JP3054321B2 - Computer graphics equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer graphics device, and more particularly to a computer graphics device which reproduces a predetermined color intended by an operator such as a designer on a computer when performing color printing or color display.

[0002]

2. Description of the Related Art In the field of computer graphics,
2. Description of the Related Art As is known in rendering, images such as patterns and figures with various colors are displayed on a computer, and the displayed images are printed in color. When an image of an object with color is to be displayed on this computer, the principle of light reflection is modeled, and the object is represented by the brightness of the light. Is not sufficient, and it is difficult to express the substantial color of the object by a simple input operation on a computer.

[0003] For this reason, there is a computer graphics apparatus which realistically expresses the material feeling of an object (Japanese Patent Laid-Open No. 4-1 / 1991)
95480, JP-A-5-40833). In this computer graphics device, the reflection coefficient and the transmission coefficient of an object are detected, and the reflected light from the object is separated into a specular reflection component and a diffuse reflection component to handle the object, thereby realizing a realistic feeling of the material of the object.

[0004]

However, the transmittance and reflectance of an object may vary greatly depending on the composition and physical properties of the object and the surface shape inherent to the object. For example, an object surface such as a body of a vehicle is formed by a painted surface having a paint color obtained by applying a paint or the like.However, in order to obtain a painted surface of a desired paint color intended by a user, a designer, or the like, A paint or the like containing a coloring material by mixing a plurality of pigments or the like must be assumed. The reflectivity of such painted surfaces is
It is known that the light-receiving element has a variable angle characteristic that varies according to an angle (hereinafter, referred to as a variable angle) obtained by changing a light receiving angle when receiving reflected light from a painted surface from a regular reflection direction. Therefore, this deflection characteristic affects the feeling of the material of the object.

Therefore, as in the conventional computer graphics apparatus, if the reflected light from the object is merely separated into the specular reflection component and the diffuse reflection component, the material appearance of the object may fluctuate due to the deflection characteristics, and the faithfulness of the object may occur. Sometimes the paint color cannot be reproduced.

An object of the present invention is to provide a computer graphics device capable of reproducing a paint color faithful to an intended color on a computer in consideration of the above fact.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, a computer graphics device according to the present invention is provided with a variable angle as a spectral reflectance for each variable angle obtained by changing a light receiving angle for receiving light reflected from an object to be coated. Measuring means for measuring the spectral reflectance,
A first characteristic amount dependent on the spectral wavelength using the variable-angle spectral reflectance measured by the measuring unit, and a second characteristic amount dependent on the variable-angle
And feature quantity calculating means for calculating a feature quantity, the feature quantity calculation
At least the first feature amount and the second feature amount obtained by the means
Color and quality with a changing unit, and a first feature quantity and the second feature quantity obtained by said changing means also changes one characteristic quantity
And reproducing means for reconstructing the spectral reflectance for each angle of change in order to control at least one of the feelings and reproducing the coating color of the object to be coated. Further, the reproducing unit can configure the spectral reflectance for each angle of change using a product or a sum of the first feature amount and the second feature amount obtained by the changing unit. The first feature quantity is a feature quantity related to wavelength.
And the second feature value is a feature value related to the deflection angle.
Can be adopted. In addition, the reproducing means sets the wavelength to λ and the deflection angle to
x, the first feature quantity is b (λ), and the second feature quantity is
α (x) and β (x), the reflected light from the surface is S (x,
λ), and the residual component is T (x, λ), and S (x, λ) + α (x) · b (λ) + β (x) + T
It is possible to reconstruct the spectral reflectance for each deflection angle based on the equation (x, λ).
it can. Further, the feature amount calculating means calculates the reflected light angle.
x, specific reference angle X, wavelength λ, measured variation
Let the angular spectral reflectance be R (x, λ) and use the variable for reconstruction.
The spectral reflectance for each angle is defined as R ′ (x, λ) expressed by Equation 21,
When mi (λ) and b (λ) are represented by Expression 22
Then, for each wavelength λ, minimize the value of Equation 23, b
(Λ) is determined as a first feature amount, and Equation 24 is calculated as a second feature amount.
It can be obtained as a feature value. In addition, the feature quantity performance
The calculating means calculates the reflected light angle as x and the specific displacement angle as a reference.
X, wavelength is λ, and measured gonioscopic spectral reflectance is R (x, λ)
And the spectral reflectance for each deflection angle for reconstruction is given by
It represents a R '(x, λ), the function f for x in (x, y)
The function for calculating the average value is represented by Equation 25, and Mi, b (λ) and
When ρ (x) is expressed by Expression 27, the value of Expression 28 is
Equation 29 to be minimized is obtained as a second feature amount, and each wave
For the length λ, b (λ) that minimizes the value of Equation 30 is the first
Can be obtained.

[0008]

In the computer graphics device of the present invention,
The measuring unit measures a variable-angle spectral reflectance as a spectral reflectance for each variable angle obtained by changing a light-receiving angle at which light reflected from the object is received. Therefore, it is possible to obtain a unique deflection characteristic possessed by a material such as a pigment or a brilliant included in the painted surface of the object to be painted. For this reason, the paint color can be represented by the reflectance at each variable angle and each wavelength, that is, the variable angle spectral reflectance. The feature value calculating means calculates a first feature value dependent on a plurality of spectral wavelengths and a second feature value dependent on the deflection angle using the measured deflection spectral reflectance. The reproducing means configures the spectral reflectance for each angle change using the obtained first characteristic amount and the second characteristic amount, and reproduces the coating color of the object to be coated. This place
In this case, the reproducing means is the same as the first feature quantity obtained by the feature quantity calculating means.
Spectral reflection for each variable angle using the product or sum with the second feature value
The rate can be configured.

As described above, since the first feature value dependent on the spectral wavelength and the second feature value dependent on the deflection angle are used, the paint color is assumed to have a high wavelength dependency. And the texture that is assumed to have a high angle dependence can be handled independently, and the coating color of the object to be coated can be reproduced in consideration of the color and the texture.

The color and the texture can be independently and arbitrarily changed by changing at least one of the first characteristic amount and the second characteristic amount.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the present embodiment, the present invention is applied to color reproduction when designing a paint color (outer plate color) of an exterior of an automobile or the like.

As shown in FIG. 3, the computer graphics device for reproducing a paint color includes a personal computer 16. This personal computer 1
Reference numeral 6 denotes a keyboard 10 for inputting color data and the like, and a computer main body 1 for calculating relevant data for generating a desired paint color according to a program stored in advance.
2 and a CRT 14 for displaying a paint color or the like, which is a calculation result of the computer main body 12. The computer main body 12 includes a CPU, a ROM, and a RAM, and has a memory for storing a feature amount described later.

[0013] The exterior colors of automobiles are broadly classified into solid paints containing color pigments as main components, color paints, and metallic paints containing luster materials as main components. The solid paint exhibits a substantially constant color irrespective of the direction in which light is irradiated or viewed. On the other hand, metallic paints are characterized by the fact that the color (especially the brightness) changes depending on the direction of light irradiation and the direction of viewing, and the behavior of the color change due to this direction is important for the paint (on design). Characteristics. In recent years, with the development of a new glittering material, the variation in the behavior of color change depending on the direction is increasing, and the ratio of metallic paints is also increasing in the automobile market.

In the case of solid paint, there is no change in color depending on the direction, so that a one-to-one relationship is established between paint and color. Therefore, once the paint is determined, the paint color is determined, and it is relatively easy to specify and reproduce the paint color.

However, in metallic paints, 1
Since one paint exhibits a plurality of colors depending on the direction, and the behavior of the change of the paint color is also an important characteristic, it is very difficult to indicate or reproduce the color of the paint.

When a new metallic paint is created at a design site, a direction to be changed is indicated by a designer's words, a sample (eg, Toba), or an image photograph based on a sample paint prepared in advance. Then, trial-and-error was carried out to prototype the paint and correct it. This method requires a great deal of time and money.

For this reason, there has been a demand for the development of a method for easily reproducing or changing the coating color of a metallic paint. In the conventional method, a large amount of data is required for the reproduction of the paint color of the metallic paint, and the color change is possible only for a limited glitter material,
Furthermore, it was impossible to change the texture.

The computer graphics apparatus of the present embodiment uses a CRT to determine the color and texture of a painted object (metallic paint).
It provides a method of accurately reproducing (displaying) the image on the screen and changing the color and texture independently and arbitrarily, and can assist in the design of a coating and the development of a coating material.

First, considering the coating texture of a painted object from the viewpoint of materials, glittering materials (aluminum powder, iron oxide, etc.) contained in the coating film strongly affect the texture of the painted object. Texture is felt.

Considering the coating texture of the coating object from the optical characteristics, the texture of the coating object (appearance) is determined by the light reflection characteristic (deformation spectral reflectance) of the coating film. It can be divided into diffuse reflection components. this house,
The specular reflection component is determined by the surface shape and the refractive index of the clear (plastic) layer on the surface of the coating film, and does not depend on the type of glitter. Therefore, this component is related to the texture common to painted objects, but is not involved in the subtle texture of each glitter material. on the other hand,
The present inventors have measured the diffuse reflection component in the layer for various glittering materials, and as a result, obtained a finding that each of the glittering materials has a unique reflection characteristic, which forms a texture unique to each glittering material. Was.

As described above, in order to reproduce the texture of each glitter material, it is necessary to accurately grasp the diffuse reflection characteristics in the layer of the coating film. Further, it is necessary to independently and arbitrarily change the color and texture. Therefore, a mathematical expression model that uses a factor to be changed as a parameter is required. If you do not assume this mathematical model, for example, if you try to change only the color, the texture will also change,
The designer cannot make the intended changes.

In this embodiment, in order to reproduce the paint color, the spectral reflectance of the surface of the object is used as a physical quantity for handling the paint color. Note that this spectral reflectance is
In the case of a sample having a complicated shape, for example, a surface such as a fiber or a metallic coating may be measured at a different value depending on the light receiving direction of the measuring instrument.In this embodiment, the incident angle to the sample and the light reflected by the sample are measured. A spectral solid angle reflectance, which is a three-dimensional spectral reflectance obtained by changing a light receiving angle or the like to a light receiving element that receives light, is used.

[0023] The spectral reflectance of a sample having a flat surface is usually measured using a Gonio Spectro Photometer.
Tometer, hereinafter referred to as gonio. ) Measured at 24 (colorimetry)
The measured spectral reflectance is referred to as spectral solid angle reflectance (Spectral Reference Factor) or variable angle spectral reflectance. This spectral solid angle reflectance is hereinafter simply referred to as reflectance R.

As shown in FIG. 4, the gonio 24 has a light source 28 and a light receiver 26 as a measuring unit. Gonio 2
4 includes an incident optical axis 32 of light traveling from the light source 28 to the measurement point Ob of the sample 30 and a reflected optical axis 34 in a regular reflection direction when the light of the incident optical axis 32 is regularly reflected at the measurement point Ob. It provides that the incident plane D ₁ plane. This gonio 24
Then, the axis connecting the light receiver 26 and the measurement point Ob is defined as the measurement optical axis 3.
As 6, the photodetector 26 as the measuring optical axis 36 is contained in the plane of incidence D ₁ is a mechanism that moves in three dimensions (not shown). That is, the most common gonio has a mechanism in which the light source unit and the light receiving unit move in the plane of incidence around the measurement point.

The reflectivity R is calculated based on the reflection optical axis 34 and the measurement optical axis 36.
, Ie, a reflection angle x (unit: deg, hereinafter referred to as a variable angle x) from the regular reflection direction of the light receiving unit, and a light wavelength λ (unit: nm). ).

R (x, λ) (1) where the deflection angle x is 0 ° when the reflection optical axis 34 and the measurement optical axis 36 coincide with each other, and the deflection angle x is from the regular reflection direction to the light source section. The sign of the variable angle x obtained from the position of the light receiving unit 26 rotated clockwise (in the direction of the variable angle x in FIG. 4) is defined as a positive sign.

As shown in FIG. 5, the variable angle x can be determined in a rectangular coordinate system based on an incident surface or the like. That is, the normal direction ＄ N of the sample 30, the incident direction 方位 L which is the azimuth between the sample 30 and the light source 28, the light receiving direction か ら R from the sample 30 to the light receiver 26, the specular reflection direction of the light regularly reflected by the sample 30 ＄ P is determined, and a surface including the normal direction ＄ N and the specular reflection direction ＄ P is defined as an incident surface D ₁ , and a surface including the normal direction ＄ N and the light receiving direction ＄ R is defined as a light receiving surface D ₂ . Thus, the angle of the angle theta ₁ between the normal direction $ N to the incident direction $ L, the angle theta ₂ between the normal direction $ N and the light-receiving direction $ R, an incident surface D ₁ and the light-receiving surface D ₂ θ ₃ is determined. When the surface of the sample 30 has directionality (for example, a woven fabric, a brush finished surface, or the like), the reference direction of the sample surface (painted surface) around the measurement point Ob (FIG. 5)
Is the angle θ away from the entrance surface D _{1
And 4} . Therefore, the reflectance R in the above equation (1) can be expressed by the following equation (2) as a general equation.

R (λ, θ ₁ , θ ₂ , θ ₃ , θ ₄ ) (2) where θ ₁ : incident angle (deg) of light source θ ₂ : light receiving angle (deg) θ ₃ : azimuth angle (deg) θ ₄ : Rotation angle (deg)

The above equation (2) has four angle parameters represented by θ ₁ , θ ₂ , θ ₃ , and θ _4. The intensity distribution of reflected light on a general painted surface (the intensity of reflected light is
The distribution represented by the distance from the irradiation point as a center) is always a similar shape of Spherical Symmetry with the specular reflection direction ΔP as an axis, regardless of the incident angle θ ₁ of the incident light.
It is known that Therefore, the reflectivity is
It is represented only by the displacement x between P and ΔR.

Therefore, the reflectivity of the painted surface is opposite
As a function of the deflection angle x between the launch direction ΔP and the light receiving direction ΔR
Thus, as shown in the above equation (1), the reflectance R (x, λ)
Can be expressed as For example, the light receiving angle θ_Two Angles other than
The condition is set to a predetermined value (θ₁= 60 °, θ_Three = 0 °, θ_Four = 0
°) and the deflection angle x is 0 ° to 90 ° (in this case, x =
θ ₁−θ_Two ), The reflectance R (x, λ)
Is measured by gonio, the reflectance R (x, λ) is 0 ° <x <
It is found in the 90 ° angle range.

If the reflectance R (x, λ) is determined by the following [angle condition], the reflectance R (x, λ) can be determined in an angle range of −30 ° <x <150 °.

[Angle Condition] R (x, λ) = R (−x, λ) (−30 ° <x <0 °) = R (90 °, λ) (90 ° <x <150 °)

In the following description, the angle condition (θ
Even in cases other than ₁ = 60 °, θ ₃ = 0 °, θ ₄ = 0 °), the reflectance R (x, λ) obtained by calculating the variable angle x from the relationship between the regular reflection direction ΔP and the light receiving direction ΔR is used. .

[Measurement of Deflection Spectral Reflectance] The reflectance of the painted surface is a reflectance having a continuous characteristic of the deflection x and the wavelength λ, and can be approximately treated as follows.

First, the deformation angle x (0 ° to 90 °) is converted to a boundary value x.
_j (j = 1, 2,..., n, 0 ° = x ₁ <x ₂ <.
<X _n = 90 °), an appropriate division (hereinafter referred to as an appropriate division) is performed, such as subdivision into [n + 1] equal intervals or a range in which the change in reflectance is sharp (see FIG. 6A). ). The appropriate division is preferably set so that 19 to 91 data numbers can be obtained at intervals of 1 ° to 5 °.

Similarly, regarding the wavelength λ, for example, the visible wavelength is considered as a wavelength range of 380 (nm) ≦ λ ≦ 720 (nm), and this visible wavelength range is defined as a boundary wavelength λ _k (k = 1, 2,. ..M,
380 nm = λ ₁ <λ ₂ ... <Λ _m = 720 nm) and appropriately divided into [m + 1] pieces (see FIG. 6B). The appropriate division of the wavelength range is preferably set so that 18 to 35 data numbers can be obtained at intervals of 10 to 20 nm.

Therefore, the reflectance R (x, λ) of the painted surface is
The reflectances R (x ₁ , λ ₁ ), R (x ₂ ,
λ ₁ ),..., R (x _n , λ _m ). That is, as shown in FIG.
In a three-dimensional coordinate system having axes of (x, λ), the deflection angle x, and the wavelength λ, the reflectance R (x, λ) is a surface such as a continuous curved surface (hereinafter, referred to as a continuous surface) 70. become. Reflectivity R
The continuous surface 70 representing (x, λ) can be obtained by interpolation from a plurality of discrete points included on the continuous surface 70.

As shown in FIGS. 7 (a) to 7 (c), the painted surface of the sample whose surface is painted may be a colored pigment for determining the color, a glittering material such as metal or pearl mica, or a clear surface. Is composed of

As shown in FIG. 7A, the painted surface on which the metallic coating is applied is composed of a clear coat layer 40, a metallic base layer 42, an intermediate coating layer 44, and an electrodeposition layer 46. The metallic base layer 42 contains a pigment 54 and aluminum 56. As shown in FIG. 7 (b), the painted surface on which the pearl mica coating is applied includes a clear coat layer 40, a mica base layer 48, a color base layer 50,
It is composed of an intermediate coating layer 44 and an electrodeposition layer 46. The mica base layer 48 contains a titanium-coated mica pigment 58. As shown in FIG. 7C, the painted surface by the solid painting is composed of an overcoat layer 52, an intermediate coat layer 44, and an electrodeposition layer 46. The overcoat layer 52 contains the coloring pigment 60.

The surface shape of the continuous surface of the reflectance R (x, λ) is also different due to the difference in the coating with these glittering materials and various substances. The reflectance R (x, λ) depends on the types and amounts of the pigment and the glittering material.

Next, the optical effect of each component will be described. The components of the outer color coated plate can be broadly classified into a light absorbing material such as a general pigment, a light reflecting material such as an aluminum piece, and a light transmitting / interfering material such as a mica piece. Light reflected from the skin color is a result of the interaction of these materials and specular reflection at the coating surface. The outline of the bending characteristic of each of these materials is shown below.

<Light Absorbing Material> A substantially constant spectral reflectance is exhibited over all the deformation angles. Therefore, it can be expressed by the following equation (3).

R (x, λ) = R _O (λ) (3)

<Light Reflective Material> Each piece of material exhibits a certain spectral reflectance only in the regular reflection direction. In the coating layer, each material piece exists with an inclination, so the behavior of multiple material pieces is integrated (macroscopic bending characteristic).
Can be expressed by the following equation (4) as a product of a certain spectral reflectance R ₁ (λ) and a coefficient k ₁ (x) that is a function of the deflection angle. In the following equation, * is used as a multiplication symbol.

R (x, λ) = R ₁ (λ) * k ₁ (x) (4)

<Light Transmitting / Interfering Material> As shown in FIG. 8A, regarding transmission, it is considered that each piece of material itself has a spectral transmittance determined by the optical path length in the piece of material. Since the optical path length is determined by the angle of incidence on the piece of material, the spectral transmittance t of the piece of material is a function of the angle of incidence. Therefore, it can be expressed by the following equation (5).

[0047]

(Equation 1)

Here, t (x ₁ , λ): Spectral transmittance of the material piece with respect to the light beam having an incident angle x ₁ on the material piece τ (λ): Spectral transmittance per unit optical path length d: Thickness of the material piece x ₁ : angle of incidence on the piece of material

On the other hand, as shown in FIG. 8B, with respect to interference, each piece of material has a certain spectral reflectance only in the regular reflection direction in the same manner as the reflective material (however, this is because light interference It is the result that occurred.) The major difference from the reflective material is that the spectral reflectance changes depending on the incident angle.

That is, the refractive index n in the space of the refractive index n ₀
Considering the case where there is a coated plate coated with _one binder and a coherent glittering material having a refractive index of n _{2 in} the binder, the relationship between each incident angle and the refractive index is n ₀ * sin (x ₀ ). = N ₁ * sin (x ₁ ) = n ₂ *
sin (x ₂ ).

On the other hand, の of the optical path length in the coherent material is p = n ₂ * d / (1.0−sin (x ₂ ) ² ) ^1/2. _{rewriting, p = n 2 * d /} (1.0-n 0 2 / n 2 2 * sin (x 0)
² ) ^1/2 . Given the refractive index n ₀ of the space 1.0 _{(air), p = n 2 * d} / (1.0-1.0 / n 2 2 * sin
(X ₂ ) ² ) ^1/2 .

The light ray incident on the coherent material has an optical path length longer by 2p than the light ray reflected on the surface of the material. On the other hand, the phase of a light ray reflected on the surface of the same material changes by an angle π on the reflection surface, and the phase difference between the two light rays is Δ = 2p / λ * 2π + π. Therefore, the combination of the two light beams is sin (x) + sin (x + △) = 2 cos (− △ / 2) * sin (x + △ / 2), and the light intensity is k = 2 cos (− △ / 2). Will be modulated. Δ is a function of the wavelength λ and the optical path length p, and since the optical path length p is a function of the incident angle x ₀ , Δ is rewritten as dlt (x ₀ , λ) to reflect the interference phenomenon of the coherent material. expressed as a percentage, x ₀ which can be a 1.0 or higher value, the function of the λ i (x _0, λ) become.

I (x ₀ , λ) = 2 cos (−dlt (x
₀ , λ) / 2) In the coating layer, individual material pieces are present with an inclination, and transmission and interference are complicatedly repeated. The resulting macroscopic behavior can be considered as a function of the angle of incidence x ₀ , the variable angle x and the wavelength. For convenience, let the incident angle be x ₀ = 60
When considered as a constant of °, it can be expressed by the following equation (6).

R (x, λ) = R ₂ (x, λ) (6)

The specularly reflected light from the coating film surface exists only in the specular reflection direction and is a function of the surface condition (smoothness, etc.) of the coating film and the refractive index of the surface layer of the coating film.

In an actual outer color coating plate, an interaction between these materials (for example, in a metallic coating plate, reflected light from an aluminum piece is further reflected on a general pigment and then emitted outside the coating plate). , Its behavior is complex.

Therefore, it is extremely difficult to determine the gonioscopic spectral reflectance of the paint from the behavior of each of these paint constituents, but to derive the gonioscopic spectral reflectance characterized by the paint constituent. However, it is possible to extract the features.

As described above, the skin color can be represented by the reflectance at each angle and each wavelength (ie, the spectral reflectance at each angle). However, the data amount is large, and it is difficult to change the color and texture. Therefore, there is a need for a method of reducing the amount of data and facilitating control of color and texture. In the present embodiment, based on the characteristics of the skin color, the variable-angle spectral reflectance is converted into a component that depends on the variable angle (hereinafter, characteristic amount related to variable angle) and a component that depends on the spectral wavelength (hereinafter, characteristic amount related to wavelength). Using the separated model formula (detailed later),
It is easy to control color and texture.

[Outline] As shown in FIG. 1, the method for facilitating the control of the color and texture in this embodiment is as follows.
As 1, the gonio-spectral reflectance of the outer color plate is actually measured by the above gonio. In the next step S2, a characteristic amount (one or a plurality of variables or functions) relating to the deviation and a characteristic amount (a set of spectral reflectivities) relating to the wavelength are extracted from the one actually measured spectral reflectance. .

In the next step S3, the extracted variable-angle spectral reflectances are not stored, but are stored in advance. Can be reproduced, and the amount of data that must be stored can be reduced. Further, in this step S3, the texture is changed while maintaining the color of the outer skin color by changing the extracted feature quantity relating to the deflection angle, or the texture of the outer skin color is changed by changing the feature quantity relating to the wavelength. It is possible to change the color while maintaining. Further, in step S3, the feature amount related to the deflection angle is replaced with the feature amount related to the deflection angle extracted from the deflection angle spectral reflectance of another outer panel color, and the same is performed for the feature amount related to the wavelength. By maintaining color and replacing only the texture with that of other materials,
Only the colors can be replaced while maintaining the texture.

For a paint containing a brilliant material having a strong hue change due to interference or the like, in addition to the characteristic amount relating to the deflection angle and the characteristic amount relating to the wavelength, a model representing the characteristic amount representing the hue change (a function of the deflection angle and the wavelength). In addition to the expression, it is possible to change the color and texture while maintaining the hue change effect, adjust the strength of the hue change effect, and replace the hue change effect with another material. The feature value representing the hue change effect can also be extracted from one actually measured variable-angle spectral reflectance. However, when the feature value representing the hue change effect is introduced, the data amount described above is used. Since the effect of reduction may decrease,
It is preferable to use it selectively as needed.

When the color change, the texture change, and the hue change effect change are performed, a measurement error (variation) in actually measuring the variable angle spectral reflectance is amplified depending on the change, and the color change in the change direction is performed. May be discontinuous. In order to prevent this, a process (noise removal) for reducing the measurement variation is performed on the actually measured variable-angle spectral reflectance data. The basis of this noise removal is smoothing processing, but by controlling whether or not to perform the processing depending on the magnitude of the reflectance, the effect is high and the original characteristic of the variable-angle spectral reflectance is impaired. Can be treated as if not.

In step S3, the new or modified reconstructed variable-angle spectral reflectance is used, and in the next step S4, CAD frame image surface data or the like is obtained.
An image of a paint color based on the obtained variable-angle spectral reflectance is displayed.

[Color Change, Texture Change] As described above, the outer panel color is the reflectance at each angle and each wavelength (ie, the angle spectral reflectance).
Therefore, in order for the designer to change the color of the outer plate, the designer only has to change the reflectance of each of the variable-angle spectral reflectances. However, the amount of data is huge,
The operation of changing the variable-angle spectral reflectance point by point is practically impossible. For this reason, there is a need for a method for quickly and accurately performing a change requested by a designer.

The main characteristics of the skin color are color and texture.
It is recalled that when the designer changes the skin color, it changes each of these properties. For example, if you want to change the color of the silver aluminum metallic skin, you can add "a little reddish color to the silver while keeping the texture of the aluminum metallic"
It is often presented with an abstract concept such as "increase the metallic feeling while keeping the silver color as it is". Therefore, it is desirable to establish a method for changing the color and a method for changing the texture, and to change the entire variable angle spectral reflectance by these methods. A change in color corresponds to changing the type and amount of a coloring pigment in the paint, and a change in texture corresponds to changing the type and amount of a brilliant in the paint.

When changing the color while maintaining the texture of the outer panel color, for example, the designer performs an operation of changing the color at a certain angle. If this operation is reflected only in that deflection, the result will not be what the designer wants. The designer intends to change the color pigment in the paint through a color change at a certain angle, in which case the color must change for all the angles, not just the color of the angle. Must. At that time, how to change the color at an angle other than the bending angle at which the designer has changed is a problem. In order to maintain the texture and change the color,
It is necessary to separate the texture information and the color information from the variable-angle spectral reflectance, change the color information, and then combine the information with the texture information again.

On the contrary, when the texture is changed while maintaining the color of the skin color, for example, the designer performs an operation such as "increase the contrast between the highlight portion and the shade portion". The designer intent of this operation is to change the glitter material and must change the gonio-spectral reflectance of the entire gonio. At that time, since a change in the color pigment is not intended, it is not desirable that a change in color except for light and dark occurs. Therefore, also in this case, it is necessary to separate the texture information and the color information from the variable-angle spectral reflectance, change the texture information, and then synthesize the color information again.

Further, a change is made so that the color is maintained and the texture is replaced with that of another glittering material. For example, there is a case where the material is changed to mica based on a red metallic outer plate color. In that case, at the same time as separating the texture information and the color information from the red metallic bending angle spectral reflectance, the texture information is also obtained from the mica bending angle spectral reflectance, and the red metallic texture information is obtained. It needs to be replaced.

Therefore, as shown in step S2 of FIG. 2, the feature quantity relating to the deflection angle is treated as the feature quantity relating to the texture as the feature quantity extracted in step S2 in FIG.
If the feature value related to the wavelength is treated as a feature value related to the color while maintaining the texture of the skin color, and the process of changing each feature value independently or mutually is performed, the color change,
The texture can be changed.

[Separation and Change of Color Information] Color information is generally represented by spectral reflectance. In the case of the variable-angle spectral reflectance, the spectral reflectance is determined for each variable angle, and the variable-angle spectral reflectance is calculated based on the spectral reflectance at a certain variable angle or the spectral reflectance obtained from a plurality of variable angles. The color information of the reflectance can be represented (however, excluding a case where a hue change effect is provided).

For changing the color information, for example, there is a method of changing the reflectance of each wavelength using a graphic equalizer, or a method of changing tristimulus values or Munsell values and reflecting the results on the spectral reflectance. . The method of changing the color information does not matter as long as the spectral reflectance is changed as a result.

Further, if the variable angle spectral reflectance is modeled, the variable angle of the spectral reflectance representing the color information does not need to match the variable angle for performing the color changing operation. That is, the color can be changed at an arbitrary angle.

[Separation and Change of Texture Information] There is no general method for expressing texture information. For example, the texture of the skin color may be displayed using the luminous reflectance Y for each change in angle, but it goes without saying that the Y value has color dependency, and The value of Y differs between the case of and the case of blue. Therefore, if the information of the texture is expressed using the Y value for each angle of change, it is not only difficult to change only the texture intended to change the amount or the type of the glitter material as described above, but also it becomes difficult. In addition, it is necessary to change the texture information with the color change, and the processing becomes very complicated.

Therefore, it is a technical point to extract texture information that does not depend on color. In the present method, the coefficient to be multiplied by the reference spectral reflectance (and in the method of the present invention, the reference spectral reflection Both of the coefficients added to the rate are functions of the deflection angle, and are used as texture information. Since these functions do not depend on the color and show the behavior of the glittering material, only the texture as described above can be changed, and no special processing is required when changing the color.

Some of the glittering materials exhibit a color depending on the reflection angle due to interference, and others have a coloring of the glittering material itself. The color presented by these brilliant materials is different from the color presented by the coloring pigment, which is a major factor determining the color of the skin color, and is not used as color information of the gonio-spectral reflectance, but is used as texture information. Need to be treated as part of In this method, the gonioscopic spectral reflectance reconstructed by an operation on the above-mentioned reference spectral reflectance (multiplying by a coefficient for each gonio and adding another coefficient) and the gonioscopic spectral reflectivity actually measured are calculated. Is used as texture information representing this characteristic.

The change of the texture is performed by multiplying each feature amount, which is the texture information, by a coefficient in response to the intention of strengthening or weakening the texture. Also, by replacing these characteristic amounts with the characteristic amounts of other glittering materials, it is possible to realize a change in the glittering material.

The following equation (7) shows an example of a model formula in which the variable-angle spectral reflectance is separated into a variable-angle characteristic amount and a wavelength-related characteristic amount based on the characteristics of the outer panel color. R (x, λ) = S (x, λ) + α (x) * b (λ) + β (x) + T (x, λ) (7) where R (x, λ): goniospectroscopy Reflectivity (measured value) S (x, λ): 0 ≦ x ≦ 1, S (x, λ) = R (x, λ) −R (2, λ) 1 <x, S (x, λ) ) = 0 b (λ): spectral reflectance at variable angle x ₀ with R (x
₀ , λ) α (x): When 0 ≦ x ≦ 1, α (x) = α (2) When 1 <x, b (λ) is an explanatory variable, R (x, λ) is an objective variable, and 1
Slope when the next regression is performed β (x): 0 (x) = 1, β (x) = β (2) 1 <x, b (λ) is an explanatory variable, and R (x, λ) is an objective T (x, λ): 0 (x, λ), T (x, λ) = T (2, λ) 1 <x, T (x, λ) = R (x, λ)-(α (x) * b (λ) +
β (x))

As can be understood from the above equation (7), this model has reversibility. That is, as long as the terms on the right side are not changed, the reflectance R (x, λ) as the original data can be restored.

Each term of the model equation by the equation (7) can be considered as follows. S (x): Reflected light from coating film surface α (x) * b (λ) + β (x): Reflectivity by light absorbing and reflecting material T (x, λ): By light transmitting / interfering material Reflectivity

From the viewpoint of design, b (λ) is a parameter related to color α (x), β (x) is a parameter related to flip-flop property T (x, λ) is a parameter related to color flop property You can also.

In the above equation (7), the region where the value of S (x, λ) is 0 is set to 1 <x in consideration of the measurement opening angle of the goniospectrometer (gonio 24). is there.

A certain variable angle x ₀ is set to x ₀ = 40. It is considered that the influence of the interference decreases as the deflection angle increases, considering the characteristics of the coherent material. Therefore,
x ₀ = “the largest measured deflection” is the residual component T
The coherent component can be better represented at (x, λ).
However, in actuality, measurement data with a large deflection angle has a problem in that reliability is reduced (increase in variation) due to insufficient measurement light quantity, and it is questionable to use b (λ) in the above equation. , X ₀ = 40.

The color control is performed by converting b (λ) in equation (7) to b ′ (λ)
It is expressed by changing to That is, R ′ (x, λ) = S (x, λ) + α (x) * b ′ (λ) + β
R ′ (x, λ) obtained by (x) + T (x, λ) is the variable-angle spectral reflectance after color control.

Further, α (x), β (x), T (x, λ)
, The apparent bending characteristic can be changed. For example, coefficients ka, kb, and kt for controlling the strength of the flip-flop property and the color flop property are introduced, and α ′ (x) = ka * α (x) β ′ (x) = kb * β (x) T R '(x, λ) = S (x, λ) + α' (x) * b '(λ) + (x, λ) = kt * T (x, λ)
By calculating β ′ (x) + T ′ (x, λ), a variable-angle spectral reflectance with different color and variable-angle characteristics is obtained.

Next, a process of reconstructing a paint color by performing color control and material control will be described with reference to the flowchart of FIG.

When the power switch (not shown) of the computer graphics apparatus including the personal computer 16 is turned on and the processing shifts to the processing for reproducing the paint color, the processing routine shown in FIG. 9 is executed.

In step 102, the goniometer 24 measures the variable-angle spectral reflectance R of the outer color plate. Next, after removing noise from the measurement data in step 104, a feature amount is extracted in the next step 106. In this step 104, a noise component in the measurement data is removed by a selective smoothing process. Step 106
Then, S (x, λ), α (x), β (x), b (λ),
Calculate T (x, λ). In the next step 108, at least one of color control and material control is performed using the extracted feature amount, and in the next step 110, the variable-angle spectral reflectance is reconstructed. In this step 108, α ′
(x), β ′ (x), b ′ (λ), T ′ (x, λ) are determined. In step 110, S (x, λ), α ′
(x), β ′ (x), b ′ (λ), T ′ (x, λ) to R ′
(x, λ) is calculated. In the next step 112, an image of the paint color based on the reconstructed variable angle spectral reflectance is displayed. In the next step 114, it is determined whether or not the paint color of the displayed image is the intended paint color by the determination instruction input (OK / NG) of the keyboard 10, and steps 108 to 108 are performed until the paint color becomes the intended paint color. Step 112 is repeatedly executed. As described above, the smoothing of the measurement data in step 104 and the extraction of the feature amount in step 106 need only be performed once for the original measurement data.

(Noise Removal of Measurement Data) Next, the details of the step 104 will be described.

When measuring the gonio-spectral reflectance of an outer color coating plate, the gonio photodetector 26 is used in a region where the gonio is large.
Becomes extremely small, and the noise component relatively increases.

When a colored image of an actual vehicle is created using the measured data of the gonio-spectral reflectance as it is (without any processing), in a portion having a large gonio with respect to direct light, the appearance due to sky light is reduced. Being dominant, the effects of noise are almost inconspicuous.

However, when the measurement data is directly applied to the model formula in this embodiment, the noise component is T
(X, λ) is concentrated and stored. When color control is performed, the newly determined b ′ (λ) becomes the original b (λ).
If it is smaller, the noise component in R ′ (x, λ) obtained by the reconstruction will increase relatively. this is,
This is because the noise component is stored in T (x, λ) as an absolute amount, so that T (x, λ) is also used at the time of reconstruction. Therefore, in this embodiment, it is preferable to perform noise removal processing on the measurement data.

As described above, the noise component relatively increases when the amount of light incident on the gonio light receiver is small. Therefore, it is sufficient to perform the noise removal processing only when the amount of incident light is small.
The quantity of light incident on the light receiving sensor itself cannot be known. For this reason, in this embodiment, switching of the noise removal processing is performed according to the luminous reflectance Y under the C light source at each angle of change.

The noise removal was performed by a smoothing process using a two-dimensional filter. When such a two-dimensional filter is used, the processing of the data edge becomes a problem. In the present embodiment, the map shown in the following Table 1 is used to deform (delete) the shape of the filter according to the shape of the data edge. )
The method was adopted.

[0094]

[Table 1]

That is, if an arbitrary reflectance R (x, λ) is defined as a reflectance r [x] [y], the reflectance r ′ [x] [y] after noise removal is (x−5). y-1) to (x +
When data exists in the entire range of (5, y + 1), it can be expressed by the following equation (8).

[0096]

(Equation 2)

Considering the end of the data, (x−v
If data exists in the entire range from (i, y-vj) to (x + ui, y + uj) (vi, ui <= 5 and vj, uj <= 1), the following equation (9) is used. Can be represented by

[0098]

(Equation 3)

In the present embodiment, the switching of the noise removal processing in step 104 is turned on when the luminous reflectance Y at all the variable angles (ie, vi to ui) in the mask range is equal to or smaller than the set threshold value. Noise removal processing is performed), and the others are off.

In the actual measurement data, a sharp change in the reflectance is observed near the deformation angle of 0 °. That is, a high frequency component exists. For this part, the application of the mask makes the rise in reflectivity fluctuate, which is undesirable. That is, high frequency components to be stored are cut off. In the present embodiment, the noise removal processing is not performed around the variable angle of 0 ° due to the switching processing described above, so that the undesirable high-frequency component cut is avoided.

(Extraction of Feature Amount) Next, step 10
6 will be described in detail.

Α (x), β in the range where the variable angle x is 2 ° or more
The feature amounts of (x) and T (x, λ) are obtained by performing a first-order regression for each variable angle using R (x, λ) as an objective variable and b (λ) as an explanatory variable. That is, the slope of the primary regression result is α (x), the intercept is β (x), and the residual is T (x,
λ). At this time, b (λ) is the spectral reflectance R (40, λ) at the variable angle of 40 °. Also, S within this range
(X, λ) is set to 0.

[0103] R (x, λ), b (λ) and linear regression relating, as described below, R for a certain wavelength lambda ₁
Considering the value of (x, λ ₁ ) and the value of b (λ ₁ ) as one data set, two measured value groups (R (x, λ) and b (Λ)).

<Primary regression with respect to R (x, λ) and b (λ)> For a variable angle x, Table 2 shown below is assumed.

[0105]

[Table 2]

In FIG. 10A, the explanatory variable x is plotted on the horizontal axis,
The data distribution in which the data in Table 2 above is plotted on two-dimensional coordinates with the objective variable y set on the vertical axis is shown. The primary regression is an operation for finding a straight line that has the highest correlation (applies) to the data distribution in FIG. 10A (FIG. 10B).
reference). That is, the slope α and the intercept β are determined.

When the variable angle x is in the range of 0 ° to 1 °, S
(X, λ) is the spectral reflectance R (x,
λ) and the spectral reflectance R (2, λ) at the variable angle of 2 °. In the model formula of the present embodiment, the spectral reflectance R (2, λ) at the variable angle of 2 ° is also α (x), β (x), b (x),
Since T (x, λ) must be represented by a feature quantity, α (x), β (x), and T (x, λ) in this displacement range are
Α (2), β (2), and T (2, λ), respectively.

That is, for 0 <x ｀ <= 1, S (x ′, λ) = R (x ′, λ) −R (2, λ), and R (2, λ) = α (2) * B (λ) + β (2) + T
(2, λ), S (x ′, λ) = R (x ′, λ) − (α (2) * b
(Λ) + β (2) + T (2, λ)). When rewritten into a form representing the spectral reflectance for each variable angle, R (x ′, λ) = S (x ′, λ) + (α (2) * b
(Λ) + β (2) + T (2, λ)), so that R (x, λ) = S (x, λ) + α (x) *, which is a general form in which the value of the deflection angle x is not limited. b (λ) + β
Compared with (x) + T (x, λ), α (x ′) = α (2) β (x ′) = β (2) T (x ′, λ) = T (2, λ)

FIG. 1 shows details of the feature amount extraction processing described above.
1 will be further described with reference to the flowchart of FIG. In step 202 of FIG. 11, the spectral reflectance R (4
0, λ), that is, a discrete value D [i] (1 ≦ i ≦ 35, that is, 390 nm to 73) for each wavelength at which b (λ) is measured.
(Corresponding to data every 10 nm at 0 nm)
The average value Davg is obtained using the following equation (10).

[0110]

(Equation 4)

In the next step 204, the variance Dsxx of D [i] is obtained using the following equation (11).

[0112]

(Equation 5)

Next, at step 206, 2 <x ≦ 9
For each variable angle x of 0, the spectral reflectance R (x,
λ) is measured at each discrete wavelength R [x] (i: 1 ≦≦
i ≦ 35), and the average value Ravg [x] is obtained using the following equation (12).

[0114]

(Equation 6)

In the next step 208, D [i] and R
The covariance Rsxy of [x] [i] is obtained using the following equation (13).

[0116]

(Equation 7)

In the next step 210, the gradient α [x] is obtained using the following equation (14). α [x] = Rsxy [x] / Dsxx (14)

In the next step 212, the intercept b [x] is obtained using the following equation (15). β [x] = Ravg [x] −α [x] * Davg (15)

In the next step 214, the residual component T
[X] [i] is obtained using the following equation (16).

T [x] [i] = R [x] [i] − (α [x] * D [i] + β [x]) (16)

Next, at step 216, S [x]
[I] is set to 0 (S [x] [i] = 0.0), and in the next step 218, for each variable angle x of 0 ≦ x ≦ 1, S [x] [i] is It is determined using equation (17).

S [x] [i] = R [x] [i] −R [2] [i] (17)

In the next step 220, the values calculated as described above are converted into α [x], β [x], T [x].
Set to [i].

Α [x] = α [2] β [x] = β [2] T [x] [i] = T [2] [i]

Next, in the step 108, when color control is performed, it is realized by replacing b (λ) with another b ′ (λ). A method of converting b (λ) into b ′ (λ) (color control man-machine interface) is omitted. In an experiment described later, b (λ) of another coated plate is changed to b ′ (λ)
And

When material control (apparent) is performed, a part or all of α [λ], β [λ], and T [x, λ] are replaced with another α ′ [λ], This is realized by replacing β ′ [λ] and T ′ [x, λ]. As in the case of the above color control, the conversion method is omitted. In the experiments described below,
α [λ], β [λ], and T [x, λ] represent ka and k respectively.
b ′, kt and α ′ [λ], β ′ [λ], T ′
[x, λ].

Next, in the reconstruction of step 110,
The variable-angle spectral reflectance after the color control and the material control are obtained by calculating R ′ (x, λ) according to a model formula.

FIG. 12 and FIG.
The experimental results of the effect of the noise removal processing of No. 04 and the effect on the chromaticity are shown.

FIG. 12A shows the distribution of the spectral reflectance before the noise removal processing, and FIG. 12B shows the distribution of the spectral reflectance after the noise removal processing. FIG. 12 (C)
12 (E) show the effects and influences at each angle change before and after the noise removal processing, FIG. 12 (C) shows L * at each angle change, and FIG. 12 (D) shows the L * at each angle change. a * and b * are shown in FIG.
2 (E) shows the color difference for each change in angle.

When comparing FIGS. 12A and 12B, it is understood that the effect of the noise elimination processing is remarkable. Further, from FIGS. 12C and 12D, it is understood that the noise removal processing has little effect on the chromaticity.

FIGS. 13A and 13B show the spectral distribution obtained from the data before the noise removal processing.
(A) shows α (x) and β (x), and FIG. 13 (B) shows T (x, λ). FIGS. 13C and 13D show spectral distributions obtained from data after the noise removal processing, and FIG. 13C shows α (x) and β (x).
3 (D) shows T (x, λ). As can be understood from FIG. 13, a stable α
(X), β (x) and T (x, λ) are obtained.

Next, FIGS. 14 and 15 show various characteristic amounts obtained for each type of glittering material. Α for each glitter material
Table 3 below shows the relationship between (x), β (x), and T (x, λ).
Shown in

[0133]

[Table 3]

The following features can be obtained from FIGS. Features: For solids, α (x) is 1.0, β
(X). Both T (x, λ) are almost constant at 0.0. This is a well-known solid characteristic (because only the light-absorbing material is used, the spectral reflectance becomes almost uniform outside the regular reflection area).
(See FIGS. 14A and 14B).

Characteristic: For mica and mica metallic, T (x, λ) is non-zero, and the smaller the deflection angle, the larger the amplitude. This indicates the coherence of the glitter material (see FIGS. 14 (F) and 14 (H)).

Characteristic: For MIO, T (x, λ) is almost as small as solid (see FIG. 15B).

Features: About White Pearl Mica
The coherence of the glittering material is well reproduced at T (x, λ) (see FIG. 15D). In addition, T
The reason why the polarity of (x, λ) is reversed is that the spectral reflectance of the variable angle of 40 ° is used as b (λ).
It is believed that the use of a spectral reflectance of 0 ° eliminates polarity reversal.

(Color Control and Material Control) Next, FIGS. 16 to 18 show the results of experiments performed on color control and material control. FIG. 16 to FIG. 18 show chromaticity diagrams of the coated plate on which the color control and the material control are performed and the control result. In this experiment, control is performed on the basis of the painted plate 1 for a total of four sets of two painted plates of similar colors made of the same kind of brilliant material shown in Table 4 below, and this is equivalent to creating the painted plate 2. . That is, from the reflectance R1 (x, λ) of the coated plate 1, S1 (x,
λ), α1 (x), β1 (x), b1 (λ), T1
(X, λ) is obtained to extract the feature amount, and from the reflectance R2 (x, λ) of the painted plate 2 to S2 (x, λ), α2
(X), β2 (x), b2 (λ), and T2 (x, λ) are obtained to extract feature amounts. Of the extracted features,
S1 (x, λ), α1 (x), β1 (x), T of painted plate 1
1 (x, λ) and the reflectance R1 ′ (x, λ) of the new coating color using the b2 (λ) of the coating plate 2 as described above.

[0139]

[Table 4]

FIGS. 16A to 16F are chromaticity diagrams of 3K4 painted plate 1 and 3K3 painted plate 2, which are set 1 in Table 4, and chromaticities of control results obtained by performing color control and material control. It shows. FIG. 16A shows 3K4 painted plate 1 (dotted line) and 3K3
FIG. 16 shows L * for each deflection angle for the painted plate 2 (solid line) of FIG.
(B) shows each a * and b * for each deflection angle. FIG.
In (C), L * for each angle of deformation of the 3K3 painted plate 2 is represented by a solid line.
L * as a result of performing color control on the coated plate 1 of K4 is indicated by a dotted line. FIG. 16 (D) shows a *,
b *, a * of the result of performing color control on the 3K4 coated plate 1,
b *. In FIG. 16E, L * for each angle of deformation of the 3K3 painted plate 2 is shown by a solid line, and L * as a result of performing color / material control on the 3K4 painted plate 1 is shown by a dotted line. FIG. 16 (F)
Shows a * and b * for each angle of deformation of the 3K3 painted plate 2 and a * and b * as a result of performing color / material control on the 3K4 painted plate 1.

FIGS. 17A to 17F are chromaticity diagrams of the painted plate 1 of 8E3 and the painted plate 2 of 8J4, which are set 2 in Table 4, and the chromaticity of the control result obtained by performing color control and material control. FIG. FIG. 17A shows 8E3 painted plate 1 (dotted line) and 8J
4 shows the L * for each angle of deformation for the painted plate 2 (solid line) of FIG.
FIG. 7 (B) shows a * and b * for each deflection angle. FIG.
In (C), L * for each deflection of the 8J4 painted plate 2 is represented by a solid line,
L * as a result of performing color control on the coated plate 1 of E3 is indicated by a dotted line. FIG. 17 (D) shows a *,
b *, a * of the result of performing color control on the 8E3 coated plate 1,
b *. In FIG. 17 (E), L * for each change in angle of the 8J4 painted plate 2 is shown by a solid line, and L * as a result of performing color and material control on the 8E3 painted plate 1 is shown by a dotted line. FIG. 17 (F)
Shows a * and b * for each angle of deformation of the 8J4 coated plate 2 and a * and b * as a result of performing color and material control on the 8E3 coated plate 1.

FIGS. 18 (A) to 18 (H) show 4K9 painted plate 1 and 4L5 painted plate 2 and 8G, which are set 3 and set 4 in Table 4, respectively.
FIG. 3 shows a chromaticity diagram of a painted plate 1 of No. 2 and a painted plate 2 of 8J6, and a chromaticity diagram of a control result obtained by performing color control and material control. FIG. 18 (A) shows L * for each change in angle for a 4K9 painted plate 1 (dotted line) and a 4L5 painted plate 2 (solid line).
Shows a * and b * for each deflection angle. In FIG. 18 (C), L * for each change angle of the 4L5 painted plate 2 is indicated by a solid line, and L * obtained by performing color control on the 4K9 painted plate 1 is indicated by a dotted line. FIG.
(D) shows a *, b * for each deformation angle of the 4L5 painted plate 2 and 4
A * and b * as a result of performing color control on the coated plate 1 of K9 are shown. FIG. 18E shows an 8G2 painted plate 1 (dotted line).
L * for each angle change is shown for the painted plate 2 (solid line) of 8J6, and a * and b * for each angle change are shown in FIG.
In FIG. 18 (G), L * for each deformation angle of the 8J6 painted plate 2 is indicated by a solid line, and L * as a result of performing color control on the 8G2 painted plate 1 is indicated by a dotted line. FIG. 18 (H) shows a * and b * for each deformation angle of the 8J6 painted plate 2 and a * and b * as a result of performing color control on the 8G2 painted plate 1.

As understood from these figures, good results were obtained for color control and material control.

As described above, the skin color can be represented by the reflectance at each angle and each wavelength (variable angle spectral reflectance). In the above, for ease of controlling the color and texture, a model formula separated into a feature value related to the deflection angle and a feature value related to the wavelength is illustrated, but the present invention is not limited to the above model formula. , And a method for facilitating control of color and texture.

The following description has the following definitions. [Definition] x: Reflected light angle X: Reference specific deflection angle λ: Wavelength R (x, λ): Deflection spectral reflectance by actual measurement R ′ (x, λ): Deflection spectral component R by model formula '' (x, λ): Deflection spectral component by model formula

(Equation 8)

[Structure 1] The model formula is represented by the following formula (18).

(Equation 9) Regarding this equation (18),

(Equation 10) Then, for each wavelength λ, the value of the following equation (19) is

[Equation 11]

[Structure 2] The method according to Structure 1, wherein N = 1.

[Structure 3] The model formula is expressed by the following formula (20).

(Equation 12) About this equation (20),

(Equation 13) When the value of the following equation (21) is

[Equation 14] A method in which b (λ) that minimizes the feature amount is used.

[Structure 4] A method according to Structure 3, wherein N = 1.

[Structure 5] The model formula is represented by the following formula (23): R ′ (x, λ) = α (x) ^* b (λ) + β (x) (23) 23), b (λ) = R (X, λ) as a first feature amount, and for each x, the value of the following equation (24) is

(Equation 15) A method in which α (x) and β (x) that are minimized are used as the second and third feature amounts.

[Structure 6] In the method according to any one of Structures 1 to 5, T (x, λ) = R (x, λ) −R ′ (x, λ) (25) T (x, λ) is further defined as one feature quantity, and R ″ (x, λ) = R ′ (x, λ) + T (x, λ) (26) .

[Arrangement 7] In any one of Arrangement 1 to Arrangement 6, a characteristic amount other than b (λ) is obtained in advance for each luminous material type, and a characteristic amount of an arbitrary luminous material type and an arbitrary amount are determined. Method of creating a new paint color by combining with b (λ).

[Arrangement 8] In the method of any one of Arrangements 1 to 6, by changing b (λ),
A method that preserves the texture of the paint color and changes only the color.

[Structure 9] In the structure 1 or 2, m
By changing i (λ), the paint color is maintained,
A method to change only the texture.

[Structure 10] In the structure 1 or 2,
The model equation is changed to the following equation (27),

(Equation 16) A method in which only the texture is changed by adjusting the value of k to maintain the paint color.

[Structure 11] In the structure 3 or 4,
By changing Mi, the paint color is maintained, and only the texture is changed.

[Structure 12] In the structure 3 or 4,
The model equation is changed to the following equation (28),

[Equation 17] A method in which only the texture is changed by adjusting the value of k to maintain the paint color.

[Configuration 13] In Configuration 5, the model formula is changed to the following formula (29), and R '(x, λ) = kα ^* α (x) ^* b (λ) + kβ ^* β (x ) (29) A method of adjusting the values of kα and kβ to maintain the paint color and change only the texture.

[Arrangement 14] In the arrangement 6, the model equation is changed to the following equation (30), and R ″ (x, λ) = R ′ (x, λ) + k _T ^* T (x, λ ) by adjusting the value of · · · (30) k _T, the color of the paint color is retained,
A method of changing only the texture (mainly the interference light component).

[Structure 15] In the noise elimination processing of the measured variable-angle spectral reflectance data, two points in the wavelength direction and the variable-angle direction are used.
A method in which smoothing processing is simultaneously performed in the direction, and this processing is performed only for a portion having a low spectral reflectance.

[Operation of Configurations 1 to 15] According to Configurations 1 to 4, by using a model formula relating to the gonio-spectral reflection characteristics of each brilliant material included in the coating, the gonio-direction can be reduced. Accurate display and inspection of color and texture can be performed with data and measurement.

According to Configuration 1 or 2, it is a function of wavelength.

(Equation 18) Is used as a feature value, so that the difference between the measured data and the data based on the model formula is small.

According to the configuration 5, α, which is a function of the deflection angle,
(x) Since β (x) is used as the feature quantity, the difference between the actually measured data and the data based on the model formula is small.

According to the configuration 6, T mainly representing the interference light component
Since (x, λ) is used as the feature quantity, there is no deviation between the measured data and the data based on the model formula.

According to the configuration 8, by changing the spectral reflectance b (λ), which is one of the characteristic amounts, only the texture can be changed while maintaining the color.

According to the configurations 7 to 13, only the color can be changed while maintaining the texture by changing or replacing the feature amount other than b (λ).

According to the fourteenth aspect, the intensity of the interference effect can be changed by changing the characteristic amount T (x, λ).

According to the fifteenth aspect, the variable-angle spectral reflectance data is two-dimensionally smoothed only in a portion having a low reflectance, so that a steep change in reflectance near regular reflection is maintained, and a low reflectance is obtained. The noise of the section can be reduced.

Table 5 below shows correspondence between the structures 1 to 6 described above and the operation of this structure.

[0170]

[Table 5]

FIG. 19 shows the variable-angle spectral reflectances of a plurality of wavelengths (five wavelengths in FIG. 19) obtained by measuring four types of painted surfaces including various glittering materials using the methods of the above-described configurations 1 and 2. Is shown as a variable angle distribution. As can be seen from the figure, the logarithm of the gonioscopic spectral reflectance (for the diffuse reflection component) is a polynomial of the gonio (x) whose coefficient is a function of wavelength (log _mi (λ)) (in configuration 2, With the knowledge that the approximation can be accurately approximated by the linear expression), the contributions of the variable angle x and the wavelength λ to R (x, λ) in Formulas 1 and 2 are formulated by the model formula shown in Configuration 1, and m _i (λ) and b (λ) which are coefficients of x
Was proposed. That is, the model formula is not derived from general statistical processing, but is determined so that the optical characteristics of the coating can be accurately reflected.

With this model formula, the variable-angle spectral reflectance of the painted surface containing various glittering materials can be approximated with high accuracy. Configuration 2 has a lower approximation accuracy than Configuration 1, but has a smaller number of coefficients and is easier to handle. Therefore, it is effective as a model formula of a luminous material (titanium graphite, green mica, etc.) in which the angle dependence of the logarithm of the spectral reflectance is close to a straight line.

The difference of the methods 3 and 4 from the methods 1 and 2 is that the coefficient of the deflection angle (x) is calculated by a function of the wavelength (log m
_i (λ)) instead of a constant (M _i ).
That is, the glittering material that satisfies the assumption that the angular dependence of the variable-angle spectral reflectance R (x, λ) is constant regardless of the wavelength (λ) (the shape of the curve for each wavelength in FIG. 19 is similar) For example, the titanium graphite of FIG. 19B, FIG.
9 (d) MIO) provides a simpler model than the configurations 1 and 2.

As described above, the “deformation spectral reflectance (R (x,
λ)) is constant regardless of wavelength (λ). ”
It is assumed that titanium graphite, MIO
However, the adaptation range is narrow (when applied to other cases, the error increases as shown in FIG. 20, and the color and texture reproduction accuracy deteriorates). However, the parameter (b (λ)) indicating the color and the parameter (M
_i ) are completely separated and the number of parameters indicating the texture is small (N in configuration 3 and 1 in configuration 4).
The texture can be changed very easily. Therefore, for the glittering material that satisfies the above assumption, each texture can be simply represented by the parameter (M _i ), and the color and texture can be changed. However, it is not possible to change to a texture that takes into account that the degree of freedom of the change is narrow and that the brilliant material does not hold the above assumption.

FIG. 20 shows an error between each model formula and the measured data.
The difference is represented by the color difference (CIE1976 (L^*a ^*b^*) Color system, J
IS Z8730). The glittering material is shown in FIG.
Shows white mica (pigment is red), titanium graphite
(Pigment is blue) and MIO (pigment is blue). Th
The reproducibility (small color difference) of the glitter materials
1, configuration 2, and configuration 4 are superior in this order. Secondary (in configuration 1
In the case of the model of N = 2), the diffuse reflection area with a deflection angle of 15 ° or more
Error is less than 2 color difference in the area. Which glitter material
Even, it can reproduce the color and texture almost the same as the real thing
You. The titanium graphite shown in FIG.
For the MIO shown in (d), the reproduction accuracy of the model
Despite differences, color difference is 1 or less even in the case of Configuration 4.
Thus, the model of Configuration 4 can be applied. Ma
In addition, as an application example of the configuration 2, the grid shown in FIG.
On mica.

Next, the features of the above configuration 9 will be described. In the above configurations 1 and 2, b (λ) is a term that gives a spectral reflectance that does not depend on the angle of change.
_i (λ) is a term that gives the angle dependence of the spectral reflectance, and is a feature value that reflects the texture (including the angle-dependent color change due to the light interference of the glitter material) as described above. is there. Therefore, while maintaining the b (lambda), by changing the m _i (lambda), while maintaining the average color of the paint color (corresponding to the color exhibited by the color pigment), it can be changed texture. As a specific method of this change processing, the following (A) to (C)
There is.

[0177] (A) for each luminous material previously created a database of m _i (λ), replacing the pre-change m _i a (lambda) to any luminous material of m _i (λ) '. Since this corresponds to the replacement of the glittering material, it becomes relatively easy to produce a coated article having the changed color and texture.

(B) m _i (λ) is changed by a constant value (△ m _i ) to change the angle dependence of lightness. Angle dependence of lightness is closely related to texture. Characteristically, since it is only necessary to change by a constant value (△ m _i ) irrespective of the wavelength λ, the change processing is easy, and any change that is not restricted by the characteristics of the actual coating is possible. In some cases, it is not possible to produce a painted product with the changed color and texture using existing materials (shining materials). By obtaining reflection characteristics corresponding to the color and texture from the parameters (features), development of a new glittering material can be supported.

(C) Approximate _mi (λ) (model dimension is Nth order) for each luminous material with a polynomial (Mth order) of wavelength λ, and create a database of its coefficients. The coefficients are arbitrarily changed (on the N × M-dimensional space) to change the texture. The characteristics of each luminous material are represented by points in an N × M dimensional space, and changes can be made with reference to them. Note that the case where the change destination is restricted only on those points corresponds to (A). This modification method extends (B), and enables angle dependence of hue and saturation in addition to lightness. The usage and characteristics are the same as those described in (B) above.

The feature of the above configuration 11 is texture control when the spectral reflectance does not have an angle dependency (the restriction on the glittering material is the same as described in the configuration 3 or the configuration 4). The method is the same as the method (B) described above, and the same can be said for its features. However, real luminous material by selecting only values, corresponding to the replacement of the luminous material as m _i after the change.

Next, the above configurations 5, 6, 7, 8, 13, 1
The model formulas and feature values in 4 and 15 will be described.
Here, it is considered how the spectral reflectance at a certain angle changes based on the spectral reflectance at a certain angle.

In the case of a solid paint, its spectral reflectance is substantially constant except for the regular reflection angle. Specular reflection occurs only at the specular reflection angle (and the angle range obtained by adding the measurement opening angle of the goniospectrometer (Gonio 24)), the reflection intensity is extremely large, and depends on the properties and amount of the pigment inside the coating. do not do. Therefore, it is considered that all reflections at the above-mentioned reflection angle (or angle range) are specular reflections, and can be treated as a feature quantity which is not affected by color change or material change.

On the other hand, in a paint containing a brilliant material having a small hue change effect such as interference, the spectral reflectance changes in accordance with the change in angle. The present inventors have analyzed the gonio-spectral reflectance of a paint containing a glittering material having a small hue change effect, and have noticed that the spectral reflectance is substantially similar at gons other than the specular angle. This phenomenon is similar to the fact that the amount of light applied to the coating changes according to the change in the angle. Based on the fact that the appearance of an object when illuminating a certain object is determined by the product of the reflectance of the object and the light intensity, we consider using the effect of the glitter as a change in the light intensity. As a result, the method of multiplying the reference spectral reflectance by a coefficient that is a function of the angle of change could reproduce the outline of the spectral reflectance that changes according to the angle of change. Focusing on the fact that there is a parallel change in the reflectance direction in addition to a similar change between the spectral reflectances of the respective deflection angles, a function of the deflection angle is used as a reference spectral reflectance. After multiplying by a coefficient, the method of multiplying the coefficient by another coefficient, which is a function of the change in angle, was studied. As a result, it was confirmed that the spectral reflectance changing according to the change in angle was reproduced more accurately. Furthermore, as in the case of solid paint, the specular reflectance at the specular reflection angle is only the specular reflection characteristic, so that the spectral reflectance at other angles can be reproduced based on the spectral reflectance as a reference. Was completed.

This method can be regarded as modulation of the spectral reflectance as a reference. That is, the coefficient by which the reference spectral reflectance is multiplied is the amplification factor for the spectral reflectance, and the added coefficient is the bias. Amplification and bias, which are functions of the deflection angle, can be considered as characteristic values of the paint.

Further, a paint containing a glitter material having a hue change effect such as interference will be considered. As described above, these effects produce a spectral reflectance specific to the glittering material in accordance with the change in angle. In the case of a paint containing a brilliant material having no hue change effect such as interference, the spectral reflectance at each angle was obtained by modulating the reference spectral reflectance. The spectral reflectance of the brilliant material having the effect is different from the reference spectral reflectance, and is not reproduced by modulation. Conversely, components that could not be reproduced by the above-described modulation of the spectral reflectance as the reference can be considered to be the effect of the color or interference of the glitter material itself, that is, the hue change effect. Therefore, the difference between the original variable-angle spectral reflectance and the variable-angle spectral reflectance obtained by modulating the reference spectral reflectance can be considered as a feature amount of the hue change that is a function of the variable angle and the wavelength. .

As described above, the present method is to extract the characteristic amount from the individually measured variable-angle spectral reflectance, and there is no need to prepare in advance any constant or characteristic amount for each glitter material. It is immediately applicable to glittering materials. In addition, by introducing the feature value of the hue change, the actually measured gonio-spectral reflectance and the gonio-spectral reflectance reconstructed from each feature value completely match, and the smoothness from the actually measured skin color is obtained. Color change and texture change are possible.

Next, the effect of reducing the data amount by the configurations 5 and 6 will be described. According to this model formula, for a solid paint and a paint containing a glittering material having no hue change effect,
The feature amount can be expressed with a small data amount, and the data amount for reproducing the variable-angle spectral reflectance can be reduced.

For example, the variable angle spectral reflectance is changed from 0 to 90.
Degree (in 1 degree increments), spectral reflectance 390 to 730 nm (1
When measured at 0 nm intervals), the data number is 91 * 3
5 = 3185 real numbers (reflectance). However, according to this method, one reference spectral reflectance (35 pieces) and amplification rate and bias (91 pieces *
Only 2) is a total of 217 real numbers, and the data amount can be reduced to about 6.8% of the original number.

On the other hand, in the case of a paint containing a glittering material having a hue change effect, a characteristic amount of hue change is required, and the data amount cannot be reduced. However, in practice,
The characteristic amount of hue change is obtained from the original gonio-spectral reflectance, and only when the value is so large that it cannot be ignored, this characteristic amount may be stored, and the gonio-spectral reflectance of many paint colors is stored. In this case, the effect of data reduction by this method can be obtained.

Next, the noise removal of the variable angle spectral reflectance by the configuration 15 will be described. The bend spectral reflectance can be plotted in three dimensions: the bend axis, the wavelength axis orthogonal to it, and the reflectivity axis perpendicular to the plane containing those axes. Since the outer-plate color paint is composed of a pigment having no sharp change in reflectance in the wavelength direction, the change is gentle in the wavelength direction of the variable-angle spectral reflectance. Considering that in terms of signal frequency, the frequency of the change in the wavelength direction of the skin color paint is low, and conversely, if the measured data contains a high frequency component, , Measurement variation components, which are considered to be removed. Such removal of high-frequency components can be generally performed by a smoothing process.

On the other hand, the change in the angle of change is gentle except in the vicinity of specular reflection, but the change is sharp in the vicinity of specular reflection. Therefore, in the method of changing the angle, it is possible to remove the noise by the above-described smoothing process other than near the regular reflection, but it is inappropriate to perform the process near the regular reflection. (If this is done, it will result in distorting the original measured value instead of removing the noise.) Also, if the amount of light is small, the measured value tends to fluctuate. When the amount is large, there is a characteristic that the variation hardly occurs. When this is compared with the above-mentioned change in the bending direction, it is considered that there is little variation in the measured value in the vicinity of the regular reflection where the reflectance is high, and it is not necessary to perform the filtering process.

Therefore, by performing two-dimensional smoothing processing on the variable-angle spectral reflectance data to be processed only when the reflectance value is low, the data in the wavelength direction and the variable-angle direction can be obtained. A highly effective noise elimination using both of the data to be performed can be realized.

Next, a description will be given of a method of extracting feature values in the method of the fifth or sixth configuration. First, a flat painted plate coated with the original outer plate color is applied to a goniospectrophotometer to measure the goniospectroscopic reflectance. In this measurement, for example, the incident angle of light is 60 degrees with respect to the normal line of the painted plate, and the light receiving angle (that is, the deflection angle) of light is 0.
(Specular reflection) in 1 degree increments at 90 degrees, 3 for each deflection angle
What is necessary is just to obtain the reflectance from 90 to 730 nm every 10 nm. Thereafter, the data obtained by the above measurement is input to a computer, and a noise removal process is performed. The procedure of this processing is as follows. For each variable angle, the luminous reflectance Y is determined from the spectral reflectance of the variable angle, and when the luminous reflectance Y is smaller than a predetermined value, the spectral reflectance of the variable angle is determined. Performs smoothing processing on the rate data in the deflection direction and wavelength direction,
The result is used as spectral reflectance data from which noise removal has been completed. In this case, the luminous reflectance Y was used to determine whether or not to perform the smoothing process. However, if the value is related to the amount of light incident on the light receiver of the goniospectrophotometer, another value is used. It is also possible to use the sum of the reflectances of the respective wavelengths, for example, for the spectral reflectance for each angle of change.

After the noise removal is completed, the spectral reflectance at the variable angle of 40 degrees is set as the reference spectral reflectance. The reference spectral reflectance is used as a feature value relating to color. In this case, the spectral reflectance of the variable angle of 40 degrees is used, but the spectral reflectance of another variable angle may be used. It is desirable that the reference spectral reflectance be less affected by the glittering material, and from that viewpoint, it is desirable that the spectral reflectance be as large as possible with a variable angle. However, on the other hand, when the deflection angle is large, the reflectance becomes very low, and sufficient measurement accuracy cannot be obtained in many cases. Therefore, under the present circumstances, it is necessary to use a spectral reflectance with a large deflection angle as long as sufficient measurement accuracy can be obtained, and this is accompanied by an improvement in accuracy of the measuring instrument. A larger deflection spectral reflectance should be used.

After that, processing relating to the regular reflection area is performed.
That is, a difference between the spectral reflectance of 0 degree and the spectral reflectance of 1 degree and the spectral reflectance of 2 degrees of variable angle is obtained, and the difference is defined as a regular reflection light component at each angle (0 degree and 1 degree). In this case, 0
Although this processing was performed for the degree and the degree, the specularly reflected light is generated only at the specular reflection angle (that is, 0 degree) in principle. This is because the measurement opening angle of the spectrometer was considered. If an ideal measuring device is used, this process may be a process of calculating a difference between a spectral reflectance of 0 degree and a spectral reflectance of 1 degree.

Thereafter, the characteristic amount relating to the texture is obtained. For each variable angle of 2 degrees or more, the reflectance of each wavelength is used as the objective variable, and the reflectance of each wavelength of the reference spectral reflectance is used as an explanatory variable, linear regression is performed, and the slope and intercept of the result are calculated as follows: The characteristic amount of the texture at the deflection angle is used. The slope is a coefficient to be multiplied by the reference spectral reflectance, and the intercept is a coefficient to be added after multiplying the reference spectral reflectance by the previous coefficient. The inclination and intercept are obtained for each of the variable angles, and each is defined as a function of the variable angle, and is defined as a first characteristic amount and a second characteristic amount related to the texture. For these values of 0 ° and 1 °, 2 ° is substituted.

Further, for each displacement angle of 2 degrees or more, the spectral reflectance is reconstructed from the first and second feature values relating to the texture and the feature value relating to the color, and its value and the original (actually measured) displacement angle are reconstructed. Is determined for each wavelength, and that value is defined as the third characteristic amount relating to the deflection angle and the texture at that wavelength.
This processing is performed for each angle and wavelength of 2 degrees or more to make this feature a function of the angle and wavelength.
For these values of 0 ° and 1 °, the angle 2
Assign a value to degrees.

When the third feature value relating to the texture is smaller than the predetermined value at all the deflection angles and all the wavelengths, this feature value is omitted, and the first and second feature values relating to the color feature value and the texture are obtained. It is possible to store only the characteristic amount of No. 2 and roughly reproduce the original variable-angle spectral reflectance.

Next, a description will be given of a color changing method using the methods of the constitutions 5, 6, and 8. It is assumed that the feature amount has been extracted by the above method.

[0200] The color change is based on the characteristic amount of the color (in this case,
This is realized by changing the spectral reflectance at a variable angle of 40 degrees). The characteristic amount relating to the color after the change is obtained by multiplying the first characteristic amount relating to the texture (function of the variable angle) for each of the variable angle and each wavelength, and the second characteristic amount relating to the texture (the function of the variable angle). 3 is added (the function of the change in angle and the wavelength), and especially for the change in the angle of 1 degree or less, the texture is maintained and the color is changed by adding the regular reflection component (the function of the change in the angle and the wavelength). Is obtained.

The present embodiment does not ask the means for changing the characteristic amount relating to the color, but may use any means as long as the characteristic amount relating to the color is eventually changed. For example, the reflectance for each wavelength may be increased or decreased by a graphic equalizer, or this feature may be converted into a tristimulus value or a Munsell value,
After performing a change operation on those values, a feature amount regarding the color changed from the changed tristimulus value or Munsell value may be obtained by using a known neural network or the like.

It is also possible to replace the feature quantity relating to the color with a feature quantity relating to a color extracted from another paint color, instead of changing the feature quantity relating to the color. It is also possible to use the calculated spectral reflectivity or the spectral reflectivity generated by calculation as a feature quantity relating to color.

Further, the spectral reflectance to be operated for color change may be any of the deflection angles for which the respective characteristic amounts are obtained.
For example, when the spectral reflectance at a variable angle of 40 degrees is used as a feature amount for changing to a color, the color can be changed for the spectral reflectance at a variable angle of 20 degrees. In this case, a color-related feature quantity (that is, a spectral reflectance at a variable angle of 40 degrees) may be calculated such that the spectral reflectance at the variable angle of 20 degrees becomes the specified (after color change) spectral reflectance. . Needless to say, at this time, the feature amount regarding each texture is not changed.

These color changing operations may be performed while looking at the R plate or the image of the car created based on the variable angle spectral reflectance to be changed. In this case, the color changing operation is performed. Immediately after the operation, it is desirable to reconfigure the changed spectral reflectance after the change and perform the operation while interactively checking the result of the change.

Next, a method of changing the texture will be described. It is assumed that the feature amount has been extracted by the above method.

[0206] The texture change is realized by changing the characteristic amounts of the three textures. After the change, the color-related feature amounts are, for each reflection angle and each wavelength, a second feature amount (a function of the variable angle) and a changed third feature amount (a function of the variable angle and the wavelength) related to the changed texture. In particular, for a deflection angle of 1 degree or less, the specular reflection component (a function of the deflection angle and the wavelength) is further added to maintain the color and change the texture reflection factor. can get. Of course, any one or two of the three characteristic amounts may be changed.

A part of the present invention is to provide a method for changing the characteristic amount relating to three textures. For example, when the saturation / brightness / difference (flip-flop feeling) accompanying the change in the deflection angle is increased, the deflection angle is changed. Constants that do not depend on the texture
By multiplying the characteristic amount of, the characteristic amount can be changed. In the case where only the contrast is enhanced, the second characteristic amount related to the texture is multiplied by a constant coefficient independent of the deflection angle. What is necessary is just to change the characteristic amount. Further, in order to enhance the effect of the hue change accompanying the change in the angle of change, the third characteristic amount relating to the texture is multiplied by a constant coefficient independent of the angle of change and wavelength. What is necessary is just to change the characteristic amount. These methods are one of the simplest and most effective methods of changing the characteristic amount related to the texture for changing the texture.However, the present invention does not ask any means for changing the characteristic amount related to the texture. Even if it is used, it suffices if the characteristic amount related to the texture is changed as a result. For example, the first feature value relating to the texture for each variable angle may be increased / decreased by a graphic equalizer. In particular, for the third feature value relating to the texture, a component in the wavelength direction for each variable angle may be spectrally separated. Considering the reflectance, the values corresponding to the tristimulus values and the Munsell values for each deflection angle are determined from the spectral reflectance, and these values are displayed on a graph with the horizontal axis being the deflection angle. It may be increased or decreased by an equalizer. As a method of calculating the spectral reflectance from the changed Munsell value, the method described above in the description of the change of the feature amount regarding the color can be applied. Furthermore, there is a method of multiplying these texture-related features by a coefficient that is a function of the deflection angle,
In that case, for example, it is possible to change the texture such that the flip-flop feeling is increased in an area near regular reflection and the effect is weakened in an area far from regular reflection.

It is also possible to replace the characteristic amounts relating to the textures with the characteristic amounts relating to the textures extracted from other paint colors instead of changing them. In this case, all the characteristic amounts relating to the three textures are replaced. As a result, all the textures are exchanged, and, for example, by replacing only the third feature value relating to the texture, it is possible to replace only the effect of the hue change with that of another paint. Furthermore,
It is also possible to use a value generated computationally as a characteristic amount related to the texture.

[0209] These texture changing operations may be performed while viewing the image of an R-painted plate or a car created based on the variable-angle spectral reflectance to be changed. In this case, the texture changing operation is performed. After that, immediately reconstruct the changed spectral reflectivity after the change,
It is desirable to perform the operation while interactively checking the result of the change.

The embodiment of the present invention has been described above. The embodiment of the present invention has the following aspects in addition to the requirements described in the claims.

[Embodiment 1] With respect to the coating color of the coating surface formed on the object to be coated, the spectral reflectance at each angle of change in which the light receiving angle when receiving the reflected light of the coating color is changed is measured. From the spectral reflectance for each angle, a first characteristic amount dependent on the spectral wavelength and one or more characteristic values independent of the deflection angle are obtained, and the value of the received light angle is raised to the power of one or more predetermined coefficients. One or more values obtained by raising the characteristic value to the power are obtained from the one or more values obtained as a result, and this is used as a second feature amount. The one or more second feature amounts and the first A paint color reproduction method that reconstructs the spectral reflectance for each angle of change by calculating the product of the characteristic amount and the characteristic amount.

More specifically, as described in the above configuration 1 or 2, the model formula is represented by formula (18), and b (λ)
As the first feature value,

[Equation 19] Is defined as a second feature value.

[Embodiment 2] With respect to the coating color of the coating surface formed on the object to be coated, the spectral reflectance at each variation angle at which the light receiving angle when receiving the reflected light from the coating surface is measured, and this variation is measured. From the spectral reflectance for each angle, a first characteristic amount dependent on the spectral wavelength, and from the first characteristic amount and the spectral reflectance for each of the deflection angles, one or more spectral wavelengths are obtained for each of the deflection angles. Instead, a third characteristic amount that is a constant value is obtained, and a product of the first characteristic amount and one or more third characteristic amounts, or a product and a sum thereof are obtained, thereby obtaining a spectral value for each angle of change. A paint color reproduction method that reconstructs reflectance.

More specifically, as described in the above configuration 5, the model formula is expressed by formula (23), b (λ) is used as the first feature value, and α (x) and β (x ) Is a third feature value.

[Embodiment 3] With respect to the coating color of the coating surface formed on the object to be coated, the spectral reflectance is measured for each variation angle at which the light receiving angle when receiving the reflected light from the coating surface is measured. From the spectral reflectance for each angle, a first characteristic amount dependent on the spectral wavelength, and from the first characteristic amount and the spectral reflectance for each of the deflection angles, regardless of one or more spectral wavelengths and the deflection angle. A characteristic value to be a constant value is obtained, and at one or more values obtained by raising the value of the light receiving angle by one or more predetermined coefficients, the spectral wavelength is changed for each deflection angle obtained by raising the characteristic value to the power. In this case, one or more values that are constant values are obtained, and the obtained values are used as a fourth feature amount, and the product of the one or more fourth feature amounts and the first feature amount is obtained. A paint color reproduction method that reconstructs each spectral reflectance.

More specifically, as described in the above configuration 3 or 4, the model formula is represented by formula (20), b (λ) is set as the first feature value, and

(Equation 20) Is the fourth feature value.

[Embodiment 4] The spectral reflectance for each of the deflection angles reconstructed by the method of the above-described Embodiments 1, 2, and 3 and the measured spectral reflectance for each of the deflection angles are shown for each of the deflection angle and the spectral wavelength. A paint color for reconstructing a spectral reflectance for each angle of change by obtaining a fifth characteristic amount determined by the difference and obtaining the sum of the reconstructed spectral reflectance for each angle of change and the fifth characteristic amount. How to reproduce.

More specifically, as described in the above configuration 6, when expressing the model equation by equation (26), T (x, λ) expressed by equation (25) is used as the fifth feature quantity. I do.

[Embodiment 5] A paint color changing method for changing the color of the paint color by changing the first feature value obtained by the method of the above embodiments 1, 2, 3 and 4.

[Embodiment 6] The second feature amount, the third feature amount, and the second feature amount obtained by the methods of the first, second, third, and fourth embodiments are described below.
A paint color changing method for changing the texture of the paint color by changing the fourth feature value and the fifth feature value.

[Embodiment 7] In the method of the above Embodiments 1, 2, 3 and 4, the smoothing process is performed simultaneously on the measured spectral reflectance for each of the deflection angles in the two directions of the spectral wavelength direction and the deflection angle direction. A method of reducing the noise component of the measured spectral reflectance for each variable angle by controlling according to the value of the spectral reflectance.

In the above embodiment, the case where an image is displayed using the new or reconstructed variable-angle spectral reflectance has been described. However, the present invention is not limited to the display of an image. For example, the application of a composition that requires setting of the mixing ratio of pigments requiring skill is applied to computer color matching (CCM), which is obtained by computer calculation as a composition of basic color materials (colorants such as pigments) according to the Kubelka-Munk theory. Is possible. In the CCM, a computer calculates a mixing ratio of a plurality of pigments having known reflectances so as to match the reflectance of a color sample measured by a spectrophotometer or the like. As another example, in order to reproduce the paint color intended by designers and users, CCM
Can be applied to the case where the mixing ratio of the colorant is determined by using the formula (1).

[0223]

As described above, according to the present invention, the first characteristic value dependent on the spectral wavelength and the second characteristic value dependent on the variable angle are obtained by using the variable-angle spectral reflectance of the object to be coated. Since the coating color of the object to be coated is reproduced by obtaining the characteristic amount, there is an effect that the coating color of the object to be coated can be changed to the intended color and texture.

[Brief description of the drawings]

FIG. 1 is an image diagram conceptually showing steps of a color and texture control method according to an embodiment.

FIG. 2 is an image diagram for explaining the concept of color change and texture change.

FIG. 3 is a schematic configuration diagram of a computer graphics device for reproducing a paint color including the personal computer of the present embodiment.

FIG. 4 is a conceptual diagram for explaining a configuration of a gonio.

FIG. 5 is a diagram showing a coordinate system for explaining a deflection angle used in the present embodiment.

FIG. 6 is an explanatory diagram for explaining that reflectance is treated approximately.

FIG. 7 is an image diagram showing a configuration of a painted surface, and FIG.
Is a metallic painted surface, (b) is a pearl mica painted surface,
(C) shows a solid painted surface.

FIG. 8 is an explanatory diagram for explaining the behavior of light by a light transmitting / interfering material.

FIG. 9 is a flowchart showing a flow of processing for reconstructing a paint color.

FIG. 10 is a diagram used to explain first-order regression.

FIG. 11 is a flowchart illustrating details of a feature amount extraction process.

FIG. 12 is a diagram showing experimental results of effects of noise removal processing and effects on chromaticity.

FIG. 13 is a diagram showing experimental results of effects of noise removal processing and effects on chromaticity.

FIG. 14 is a diagram showing various characteristic amounts obtained for each brilliant material type.

FIG. 15 is a diagram showing various characteristic amounts obtained for each glitter material type.

FIG. 16 is a diagram showing chromaticity diagrams of a 3K4 painted plate and a 3K3 painted plate.

FIG. 17 is a diagram showing chromaticity diagrams of a painted plate of 8E3 and a painted plate of 8J4.

18 (A) to (D) are diagrams showing chromaticity diagrams of a 4K4 painted plate and a 4L5 painted plate, and (E) to (H) are 8G2.
FIG. 3 is a diagram showing a chromaticity diagram of a painted plate of No. 8 and a painted plate of 8J6.

FIG. 19 is a diagram showing a bend distribution of a bend spectral reflectance of a plurality of wavelengths measured on a painted surface.

FIG. 20 is a diagram illustrating the relationship between the color difference and the error between the measured angle and the measured data according to the model formula.

[Explanation of symbols]

 16 Personal computer 24 Gonio

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Hattori 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Yuji Uchiyama 1 share of 41 Ochimichi, Yakumichi, Nagakute-cho, Aichi-gun, Aichi Prefecture (72) Inventor Toshi Ishihara 41 in Ochimichi, Nagakute-cho, Aichi-gun No. Kansai Paint Co., Ltd. (56) References JP-A-5-324850 (JP, A) JP-A-4-88584 (JP, A) JP-A-64-79889 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G06T 15/00-15/70 G06F 17/50 JICST file (JOIS)

Claims (7)

(57) [Claims] 1. A measuring means for measuring a variable-angle spectral reflectance as a spectral reflectance for each variable angle obtained by changing a light-receiving angle for receiving reflected light from an object to be coated, and a variable-angle spectrum measured by the measuring means. A first feature value dependent on the spectral wavelength using the reflectance, and a second feature value dependent on the deflection angle.
Characteristic amount calculating means for calculating the characteristic amount of the first characteristic amount and the second characteristic amount obtained by the characteristic amount calculating means.
Changing means for changing at least one characteristic amount of the collection amount, and changing the angle by using the first characteristic amount and the second characteristic amount obtained by the changing means to control at least one of color and texture. Reconstructing means for reconstructing the spectral reflectance of the object to reproduce the coating color of the object to be coated. 2. The method according to claim 1, wherein the reconstructing means reconstructs a spectral reflectance for each change angle using a product or a sum of the first feature quantity and the second feature quantity obtained by the changing means. The computer graphics device according to claim 1, wherein 3. The computer graphics device according to claim 1, wherein the first characteristic amount is a characteristic amount related to a wavelength. 4. The computer graphics apparatus according to claim 1, wherein the second feature amount is a feature amount related to a deflection angle. 5. The reproducing means, wherein the wavelength is λ, the deflection angle is x,
The first feature amount is b (λ), and the second feature amount is α
(X) and β (x), the reflected light from the surface is S (x,
λ), and the residual component is T (x, λ), and S (x, λ) + α (x) · b (λ) + β (x) + T
5. The computer graphics device according to claim 1, wherein the spectral reflectance for each angle of change is reconstructed based on the equation (x, λ). 6. The feature amount calculating means sets a reflected light angle as x, a reference specific deflection angle as X, a wavelength as λ, and a measured deflection angle spectral reflectance as R (x, λ). R ′ (x, λ) represented by Equation 21 is used as
When mi (λ) and b (λ) are expressed by Expression 22, the value of Expression 23 is minimized for each wavelength λ, b
5. The computer graphics apparatus according to claim 1, wherein (λ) is obtained as a first feature amount, and Expression 24 is obtained as a second feature amount. (Equation 21) (Equation 22) (Equation 23) (Equation 24) 7. The reconstructing apparatus according to claim 1, wherein the reflected light angle is defined as x, a specific deformation angle as a reference is defined as X, a wavelength is defined as λ, and the measured bending spectral reflectance is defined as R (x, λ). R ′ (x, λ), which represents the spectral reflectance for each angle of change, and the function for calculating the average value of x of the function f (x, y) are given by Equation 2
5, and when Mi, b (λ) and ρ (x) are represented by Expression 27, Expression 29 that minimizes the value of Expression 28 is obtained as a second feature amount, and for each wavelength λ, 5. The computer graphics device according to claim 1, wherein b (λ) that minimizes the value of Expression 30 is obtained as a first feature amount. (Equation 25) (Equation 26) [Equation 27] [Equation 28] (Equation 29) [Equation 30]