Illumination method and illumination light spectral distribution determination system

Abstract

Illumination method for an object to be observed and a background, the illumination method comprising the following steps: while irradiating the object to be observed and the background with a first light source, obtaining the relationship between wavelength and spectral radiant luminance for the object to be observed, determining one or more representative wavelengths based on the wavelength corresponding to the maximum value of the spectral radiant luminance related to the object to be observed and the wavelength, the first light source being a light source that emits light having an average color rendering index of 40 or more, a color temperature in the range of 3000 K to 10000 K, and a continuous spectrum in the wavelength range of 380 nm to 780 nm; while irradiating the object to be observed and the background with the first light source, obtaining the relationship between wavelength and spectral radiant luminance for the background, determining one or more comparison wavelengths based on the wavelength corresponding to the maximum or minimum value of the spectral radiant luminance related to the background and the wavelength; and irradiating the object to be observed and the background with light of the representative wavelength and the comparison wavelength.

Description

Technical Field

[0001] The present invention relates to an illumination method for improving the visual recognition of an object to be observed and an illumination light spectral distribution determination system. Background Art

[0002] In medical diagnosis, product inspection in manufacturing, etc., illumination light is irradiated onto an object for observation. In this case, it is preferable to select illumination light that improves the visual recognition of the object to be observed. Conventionally, the selection of illumination light that improves the visual recognition of the object to be observed has been carried out by each observer subjectively through repeated trial and error.

[0003] Patent Document 1 discloses a method for efficiently using illumination light based on control of the spectral distribution characteristics of illumination and the spectral reflection characteristics of color materials, and an illumination system using this method. However, Patent Document 1 does not disclose the determination of illumination light that improves the visual recognition of an object to be observed.

[0004] Thus, conventionally, an illumination method and an illumination light spectral distribution determination system that improve the visual recognition of an object to be observed without relying on the subjectivity and trial and error of an observer have not been developed.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document: Japanese Patent Application Laid-Open No. 2014-135195 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] Therefore, there is a need for an illumination method and an illumination light spectral distribution determination system that improve the visual recognition of an object to be observed without relying on the subjectivity and trial and error of an observer. The subject of the present invention is to provide an illumination method and an illumination light spectral distribution determination system that improve the visual recognition of an object to be observed without relying on the subjectivity and trial and error of an observer.

[0010] Means for Solving the Problems

[0011] The lighting method of the first aspect of the present invention is a lighting method for an observation object and a background, comprising the following steps: determining an isochromatic function, and obtaining an xy chromaticity diagram according to the isochromatic function; in a state where the observation object and the background are irradiated with a first light source, obtaining the relationship between the wavelength and the spectral radiance for the observation object, and determining one or more representative wavelengths according to the wavelength corresponding to the maximum value of the spectral radiance related to the observation object and the wavelength, wherein the first light source is a light source that emits light with an average color rendering index of 40 or more, a color temperature in the range of 3000K to 10000K, and a continuous spectrum in the wavelength range of 380 nm to 780 nm; determining a comparison wavelength of the representative wavelength in such a manner as to increase the contrast between the observation object and the background according to the representative wavelength and the xy chromaticity diagram; and irradiating the observation object and the background with light of the representative wavelength and the comparison wavelength.

[0012] According to the lighting method of this aspect, according to the representative wavelength and the xy chromaticity diagram, the comparison wavelength of the representative wavelength is determined in such a manner as to increase the contrast between the observation object and the background, so that the visual recognition of the observation object can be improved without relying on the subjectivity and trial-and-error of the observer.

[0013] In the lighting method of the first embodiment of the first aspect of the present invention, before obtaining the comparison wavelength, a prohibited use band of the comparison wavelength is determined, and the comparison wavelength is determined outside the prohibited use band.

[0014] According to the lighting method of this embodiment, by determining the prohibited use band of the comparison wavelength, the preference of the observer for the color of the image can be reflected.

[0015] In the lighting method of the second embodiment of the first aspect of the present invention, in the step of obtaining the comparison wavelength, the representative wavelength is one wavelength, and the wavelength closest to the wavelength in a complementary color relationship with the representative wavelength in the xy chromaticity diagram is set as the comparison wavelength.

[0016] According to the lighting method of this embodiment, by setting the wavelength in a complementary color relationship with the representative wavelength in the xy chromaticity diagram as the comparison wavelength, the contrast between the observation object and the background can be increased.

[0017] In the lighting method of the third embodiment of the first aspect of the present invention, in the step of obtaining the comparison wavelength, the representative wavelength is multiple wavelengths, and the wavelength corresponding to the point with the largest sum of color differences between the multiple points representing the multiple representative wavelengths in the xy chromaticity diagram is set as the comparison wavelength.

[0018] According to the lighting method of the present embodiment, by setting the wavelength corresponding to the point in the xy chromaticity diagram with the maximum sum of color differences between multiple points representing multiple representative wavelengths as the comparison wavelength, the contrast between the observation object and the background can be increased.

[0019] In the lighting method of the fourth embodiment of the first mode of the present invention, in the step of obtaining the comparison wavelength, the representative wavelengths are multiple wavelengths, and the wavelength closest to the wavelength in the xy chromaticity diagram that is in a complementary color relationship with the average wavelength of the multiple representative wavelengths is set as the comparison wavelength.

[0020] According to the lighting method of the present embodiment, by setting the wavelength closest to the wavelength in the xy chromaticity diagram that is in a complementary color relationship with the average wavelength of multiple representative wavelengths as the comparison wavelength, the contrast between the observation object and the background can be increased.

[0021] The lighting method of the second mode of the present invention is a lighting method for an observation object and a background, and the lighting method includes the following steps: in a state where the observation object and the background are irradiated with a first light source, obtaining the relationship between the wavelength and the spectral radiant luminance for the observation object, and determining one or more representative wavelengths according to the wavelength corresponding to the maximum value of the spectral radiant luminance related to the wavelength of the observation object, where the first light source is a light source that emits light with an average color rendering index of 40 or more, a color temperature in the range of 3000K to 10000K, and a continuous spectrum in the wavelength range of 380 nm to 780 nm; in a state where the observation object and the background are irradiated with the first light source, obtaining the relationship between the wavelength and the spectral radiant luminance for the background, and determining one or more comparison wavelengths according to the wavelength corresponding to the maximum value or minimum value of the spectral radiant luminance related to the wavelength of the background; and irradiating the observation object and the background with the light of the representative wavelength and the comparison wavelength.

[0022] According to the lighting method of the present mode, in a state where the observation object and the background are irradiated with the first light source, obtaining the relationship between the wavelength and the spectral radiant luminance for the background, and determining one or more representative wavelengths according to the wavelength corresponding to the maximum value of the spectral radiant luminance related to the wavelength of the observation object, in a state where the observation object and the background are irradiated with the first light source, obtaining the relationship between the wavelength and the spectral radiant luminance for the background, and determining one or more comparison wavelengths according to the wavelength corresponding to the maximum value or minimum value of the spectral radiant luminance related to the wavelength of the background, and irradiating the observation object and the background with the light of the representative wavelength and the comparison wavelength. Therefore, the representative wavelength and the comparison wavelength are determined in a manner that increases the contrast between the observation object and the background, and the visual recognition of the observation object can be improved without relying on the subjective judgment and trial-and-error of the observer.

[0023] In the lighting method of the first embodiment of the second aspect of the present invention, before obtaining the representative wavelength and the comparison wavelength, a prohibited use band for the representative wavelength and the comparison wavelength is determined, and the representative wavelength and the comparison wavelength are determined outside the prohibited use band.

[0024] According to the lighting method of the present embodiment, by determining the prohibited use band, it is easy to determine the representative wavelength and the comparison wavelength. In addition, the prohibited use band can be used to reflect the preferences of the observer.

[0025] The lighting light spectral distribution determination system of the third aspect of the present invention is configured to include: a first light source that emits light having an average color rendering index of 40 or more, a color temperature in the range of 3000K to 10000K, and a continuous spectrum in the wavelength range of 380 nm to 780 nm; a spectral radiance meter; and a processor connected to the spectral radiance meter, and the lighting light spectral distribution determination system determines the representative wavelength and the comparison wavelength according to the method described in claim 1 or 6.

[0026] According to the lighting light spectral distribution determination system of the present aspect, it is possible to determine the lighting light in such a way that the contrast ratio between the observation object and the background increases.

[0027] The lighting system of the fourth aspect of the present invention includes the lighting light spectral distribution determination system of the third aspect and a second light source that irradiates the determined lighting light.

[0028] According to the lighting system of the present aspect, it is possible to improve the visual recognition of the observation object without depending on the subjectivity and trial and error of the observer.

[0029] In the lighting system of the first embodiment of the fourth aspect of the present invention, the second light source includes the first light source and a plurality of filters.

[0030] By using the first light source, a simple lighting system can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a diagram showing the structure of a lighting system for implementing the lighting method of the present invention.

[0032] Figure 2 It is a flowchart for explaining the lighting method of the present invention.

[0033] Figure 3 It is a diagram showing an xy chromaticity diagram determined according to the metamerism function.

[0034] Figure 4 It is a diagram showing the relative value of the spectral irradiance of a xenon light source without a filter.

[0035] Figure 5is an image of an observation object and a background irradiated by a xenon light source without a filter.

[0036] Figure 6 is a graph showing the spectral radiance of the partition of the observation object labeled No. 1 irradiated by a xenon light source without a filter in Figure 5

[0037] Figure 7 is a graph showing the spectral radiance of the partition of the background labeled No. 25 irradiated by a xenon light source without a filter in Figure 5

[0038] Figure 8 is for explaining Figure 2 the flowchart of step S1040.

[0039] Figure 9 is a graph showing the spectral radiance of the partition of the observation object labeled No. 1 irradiated with light of a representative wavelength (470 nm) and a comparison wavelength (560 nm) in Figure 5

[0040] Figure 10 is a graph showing the spectral radiance of the partition of the background labeled No. 25 irradiated with light of a representative wavelength (470 nm) and a comparison wavelength (560 nm) in Figure 5

[0041] Figure 11 is an image of an observation object and a background irradiated with light of a representative wavelength (470 nm) and a comparison wavelength (560 nm).

[0042] Figure 12 is a graph showing the spectral radiance of the partition of the observation object labeled No. 1 irradiated by a xenon light source without a filter in Figure 5

[0043] Figure 13 is a graph showing the spectral radiance of the partition of the background labeled No. 25 irradiated by a xenon light source without a filter in Figure 5

[0044] Figure 14 is an image of an observation object and a background irradiated by a xenon light source without a filter.

[0045] Figure 15 is a graph of the xy chromaticity diagram determined according to the metamerism function.

[0046] Figure 16 is for explaining in the case where two wavelengths are representative values Figure 2 ​​​​​​Flowchart of step S1040

[0047] Figure 17 It is a diagram showing an xy chromaticity diagram determined according to an equal-color function

[0048] Figure 18 It is a diagram showing the spectral radiance distribution of an object to be observed under illumination by a first light source

[0049] Figure 19 It is a diagram showing the spectral radiance distribution of a background under illumination by a first light source

[0050] Figure 20 It shows an image of an object to be observed and a background under illumination by a first light source

[0051] Figure 21 It shows an image of an object to be observed and a background under illumination by a second light source that emits light of a representative wavelength and a comparison wavelength in other embodiments of the first aspect of the present invention

[0052] Figure 22 It is a flowchart for explaining an illumination method according to the second aspect of the present invention

[0053] Figure 23 It is a diagram showing the spectral radiance distribution of an object to be observed under illumination by a first light source

[0054] Figure 24 It is a diagram showing the spectral radiance distribution of a background under illumination by a first light source

[0055] Figure 25 It shows an image of an object to be observed and a background under illumination by a second light source that emits light of a representative wavelength and a comparison wavelength in a first embodiment of the illumination method according to the second aspect of the present invention

[0056] Figure 26 It is a diagram showing the spectral radiance distribution of an object to be observed under illumination by a first light source

[0057] Figure 27 It is a diagram showing the spectral radiance distribution of a background under illumination by a first light source

[0058] Figure 28 It shows an image of an object to be observed and a background under illumination by a second light source that emits light of a representative wavelength and a comparison wavelength in a second embodiment of the illumination method according to the second aspect of the present invention

[0059] Figure 29 It is a diagram showing the spectral radiance distribution of an object to be observed under illumination by a first light source

[0060] Figure 30 It is a diagram showing the spectral radiant luminance distribution of the background under irradiation by the first light source.

[0061] Figure 31 It represents an image when the object to be observed and the background are irradiated by the second light source that emits light of the representative wavelength and the comparison wavelength in the third embodiment of the illumination method according to the second aspect of the present invention. Detailed Embodiments

[0062] Figure 1 It is a diagram showing the structure of the illumination system 100 for implementing the illumination method of the present invention. The illumination system 100 includes a light source unit 110, a two-dimensional spectral radiant luminance meter 120, and a processor 130. The light source unit 110 includes a plurality of filter-replaceable light sources 111, an optical fiber 113, and a light projection unit 115. Illumination light of a plurality of desired wavelengths is generated by the plurality of filter-replaceable light sources 111, transmitted to the light projection unit 115 via the optical fiber 113, and the object 200 is irradiated with the illumination light from the light projection unit 115. The commonly used light source is a light source that emits light having a continuous spectrum in the wavelength range of 380 nm to 780 nm, with an average color rendering index (Ra) of 40 or more and a color temperature in the range of 3000K to 10000K. The light source having the above properties is called the first light source. The first light source is, for example, a xenon light source, a metal halide lamp, a mercury lamp, a halogen lamp, a white LED (light-emitting diode), etc. The filter-replaceable light source 111 is a combination of the first light source and a replaceable filter. As an example, the plurality of filters are filters that transmit light of a specific wavelength, and the interval of the specific wavelengths is 10 nm. By appropriately selecting the filters of the plurality of filter-replaceable light sources 111 in this way, the light source unit 110 functions as a spectral variable light source. The object 200 is the object to be observed and the background. The two-dimensional spectral radiant luminance meter 120 measures the spectral radiant luminance of the object 200 under specified conditions described later. The measured spectral radiant luminance of the object 200 is sent to the processor 130, and the processor 130 determines the illumination light for enhancing the contrast between the object to be observed and the background and improving the visual recognition of the observer. The illumination light determined in this way is realized by the plurality of filter-replaceable light sources 111. The light source of the illumination light for improving visual recognition thus realized is called the second light source. Generally, the second light source can be, in addition to being a combination of the first light source and the filter, a light source independent of the first light source.

[0063] The illumination light spectral distribution determination system of the present invention is for determining the second light source, and is composed of the first light source, the spectral radiant luminance meter 120, and the processor 130. The illumination system 100 is a system formed by combining the above illumination light spectral distribution determination system and the above second light source.

[0064] In the following description, the first light source is a xenon light source.

[0065] Figure 2 is a flowchart of an illumination method for explaining a first aspect of the present invention.

[0066] In Figure 2 step S1010, an isochromatic function corresponding to a color sensor of a camera such as an observer or machine vision is determined.

[0067] First, the case of determining the isochromatic function of an observer will be described. Under normal white light such as sunlight or white LED light, individual differences in the way observers perceive colors can be ignored. However, under illumination light whose light color has been adjusted for metamerism, individual differences in the way observers perceive colors cannot be ignored. Therefore, in order to improve the visual discrimination inherent to an observer, it is preferable to obtain an isochromatic function for each observer. However, in the case where the visual discrimination of a standard observer is improved by emphasizing the contrast between the observation object and the background while ignoring the visual discrimination inherent to the observer, this step can be omitted and a standard isochromatic function can be used.

[0068] Next, the case of determining the isochromatic function of a color sensor of a camera will be described. Since there is no isochromatic function for the color sensor of a camera, it is necessary to obtain the isochromatic function of the color sensor of the camera.

[0069] The isochromatic function is determined through an isochromatic experiment. In the isochromatic experiment, a light source that generates light of a single wavelength and a light source that generates light of RGB light combining primary stimuli are prepared. As the above two light sources, two sets of light source units 110 can also be used. Through the above two light sources, the adjacent two regions of a white screen are irradiated with light of a single wavelength and light of RGB light combining primary stimuli respectively. Based on the image data taken in by the camera, the light amounts of the RGB light are adjusted so that the colors of the above two regions are judged to be metameric. In this way, the values of conditional metamerism are determined for each single wavelength, and the isochromatic function is defined.

[0070] In Figure 2 step S1020, an xy chromaticity diagram is obtained according to the isochromatic function obtained in step S1010 or a standard isochromatic function. When the stimulus values are represented by X, Y, and Z, the chromaticity values (x, y) are expressed by the following expressions.

[0071] [Equation 1]

[0072]

[0073] x and y are obtained by substituting the values of the isochromatic function for each wavelength into the stimulus values in the above formula, thereby determining the xy chromaticity diagram.

[0074] Figure 3This is a diagram showing the xy chromaticity diagram determined according to the equal-color function. The method of using the xy chromaticity diagram will be described later.

[0075] In Figure 2 In step S1030, the spectral data (spectral radiance data) of the object to be observed is obtained, and the representative wavelength of the object to be observed is determined based on the spectral data.

[0076] In order to obtain the spectral data of the object to be observed, the spectral data (spectral radiance data) of the object to be observed is obtained in a state where the object to be observed and the background are irradiated by a xenon light source (first light source) without a filter.

[0077] Figure 4 This is a diagram showing the relative value of the spectral irradiance of a xenon light source without a filter. Figure 7 The horizontal axis of Figure 4 represents the wavelength, and the unit is nanometer.

[0078] Figure 5 This is an image of the object to be observed and the background irradiated by a xenon light source without a filter. The image is divided into 5 parts vertically and horizontally and divided into 25 partitions. In Figure 5 the dark area including the partition labeled 1 is the area of the object to be observed, and in Figure 5 the light area including the partition labeled 25 is the area of the background.

[0079] Figure 6 This is a graph showing the spectral radiance of the partition of the object to be observed labeled 1 irradiated by a xenon light source without a filter in Figure 5 The horizontal axis of the graph represents the wavelength, and the unit is nanometer. The vertical axis of the graph represents the luminance, and the unit is watts per steradian per square meter per nanometer.

[0080] According to Figure 6 the spectral radiance of the object to be observed shown, the representative wavelength of the object to be observed is determined. The representative wavelength can also be selected from the wavelengths corresponding to the maximum value of the spectral radiance. The wavelengths corresponding to the maximum value of the spectral radiance in Figure 6 are 470 nanometers and 720 nanometers. Either one or both of the above two wavelengths can be used as the representative wavelength. In this embodiment, 470 nanometers is used as the representative wavelength of the object to be observed.

[0081] In Figure 2 in step S1040, the comparison wavelength of the representative wavelength is obtained based on the representative wavelength and the xy chromaticity diagram.

[0082] Figure 7 This is a diagram showing the object to be observed irradiated by a xenon light source without a filter in Figure 5A graph of the spectral radiance of the partition of the background labeled with number 25. The horizontal axis of the graph represents wavelength in nanometers. The vertical axis of the graph represents luminance in watts per steradian per square meter per nanometer. In Figure 7 , the solid line of the graph represents the spectral radiance of the partition of the background, and the dashed line represents the spectral radiance of the partition of the object under observation. The spectral radiance of the partition of the object under observation is the same as the spectral radiance shown in Figure 6 .

[0083] Assume that when the background is colorless or achromatic (white to gray), the spectral distribution of the illumination light that maximizes the contrast between the object under observation and the background is determined by the product of the light of the representative wavelength and the light of the following wavelength, which corresponds to the color that has a complementary color relationship with the color corresponding to the representative wavelength. Therefore, in order to emphasize the contrast between the object under observation and the background, consider selecting the wavelength corresponding to the color that has a complementary color relationship with the color corresponding to the representative wavelength as the contrast wavelength.

[0084] On the other hand, also consider the case where the observer of the illumination method wants to adjust the color of the background. As an example, when the user wants to reduce the red color of the background, the wavelength range of 570 nanometers or more can also be set as the prohibited wavelength region Z for use.

[0085] Figure 8 is a flowchart for explaining Figure 2 step S1040.

[0086] In Figure 8 step S2010, determine the point A corresponding to the representative wavelength of 470 nanometers on the spectral locus in the xy chromaticity diagram shown in Figure 3 . Here, the spectral locus is the curve on the outer periphery of the xy chromaticity diagram.

[0087] In Figure 8 step S2020, determine the straight line AW connecting the point A and the white point W in the xy chromaticity diagram shown in Figure 3 .

[0088] In Figure 8 step S2030, determine the intersection point B of the straight line AW and the spectral locus in the xy chromaticity diagram. The point B is the point corresponding to the color that has a complementary color relationship with the color of the representative wavelength. In addition, the point B is the point with the largest color difference from the point A corresponding to the representative wavelength of 470 nanometers.

[0089] In Figure 8 step S2040, determine the region Z corresponding to the prohibited wavelength band of the contrast wavelength in the xy chromaticity diagram shown in Figure 3 .

[0090] In Figure 8 step S2050, in Figure 3In the xy chromaticity diagram shown, a point on the spectral locus outside the region Z is designated as point C, and the point C that minimizes the angle θ formed by the straight line AB and the straight line AC is found. The wavelength corresponding to point C is set as the comparison wavelength. The wavelength corresponding to point C is not included in the prohibited wavelength band Z and is the wavelength closest to the wavelength having a complementary color relationship with the representative wavelength. Here, in this embodiment, the wavelength interval of the filter is 10 nanometers, and thus the comparison wavelength is 560 nanometers.

[0091] In addition, when implementing Figure 8 Steps S2010 to S2050, a method of representing the spectral locus by implicit function curve fitting can also be used.

[0092] In Figure 2 Step S1050, the observation object and the background are irradiated with a second light source composed of light combining the representative wavelength (470 nanometers) and the comparison wavelength (560 nanometers).

[0093] Figure 9 represents the spectral radiant luminance of the partition of the observation object numbered 1 irradiated with light of the representative wavelength (470 nanometers) and the comparison wavelength (560 nanometers) in Figure 5 The chart. Figure 9 The horizontal axis of the chart of Figure 9 represents wavelength, and the unit is nanometer. Figure 10 , Figure 12 and Figure 13 The horizontal and vertical axes of the charts of

[0094] Figure 10 also have the same meaning. Figure 5 represents the spectral radiant luminance of the partition of the background numbered 25 irradiated with light of the representative wavelength (470 nanometers) and the comparison wavelength (560 nanometers) in

[0095] Figure 11 represents an image of the observation object and the background irradiated with light of the representative wavelength (470 nanometers) and the comparison wavelength (560 nanometers). In Figure 11 , "front" represents the region of the observation object, and "back" represents the region of the background.

[0096] Figure 12 represents the spectral radiant luminance of the partition of the observation object numbered 1 irradiated with a xenon light source without a filter in Figure 5 The chart.

[0097] Figure 13 represents the spectral radiant luminance of the partition of the observation object numbered 1 irradiated with a xenon light source without a filter in Figure 5A chart of the spectral radiance of the partitioned background marked with the number 25.

[0098] Figure 14 is an image showing an object and a background irradiated by a xenon light source without a filter. In Figure 14 "front" represents the area of the object, and "back" represents the area of the background.

[0099] The JIS-based contrast ratio between the object and the background in the Figure 11 image obtained by the lighting method of the present invention is 32.8% higher than that in the Figure 14 image obtained by the conventional lighting method. Thus, by the lighting method of the present invention, an image suitable for observation with enhanced contrast between the object and the background can be provided.

[0100] Generally, when the irradiated surface is a uniformly diffusing reflecting surface, the spectral radiance of the surface is the product of the spectral irradiance of the surface and the spectral reflectance of the surface. Therefore, by determining the spectral irradiance considering the spectral reflectance of the object, the visual recognition of the object can be improved.

[0101] Next, as another embodiment, the method for obtaining the comparison wavelength in the case where 720 nm, corresponding to another maximum value of the spectral radiance of Figure 8 is taken as a representative value, will be described according to the flowchart of Figure 6

[0102] Figure 15 is a diagram showing the xy chromaticity diagram determined according to the color matching function.

[0103] In Figure 8 step S2010 of Figure 15 , the point A corresponding to the representative wavelength of 720 nm on the spectral locus in the xy chromaticity diagram shown in

[0104] is determined. Figure 8 In

[0105] step S2020 of Figure 8 , the straight line AW connecting the point A and the white point W in the xy chromaticity diagram is determined.

[0106] In

[0107] step S2030 ofFigure 6 Method for obtaining a comparison wavelength when two wavelengths, 470 nm and 720 nm, corresponding to two maxima of the spectral radiance are set as representative values.

[0108] Figure 16 It is used to illustrate the case where two wavelengths are used as representative values. Figure 2 Flowchart of step S1040.

[0109] Figure 17 It is a diagram showing an xy chromaticity diagram determined according to the color matching function.

[0110] In this embodiment, in the Figure 17 shown xy chromaticity diagram, the interval between the points representing the two wavelengths corresponding to the two maxima of the spectral radiance on the spectral locus encloses the white point. That is, the angle of the interval between the points representing the two wavelengths on the spectral locus observed from the white point is greater than 180 degrees.

[0111] In Figure 16 step S3010, the points A and A' corresponding to the representative wavelengths 720 nm and 470 nm respectively in the xy chromaticity diagram of Figure 17 are determined.

[0112] In Figure 16 step S3020, the straight line AW connecting point A and the white point W and the straight line A'W connecting point A' and the white point W in the xy chromaticity diagram of Figure 17 are determined.

[0113] In Figure 16 S3030, the intersection point P of the straight line AW and the spectral locus and the intersection point P' of the straight line A'W and the spectral locus in the xy chromaticity diagram of Figure 17 are determined. In the interval between points P and P' on the spectral locus, there are points corresponding to the following wavelength: this wavelength is the wavelength that improves visual recognition for the two wavelengths.

[0114] In Figure 16 S3040, in the xy chromaticity diagram of Figure 17 a point moving between points P and P' on the spectral locus is set as point C, the point C that maximizes the sum of the lengths of line segment PC and line segment P'C is set as point B, and the wavelength corresponding to point B is set as the comparison wavelength. The wavelength corresponding to point B is 515 nm. Here, point B approximately corresponds to the point where the sum of the color differences from point A and from A' is the largest. In this embodiment, the wavelength interval of the filter is 10 nm, so the comparison wavelength is 520 nm.

[0115] When three or more wavelengths are selected as representative wavelengths, the comparison wavelength can also be determined by the same process.

[0116] When the distance between the coordinates of multiple points representing multiple wavelengths on the spectral locus is 0.1 or less, the average value of the multiple wavelengths is used as the representative wavelength and the comparison wavelength is determined according to the Figure 8 flow chart shown, and substantially the same result can be obtained.

[0117] Other embodiments of the illumination method according to the first aspect of the present invention will be described.

[0118] Figure 18 It is a diagram showing the spectral radiant luminance distribution of an object to be observed when irradiated with a first light source (a xenon light source without a filter). Figure 18 The horizontal axis of Figure 18 represents the wavelength,

[0119] In Figure 18 according to Figure 2 step S1030 of Figure 18 the representative wavelength is determined to be 550 nm based on the maximum value of the spectral reflection luminance of Figure 2 . Then, according to Figure 8 step S1040 of

[0120] Figure 19 and the flow chart of Figure 19 the comparison wavelength of the background is determined to be 430 nm. It should be noted that the wavelength band from 670 nm to 780 nm is prohibited from being used. Figure 19 is a diagram showing the spectral radiant luminance distribution of the background when irradiated with the first light source. Figure 19 The horizontal axis of

[0121] represents the wavelength, Figure 18 and Figure 19 the vertical axis represents the spectral radiant luminance. In this embodiment, the spectral radiant luminance distribution of

[0122] Figure 20 is not used, but is shown for reference.

[0123] Figure 21 represents an image when an object to be observed and a background are irradiated with a second light source that emits light of the representative wavelength and the comparison wavelength in another embodiment of the first aspect of the present invention. When comparing the Figure 21 image with the Figure 20 image, the contrast of the object to be observed with respect to the background increases.

[0124] Next, the illumination method according to the second aspect of the present invention will be described.

[0125] Figure 22 is a flowchart of an illumination method for explaining the second mode of the present invention.

[0126] In Figure 22 step S4010, the observation object and the background are irradiated with a first light source.

[0127] In Figure 22 step S4020, the spectral radiant luminance distributions of the observation object and the background are obtained.

[0128] In Figure 22 step S4030, considering the spectral radiant luminance distributions of the observation object and the background, a band to be prohibited from use is determined. As an example, the band to be prohibited from use can also be set as a region where the spectral radiant luminance distributions of the observation object and the background have a similar shape.

[0129] In Figure 22 step S4040, a representative wavelength is determined according to the spectral radiant luminance distribution of the observation object.

[0130] In Figure 22 step S4050, a comparison wavelength is determined according to the spectral radiant luminance distribution of the background.

[0131] In Figure 22 step S4060, the observation object and the background are irradiated with a second light source that emits light of the above-mentioned representative wavelength and the above-mentioned comparison wavelength.

[0132] A first embodiment of the illumination method of the second mode of the present invention will be described.

[0133] Figure 23 is a graph showing the spectral radiant luminance distribution of the observation object when irradiated with the first light source. Figure 23 The horizontal axis of Figure 23 represents wavelength,

[0134] Figure 24 is a graph showing the spectral radiant luminance distribution of the background when irradiated with the first light source. Figure 24 The horizontal axis of Figure 24 represents wavelength,

[0135] According to Figure 22 step S4030, considering the spectral radiant luminance distributions of the observation object and the background, a band to be prohibited from use is determined. In this embodiment, the band to be prohibited from use is 670 nm to 780 nm.

[0136] According to Figure 22In step S4040, a representative wavelength is determined based on the spectral radiant luminance distribution of the observation object. The representative wavelength is set to be the wavelength at which the maximum value of the spectral radiant luminance distribution of the observation object is represented outside the prohibited use band, i.e., 550 nm. Generally speaking, the representative wavelength can also be selected from all or a part of all the multiple wavelengths at which the maximum value of the spectral radiant luminance distribution of the observation object is represented outside the prohibited use band. Alternatively, it can also be set to the average value of all or a part of the above-mentioned all the multiple wavelengths.

[0137] According to Figure 22 In step S4050, a comparison wavelength is determined based on the spectral radiant luminance distribution of the background. The comparison wavelength is set to be the wavelength at which the maximum value of the spectral radiant luminance distribution of the background is represented outside the prohibited use band, i.e., 660 nm. Generally speaking, the comparison wavelength can also be selected from all or a part of all the multiple wavelengths at which the maximum value of the spectral radiant luminance distribution of the background is represented outside the prohibited use band. Alternatively, it can also be set to the average value of all or a part of the above-mentioned all the multiple wavelengths.

[0138] In Figure 23 and Figure 24 the representative wavelength, the comparison wavelength, and the prohibited use band are shown.

[0139] Figure 25 Fig. shows an image in the case where an observation object and a background are irradiated with a second light source that emits light of the representative wavelength and the comparison wavelength in the first embodiment of the illumination method according to the second aspect of the present invention. Compared with the image in the case where the object is irradiated with the first light source Figure 25 the contrast of the observation object relative to the background increases. Figure 20 the image

[0140] A second embodiment of the illumination method according to the second aspect of the present invention will be described.

[0141] Figure 26 Fig. is a diagram showing the spectral radiant luminance distribution of the observation object when irradiated with the first light source. Figure 26 The horizontal axis of Figure 26 represents the wavelength,

[0142] Figure 27 and the vertical axis of Figure 27 represents the spectral radiant luminance. Figure 27 Fig. is a diagram showing the spectral radiant luminance distribution of the background when irradiated with the first light source.

[0143] According to Figure 22 In step S4030, considering the spectral radiant luminance distributions of the observation object and the background, a prohibited use band is determined. In this embodiment, the prohibited use band is 670 nm to 780 nm.

[0144] According to Figure 22 step S4040, the representative wavelength is determined based on the spectral radiance distribution of the object to be observed. The representative wavelength is set to the wavelength that represents the maximum value of the spectral radiance distribution of the object to be observed outside the prohibited wavelength band, i.e., 550 nm. Generally, the representative wavelength can also be selected from all or a part of all the wavelengths that represent the maximum value of the spectral radiance distribution of the object to be observed outside the prohibited wavelength band. Alternatively, it can also be set to the average value of all or a part of the above-mentioned all wavelengths.

[0145] According to Figure 22 step S4050, the comparison wavelength is determined based on the spectral radiance distribution of the background. The comparison wavelength is set to the wavelength that represents the minimum value of the spectral radiance distribution outside the prohibited wavelength band, i.e., 430 nm. Generally, the comparison wavelength can also be selected from all or a part of all the wavelengths that represent the minimum value of the spectral radiance distribution of the background outside the prohibited wavelength band. Alternatively, it can also be set to the average value of all or a part of the above-mentioned all wavelengths.

[0146] In Figure 26 and Figure 27 the representative wavelength, the comparison wavelength, and the prohibited wavelength band are shown.

[0147] Figure 28 It shows an image in the case where the object to be observed and the background are irradiated with a second light source that emits light of the representative wavelength and the comparison wavelength in the second embodiment of the illumination method according to the second aspect of the present invention. If the Figure 28 image is compared with the Figure 20 image, only the color of the leaves of the object to be observed is emphasized with respect to the soil of the background.

[0148] A third embodiment of the illumination method according to the second aspect of the present invention will be described.

[0149] Figure 29 is a graph showing the spectral radiance distribution of the object to be observed when irradiated with the first light source. Figure 29 The horizontal axis of Figure 29 represents the wavelength, and

[0150] Figure 30 is a graph showing the spectral radiance distribution of the background when irradiated with the first light source. Figure 30 The horizontal axis of Figure 30 represents the wavelength, and

[0151] According to Figure 22In step S4030, considering the spectral radiance distribution of the observation object and the background, the prohibited wavelength band is determined. In this embodiment, the prohibited wavelength band is from 670 nm to 780 nm.

[0152] According to Figure 22 step S4040, the representative wavelength is determined based on the spectral radiance distribution of the observation object. The representative wavelength is set to 430 nm, which is the wavelength representing the minimum value of the spectral radiance distribution outside the prohibited wavelength band. Generally, the representative wavelength can also be selected from all or part of all the wavelengths representing the minimum values of the spectral radiance distribution of the observation object outside the prohibited wavelength band. Alternatively, it can also be set to the average value of all or part of the above-mentioned all wavelengths.

[0153] According to Figure 22 step S4050, the comparison wavelength is determined based on the spectral radiance distribution of the background. The comparison wavelength is set to 660 nm, which is the wavelength representing the maximum value of the spectral radiance distribution outside the prohibited wavelength band. Generally, the comparison wavelength can also be selected from all or part of all the wavelengths representing the maximum values of the spectral radiance distribution of the background outside the prohibited wavelength band. Alternatively, it can also be set to the average value of all or part of the above-mentioned all wavelengths.

[0154] In Figure 29 and Figure 30 , the representative wavelength, the comparison wavelength, and the prohibited wavelength band are shown.

[0155] Figure 31 Fig. shows an image in the case where the observation object and the background are irradiated with the second light source emitting light of the representative wavelength and the comparison wavelength in the third embodiment of the illumination method according to the second aspect of the present invention. If the Figure 31 image is compared with the Figure 20 image, only the color of the soil of the background is emphasized with respect to the leaves of the observation object.

[0156] In addition, the third embodiment is an embodiment in which the leaves as the "observation object" and the soil as the "background" in the second embodiment are swapped. In the third embodiment, if the "observation object" is set to soil and the "background" is set to leaves, the illumination method of the third embodiment is substantially the same as the illumination method of the second embodiment.

[0157] The illumination method can be determined according to the above embodiments based on the properties of the spectral radiance distributions of the observation object and the background and the purpose of observation. The most preferable illumination method can also be determined after implementing the illumination method of the embodiment.

Claims

1. A lighting method, which is a lighting method for an object to be observed and a background, wherein, the lighting method includes the following steps: Determine an isochromatic function, and obtain an xy chromaticity diagram according to the isochromatic function; In a state where the object to be observed and the background are irradiated with a first light source, obtain the relationship between wavelength and spectral radiance for the object to be observed, and determine one or more representative wavelengths according to the wavelength corresponding to the maximum value of the spectral radiance related to the object to be observed and the wavelength. The first light source is a light source that emits light with an average color rendering index of 40 or more, a color temperature in the range of 3000K to 10000K, and a continuous spectrum in the wavelength range of 380 nm to 780 nm; According to the representative wavelength and the xy chromaticity diagram, determine the contrast wavelength of the representative wavelength in a manner that increases the contrast between the object to be observed and the background; and Irradiate the object to be observed and the background with light that combines the representative wavelength and the contrast wavelength.

2. The lighting method according to claim 1, wherein, Before obtaining the contrast wavelength, determine a prohibited use band for the contrast wavelength, and determine the contrast wavelength outside the prohibited use band.

3. The lighting method according to claim 1 or 2, wherein, In the step of obtaining the contrast wavelength, if the representative wavelength is one wavelength, set the wavelength that is closest to the wavelength in a complementary color relationship with the representative wavelength in the xy chromaticity diagram as the contrast wavelength.

4. The lighting method according to claim 1 or 2, wherein, In the step of obtaining the contrast wavelength, if the representative wavelength is multiple wavelengths, set the wavelength corresponding to the point with the largest sum of color differences between the multiple points representing the multiple representative wavelengths in the xy chromaticity diagram as the contrast wavelength.

5. The lighting method according to claim 1 or 2, wherein, In the step of obtaining the contrast wavelength, if the representative wavelength is multiple wavelengths, set the wavelength that is closest to the wavelength in a complementary color relationship with the average wavelength of the multiple representative wavelengths in the xy chromaticity diagram as the contrast wavelength.

6. A lighting method, which is a lighting method for an object to be observed and a background, wherein, the lighting method includes the following steps: In a state where the object to be observed and the background are irradiated with a first light source, obtain the relationship between wavelength and spectral radiance for the object to be observed, and determine one or more representative wavelengths according to the wavelength corresponding to the maximum value of the spectral radiance related to the object to be observed and the wavelength. The first light source is a light source that emits light with an average color rendering index of 40 or more, a color temperature in the range of 3000K to 10000K, and a continuous spectrum in the wavelength range of 380 nm to 780 nm; In a state where the object to be observed and the background are irradiated with the first light source, obtain the relationship between wavelength and spectral radiance for the background, and determine one or more contrast wavelengths according to the wavelength corresponding to the maximum or minimum value of the spectral radiance related to the background and the wavelength; and Irradiate the object to be observed and the background with light that combines the representative wavelength and the contrast wavelength.

7. The lighting method according to claim 6, wherein, Before obtaining the representative wavelength and the comparison wavelength, a prohibited use band for the representative wavelength and the comparison wavelength is determined, and the representative wavelength and the comparison wavelength are determined outside the prohibited use band.

8. An illumination light spectral distribution determination system, wherein, the illumination light spectral distribution determination system includes: a first light source that emits light having an average color rendering index of 40 or more, a color temperature in the range of 3000K to 10000K, and a continuous spectrum in the wavelength range of 380 nm to 780 nm; a spectral radiance meter; and a processor connected to the spectral radiance meter, the illumination light spectral distribution determination system determines a representative wavelength and a comparison wavelength according to the method described in claim 1 or 6.

9. A lighting system, wherein, The illumination system includes: the illumination light spectral distribution determination system described in claim 8; and a second light source that irradiates the determined illumination light.

10. The lighting system according to claim 9, wherein, The second light source includes the first light source and a plurality of filters.

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