufacturing method according to claim 6,
When generating a parallel line, a starting point is set on a two-dimensional plane in which an angular distribution is defined, a reference point with the initial position on this starting point is defined, and this reference point is defined as `` current position defined. The process of moving a predetermined length in a direction corresponding to a certain angle value ”is repeated, and the process of forming a single line from the movement locus of the reference point is performed for a number of origins defined at predetermined intervals. A method for producing an embossed sheet expressing an anisotropic reflective surface of wood, characterized in that a large number of lines are formed. In the manufacturing method in any one of Claims 1-7,
A method for manufacturing an embossed sheet expressing an anisotropic reflecting surface of wood, wherein the angle range is set to 90 ° when an angle image is obtained. In the manufacturing method in any one of Claims 1-8,
When obtaining the first basic image, a cut surface of natural wood is arranged on the XY plane, a line sensor is arranged above the cut surface so as to be parallel to the Y axis, and the Y axis on the cut surface An image of a linear region parallel to the image is captured, and the line sensor is used to move the cut surface in the X-axis direction while irradiating the linear region with illumination light from a first direction. Try to capture the image of the cut surface,
When obtaining the second basic image, a cut surface of natural wood is arranged on the XY plane, a line sensor is arranged above the cut surface so as to be parallel to the Y axis, and the Y axis on the cut surface An image of a linear region parallel to the image is captured, and the line sensor is used to move the cut surface in the X-axis direction while illuminating illumination light from a second direction with respect to the linear region. A method for manufacturing an embossed sheet expressing an anisotropic reflective surface of wood grain, characterized in that an operation of capturing an image of a cut surface is performed. In the manufacturing method of Claim 9,
When the line sensor is arranged directly above the Y axis and the first basic image is obtained, illumination light is irradiated from the negative region of the X axis, and when the second basic image is obtained, the X axis A method for producing an embossed sheet expressing an anisotropic reflection surface of wood, wherein illumination light is irradiated from a positive region of In the manufacturing method according to claim 9 or 10,
A method for manufacturing an embossed sheet expressing an anisotropic reflective surface of wood, characterized in that a linear light source parallel to the Y axis is used as illumination light. In the manufacturing method in any one of Claims 1-11,
An anisotropic reflection of a grain characterized by obtaining a correction image by photographing a white diffuser in the same photographing environment as that of a natural tree, and correcting the basic image using the correction image. A method of manufacturing an embossed sheet expressing a surface. An apparatus for producing an embossed sheet expressing an anisotropic reflective surface of wood,
Photographing a cut surface of a natural wood sample as a first basic image obtained by photographing with illumination light from the first direction and illumination light from the second direction. An image input means for inputting a second basic image obtained by
For each pixel constituting the first basic image and each pixel constituting the second basic image, a difference image having a pixel value as a pixel value difference between a pair of pixels at corresponding positions is obtained. Difference image calculation means;
The pixel value of each pixel constituting the difference image is converted into a predetermined angle based on a correspondence relationship defined in advance to associate the pixel value range of the pixels constituting the difference image with a predetermined angle range. An angle image calculation means for obtaining an angle image by
A line generating means for defining an angle distribution on a two-dimensional plane based on the angle image and generating a line having a direction corresponding to the angle defined at each position;
An embossed sheet creating means for creating an embossed sheet expressing the line as an uneven pattern;
An embossed sheet manufacturing apparatus expressing an anisotropic reflecting surface of wood, characterized by comprising: An apparatus for producing an embossed sheet expressing an anisotropic reflective surface of wood,
Photographing a cut surface of a natural wood sample as a first basic image obtained by photographing with illumination light from the first direction and illumination light from the second direction. An image input means for inputting a second basic image obtained by
For each pixel constituting the first basic image and each pixel constituting the second basic image, a comparison image having a pixel value ratio of a pair of pixels at corresponding positions is obtained. Contrast image calculation means;
The pixel value of each pixel constituting the contrast image is converted to a predetermined angle based on a correspondence relationship defined in advance to associate the pixel value range of the pixels constituting the contrast image with a predetermined angle range. An angle image calculation means for obtaining an angle image by
A line generating means for defining an angle distribution on a two-dimensional plane based on the angle image and generating a line having a direction corresponding to the angle defined at each position;
An embossed sheet creating means for creating an embossed sheet expressing the line as an uneven pattern;
An embossed sheet manufacturing apparatus expressing an anisotropic reflecting surface of wood, characterized by comprising: An apparatus for producing an embossed sheet expressing an anisotropic reflective surface of wood,
Photographing a cut surface of a natural wood sample as a first basic image obtained by photographing with illumination light from the first direction and illumination light from the second direction. An image input means for inputting a second basic image obtained by
For each pixel constituting the first basic image and each pixel constituting the second basic image, a difference image having a pixel value as a pixel value difference between a pair of pixels at corresponding positions is obtained. Difference image calculation means;
For each pixel constituting the difference image, a rank value indicating the magnitude order of the pixel value in the difference image is determined so as not to overlap, and the pixel value of each pixel constituting the difference image is determined as the rank. A ranking image calculation means for obtaining a ranking image by converting it into a value;
The pixel value of each pixel constituting the rank image is converted into a predetermined angle based on a correspondence relationship defined in advance to associate the pixel value range of the pixels constituting the rank image with a predetermined angle range. An angle image calculation means for obtaining an angle image by
A line generating means for defining an angle distribution on a two-dimensional plane based on the angle image and generating a line having a direction corresponding to the angle defined at each position;
An embossed sheet creating means for creating an embossed sheet expressing the line as an uneven pattern;
An embossed sheet manufacturing apparatus expressing an anisotropic reflecting surface of wood, characterized by comprising: An apparatus for producing an embossed sheet expressing an anisotropic reflective surface of wood,
Photographing a cut surface of a natural wood sample as a first basic image obtained by photographing with illumination light from the first direction and illumination light from the second direction. An image input means for inputting a second basic image obtained by
For each pixel constituting the first basic image and each pixel constituting the second basic image, a comparison image having a pixel value ratio of a pair of pixels at corresponding positions is obtained. Contrast image calculation means;
For each pixel constituting the contrast image, a rank value indicating the magnitude order of the pixel values in the contrast image is determined so as not to overlap, and the pixel value of each pixel constituting the contrast image is determined as the rank A ranking image calculation means for obtaining a ranking image by converting it into a value;
The pixel value of each pixel constituting the rank image is converted into a predetermined angle based on a correspondence relationship defined in advance to associate the pixel value range of the pixels constituting the rank image with a predetermined angle range. An angle image calculation means for obtaining an angle image by
A line generating means for defining an angle distribution on a two-dimensional plane based on the angle image and generating a line having a direction corresponding to the angle defined at each position;
An embossed sheet creating means for creating an embossed sheet expressing the line as an uneven pattern;
An embossed sheet manufacturing apparatus expressing an anisotropic reflecting surface of wood, characterized by comprising: