WO2019228205A1

WO2019228205A1 - Optimization method for color perception of filter, and transmission spectrum

Info

Publication number: WO2019228205A1
Application number: PCT/CN2019/087540
Authority: WO
Inventors: 杨骏臣; 林福丁; 陈铂
Original assignee: 北京以色佳科技有限公司
Priority date: 2018-05-29
Filing date: 2019-05-20
Publication date: 2019-12-05
Also published as: CN110542941A; CN110542941B

Abstract

An optimization method for the color perception of a filter, and a transmission spectrum. The optimization method comprises: step 1, expressing the transmissivity T of a filter as a function t of parameters of an optical device of the filter; step 2, expressing color perception parameters of a color or color group needing to be optimized as a function comprising a light source D and the transmissivity T of the filter; step 3, on the basis of the expression of the color perception parameters obtained in step 2, in a 1976CIE L*a*b* color perception space, according to the chroma needing to be optimized, selecting an optimized vector, and expressing an integrated color difference of the projection of the color or color group on a plane of the chroma needing to be optimized as E_{optimized color axis} _,T; and step 4, carrying out multi-objective optimization according to the E _{optimized color axis} _,T, brightness and white point displacement required for optimizing a transmission spectrum, and selecting a suitable solution, namely the transmissivity T of the filter, and then optimally designing the parameters of the optical device of the filter on the basis of the function t. Therefore, the requirement of a user for the color perception is met.

Description

Optimization method of filter color perception and transmission spectrum

Technical field

The invention relates to a design method of an optical filter, in particular to an optimization method of color perception of a filter and a transmission spectrum.

Background technique

The human eye recognizes the light signal by superposing the three-color frustum signal. Therefore, human perception of the color of visible light is not a simple linear superposition of different wavelengths of light in the visible light wave range. In the design of the existing optical filter, it is difficult to effectively meet the user's color perception needs and to accurately control the target color or color group to be optimized. In similar patents, such as "Multi-band color vision filter and method using linear program solver optimization" (CN103688145A); "A colorant-based optical device and its artificial intelligence design method" (CN106199953A); In "Optical device design method, spectrum and brightness measurement method for optimizing human color perception" (CN106326582A); and "Artificial Intelligence Lenses and Design Methods for Improving Color Perception and Correcting Color Blindness and Weakness Vision" (CN106249406A), the author just selected a set of colors And optimize the distance between each other in the color space, such as red and green, to optimize the color difference. The limitation of this method is that it cannot effectively control whether the optimized distance is in the direction of the color or color group of its optimization target while optimizing the distance of the color in the color space. Different from previous patents, this patent accurately defines and mathematically expresses the color axis of the color and color group in the color space that needs to be optimized (that is, by the hue chroma vector of the color), so it is accurate in the optimization Controls the optimization goals. That is to say, during the optimization process, it is precisely controlled that the optimization is performed on the color axis of the target color or color group. As a result, precise control over the specific colors or color groups needed to be optimized is achieved. Based on this, the method can perform multi-objective vector optimization according to the designer's needs. These vectors can be strictly contrasted colors or non-contrast colors. Therefore, compared with the single method which is only optimized for contrast color and color difference in the above patent, the method of this patent truly realizes the multi-objective non-linear optimization feature.

Summary of the Invention

An object of the present invention is to provide a method for optimizing color perception of a filter and a transmission spectrum, which can effectively realize a user's color perception needs.

Technical solution to achieve the purpose of the present invention:

The method for optimizing the color perception of a filter and the transmission spectrum are characterized by the following steps:

Step 1: Express the transmittance T of the filter as a function t of each parameter of the filter optics;

Step 2: Express each color sense parameter of the color or color group to be optimized as a function including the light source D and the filter transmittance T:

Step 3: Based on the expression of each color sense parameter obtained in step 2, in the 1976 CIE L ^* a ^* b ^* color sense space, select an optimized vector according to the chromaticity required to be optimized.

The comprehensive color difference of the color group projected on the chromaticity plane to be optimized is expressed as E _{optimized color axis, T} ;

Step 4: Perform multi-objective optimization based on the E- _{optimized color axis, T} , brightness L ^*, and white point displacement required to optimize the transmission spectrum, and select the appropriate solution, namely the transmittance T of the filter, and then optimize the filter based on the function t Various parameters of the optical device.

Further, in step 1, the function t is established by the following method:

The comprehensive light absorption of the effective light absorption component of the filter is expressed as A (λ) = Σ _{i = 1 ... N} c _i · ε _i · l _i (λ), where N is the total number of effective light absorption components and l _i is the effective light absorption component i valid in all its dielectric layer total thickness distribution, ε _i a _i as an active ingredient of the molar absorption coefficient, c _i a _i is the average concentration of an active ingredient in the dielectric layer of all of its distribution, λ is the wave length of visible light ;

The comprehensive transmittance of the effective reflecting interface of the filter is expressed as F (λ) = [1-f ₁ (λ)] · [1-f ₂ (λ)] ... · [1-f _j (λ)] ... · [ 1-f _M (λ)], where M is the total number of effective reflective interfaces, and f _j is the _reflectance of the effective reflective interface j;

The comprehensive transmittance of the filter is expressed as T (λ) = F (λ) 10 ^{-A (λ)} , that is, T = t (λ, f _j , c _i , ε _i , l _i ).

Further, in step 2, the color sense parameters of the color or color group to be optimized are expressed as a function including the light source D and the filter transmittance T, and are implemented by the following methods:

When using a filter, the spectrum of any color U under the light source D is expressed as

U _{k, T} (λ) = D (λ) · T · MC _k (λ);

That is, U _{k, T} (λ) = D (λ) · t (λ, f _j , c _i , ε _i , l _i ) · MC _k (λ)

among them

Among them, MC is the selected color reflectance,

Color matching function for the observer;

In the CIE L ^{^{^*}} a ^* b ^* color space, L ^* lightness identification or luminance coordinate, a ^* and b ^* are the coordinates on the two chroma chroma _{_{contrast, X k, Y k, Z}} k k U for the three colors Color stimulus value; k indicates different colors in the selected color group.

Further, in step 2, the white point displacement expression after the light source D passes the filter is obtained by the following method,

X _n , Y _n , Z _n are the three-color stimulus values of the standard illuminant at the full reflector. The spectrum of the objective white point under the illumination of the light source D is expressed as U _{0, T} (λ) = D (λ) · T. Use The three-color stimulus value of the white point after the filter is expressed as X _{n, T} , Y _{n, T} , Z _{n, T} ;

When no filter is used, the brightness of the standard illuminator passing through the filter at the full reflector is expressed as L ^* ₀ ;

The integrated brightness after using the filter, that is, the brightness of the standard illuminating body passing through the filter at the full reflector is expressed as L ^* _{0, T} ;

The white point displacement after using the filter is expressed as:

or

Further, in step 3, E _{optimizes the color axis and T is} obtained by the following method:

When using a filter, the observer's color perception parameters are expressed as follows:

Color U _{k, T} hue chroma vector

Optimize vector

0 ° ≤α≤360 °;

The color difference of the selected color on the chromaticity plane to be optimized is

The comprehensive color difference of the selected color group on the chromaticity plane to be optimized is

Further, in step 4, multi-objective optimization is implemented by the following methods:

Comprehensive target = w ₀ · L ^* _{0, T} + w ₁ · E _{optimized color axis 1, T} + w ₂ · E _{optimized color axis 2, T} + ... + w _n · E _{optimized color axis n, T} + w _{n + 1} · White point displacement, where the value range of weight variable w is 0≤w≤1, and w ₀ + w ₁ + w ₂ + ... w _{n + 1} = 1.

Further, in step 4, the parameters of the filter optics refer to f, ε, c, and l.

Further, the filter is an optical eyepiece, or a thin film, or a superposition of a multilayer film, or an optical eyepiece and a thin film.

The invention has the beneficial effects:

In the present invention, the transmittance T of the filter is expressed as a function t of each parameter of the filter optics; the color sense parameters of the color or color group to be optimized are expressed as a function including the light source D and the transmittance T of the filter: 1976 CIE L ^* a ^* b ^{* In the} color space, select the optimal vector according to the chromaticity required to be optimized

The comprehensive color difference of the color group projected on the chromaticity plane to be optimized is expressed as E- _{optimized color axis, T} ; multi-objective optimization is performed according to the E- _{optimized color axis, T} , brightness L ^*, and white point displacement required to optimize the transmission spectrum. , And select the appropriate solution, namely the transmittance T of the filter, and then optimize the parameters of the filter optics based on the function t. That is, the present invention finally solves the transmittance T of the filter according to the set color perception needs, and further optimizes the parameters of the filter optical components, which can effectively meet the user's color perception needs.

In the present invention, the color sense space 1976 CIE L ^* a ^* b ^{* is} used to express the change of color sense parameters of the mathematical model of the method. In CIE L ^* a ^* b ^* , L ^* stands for lightness or lightness, and a ^* and b ^* are chroma coordinates on two contrasting chroma, here referred to as chroma and chroma coordinates. The coordinates of CIE L ^* a ^* b ^* objective white are (0,0) under any specified brightness conditions. Optimize vector

Is a vector on the a ^* b ^* plane, starting at (0,0) and having an angle α with the a ^* > 0 coordinate axis, where 0≤α≤360. When any set of opposite color pairs or multiple sets of opposite color pairs are optimized, the color group is projected on the chromaticity plane to be optimized by mathematical optimization by optimizing the vector. This method can clearly point to the chromaticity needed to be optimized, so the optimization result does not depend on the selection of the color group of the optimization object.

Another feature of the present invention is multi-objective optimization. For example, the present invention can selectively change people's color perception of one or more groups of light waves or colors according to user needs. To achieve this kind of color perception change, you can independently adjust one or more other color perception parameters of the user, including the optical brightness of certain specific light waves, the overall optical brightness of the light transmitted by the light source, the position of the visual white point, Color difference and color gamut range of multiple specific color pairs.

The present invention can be applied to the field of chromology, such as to make users perceive a stronger degree of color; the present invention can be applied to the field of medicine, such as to help change and correct the color perception of color-blind and color-blind persons; the present invention can also be applied to improve traffic or Security in the required field, such as by enhancing or reducing certain special colors; the filter of the present invention can also cooperate with other materials to achieve complex functions including changing color perception, for example, the method of the present invention can be combined with optical focusing to Used in myopia glasses that can help correct color weakness and color blindness. The filter of the present invention can be an optical eyepiece, lens, or lens; it can be a thin film; it can also be a multi-layer thin film stack or a lens and thin film stack by various methods: such as physical or vapor deposition methods such as Organic or inorganic material coating methods, etc. For example, when applied to glasses with improved red-green blindness, it can be used in the form of myopia with lenses or materials with specific light-concentrating effect; it can also be combined with lenses or materials with no light-concentrating effect. It is used in the form of power sunglasses or flat glasses; it can also be used in the form of contact lenses directly combined with polymer materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of a filter design method of the present invention;

2 is a schematic diagram of a transmission spectrum;

3 is a schematic diagram of a transmission spectrum II;

4 is a schematic diagram of a transmission spectrum III;

Fig. 5 is a schematic diagram of a transmission spectrum IV.

Detailed ways

In practice, the present invention uses 15 Fassworth colors and 5 Munsell pastel colors for color blindness and color weakness testing: 10B5 / 4, 10Y5 / 4, 10R5 / 4, 10RP5 / 4, and 10PB5 / 4 The 20 color color groups are referred to herein as "20 color groups". Because the optimization process of the present invention does not depend on the selected color, the simple "8 color groups" which respectively represent red, green, yellow, and blue are selected, including 10B5 / 4, 5B5 / 4, 10G5 / 4, 5G5 / 4, and 10Y5. / 4, 5Y5 / 4, 10R5 / 4, 5R5 / 4.

Referring to FIG. 1, the filter design of the present invention includes the following steps:

In step 1, the function t is established as follows:

When selecting a filter having N layers with light-absorbing dyes and M-layer reflective dielectric layers,

A (λ) = ∑ _{i = 1 ... N} c _i · ε _i · l _i (λ)

F (λ) = [1-f ₁ (λ)] · [1-f ₂ (λ)] ... · [1-f _j (λ)] ... · [1-f _M (λ)]

T (λ) = F (λ) 10 ^{-A (λ)}

T = t (λ, f _j , c _i , ε _i , l _i )

Where λ is specified as the wavelength of visible light from 380 nm to 780 nm. N is the total number of effective light-absorbing components. M is the total number of effective reflective medium layers. l _i is the effective total thickness of the effective light absorption component i in all the dielectric layers in which it is distributed. ε _i is the molar absorption coefficient of the active ingredient A _i . c _i is the average concentration of the active ingredient A _i in all the dielectric layers in which it is distributed. f _j is the _reflectance of the effective reflective interface j. F (λ) is the mathematical expression of the integrated transmittance of all reflected light interfaces of the filter for visible light λ. T (λ) is the mathematical expression of the integrated transmittance of the designed optical filter for visible light λ. It can be considered that the integrated transmitted light T (λ) of the optical filter is a non-linear equation for f _j , c _i , ε _i , l _i under different light waves λ. That is to say, the integrated transmission spectrum T of the optical filter is a matrix of t (f _j , c _i , ε _i , l _i ) under different light waves.

In step 2, the color sense parameters of the color or color group to be optimized are expressed as a function including the light source D and the transmittance T of the filter, and are implemented by the following methods:

When no optical filter is used, the spectrum of any color U under the illumination of light source D can be expressed as

U _k (λ) = D (λ) MC _k (λ)

When using the filter T, the spectrum of any color U under the illumination of the light source D can be expressed as

U _{k, T} (λ) = D (λ) · T · MC _k (λ)

U _{k, T} (λ) = D (λ) · t (λ, f _j , c _i , ε _i , l _i ) · MC _k (λ)

among them

Where D is the light source, such as CIE standard light emitter D65. MC is the reflectance of the selected color. U can be expressed as a specific light source D, the color absorbed into the human eye or the reflected light in the detector, that is, the light source D and the color reflectance MC at different wavelengths λ is a mathematical expression of the wavelength λ.

For the observer color matching function, the CIE standard observer color matching function can be used, or the individual color matching function can be used according to a specific group or individual. In the CIE L ^* a ^* b ^* color space, L ^* identifies lightness or lightness coordinates. a ^* and b ^* are chromaticity and chromaticity coordinates. X _k , Y _k , and Z _k are tristimulus values of color U _k . Through the above formula group, the color U under any specific light source can be expressed in the CIE L ^* a ^* b ^* color space through a classic equation. Its parameters _{_{_{U k, X k, Y k}}} , Z k, L * k, a * k, b * k are expressed in arbitrary reflectance colors MC, D is a function of the light source. When using an optical filter, its parameters U _{k, T} , X _{k, T} , Y _{k, T} , Z _{k, T} , L ^* _{k, T} , a ^* _{k, T} , b ^* _{k, T} can be expressed Under the conditions of given color and light source, the wavelength λ, the reflectance f of the effective reflective medium layer of the optical filter, the molar absorption coefficient ε and the average concentration c of the effective light absorption component of the optical filter in all the medium layers where it is distributed A function of the effective total thickness l. Here k is used to label the different colors in the selected color group. Because the present invention uses a 20-color set or an 8-color set. Here, the different colors selected are marked by k, for example, k = 1, 2, 3, 20 in the 20 color group; k = 1, 2, 3, 8 in the 8 color group.

In step 2, the white point displacement expression after the light source D passes the filter is obtained by the following method,

X _n , Y _n , and Z _n are the three-color stimulus values of the CIE standard illuminant at the full reflector. When the filter T is used, the spectrum of the objective white point under the illumination of the light source D can be expressed as U _{0, T} (λ) = D (λ) · T. Therefore, the tristimulus values of the white point after using the filter can be expressed as X _{n, T} , Y _{n, T} , Z _{n, T.}

When the filter T is not used, the brightness of the standard illuminator passing the filter at the full reflector can be expressed as: L ^* ₀ ;

The integrated brightness after using the filter T, that is, the brightness of the standard illuminant passing through the filter at the full reflector can be expressed as: L ^* _{0, T} ;

The white point displacement after using the filter T can be expressed in several ways:

An expression of white point displacement is

In step 3, E _{optimizes the color axis and T is} obtained as follows:

When using the optical filter T, the observer's color perception parameters can be expressed as:

Color U _{k, T} hue chroma vector

Optimize vector

0 ° ≤α≤360 °;

From the above, the color perception parameters of objective white and any selected color in the color space can be expressed as a function of this color U and the transmission spectrum T of the optical filter used, that is, this color can be expressed based on the effective A mathematical expression of the concentration C _{i of the} light absorbing component and the reflectance f _j of the effective reflective medium layer. By using the present invention, the parameters of the optical filter as described above can be adjusted to achieve the desired color sensor parameters.

In step 4, multi-objective optimization is achieved by the following methods:

During the implementation, in some optimization adjustments, D65 is used as the light source and the colors in the "20 color group" are used as the color group. The optical filter parameters can be optimized to obtain the transmission spectrum to achieve the following requirements: The point displacement d ' _{0, T} ≤ 0.01 and its brightness L ^* _{0, T} is not less than 43 while maximizing the red-green color difference, that is, to optimize the color axis 1 to select α = 0 °. Select weights w ₀ = 0.2; w ₁ = 0.4; w ₂ = 0.4. The obtained transmission spectrum is shown in Figure 2. In the interval of 430nm to 620nm, there are only two optical stop bands with an average transmittance lower than 10%. The first optical stopband is in the wavelength range of 430nm to 510nm. The two optical stop bands are in the wavelength range from 550nm to 610nm.

In some optimization adjustments, with D65 as the light source and the colors in the "8 color group" as the color group, the following requirements can be achieved by optimizing the optical filter parameters to obtain the transmission spectrum: the white point displacement of the D65 light source d ' _{0, T} ≤0.01 and its brightness L ^* _{0, T} is not less than 40 while maximizing the red-green color difference, that is, to optimize the color axis 1 select α = 0 ° select the weight w0 = 0.2; w1 = 0.4; w2 = 0.4 . The obtained transmission spectrum is shown in Fig. 3. In the interval of 430nm to 620nm, there are only three optical stopbands with an average transmittance lower than 10%. The first optical stopband is in the wavelength range of 430nm to 462nm. The optical stopband is in the wavelength range of 462nm to 510nm; the third optical stopband is in the wavelength range of 540nm-610nm.

In some optimization adjustments, with D65 as the light source and the colors in the "8 color group" as the color group, the following requirements can be achieved by optimizing the optical filter parameters to obtain the transmission spectrum: the white point displacement of the D65 light source d ' _{0, T} ≤0.02 and its brightness L ^* _{0, T} is not less than 75 while maximizing the red-green color difference, that is, to optimize the color axis 1 to select α = 0 °. Select weights w0 = 0.3; w1 = 0.3; w2 = 0.4. The obtained transmission spectrum is shown in Figure 4. In the interval of 430nm to 620nm, there are only two optical stop bands with an average transmittance below 40%. The first optical stop band is in the wavelength range of 430nm to 470nm. The two optical stop bands are in the wavelength range from 550nm to 620nm.

In some optimization adjustments, with D65 as the light source and the colors in the "20 color group" as the color group, the following requirements can be achieved by optimizing the optical filter parameters to obtain the transmission spectrum: the white point displacement of the D65 light source d ' _{0, T} ≤ 0.04 and maximize its brightness L ^* _{0, T} is not less than 75 while maximizing the red-green color difference, that is, optimize the color axis 1 to select α = 0 °. Select weights w0 = 0.3; w1 = 0.3; w2 = 0.4. The obtained transmission spectrum is shown in Fig. 5. In the interval of 430nm to 620nm, there is only one optical stop band with an average transmittance lower than 40% in the wavelength range of 550nm-620nm.

Claims

The method for optimizing the color perception of a filter and the transmission spectrum are characterized by the following steps:

Step 1: Express the transmittance T of the filter as a function t of each parameter of the filter optics;

Step 2: Express each color sense parameter of the color or color group to be optimized as a function including the light source D and the filter transmittance T:

Step 3: Based on the expression of each color sense parameter obtained in step 2, in the 1976 CIE L * a * b * color sense space, select an optimized vector according to the chromaticity required to be optimized.
The comprehensive color difference of the color group projected on the chromaticity plane to be optimized is expressed as E optimized color axis, T ;

Step 4: Perform multi-objective optimization based on the E- optimized color axis, T , brightness L *, and white point displacement required to optimize the transmission spectrum, and select the appropriate solution, namely the transmittance T of the filter, and then optimize the filter based on the function t Various parameters of the optical device.
The method according to claim 1, wherein in step 1, the function t is established by the following method:

The comprehensive light absorption of the effective light absorption component of the filter is expressed as A (λ) = Σ i = 1 ... N c i · ε i · l i (λ), where N is the total number of effective light absorption components and l i is the effective light absorption component i valid in all its dielectric layer total thickness distribution, ε i a i as an active ingredient of the molar absorption coefficient, c i a i is the average concentration of an active ingredient in the dielectric layer of all of its distribution, λ is the wave length of visible light ;

The comprehensive transmittance of the effective reflecting interface of the filter is expressed as F (λ) = [1-f 1 (λ)] · [1-f 2 (λ)] ... · [1-f j (λ)] ... · [ 1-f M (λ)], where M is the total number of effective reflective interfaces, and f j is the reflectance of the effective reflective interface j;

The comprehensive transmittance of the filter is expressed as T (λ) = F (λ) 10 -A (λ) , that is, T = t (λ, f j , c i , ε i , l i ).
The method according to claim 2, characterized in that, in step 2, the color sense parameters of the color or color group to be optimized are expressed as a function including the light source D and the filter transmittance T, and are implemented by the following methods:

When using a filter, the spectrum of any color U under the light source D is expressed as

U k, T (λ) = D (λ) · T · MC k (λ);

That is, U k, T (λ) = D (λ) · t (λ, f j , c i , ε i , l i ) · MC k (λ)

among them

Among them, MC is the selected color reflectance,
Color matching function for the observer;

In the CIE L * a * b * color space, L * lightness identification or luminance coordinate, a * and b * are the coordinates on the two chroma chroma contrast, X k, Y k, Z k k U for the three colors Color stimulus value; k indicates different colors in the selected color group.
The method according to claim 3, wherein in step 2, the white point displacement expression after the light source D passes through the filter is obtained by the following method,

X n , Y n , Z n are the three-color stimulus values of the standard illuminant at the full reflector. The spectrum of the objective white point under the illumination of the light source D is expressed as U 0, T (λ) = D (λ) · T. Use The three-color stimulus value of the white point after the filter is expressed as X n, T , Y n, T , Z n, T ;

When no filter is used, the brightness of the standard illuminator passing through the filter at the full reflector is expressed as L * 0 ;

The integrated brightness after using the filter, that is, the brightness of the standard illuminating body passing through the filter at the full reflector is expressed as L * 0, T ;

The white point displacement after using the filter is expressed as:

or

or
The method according to claim 4, characterized in that in step 3, E optimizes the color axis and T is obtained by the following method:

When using a filter, the observer's color perception parameters are expressed as follows:

Color U k, T hue chroma vector

Optimize vector
0 ° ≤α≤360 °;

The color difference of the selected color on the chromaticity plane to be optimized is

The comprehensive color difference of the selected color group on the chromaticity plane to be optimized is
The method according to claim 5, characterized in that in step 4, the multi-objective optimization is implemented by the following method:

Comprehensive target = w 0 · L * 0, T + w 1 · E optimized color axis 1, T + w 2 · E optimized color axis 2, T + ... + w n · E optimized color axis n, T + w n + 1 · White point displacement, where the value range of weight variable w is 0≤w≤1, and w 0 + w 1 + w 2 + ... w n + 1 = 1.
The method according to claim 6, characterized in that in step 4, the parameters of the filter optics are f, ε, c and l.
In some variations of the optimized red-green difference, the method according to any one of claims 1-7, wherein the optimized transmission spectrum meets the following requirements:

In the range of 430nm to 620nm, there are only two optical stop bands with an average transmittance below 10%. The first optical stop band is in the wavelength range of 430nm to 510nm. The second optical stop band is at 550nm. To 610nm.
In some variations of the optimized red-green difference, the method according to any one of claims 1-7, wherein the optimized transmission spectrum meets the following requirements:

In the range from 430nm to 620nm, there are only three optical stop bands with an average transmittance below 10%. The first optical stopband is in the wavelength range of 430nm to 462nm; the second optical stopband is in the range of 462nm to In the wavelength range of 510nm; the third optical stop band is in the wavelength range of 540nm-610nm.
In some variations of the optimized red-green difference, the method according to any one of claims 1-7, wherein the optimized transmission spectrum meets the following requirements:

In the range of 430nm to 620nm, there are only two optical stop bands with an average transmittance below 40%. The first optical stop band is in the wavelength range of 430 nm to 470 nm. The second optical stop band is at 550 nm. To 620nm.
In some variations of the optimized red-green difference, the method according to any one of claims 1-7, wherein the optimized transmission spectrum meets the following requirements:

In the interval of 430nm to 620nm, there is only one optical stop band with an average transmittance of less than 40% in the wavelength range of 550nm-620nm.
The method according to any one of claims 1 to 7, characterized in that the filter is an optical eyepiece, or a film, or a superposition of a multilayer film, or a superposition of an optical eyepiece and a film.