JP2004234524A - Gloss expression method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gloss expression method capable of making a glossiness closer to reality compared to a conventional technique and preparing the image of a three-dimensional structure expressing the glossiness without being accompanied by correction work based on the sensitivity of a user. <P>SOLUTION: A change normal vector calculation part 105 decides change normal vectors for which the normal vectors of respective parts of the surface of the three-dimensional structure virtually displayed at a display device are dispersed for a displacement amount based on a stipulated distribution for the respective parts. A rendering processing part 107 applies a color sample spectral reflectance calculation function to an incident angle, an observation angle and a shifting angle, calculates spectral reflectance for the respective parts of the surface of the three-dimensional structure and calculates the values of the colors of the respective parts of the surface of the three-dimensional structure from the calculated spectral reflectance. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for outputting colors to an image created using a computer system, and more particularly to a gloss expression method.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when an image of a three-dimensional structure is created using a computer and displayed on a screen, a method of displaying the image of the three-dimensional structure with a natural glossy approximation to the real thing is a method of reflecting light on the surface. (Refer to Patent Literature 1), a method of adjusting light intensity (internal reflected light intensity), the intensity of light that exits from the surface after entering the object from the surface (internal reflected light intensity), and the like. There is a method of pasting an image (information indicating black and white fabric) virtually pasted on an image of a three-dimensional structure to give a glossy feeling or a rough feeling (see Patent Document 2). Patent Document 1 describes a method for cutting a luminance value equal to or higher than the maximum luminance that can be displayed on a screen displaying an image of a three-dimensional structure. Patent Document 2 describes a texture expressing the same glossiness as a real object. Is attached to an image of a three-dimensional structure.
[0003]
[Patent Document 1]
JP-A-5-40833
[Patent Document 2]
Japanese Patent No. 3107452
[0004]
[Problems to be solved by the invention]
Here, FIG. 10 is a diagram showing a cross section of the intensity distribution in the space on the reflection surface of the luminance of the reflected light. In this figure, (a) is a diagram showing a cross section of the intensity distribution of the luminance of the reflected light when the glossiness of the reflection surface that reflects the incident light is large, and (b) is the glossiness of the reflection surface that reflects the incident light. FIG. 7 is a diagram showing a cross section of the intensity distribution of the luminance of the reflected light when is small. (A) and (b), when the glossiness of the reflection surface is high, the directivity of the intensity distribution of the luminance of the reflected light is strong, and when the glossiness of the reflection surface is low, the intensity distribution of the intensity distribution of the reflection light is low. Poor directivity. As a result, if cutting is performed at the maximum luminance value of the display device, the range d of the intensity distribution of luminance becomes wider in the case where the glossiness of the reflection surface is small (b). As a result, in Patent Literature 1, a three-dimensional structure with a low glossiness of the reflection surface may become an image with higher luminance than a three-dimensional structure with a high glossiness of the reflection surface. Therefore, in Patent Document 1, a phenomenon occurs in which actual gloss cannot be expressed. In Patent Document 2, since the texture itself is created based on the sensibility of the user who creates the texture, it takes a lot of time to correct the glossiness, and a three-dimensional structure having a different glossiness is created by different users. Will be done.
Therefore, according to the present invention, it is possible to create an image of a three-dimensional structure expressing the glossiness without involving a correction operation based on the user's sensitivity, and the glossiness can be more approximate to the actual feeling than the conventional technology. It is another object of the present invention to provide a gloss expression method in which users with different sensibilities can create images expressing the same glossiness.
[0005]
[Means for Solving the Problems]
The present invention has been made to solve the above-described problem, and has a three-dimensional structure information storage unit that stores a normal vector for each part of a surface of a three-dimensional structure that is virtually displayed on a display device. What is claimed is: 1. A gloss expressing method in a gloss expressing device, comprising: a modified normal vector obtained by dispersing a normal vector of each part of a surface of a three-dimensional structure stored in said three-dimensional structure information storage means by a displacement amount based on a prescribed distribution. A normal vector changing step of determining the light source direction of light incident on the surface of the three-dimensional structure, an incident angle formed by the changed normal vector, and reflection of the light on the surface of the three-dimensional structure. The observation point direction to observe, the observation angle formed by the modified normal vector, the light source direction, the tilt angle formed by the surface formed by the observation point direction, and the tilt angle formed by the modified normal vector, the color obtained by applying a color to the medium. Sample spectral reflection Applying a color sample spectral reflectance calculation function to calculate the spectral reflectance of each part of the surface of the three-dimensional structure, and calculating the spectral reflectance of each part of the surface of the three-dimensional structure, A gloss expression method comprising: a color value that can be calculated from the calculated spectral reflectance and a color value determining step of determining the value.
[0006]
According to the above configuration, in the present invention, in the process of changing the normal vector, the normal vector of each portion of the surface of the three-dimensional structure virtually displayed on the display device is dispersed by the displacement amount based on the prescribed distribution. A change normal vector is determined for each of the portions, and in the process of calculating the spectral reflectance, a color sample spectral reflectance calculation function is applied to the incident angle, the observation angle, and the tilt angle, and each portion of the surface of the three-dimensional structure is determined. Is calculated, and the color value of each portion of the surface of the three-dimensional structure is determined as a color value that can be calculated from the calculated spectral reflectance in the color value determination process. As a result, the changed normal vector of each part of the surface of the three-dimensional structure is in a state of variation, so that different spectral reflectances based on each changed normal vector having a different direction, the incident angle, the observation angle, and the tilt angle are different. It will be calculated. Therefore, different spectral reflectances have different color values that can be calculated from the spectral reflectances, so that when an image of a three-dimensional structure is output, a rough feeling is generated on the surface of the three-dimensional structure, and an image of the virtual three-dimensional structure is generated. It can be used as one expression method for expressing glossiness in generation.
[0007]
In the present invention, there are a plurality of the specified distributions in the normal vector changing process, and a changed normal vector is determined for each of the plurality of specified distributions. Thus, since the variation of the changed normal vector varies depending on the prescribed distribution, it is possible to generate images of different three-dimensional structures expressing different feelings of roughness.
[0008]
Further, the present invention stores a designated luminance value calculated based on a spectral reflectance when observing light perpendicularly applied to a color sample from a predetermined angle in an oblique direction and a maximum luminance value that can be displayed by the display device. A gloss expression method in a gloss expression device comprising: a brightness value information storage unit, wherein a light source direction of light incident on a surface of the three-dimensional structure virtually displayed on the display device and a surface of the three-dimensional structure are displayed. The incident angle formed by the normal vector, the observation point direction for observing the reflection of the light on the surface of the three-dimensional structure, the observation angle formed by the normal vector, the light source direction, the surface formed by the observation point direction, and the method Apply a color sample spectral reflectance calculation function for calculating the spectral reflectance of a color sample coated with a medium to the tilt angle formed by the line vector and the spectral reflectance of each part of the surface of the three-dimensional structure. Calculate the spectral reflectance Output step, reading the maximum luminance value and the designated luminance value from the luminance value information storage means, multiplying a value obtained by subtracting the designated luminance value from the maximum luminance value by a reduction ratio and the designated luminance value A modified luminance value calculating step of calculating a modified luminance value obtained by adding the calculated spectral reflectance, and calculating a luminance value in each of the portions from the calculated spectral reflectance. For the value, the luminance value of the color value that can be calculated from the calculated spectral reflectance is converted to the changed luminance value and determined as the value of the color, and the color values of other parts are calculated for the calculated spectral reflectance. A gloss expression method comprising a color value that can be calculated from reflectance and a color value determination step of determining the color value.
[0009]
According to the configuration described above, the present invention provides a display device that applies a color sample spectral reflectance calculation function for calculating a color sample spectral reflectance to an incident angle, an observation angle, and a tilt angle in a spectral reflectance calculation process. Calculate the spectral reflectance for each part of the surface of the three-dimensional structure that is virtually displayed, and in the process of calculating the changed brightness value, multiply the value obtained by subtracting the specified brightness value from the maximum brightness value by the reduction ratio. Calculate a changed luminance value by adding the specified luminance value. In addition, a luminance value in each part is calculated from the spectral reflectance calculated in the color value determination process, and a color value of each part in which the calculated luminance value is equal to or greater than the maximum luminance value can be calculated from the calculated spectral reflectance. The luminance value of the color value is converted into a changed luminance value and determined as the color value, and the color values of other parts are determined as color values that can be calculated from the calculated spectral reflectance. With this, when the luminance value calculated from the spectral reflectance of the three-dimensional structure is equal to or more than the maximum luminance value that can be output from the display device and the luminance value must be reduced, only the luminance value equal to or more than the designated luminance value is reduced. Since the reduction is performed using the reduction ratio, it is possible to avoid further lowering the luminance of the low-luminance portion. In addition, when the brightness value calculated from the spectral reflectance of the three-dimensional structure is equal to or more than the maximum brightness value that can be output from the display device, when the brightness value needs to be reduced, a method of displaying the maximum brightness value is used. Since this is not taken, it is possible to avoid a phenomenon in which the range of the intensity distribution of the luminance based on the directivity of light reflection is such that the spectral reflectance whose luminance intensity is small is larger than the spectral reflectance whose luminance intensity is large. Therefore, it is possible to avoid a phenomenon in which a spectral reflectance having a small luminance intensity is expressed brighter.
[0010]
Further, the present invention provides the gloss expression method, wherein a changed brightness value for each of a plurality of reduction ratios is calculated in the changed brightness value calculating step, and the three-dimensional structure corresponding to each changed brightness value is calculated in the color value determining step. The color value of each part of the surface is output for each of the three-dimensional structures. Thus, the value when reducing the brightness value equal to or greater than the maximum brightness value changes according to the different changed brightness value, so that it is possible to generate images of a plurality of three-dimensional structures expressing different glossiness.
[0011]
The present invention also provides the gloss expression method, wherein the color sample spectral reflectance calculation function is a least squares method based on a correspondence relationship between a combination of an incident angle, an observation angle, and a tilt angle, and the spectral reflectance of the color sample. Is the function obtained. By applying the color sample spectral reflectance calculation function to the incident angle, the observation angle, and the tilt angle, the spectral reflectance of the color sample can be calculated.
[0012]
The present invention also provides a light source direction of light incident on a surface of a three-dimensional structure virtually displayed on a display device, an incident angle formed by a normal vector in each part of the surface of the three-dimensional structure, and the three-dimensional structure. The observation point direction for observing the reflection of light in each part of the surface, the observation angle formed by the normal vector, the light source direction, the surface formed by the observation point direction, and the tilt angle formed by the normal vector. Applying a subtracted spectral reflectance calculation function to calculate a subtracted spectral reflectance by arithmetically subtracting the spectral reflectance of the medium from the spectral reflectance of a color sample in which a color is applied to a medium at a prescribed ratio, A subtracted spectral reflectance calculating step of calculating a subtracted spectral reflectance for each part of the surface of the object; and a medium spectral reflectance for calculating the spectral reflectance of the medium at the incident angle, the observation angle, and the tilt angle. Apply the calculation function A medium spectral reflectance calculating step of calculating the spectral reflectance of the medium for each part of the surface of the three-dimensional structure; and applying the subtracted spectral reflectance or the medium spectral reflectance for each part of the surface of the three-dimensional structure. A color value determining step of determining one of the applications of the reflectance based on a prescribed ratio and determining the color value of each portion as a color value that can be calculated from the determined subtracted spectral reflectance or the medium spectral reflectance. And a gloss expression method.
[0013]
According to the above configuration, the present invention provides a subtraction method for each part of the surface of the three-dimensional structure virtually displayed on the display device by applying the subtraction spectral reflectance calculation function to the incident angle, the observation angle, and the tilt angle. The spectral reflectance is calculated, and the spectral reflectance of the medium is calculated for each part of the surface of the three-dimensional structure by applying the medium spectral reflectance calculation function to the incident angle, the observation angle, and the tilt angle. Then, for each part of the surface of the three-dimensional structure, either the application of the subtractive spectral reflectance or the application of the medium spectral reflectance is determined based on a specified ratio, and the color value of each part is determined by the determined subtractive spectral reflectance. It is determined as a color value that can be calculated from the reflectance or the medium spectral reflectance. Thus, the spectral reflectance of each portion of the surface of the three-dimensional structure is determined by subtracting the spectral reflectance of the medium from the spectral reflectance of the color sample by a specified ratio, and further, the spectral reflectance of the medium itself. Is reflected in each part of the surface of the three-dimensional structure, so that it is possible to generate an image of a virtual three-dimensional structure in which colors reflecting the influence of the medium itself are expressed.
[0014]
In addition, the present invention provides the gloss expression method described above, wherein the subtracted spectral reflectance calculation function is based on a combination of an incident angle, an observation angle, and a tilt angle, and the spectral reflectance of a color sample in which a color is applied to the medium. A function obtained by performing a least squares method based on a correspondence relationship with a subtracted spectral reflectance obtained by arithmetically subtracting a spectral reflectance at a specified ratio, and the medium spectral reflectance calculating function is based on an incident angle and an observation angle. This is a function obtained by performing the least squares method based on the correspondence between the combination of the angle and the tilt angle and the spectral reflectance of the medium. By applying this subtracted spectral reflectance calculation function to the incident angle, the observation angle, and the tilt angle, the subtracted spectral reflectance can be calculated, and the medium spectral reflectance calculation function can be calculated for the incident angle, the observation angle, and the tilt angle. If applied, the spectral reflectance of the medium can be calculated.
[0015]
Also, the present invention provides a three-dimensional structure information storage means for storing a normal vector for each part of the surface of the three-dimensional structure virtually displayed on the display device, Brightness information storage means for storing a designated brightness value calculated based on the spectral reflectance when observed from a predetermined angle and a maximum brightness value that can be displayed by a display device that displays an image of the three-dimensional structure. A glossy expression method in a glossy expression device, wherein a normal vector of each part of the surface of the three-dimensional structure stored in the three-dimensional structure information storage means is varied by a displacement amount based on a prescribed distribution. A normal vector changing process of determining a vector for each of the portions, a light source direction of light incident on the surface of the three-dimensional structure, an incident angle formed by the changed normal vector, and the light of the light on the surface of the three-dimensional structure. Observation to observe reflection Direction, the observation angle formed by the modified normal vector, the light source direction, the surface formed by the observation point direction, and the tilt angle formed by the modified normal vector, and the spectral reflectance of a color sample in which a color is applied to a medium. Applying a color sample spectral reflectance calculation function to calculate the spectral reflectance for each part of the surface of the three-dimensional structure, a spectral reflectance calculation step, and the maximum brightness value from the brightness value information storage means Reading the designated luminance value, a modified luminance value calculating step of calculating a modified luminance value by adding a value obtained by subtracting the designated luminance value from the maximum luminance value and a reduction ratio and the designated luminance value, A luminance value in each of the portions is calculated from the calculated spectral reflectance, and a color value of each portion in which the calculated luminance value is equal to or greater than the maximum luminance value is a color value that can be calculated from the calculated spectral reflectance. Before luminance value A color value determining step of converting the converted luminance value to a value of the color and determining the color value of each of the other portions as a color value that can be calculated from the calculated spectral reflectance; and a color value determining step of determining the color value. And a three-dimensional structure image outputting step of outputting a gloss.
[0016]
According to the above configuration, the present invention provides a method of dispersing a normal vector of each portion of a surface of a three-dimensional structure virtually displayed on a display device by a displacement amount based on a prescribed distribution in a normal vector changing process. The changed normal vector is determined for each part of the surface, and in the spectral reflectance calculation process, a color sample spectral reflectance calculation function is applied to the incident angle, the observation angle, and the tilt angle, and the surface of the three-dimensional structure is determined. Calculate the spectral reflectance for each part. Also, in the change luminance value calculation step, a change luminance value is calculated by adding a value obtained by multiplying a value obtained by subtracting the specified luminance value from the maximum luminance value by the reduction ratio and the specified luminance value, and in the color value determination step, the calculated spectral value is calculated. Calculate the luminance value of each part from the reflectance, and for the color value of each part where the calculated luminance value is greater than or equal to the maximum luminance value, change the luminance value of the color value that can be calculated from the calculated spectral reflectance. And the color value is determined, and the color values of the other parts are determined as color values that can be calculated from the calculated spectral reflectance. Then, a value for each portion of the three-dimensional structure image output process color is output.
As a result, a new method of expressing roughness by calculating the spectral reflectance using the modified normal vector and reducing the luminance value equal to or greater than the maximum luminance value that can be output by the display device is used. Can output an image of a three-dimensional structure that is more similar to the actual one. In addition, since it is not necessary to create a texture, it is possible to create an image of a three-dimensional structure expressing glossiness without performing a modification operation based on the user's sensitivity, and furthermore, a rule for determining a changed normal vector is provided. Since the image of the three-dimensional structure can be generated simply by specifying the reduction ratio for calculating the distribution and the changed luminance value, a user with different sensibility can generate an image expressing the same glossiness by using a glossy expression device. Can be created using
[0017]
Also, the present invention provides a three-dimensional structure information storage unit that stores a normal vector for each part of a surface of a three-dimensional structure virtually displayed on a display device, and a color sample in which a color is applied to a medium. A luminance value that stores a specified luminance value calculated based on the spectral reflectance when the applied light is observed from a predetermined angle in an oblique direction and a maximum luminance value that can be displayed by a display device that displays an image of the three-dimensional structure. A gloss expression method in a gloss expression device having information storage means, wherein a normal vector of each part of a surface of the three-dimensional structure stored in the three-dimensional structure information storage means is separated by a displacement amount based on a prescribed distribution. A normal vector changing process of determining a changed normal vector for each part, a light source direction of light incident on a surface of the three-dimensional structure, an incident angle formed by the changed normal vector, and the three-dimensional structure In each part of the surface of The observation point direction for observing the reflection of light recording, the observation angle formed by the modified normal vector, the light source direction and the tilt angle formed by the plane formed by the observation point direction and the modified normal vector, and the color sample Applying a subtracted spectral reflectance calculation function for calculating a subtracted spectral reflectance by arithmetically subtracting the spectral reflectance of the medium at a specified ratio from the spectral reflectance of the three-dimensional structure, Applying a medium spectral reflectance calculation function for calculating the spectral reflectance of the medium to the subtracted spectral reflectance calculating step of calculating the spectral reflectance, and applying the medium spectral reflectance calculating function to the incident angle, the observation angle, and the tilt angle; A medium spectral reflectance calculating step of calculating the spectral reflectance of the medium for each part of the surface of the object, and reading the maximum luminance value and the designated luminance value from the luminance value information storage means, From A modified luminance value calculating step of calculating a modified luminance value by adding a value obtained by multiplying a value obtained by subtracting the designated luminance value to a reduction ratio and the designated luminance value, and performing the subtraction spectrum for each part of the surface of the three-dimensional structure. The application of the reflectance or the application of the medium spectral reflectance is determined based on a specified ratio, and the luminance value in each of the portions is calculated based on either the calculated subtracted spectral reflectance or the medium spectral reflectance. Then, for the color value of each part whose calculated luminance value is equal to or greater than the maximum luminance value, the luminance value of the color value that can be calculated from either the calculated subtracted spectral reflectance or the medium spectral reflectance is changed. The color is converted into a luminance value and determined as the color value, and the color values of the other parts are determined as the color values that can be calculated from either the calculated subtracted spectral reflectance or the medium spectral reflectance. Value determination process and And a three-dimensional structure image outputting step of outputting the color value.
[0018]
According to the above configuration, in the present invention, in the process of changing the normal vector, the normal vector of each portion of the surface of the three-dimensional structure virtually displayed on the display device is dispersed by the displacement amount based on the prescribed distribution. A change normal vector is determined for each part, and a subtracted spectral reflectance calculation function is applied to an incident angle, an observation angle, and a tilt angle in a subtracted spectral reflectance calculation process to calculate a subtracted spectral reflectance for each of the parts. Then, in the medium spectral reflectance calculation process, a subtractive spectral reflectance calculation function is applied to the incident angle, the observation angle, and the tilt angle to calculate the medium spectral reflectance for each of the portions. Further, in the process of calculating the changed luminance value, a changed luminance value is calculated by adding a value obtained by multiplying a value obtained by subtracting the specified luminance value from the maximum luminance value by the reduction ratio and the specified luminance value. In the color value determination process, for each part of the surface of the three-dimensional structure, either the application of the subtracted spectral reflectance or the application of the medium spectral reflectance is determined based on a specified ratio, and the calculated subtracted spectral reflectance is calculated. Alternatively, the luminance value of each part is calculated based on one of the medium spectral reflectances, and the calculated subtracted spectral reflectance or medium spectral reflectance is calculated for the color value of each part where the calculated luminance value is equal to or greater than the maximum luminance value. The luminance value of the color value that can be calculated from any of the above is converted into a changed luminance value and determined as the color value of each portion, and the subtracted spectral reflectance or medium spectral value calculated for the color values of the other portions is calculated. A color value that can be calculated from any of the reflectances is determined. Further, a color value is output in a three-dimensional structure image output process.
Thus, the spectral reflectance of each part of the surface of the three-dimensional structure is determined by subtracting the spectral reflectance of the medium from the spectral reflectance of the color sample, and the spectral reflectance of the medium itself is further determined by the three-dimensional structure. Since it is applied to each part of the surface, it is possible to express the color by the spectral reflectance reflecting the influence of the medium, and furthermore, the image of the three-dimensional structure whose glossiness is more approximate to the actual one compared to the conventional technology Can be output.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a gloss expression device according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic block diagram showing a configuration of a gloss expression device according to an embodiment of the present invention. In this figure, reference numeral 1 denotes a gloss expressing device. In the present embodiment, the gloss expression device 1 monitors an image of the three-dimensional structure approximated to the glossiness of the three-dimensional structure created by actually using a color sample (a color medium is applied to a paper or the like) on a monitor or the like. For display on the display device. Note that the gloss expressing device 1 displays a plurality of images of the same three-dimensional structure in which the glossiness of the three-dimensional structure is changed on a display device, and from among the images, the glossiness is closest to the actual three-dimensional structure. The selection of the image of the three-dimensional structure is accepted.
[0020]
In FIG. 1, reference numeral 101 denotes an input unit which receives input of information such as the position of a light source of light and the observation direction of a three-dimensional structure. Reference numeral 102 denotes a three-dimensional structure data creating unit that performs a process of creating shape information of the three-dimensional structure representing the three-dimensional structure to be displayed on the display device. Reference numeral 103 denotes a reflection model parameter calculation unit that calculates a coefficient of a spectral reflectance calculation function for obtaining a spectral reflectance of a combination of an arbitrary incident angle, an observation angle, and a tilt angle.
[0021]
Reference numeral 104 denotes a paper influence subtraction calculation unit, which determines the medium of the color sample (in the present embodiment, the medium is paper and uses ink for paper) based on the spectral reflectance of the color sample for creating a three-dimensional structure. A process is performed to calculate a value obtained by subtracting the spectral reflectance of the printed sample is a color sample at a specified ratio. Reference numeral 105 denotes a modified normal vector calculation unit that performs processing for varying the normal vector of each part on the surface of the three-dimensional structure based on a prescribed distribution. In this way, a process for giving a rough feeling of paper to the surface of the three-dimensional structure is performed. Note that the changed normal vector calculation unit 105 varies the normal vectors based on different prescribed distributions. Thereby, the gloss expressing device 1 displays on the display device a plurality of images of the same three-dimensional structure expressing the glossiness for each degree of variation of the normal vector based on the specified distribution. Reference numeral 106 denotes a changed luminance value calculation unit, and a luminance value (also referred to as surface reflection intensity) that can be calculated from the spectral reflectance at which light is reflected at the same angle and in the opposite direction with respect to the normal vector is the maximum value that can be output from the display device If the luminance value is equal to or more than the luminance value, a process of reducing the luminance value to the maximum luminance value or less is performed using a predetermined calculation method. Note that this luminance value is referred to as a changed luminance value.
[0022]
Reference numeral 107 denotes a rendering processing unit, which is formed by the normal vector of the surface of the three-dimensional structure and the incident angle formed by the light source direction, the observation point for observing the three-dimensional structure, and the normal vector of the three-dimensional structure surface. Standard for determining the observation angle, the specified inclination in the spatial coordinates of each part of the surface of the three-dimensional structure, the information on the color sample indicated by the surface of the three-dimensional structure, and the degree of dispersion of the normal vector of the surface of the three-dimensional structure Based on the deviation information and the changed luminance value, the rendering reprocessing is performed by a predetermined method described later. Reference numeral 108 denotes a display processing unit which performs a process of displaying an image of the three-dimensional structure rendered by the rendering processing unit 107 on a display device. An angle storage unit 109 stores information such as a position of a light source of light incident on the three-dimensional structure received by the input unit 101 and a direction in which the three-dimensional structure is observed. Reference numeral 110 denotes a three-dimensional structure data storage unit (three-dimensional structure information storage unit) which stores the three-dimensional structure shape information created by the three-dimensional structure data creation unit 102. In addition, the shape information of the three-dimensional structure is, for example, a three-dimensional graphic modeling technique, which is a wire frame model (a technique of representing the shape by a data structure in which coordinates in space are connected by straight lines). Information on the shape. The three-dimensional structure data storage unit 110 also stores a normal vector for each part of the surface representing the three-dimensional structure. Reference numeral 111 denotes a brightness value information storage unit (brightness value information storage means), which applies light, which has been vertically applied to a color sample of a real object in which a three-dimensional structure is previously created, at an angle of 45 degrees (a predetermined angle in an oblique direction) ) Stores the designated luminance value calculated based on the spectral reflectance when observed from the above and the maximum luminance value that can be displayed by the display device.
[0023]
Reference numeral 112 denotes a spectral reflectance database in which spectral reflectances measured by actually irradiating a user with light on a color sample serving as a surface of a real three-dimensional structure are stored in advance. The spectral reflectance is recorded in association with the angle of incidence on the color sample, the observation angle of the color sample, and the tilt angle. The details of the incident angle, the observation angle, and the tilt angle will be described later. Reference numeral 113 denotes a reflection model parameter database, which stores information on coefficients of the spectral reflectance calculation function calculated by the reflection model parameter calculation unit 103. Reference numeral 114 denotes an optimal parameter database, which is a three-dimensional structure having the closest gloss to the actual three-dimensional structure received from the images of the three-dimensional structure displayed by the gloss expression device 1 on the display device. The coefficients of various parameters to be described later for rendering the image are stored.
[0024]
Then, the gloss expressing device 1 expresses the roughness of the surface of the three-dimensional structure by dispersing uniform normal vectors in each portion of the surface using a method described later, and furthermore, a medium of the color sample (this embodiment). The roughness of the color sample is expressed by reflecting the color of the paper itself in the form on the color sample using a method described later. When the luminance value of the rendered image of the three-dimensional structure is equal to or greater than the maximum luminance value that can be output from the display device that displays the three-dimensional structure, the gloss expressing device 1 performs a process of reducing the luminance value to the maximum luminance value or less. In this way, a new method is used to express the glossiness. Then, the gloss expressing device 1 displays images of the same three-dimensional structure having different glossiness according to the combination of the degree of variation of the normal vector and the degree of reduction of the luminance value. Then, the gloss expression device 1 receives a designation of a three-dimensional structure closest to the real glossiness from among a plurality of the same three-dimensional structures having different glossiness, and renders an image of the three-dimensional structure. Are stored. Then, when rendering a three-dimensional structure again using the same color sample and rendering the stored three-dimensional structure, the three-dimensional structure closest to the real one is rendered without any manual adjustment by the user by performing rendering using the stored parameters. To display. Note that the color samples for creating the real three-dimensional structure in the present embodiment are color samples printed on high-quality paper, matte paper, and art paper using the same color ink, and are actually created with each color sample. The specification of the image of the three-dimensional structure that expresses the glossiness that is most similar to the three-dimensional structure that has been obtained is accepted. Further, the above-mentioned portion on the surface of the three-dimensional structure is a small surface when the surface of the three-dimensional structure is finely divided. For example, even if this small surface corresponds to one pixel on the screen of the display device, Alternatively, this small surface may correspond to a plurality of pixels on the screen of the display device. Here, FIG. 2 is a diagram showing a small surface and a normal vector of the surface of the cylinder when the three-dimensional structure is a cylinder.
[0025]
Next, the incident angle, the observation angle, and the tilt angle will be described.
FIG. 3 is a diagram for explaining the incident angle, the observation angle, and the tilt angle. As shown in FIG. 3, the angle formed by the normal vector of the color sample and the light source direction of light incident on the color sample is the incident angle. The angle formed by the direction of the observation point for observing the color sample and the normal vector of the color sample is the observation angle. In FIG. 3, when both the direction of incidence on the color sample and the direction of the observation point from the color sample are projected onto the color sample, the angle formed by the two lines is 180 degrees (that is, a straight line). The angle when the color sample is turned on the basis of the line is the tilt angle. When the tilt angle is considered in space, the angle formed by the surface formed by the line indicating the light source direction and the line indicating the observation point direction at one point on the color sample and the normal vector of the color sample is the tilt angle.
[0026]
Then, the user previously measures the spectral reflectance of the surface of the color sample using a colorimeter for each combination of the incident angle, the observation angle, and the tilt angle. The information on the spectral reflectance of the color sample is stored in the spectral reflectance database 112. The user also measures the spectral reflectance of the paper before coloring the color sample in the same manner as the spectral reflectance of the color sample, and stores the measured spectral reflectance in the spectral reflectance database 112. The incident angle is θ, the observation angle is α, and the tilt angle is Φ.
[0027]
Next, a method for dispersing the normal vector in each part of the surface of the three-dimensional structure will be described. FIG. 4 is an enlarged view of a cross section of the surface of the three-dimensional structure when the normal vectors are virtually varied. As shown in FIG. 4, the changed normal vector calculation unit 105 of the gloss expressing device 1 generates a changed normal vector that virtually varies based on the normal vector of each part of the surface of the three-dimensional structure. . Thereby, the observation angle formed by the direction of the observation point (same as the direction from the three-dimensional structure to the viewpoint of the user who views the display device when the image of the three-dimensional structure is displayed on the display device) and the changed normal vector And the angle of incidence formed by the modified normal vector and the light source direction of the light, and the plane formed by the line indicating the light source direction and the line indicating the observation point direction at one point on the color sample and the normal vector of the color sample Based on the angle, a difference in spectral reflectance observed at the observation point occurs in each part of the surface. Thus, the color in each part of the surface of the three-dimensional structure can be changed based on the difference in spectral reflectance of each part in the surface of the three-dimensional structure, so that the gloss expression device 1 can express the difference in color as a rough feeling. .
[0028]
If the variation of the modified normal vector based on the original normal vector is increased, the spectral structure in the direction of the observation point is further reduced on the surface of the three-dimensional structure having a low spectral reflectance in the direction of the observation point. In this embodiment, the standard deviation (σ: displacement amount based on a specified distribution) of the variation of the slope of the modified normal vector is set to 3 Within degrees. Then, the changed normal vector calculation unit 105 of the gloss expressing device 1 sets the Gaussian distribution with the standard deviation = 3 degrees as a limit based on 0 degree of the changed normal vector (the same slope as the normal vector before the change). A process for determining a changed normal vector is performed based on this. Then, the modified normal vector calculation unit 105 of the gloss expressing device 1 uses the values of the standard deviation σ = 0 ° to 3 ° in increments of 0.5 ° so that the rendering processing unit 107 can determine the different inclinations of the modified normal vector. An image of the same three-dimensional structure is generated based on the criterion of variation, and the display processing unit 108 outputs the generated image of the three-dimensional structure to a display device.
FIG. 5 is a diagram showing a Gaussian distribution when the standard deviation is set to 2 degrees. In this figure, the hatched portions indicate the number of each portion on a plane where the difference between the inclination of the normal vector before change and the changed normal vector is within 2 degrees. When the Gaussian distribution is used, when the standard deviation of the Gaussian distribution is 2 degrees, the part where the difference in inclination between the normal vector before change and the changed normal vector is within 2 degrees is the entire surface. 68% of the portion.
[0029]
Next, when the spectral reflectance in the direction of the observation point of the surface of the three-dimensional structure calculated from the spectral reflectance of the color sample (the direction in which the three-dimensional structure is displayed on the display device) exceeds the luminance value of the display device. Will be described. FIG. 6 shows the incident angle θ of light. ₁ , Maximum reflection angle θ of light ₂ FIG. 7 is a diagram illustrating an intensity distribution of light luminance and a maximum luminance value that can be output by the display device when the light intensity is. Normally, incident angle θ ₁ When light is incident on the surface of the color sample, the light is reflected in all directions of the space on the surface. This figure shows the intensity distribution of the luminance that can be calculated from the spectral reflectance of the reflected light. ₁ = Θ ₂ Maximum reflection angle θ ₂ At which the intensity of the luminance is the highest (however, the angle formed by the direction in which the light incident direction is projected on the color sample and the direction in which the light is reflected is projected on the color sample is 180 degrees). In FIG. 6, Lmax represents the maximum luminance value that can be output by the display device.
[0030]
Here, it is assumed that the surface of the color sample shown in FIG. 6 is a surface of the three-dimensional structure displayed on the display device by the gloss expression device 1, and the maximum reflection angle θ ₂ It is assumed that the direction in which the light is reflected most is the direction in which the three-dimensional structure is displayed. At this time, if the luminance value that can be calculated from the spectral reflectance of the surface of the three-dimensional structure in the display direction exceeds the maximum luminance value Lmax, the luminance value cannot be expressed by the display device, and the excessive luminance value is reduced. There is a need. Therefore, the following method is performed in the present embodiment as a method of reducing the luminance value.
First, the color sample is measured using a colorimeter from an angle of 45 degrees when light is incident on the color sample vertically. Then, the user inputs the measured spectral reflectance to the gloss expressing device 1 via the input unit 101. Further, the user causes a process of calculating a luminance value from a spectral reflectance when a color sample is measured from an angle of 45 degrees input to the gloss expression device 1. The calculation of the brightness value is performed by a designated brightness value calculation unit (not shown). The luminance value calculated by the specified luminance value calculation unit is called a specified luminance value (Ld). Then, the designated luminance value Ld is recorded in the luminance value information storage unit 111.
[0031]
The algorithm for calculating the luminance value from the spectral reflectance is a well-known technique. For example, "Handbook of Color Science, edited by The Japan Society of Color Science, The University of Tokyo Press, July 25, 1981, 3rd printing, p98, p139 to p141 ”may be used. The technique of calculating a luminance value from a spectral reflectance described in this conventional technique is a technique of calculating a CIE (Commission Internationale de l'Eclairage) XYZ value from the spectral reflectance. And Y of this calculated CIEXYZ is the luminance value.
Then, the gloss expressing device 1 calculates the changed luminance value Ls by reducing the luminance value exceeding the maximum luminance value Lmax by using the following colors. The change luminance value Ls is calculated by the change luminance value calculation unit 106.
[0032]
Ls = Ld + (Lmax−Ld) × k / n
(However, n = 6, k = 1, 2, 3, 4, 5, 6)
Then, the changed luminance value calculation unit 106 calculates a changed luminance value Ls corresponding to each value of k = 1 to 6, generates images of the same three-dimensional structure having different degrees of the changed luminance value, and outputs the images to the display device. I do. Note that k / n is the reduction ratio.
[0033]
Next, a method of expressing the roughness of the color sample by reflecting the color of the color sample medium (paper in the present embodiment) itself creating the three-dimensional structure in the color sample will be described.
FIG. 7 is an enlarged view of a cross section of the color sample when the color sample ink pigment is applied to the color sample medium. The medium of the color sample is paper. As shown in the figure, when the medium of the color sample is paper such as high-quality paper, the ink pigment is extremely small, so that it protrudes more than the ink pigment to which the fiber of the high-quality paper is applied. Here, in order to reflect this situation on the rendered image of the three-dimensional structure, the gloss expression device 1 uses the spectral reflectance of color samples (spectral reflectance of color samples) and the spectral reflectance of paper (spectral reflectance of medium). Is recorded in the spectral reflectance database 112, and the paper effect subtraction calculating unit 104 calculates the subtracted spectral reflectance by subtracting the medium spectral reflectance from the color sample spectral reflectance. And stored in the spectral reflectance database 112. Here, an equation for calculating the subtracted spectral reflectance is shown below. The color sample spectral reflectance is Ms, the medium spectral reflectance is Mp, and the subtracted spectral reflectance is Mc.
[0034]
Mc = (100 × Ms−a × Mp) / (100−a)
However, a indicates the probability that the fiber of the paper jumps out of the color sample, and in the present embodiment, when the medium of the color sample is high-quality paper, a = 5 (probability of jumping 5%) is defined. In the present embodiment, when the color sample medium is mat paper or art paper, a = 0.
[0035]
Next, data of the color sample spectral reflectance Ms, the medium spectral reflectance Mp, and the subtracted spectral reflectance Mc will be described. FIG. 8 is a diagram illustrating data stored in the spectral reflectance database 112. As shown in FIG. 8, in the spectral reflectance database 112, for each color sample, the spectral value of the color sample Ms, the spectral reflectance of the medium Mp, and the spectral reflectance of the subtracted Mc for each of the tilt angle Φ, the incident angle θ, and the observation angle α. The reflectance (reflectance of light every 10 nm from 400 nm to 700 nm) is stored.
[0036]
Next, a function that allows the gloss expression device 1 to calculate the spectral reflectance based on the incident angle θ, the observation angle α, and the tilt angle Φ will be described.
First, the spectral reflectance database 112 of the gloss expression device 1 stores data of spectral reflectances of a color sample spectral reflectance Ms, a medium spectral reflectance Mp, and a subtracted spectral reflectance Mc. Therefore, the gloss expressing device 1 performs a least square method on each piece of information of the spectral reflectance, thereby obtaining a color sample spectral reflectance based on the incident angle θ, the observation angle α, and the tilt angle Φ. A reflectance calculation function, a medium spectral reflectance calculation function capable of deriving a medium spectral reflectance based on the incident angle θ, the observation angle α, and the tilt angle Φ, the incident angle θ, the observation angle α, the tilt angle Φ, A subtracted spectral reflectance calculation function that can derive a subtracted spectral reflectance by subtracting the medium spectral reflectance from the color sample spectral reflectance at a specified ratio based on the calculated spectral reflectance is calculated. The calculation of each spectral reflectance calculation function is performed by the reflection model parameter calculation unit 103 of the gloss expression device 1. That is, the reflection model parameter calculation unit 103 derives a coefficient value in each spectral reflectance calculation function. Then, the reflection model parameter calculation unit 103 records the derived coefficient values in the reflection model parameter database 113.
[0037]
The technique of calculating each spectral reflectance calculation function by performing the least square method on the information of each spectral reflectance of the color sample spectral reflectance Ms, the medium spectral reflectance Mp, and the subtracted spectral reflectance Mc described above is as follows. As well known, for example, "" Generalization of the Lambertian Model and Implications for Machine Vision, "S.K. , "K. Torrance and E. Sparrow, 1967. Theory for Off-Specular Reflection from Roughened. urfaces. Journal of the Optical Society ofAmerica, volume 57, number 9, pp 1105-1114. "techniques may be used, which is described, for example.
[0038]
When rendering an image of a three-dimensional structure created by a color sample reflecting the influence of paper, the gloss expression device 1 firstly sets the subtracted spectral reflectance Mc, the incident angle θ, and the observation angle α. Using the angle Φ, the changed luminance value Ls, the standard deviation σ for determining the changed normal vector, and the information of the color sample forming the three-dimensional structure, the spectral reflectance at each part of the surface of the three-dimensional structure And derive the luminance value. Further, the gloss expressing device 1 uses the medium spectral reflectance Mp, the incident angle θ, the observation angle α, the tilt angle Φ, the changed luminance value Ls, and the standard deviation σ for determining the changed normal vector to obtain the surface of the three-dimensional structure. Derive the spectral reflectance and luminance value in each part of. When rendering the image of the three-dimensional structure, the gloss expressing device 1 renders 95% of each part on the surface of the three-dimensional structure as a color based on the spectral reflectance calculated by the subtracted spectral reflectance Mc and the luminance value, The remaining 5% of each part on the surface of the three-dimensional structure (the same as the probability that the fiber of the high-quality paper is protruding) is a color based on the spectral reflectance calculated by the medium spectral reflectance Mc and the luminance value. Process so that
[0039]
In the present embodiment, when rendering an image of a three-dimensional structure created with art paper and matte paper, the gloss expression device 1 uses the color of the color sample medium for creating the three-dimensional structure as a color sample. No reflection processing is performed. This is because art paper or matte paper is coated on the surface of the paper, so that the paper fibers do not usually fly out of the ink pigment applied to the paper.
[0040]
Next, processing performed when the gloss expressing device 1 renders an image of a three-dimensional structure created using color samples of art paper and matte paper will be described with reference to FIG. FIG. 9 is a diagram showing a flow of processing in the gloss expression device 1.
Art paper and matte paper are used for magazines and the like, for example, and art paper and matte paper have a coating on the surface of the paper. It is paper in which the fiber of paper does not pop out.
First, the user creates a three-dimensional structure (in the present embodiment, a cylinder) having the same structure using real art paper or matte paper. Then, the user creates an image of the shape of the three-dimensional structure in the gloss expression device 1 while viewing the three-dimensional structure. The creation of the image of the shape of the three-dimensional structure is the same as the creation of an image of the shape of the three-dimensional structure processed by conventional CAD (computer-aided design) software, three-dimensional diagram creation software, or the like. Then, the user records information on the shape of the created three-dimensional structure in the three-dimensional structure data storage unit 110.
[0041]
Next, the user determines the position of the light source of light incident on the three-dimensional structure, the observation direction of the three-dimensional structure, and information (color paper or matte paper) of a color sample for creating the three-dimensional structure, and inputs the information to the input unit. Input to the gloss expression device 1 via 101. Then, the user instructs the gloss expression device 1 to render the three-dimensional structure. Then, the input unit 101 receives the rendering instruction (step S1a). Then, the modified normal vector calculation unit 105 reads the normal vector of each part on the surface of the three-dimensional structure from the three-dimensional structure data storage unit 110, and calculates the normal vector in 0.5 degree steps from σ = 0.0 to 3.0. Based on the Gaussian distribution of each standard deviation, information on a changed normal vector in which the normal vector of each part is varied is calculated (step S2a).
Next, the specified luminance value Ld recorded corresponding to the color sample information received from the user by the changed luminance value calculation unit 106 and the maximum luminance value Lmax that can be output by the display device are stored in the luminance value information storage unit 111. Read from. Then, using the read designated luminance value Ld, the maximum luminance value Lmax, and the above-described calculation formula for obtaining the changed brightness value Ls, each of the changed brightness values when k = 1 to 6 are substituted into the calculation formula. The value Ls is calculated (Step S3a).
[0042]
Next, the rendering processing unit 107 calculates the value of the coefficient of the color sample spectral reflectance calculation function for calculating the color sample spectral reflectance Ms corresponding to the color sample information received from the user from the reflection model parameter database 113. read. Then, the rendering processing unit 107 calculates the incident angle θ of the angle formed by the changed normal vector in each part of the surface of the three-dimensional structure calculated in step S2a and the direction of the light source received from the user, The observation angle α of the angle formed by the observation direction received from the user, the tilt angle Φ determined by the observation direction and the modified normal vector, the modified luminance value Ls calculated in step S3a, and the read color sample spectral reflection The rendering process is performed based on the coefficient of the rate calculation function (step S4a).
At this time, the rendering processing unit 107 first calculates the spectral reflectance of each part of the surface of the three-dimensional structure based on the incident angle θ, the observation angle α, and the tilt angle Φ, and calculates the XYZ values (color values) from the spectral reflectance. Value). When the Y value (luminance value) of the XYZ value is equal to or greater than the maximum luminance value Lmax, the Y value of the XYZ value is replaced with the changed luminance value. Thereby, the XYZ values in each part of the surface of the three-dimensional structure are determined.
[0043]
Next, based on the XYZ values of each part of the surface of the three-dimensional structure determined by the rendering processing unit 107, the display processing unit 108 assigns colors to pixels of the screen of the display device corresponding to each part of the three-dimensional structure surface. Output. Thereby, the image of the three-dimensional structure is displayed on the display device (step S5a).
Then, the rendering processing unit 107 repeats rendering of the three-dimensional structure for each combination of the standard deviation σ and the changed luminance value Ls, and the display processing unit 108 displays an image of each three-dimensional structure rendered by the rendering processing unit 107 on a display device. Output at the same time. As a result, the gloss expressing apparatus 1 has seven standard deviations σ and six changed luminance values Ls. Therefore, for the image of the three-dimensional structure created with one color sample, a total of 42 identical solids having different gloss feelings are obtained. An image of the structure is output to a display device. Note that the rendering processing unit 107 assigns a number to each of the three-dimensional structures rendered for each combination of the standard deviation σ and the changed luminance value Ls, and renders the standard deviation σ and the changed luminance value Ls when the three-dimensional structure of each number is rendered. Is temporarily stored with the coefficient k used for the calculation. Then, the display processing unit 108 attaches numbers to the images of the three-dimensional structures and displays them.
[0044]
Next, the input unit 101 of the gloss expression device 1 receives an input of the number of the image of the three-dimensional structure having a different glossiness displayed by the display processing unit 108 from the user. At this time, for example, the user irradiates the actually created three-dimensional structure with light, visually observes the real three-dimensional structure from the same direction as the observation direction of the three-dimensional structure input to the gloss expression device 1, and displays the three-dimensional structure on the display device. The number of the closest three-dimensional structure having a different glossiness is input to the gloss expression device 1. Then, from the rendering processing unit 107, the standard deviation σ when the three-dimensional structure corresponding to the received image number is rendered by the processing unit (not shown) of the gloss expression device 1 and the coefficient k used for calculating the changed luminance value Ls are output from the rendering processing unit 107. It is read and recorded in the optimal parameter database 114 in association with the information of the color sample.
[0045]
Next, a description will be given of processing when the gloss expressing device 1 renders an image of a three-dimensional structure created with a color sample of high-quality paper. Note that high quality paper is paper used as, for example, copy paper, and is not coated so that the fibers of the paper pop out when an ink pigment is applied to the high quality paper.
From FIG. 9, first, the user determines the position of the light source of the light incident on the three-dimensional structure, the observation direction of the three-dimensional structure, and information (color paper) of a color sample for creating the three-dimensional structure, and inputs the information to the input unit. Input to the gloss expression device 1 via 101. Then, the user instructs the gloss expression device 1 to render the three-dimensional structure. Then, the gloss expressing device 1 performs the processing from step S1a to step S3a described above.
[0046]
Next, since the color sample received from the user is high quality paper, the rendering processing unit 107 calculates the subtracted spectral reflectance Mc obtained by subtracting the spectral reflectance of the high quality paper (medium spectral reflectance) from the spectral reflectance of the color sample. The value of the coefficient of the subtracted spectral reflectance calculation function for calculation is read from the reflection model parameter database 113. Then, the rendering processing unit 107 calculates the incident angle θ of the angle formed by the changed normal vector in each part of the surface of the three-dimensional structure calculated in step S2a and the direction of the light source received from the user, The observation angle α of the angle formed by the observation direction received from the user, the tilt angle Φ determined by the observation direction and the changed normal vector, the changed luminance value Ls calculated in step S3a, and the read subtracted spectral reflectance A rendering process is performed based on the coefficients of the calculation function (step S4b).
[0047]
Next, since the color sample received from the user is high-quality paper, the rendering processing unit 107 determines a medium spectral reflectance Mp that is a spectral reflectance of the high-quality paper itself to which the ink pigment is not applied. The value of the coefficient of the reflectance calculation function is read from the reflection model parameter database 113. Then, the rendering processing unit 107 calculates the incident angle θ of the angle formed by the changed normal vector in each part of the surface of the three-dimensional structure calculated in step S2a and the direction of the light source received from the user, The observation angle α of the angle formed by the observation direction received from the user, the tilt angle Φ determined by the observation direction and the changed normal vector, the changed luminance value Ls calculated in step S3a, and the read medium spectral reflectance The rendering process is performed based on the coefficients of the calculation function (step S5b).
[0048]
Next, the rendering processing unit 107 determines that 95% of each portion on the surface of the three-dimensional structure is a portion expressing the spectral reflectance and the luminance value calculated by the subtraction spectral reflectance calculation function, and determines the portion on the surface of the three-dimensional structure. The remaining 5% of each part is determined as a part expressing the spectral reflectance and luminance value calculated by the medium spectral reflectance calculation function (step S6b). Then, based on the spectral reflectance and the luminance value of each part of the surface of the three-dimensional structure determined by the rendering processing unit 107, the display processing unit 108 displays the screen of the display device corresponding to each part of the three-dimensional structure surface. The color is output to the pixel (step S7b).
In addition, as for the image of the three-dimensional structure of high-quality paper, images of a plurality of the same three-dimensional structures having different glossiness are output to the display device in the same manner as the above-described art paper or matte paper, and the user may input the most realistic three-dimensional structure. Accept the number of the object whose glossiness is similar to that of the object. Then, the standard deviation σ when rendering the three-dimensional structure having that number and the coefficient k used for calculating the changed luminance value Ls are recorded in the optimal parameter database 114.
[0049]
The gloss expression device 1 performs the rendering process from the next time using the standard deviation σ recorded in association with the color sample information and the coefficient k used for calculating the changed luminance value Ls according to the user's instruction. You may do it. At that time, for example, it is checked whether or not the information of the color sample first received from the user is recorded in the optimal parameter database 114. If the information is recorded, the information is recorded corresponding to the information of the color sample. The standard deviation σ and the coefficient k used for calculating the changed luminance value Ls are read, and the rendering processing unit 107 performs rendering.
[0050]
As described above, one embodiment of the present invention has been described, but the embodiment is not limited to the above-described embodiment. Also, the gloss expression device described above has a computer system inside. The above-described process is stored in a computer-readable recording medium in the form of a program, and the program is read and executed by the computer to perform the process. Here, the computer-readable recording medium refers to a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to a computer via a communication line, and the computer that has received the distribution may execute the program.
[0051]
【The invention's effect】
As described above, according to the present invention, in the process of changing the normal vector, the normal vector of each part of the surface of the three-dimensional structure that is virtually displayed on the display device varies by the displacement amount based on the prescribed distribution. The changed normal vector is determined for each of the portions, and in the process of calculating the spectral reflectance, a color sample spectral reflectance calculation function is applied to the incident angle, the observation angle, and the tilt angle to calculate the surface of the three-dimensional structure. The spectral reflectance of each part is calculated, and the color value of each part of the surface of the three-dimensional structure is determined as a color value that can be calculated from the calculated spectral reflectance in the color value determination process. As a result, the changed normal vector of each part of the surface of the three-dimensional structure is in a state of variation, so that different spectral reflectances based on each changed normal vector having a different direction, the incident angle, the observation angle, and the tilt angle are different. It will be calculated. Therefore, different spectral reflectances have different color values that can be calculated from the spectral reflectances, so that when an image of a three-dimensional structure is output, a rough feeling is generated on the surface of the three-dimensional structure, and an image of the virtual three-dimensional structure is generated. It can be used as one expression method for expressing glossiness in generation.
[0052]
According to the present invention, there are a plurality of the specified distributions in the process of changing the normal vector, and a changed normal vector is determined for each of the plurality of specified distributions. Thus, since the variation of the changed normal vector varies depending on the prescribed distribution, it is possible to generate images of different three-dimensional structures expressing different feelings of roughness.
[0053]
According to the present invention, in the spectral reflectance calculation step, a color sample spectral reflectance calculation function for calculating the spectral reflectance of the color sample is applied to the incident angle, the observation angle, and the tilt angle, so that the display device is virtually provided. Calculates the spectral reflectance of each part of the surface of the three-dimensional structure displayed in, and in the process of calculating the changed luminance value, multiplies the value obtained by subtracting the specified luminance value from the maximum luminance value by the reduction ratio, and the specified luminance value To calculate a changed luminance value. In addition, a luminance value in each part is calculated from the spectral reflectance calculated in the color value determination process, and a color value of each part in which the calculated luminance value is equal to or greater than the maximum luminance value can be calculated from the calculated spectral reflectance. The luminance value of the color value is converted into a changed luminance value and determined as the color value, and the color values of other parts are determined as color values that can be calculated from the calculated spectral reflectance. With this, when the luminance value calculated from the spectral reflectance of the three-dimensional structure is equal to or more than the maximum luminance value that can be output from the display device and the luminance value must be reduced, only the luminance value equal to or more than the designated luminance value is reduced. Since the reduction is performed using the reduction ratio, it is possible to avoid further lowering the luminance of the low-luminance portion. In addition, when the brightness value calculated from the spectral reflectance of the three-dimensional structure is equal to or more than the maximum brightness value that can be output from the display device, when the brightness value needs to be reduced, a method of displaying the maximum brightness value is used. Since this is not taken, it is possible to avoid a phenomenon in which the range of the intensity distribution of the luminance based on the directivity of light reflection is such that the spectral reflectance whose luminance intensity is small is larger than the spectral reflectance whose luminance intensity is large. Therefore, it is possible to avoid a phenomenon in which a spectral reflectance having a small luminance intensity is expressed brighter.
[0054]
Further, according to the present invention, in the gloss expressing method, the changed brightness value for each of the plurality of reduction ratios is calculated in the changed brightness value calculating step, and the changed brightness value corresponds to each changed brightness value in the color value determining step. The color value of each part of the surface of the three-dimensional structure is output for each three-dimensional structure. Thus, the value when reducing the brightness value equal to or greater than the maximum brightness value changes according to the different changed brightness value, so that it is possible to generate images of a plurality of three-dimensional structures expressing different glossiness.
[0055]
Further, according to the present invention, in the gloss expression method, the color sample spectral reflectance calculation function is configured such that the color sample minimum reflectance is calculated based on a correspondence relationship between a combination of an incident angle, an observation angle, and a tilt angle, and the spectral reflectance of the color sample. This is a function obtained by multiplication. By applying the color sample spectral reflectance calculation function to the incident angle, the observation angle, and the tilt angle, the spectral reflectance of the color sample can be calculated.
[0056]
Further, according to the present invention, the subtracted spectral reflectance of each part of the surface of the three-dimensional structure virtually displayed on the display device by applying the subtracted spectral reflectance calculation function to the incident angle, the observation angle, and the tilt angle. Is calculated, and the spectral reflectance of the medium for each part of the surface of the three-dimensional structure is calculated by applying the medium spectral reflectance calculation function to the incident angle, the observation angle, and the tilt angle. Then, for each part of the surface of the three-dimensional structure, either the application of the subtractive spectral reflectance or the application of the medium spectral reflectance is determined based on a specified ratio, and the color value of each part is determined by the determined subtractive spectral reflectance. It is determined as a color value that can be calculated from the reflectance or the medium spectral reflectance. Thus, the spectral reflectance of each portion of the surface of the three-dimensional structure is determined by subtracting the spectral reflectance of the medium from the spectral reflectance of the color sample by a specified ratio, and further, the spectral reflectance of the medium itself. Is reflected in each part of the surface of the three-dimensional structure, so that it is possible to generate an image of a virtual three-dimensional structure in which colors reflecting the influence of the medium itself are expressed.
[0057]
Further, according to the present invention, the subtracted spectral reflectance calculation function determines the spectral reflectance of the medium from the combination of the incident angle, the observation angle, and the tilt angle, and the spectral reflectance of the color sample in which the color is applied to the medium. Is a function obtained by performing a least squares method based on the correspondence relationship with the subtracted spectral reflectance arithmetically subtracted, the medium spectral reflectance calculation function is a combination of an incident angle, an observation angle, and a tilt angle. This is a function obtained by performing the least square method based on the correspondence relationship with the spectral reflectance of the medium. By applying this subtracted spectral reflectance calculation function to the incident angle, the observation angle, and the tilt angle, the subtracted spectral reflectance can be calculated, and the medium spectral reflectance calculation function can be calculated for the incident angle, the observation angle, and the tilt angle. If applied, the spectral reflectance of the medium can be calculated.
[0058]
Further, according to the present invention, in the normal vector changing process, a changing method in which the normal vector of each portion of the surface of the three-dimensional structure virtually displayed on the display device is varied by a displacement amount based on a prescribed distribution. A line vector is determined for each portion of the surface, and in the process of calculating the spectral reflectance, a color sample spectral reflectance calculation function is applied to the incident angle, the observation angle, and the tilt angle, and for each portion of the surface of the three-dimensional structure. Is calculated. Also, in the change luminance value calculation step, a change luminance value is calculated by adding a value obtained by multiplying a value obtained by subtracting the specified luminance value from the maximum luminance value by the reduction ratio and the specified luminance value, and in the color value determination step, the calculated spectral value is calculated. Calculate the luminance value of each part from the reflectance, and for the color value of each part where the calculated luminance value is greater than or equal to the maximum luminance value, change the luminance value of the color value that can be calculated from the calculated spectral reflectance. And the color value is determined, and the color values of the other parts are determined as color values that can be calculated from the calculated spectral reflectance. Then, a value for each portion of the three-dimensional structure image output process color is output. As a result, a new method of expressing roughness by calculating the spectral reflectance using the modified normal vector and reducing the luminance value equal to or greater than the maximum luminance value that can be output by the display device is used. Can output an image of a three-dimensional structure that is more similar to the actual one. In addition, since it is not necessary to create a texture, it is possible to create an image of a three-dimensional structure expressing glossiness without performing a modification operation based on the user's sensitivity, and furthermore, a rule for determining a changed normal vector is provided. Since the image of the three-dimensional structure can be generated simply by specifying the reduction ratio for calculating the distribution and the changed luminance value, a user with different sensibility can generate an image expressing the same glossiness by using a glossy expression device. Can be created using
[0059]
Further, according to the present invention, in the process of changing the normal vector, the changed normal is obtained by dispersing the normal vector of each part of the surface of the three-dimensional structure virtually displayed on the display device by the displacement amount based on the prescribed distribution. A vector is determined for each part, and a subtracted spectral reflectance calculation function is applied to an incident angle, an observation angle, and a tilt angle in a subtracted spectral reflectance calculation process, and a subtracted spectral reflectance for each of the parts is calculated. In the spectral reflectance calculation process, a subtractive spectral reflectance calculation function is applied to the incident angle, the observation angle, and the tilt angle to calculate the medium spectral reflectance for each of the portions. Further, in the process of calculating the changed luminance value, a changed luminance value is calculated by adding a value obtained by multiplying a value obtained by subtracting the specified luminance value from the maximum luminance value by the reduction ratio and the specified luminance value. In the color value determination process, for each part of the surface of the three-dimensional structure, either the application of the subtracted spectral reflectance or the application of the medium spectral reflectance is determined based on a specified ratio, and the calculated subtracted spectral reflectance is calculated. Alternatively, the luminance value of each part is calculated based on one of the medium spectral reflectances, and the calculated subtracted spectral reflectance or medium spectral reflectance is calculated for the color value of each part where the calculated luminance value is equal to or greater than the maximum luminance value. The luminance value of the color value that can be calculated from any of the above is converted into a changed luminance value and determined as the color value of each portion, and the subtracted spectral reflectance or medium spectral value calculated for the color values of the other portions is calculated. A color value that can be calculated from any of the reflectances is determined. Further, a color value is output in a three-dimensional structure image output process. Thus, the spectral reflectance of each part of the surface of the three-dimensional structure is determined by subtracting the spectral reflectance of the medium from the spectral reflectance of the color sample, and the spectral reflectance of the medium itself is further determined by the three-dimensional structure. Since it is applied to each part of the surface, it is possible to express the color by the spectral reflectance reflecting the influence of the medium, and furthermore, the image of the three-dimensional structure whose glossiness is more approximate to the actual one compared to the conventional technology Can be output.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram illustrating a configuration of a gloss expression device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a small surface and a normal vector of the surface of the cylinder when the three-dimensional structure in the embodiment is a cylinder.
FIG. 3 is a diagram for explaining an incident angle, an observation angle, and a tilt angle in the present embodiment.
FIG. 4 is an enlarged view of a cross section of the surface of the three-dimensional structure when the normal vectors are virtually varied in the present embodiment.
FIG. 5 is a diagram showing a Gaussian distribution when a standard deviation is set to 2 degrees.
FIG. 6 shows the incident angle θ of light. ₁ , Maximum reflection angle θ of light ₂ FIG. 7 is a diagram illustrating an intensity distribution of light luminance and a maximum luminance value that can be output by the display device when the light intensity is.
FIG. 7 is an enlarged view of a cross section of the color sample when a color sample ink pigment is applied to a color sample medium in the embodiment.
FIG. 8 is a diagram illustrating data stored in a spectral reflectance database according to the present embodiment.
FIG. 9 is a diagram showing a flow of processing in the gloss expression device according to the embodiment.
FIG. 10 is a diagram illustrating a cross section of an intensity distribution in a space on a reflection surface of luminance of reflected light in the present embodiment.
[Explanation of symbols]
1 Gloss expression device
101 Input unit
102 Three-dimensional structure data creation unit
103 Reflection Model Parameter Calculator
104 Paper effect subtraction calculation unit
105 Change normal vector calculation unit
106 Change luminance value calculation unit
107 rendering processing unit
108 Display processing unit
109 Angle storage
110 Three-dimensional structure data storage unit
111 luminance value information storage unit
112 Spectral Reflectance Database
113 Reflection Model Parameter Database
114 Optimal Parameter Database

Claims (9)

A gloss expression method in a gloss expression device including a three-dimensional structure information storage unit that stores a normal vector for each part of a surface of a three-dimensional structure that is virtually displayed on a display device,
A normal vector for determining a changed normal vector in which the normal vector of each part of the surface of the three-dimensional structure stored in the three-dimensional structure information storage means is dispersed by a displacement amount based on a prescribed distribution, for each of the parts Change process,
The light source direction of light incident on the surface of the three-dimensional structure, the incident angle formed by the modified normal vector, the observation point direction for observing the reflection of the light on the surface of the three-dimensional structure, and the observation formed by the modified normal vector A color sample spectral reflectance calculation function for calculating a spectral reflectance of a color sample coated with a medium at a tilt angle formed by an angle, the light source direction, the surface formed by the observation point direction, and the modified normal vector. Applying, a spectral reflectance calculation step of calculating the spectral reflectance for each part of the surface of the three-dimensional structure,
A color value determining step of determining a color value of each part of the surface of the three-dimensional structure as a color value that can be calculated from the calculated spectral reflectance,
A gloss expression method comprising: The gloss expression method according to claim 1, wherein there are a plurality of the prescribed distributions in the normal vector changing step, and a modified normal vector is determined for each of the plurality of prescribed distributions. Brightness value information storage means for storing a designated brightness value calculated based on the spectral reflectance when the light vertically applied to the color sample is observed from a predetermined angle in an oblique direction and a maximum brightness value that can be displayed by the display device; A gloss expression method in a gloss expression device comprising:
The light source direction of light incident on the surface of the three-dimensional structure virtually displayed on the display device, the angle of incidence formed by the normal vector of the surface of the three-dimensional structure, and the reflection of the light on the surface of the three-dimensional structure. Observation direction of the observation point to be observed, the observation angle formed by the normal vector, the light source direction, the tilt angle formed by the surface formed by the observation point direction, and the tilt angle formed by the normal vector, spectral analysis of a color sample in which a color is applied to a medium. Applying a color sample spectral reflectance calculation function to calculate the reflectance, a spectral reflectance calculation step of calculating the spectral reflectance for each part of the surface of the three-dimensional structure,
Reading the maximum luminance value and the specified luminance value from the luminance value information storage means, and adding a value obtained by multiplying a value obtained by subtracting the specified luminance value from the maximum luminance value by a reduction ratio and the specified luminance value; A change luminance value calculating step of calculating a luminance value,
A luminance value in each of the portions is calculated from the calculated spectral reflectance, and a color value of each portion in which the calculated luminance value is equal to or greater than the maximum luminance value is a color value that can be calculated from the calculated spectral reflectance. A color value determining step of converting the luminance value of the color into the changed luminance value and determining the value of the color, and determining the color values of the other parts as color values that can be calculated from the calculated spectral reflectance. ,
A gloss expression method comprising: The changed luminance value for each of the plurality of reduction ratios is calculated in the changed luminance value calculating step, and the color value of each part of the surface of the three-dimensional structure corresponding to each changed luminance value is calculated in the color value determining step. The gloss expression method according to claim 3, wherein the gloss is output for each object. The color sample spectral reflectance calculation function is a function obtained by performing a least square method based on a correspondence relationship between a combination of an incident angle, an observation angle, and a tilt angle, and the spectral reflectance of the color sample. Or the gloss expression method according to claim 3. In the light source direction of light incident on the surface of the three-dimensional structure virtually displayed on the display device, the incident angle formed by the normal vector at each part of the surface of the three-dimensional structure, and at each part of the surface of the three-dimensional structure A color is applied to the medium at the observation point direction for observing the light reflection, the observation angle formed by the normal vector, the light source direction, the surface formed by the observation point direction, and the tilt angle formed by the normal vector. Applying a subtracted spectral reflectance calculation function to calculate a subtracted spectral reflectance by arithmetically subtracting the spectral reflectance of the medium from the spectral reflectance of the color sample at a specified ratio, and applying the subtracted spectral reflectance calculation function to each part of the surface of the three-dimensional structure A subtracted spectral reflectance calculation process of calculating a subtracted spectral reflectance for
Applying a medium spectral reflectance calculation function for calculating the spectral reflectance of the medium to the incident angle, the observation angle, and the tilt angle, the spectral reflectance of the medium for each part of the surface of the three-dimensional structure Calculating the medium spectral reflectance,
For each portion of the surface of the three-dimensional structure, either the application of the subtracted spectral reflectance or the application of the medium spectral reflectance was determined based on a prescribed ratio, and the color value of each portion was determined. A color value determining step of determining a color value that can be calculated from the subtracted spectral reflectance or the medium spectral reflectance,
A gloss expression method comprising: The subtracted spectral reflectance calculation function is a combination of the incident angle, the observation angle, and the tilt angle, and the spectral reflectance of the medium is arithmetically subtracted at a specified ratio from the spectral reflectance of a color sample in which a color is applied to the medium. A function obtained by performing a least squares method based on the correspondence relationship with the subtracted spectral reflectance, the medium spectral reflectance calculating function is a combination of an incident angle, an observation angle, a tilt angle, and a spectral reflectance of the medium. 7. The gloss expression method according to claim 6, wherein the function is a function obtained by performing a least-squares method based on a correspondence relationship between the glossiness and the brightness. A three-dimensional structure information storage means for storing a normal vector for each part of the surface of the three-dimensional structure virtually displayed on the display device, and observing light perpendicularly applied to the color sample from a predetermined oblique angle. Gloss in a gloss expression device comprising a designated luminance value calculated based on the spectral reflectance at the time of the above and a luminance value information storage means for storing a maximum luminance value that can be displayed by a display device for displaying an image of the three-dimensional structure. Expression method,
A normal vector for determining a changed normal vector in which the normal vector of each part of the surface of the three-dimensional structure stored in the three-dimensional structure information storage means is dispersed by a displacement amount based on a prescribed distribution, for each of the parts Change process,
The light source direction of light incident on the surface of the three-dimensional structure, the incident angle formed by the modified normal vector, the observation point direction for observing the reflection of the light on the surface of the three-dimensional structure, and the observation formed by the modified normal vector A color sample spectral reflectance calculation function for calculating a spectral reflectance of a color sample coated with a medium at a tilt angle formed by an angle, the light source direction, the surface formed by the observation point direction, and the modified normal vector. Applying, a spectral reflectance calculation step of calculating the spectral reflectance for each part of the surface of the three-dimensional structure,
Reading the maximum luminance value and the specified luminance value from the luminance value information storage means, and adding a value obtained by multiplying a value obtained by subtracting the specified luminance value from the maximum luminance value by a reduction ratio and the specified luminance value; A change luminance value calculating step of calculating a luminance value,
A luminance value in each of the portions is calculated from the calculated spectral reflectance, and a color value of each portion in which the calculated luminance value is equal to or greater than the maximum luminance value is a color value that can be calculated from the calculated spectral reflectance. A color value determining step of converting the luminance value of the color into the changed luminance value and determining the value of the color, and determining the color values of the other parts as color values that can be calculated from the calculated spectral reflectance. ,
Outputting a three-dimensional structure image outputting the color value;
A gloss expression method comprising: A three-dimensional structure information storage means for storing a normal vector for each part of the surface of the three-dimensional structure virtually displayed on the display device, and a light obliquely applied vertically to a color sample coated with a medium. Brightness information storage means for storing a designated brightness value calculated based on the spectral reflectance when observed from a predetermined angle and a maximum brightness value that can be displayed by a display device that displays an image of the three-dimensional structure. A gloss expression method in a gloss expression device,
A normal vector for determining a changed normal vector in which the normal vector of each part of the surface of the three-dimensional structure stored in the three-dimensional structure information storage means is dispersed by a displacement amount based on a prescribed distribution, for each of the parts Change process,
The light source direction of light incident on the surface of the three-dimensional structure, the incident angle formed by the modified normal vector, the observation point direction for observing the light reflection on each part of the surface of the three-dimensional structure, and the modified normal vector The angle formed by the observation angle, the light source direction, the surface formed by the observation point direction, and the change normal vector, the spectral reflectance of the medium from the spectral reflectance of the color sample at a specified ratio. Applying a subtracted spectral reflectance calculation function to calculate a subtracted spectral reflectance arithmetically subtracted, a subtracted spectral reflectance calculation step of calculating a subtracted spectral reflectance for each part of the surface of the three-dimensional structure,
Applying a medium spectral reflectance calculation function for calculating the spectral reflectance of the medium to the incident angle, the observation angle, and the tilt angle, the spectral reflectance of the medium for each part of the surface of the three-dimensional structure Calculating the medium spectral reflectance,
Reading the maximum luminance value and the specified luminance value from the luminance value information storage means, and adding a value obtained by multiplying a value obtained by subtracting the specified luminance value from the maximum luminance value by a reduction ratio and the specified luminance value; A change luminance value calculating step of calculating a luminance value,
For each part of the surface of the three-dimensional structure, either the application of the subtracted spectral reflectance or the application of the medium spectral reflectance is determined based on a specified ratio, and the calculated subtracted spectral reflectance or medium spectral reflectance is determined. The luminance value in each of the portions is calculated based on any one of the ratios. For the color value of each portion in which the calculated luminance value is equal to or more than the maximum luminance value, the calculated subtracted spectral reflectance or medium spectral reflectance is calculated. The luminance value of the color value that can be calculated from any of the above values is converted into the changed luminance value and determined as the color value, and the color values of the other parts are calculated with the subtracted spectral reflectance or the medium spectral reflectance. A color value determining process of determining a color value that can be calculated from any of the ratios,
Outputting a three-dimensional structure image outputting the color value;
A gloss expression method comprising:

Images