JP7276405B2 - Transmissive color calibration chart - Google Patents

Description

The present invention relates to a transmissive color calibration chart (hereinafter sometimes abbreviated as a color chart) for imaging equipment, particularly pathological imaging equipment.

In the field of imaging equipment, the resolution of output images is increasing, and high color reproducibility that faithfully reproduces color tones is also required.
In order to display an output image with correct reproduced colors, the imaging device uses, for example, a color chart as disclosed in Patent Document 1, and compares the colors reproduced by the imaging device with the reproduced colors on the color chart. If there is a difference in the reproduced color, it is calibrated based on the above color chart.

A color chart used for color calibration is composed of color bars of arbitrary colors. For example, it can be composed of three primary color bars of red, green and blue, and the type of color bar is the color gamut reproducible by the imaging device (hereinafter sometimes simply abbreviated as “color gamut”). ) can be selected as appropriate.

Here, the color gamut refers to a specific range in the visible region. For example, as shown in FIG. 11, the xy It can be represented using a chromaticity diagram. The color gamut can be indicated by a triangle in which the chromaticity coordinates, which are the vertexes of the colors R, G, and B, are determined in the xy chromaticity diagram and connected by straight lines.
Color gamuts have conventionally been defined by various color gamut standards, such as the sRGB standard and the NTSC standard. The sRGB standard is an international standard established by the International Electrotechnical Commission (IEC), and the NTSC standard is an analog television color gamut standard created by the National Television Standardization Committee of the United States. Recently, new standards that cover even wider color gamuts have emerged, such as the Adobe RGB standard and the digital cinema reference projector (D-Cinema Ref.PJ) standard.
Imaging devices are designed to be compatible with these color gamut standards, and are capable of reproducing pointer colors contained within the gamut of the imaging device when outputting images. Pointer color refers to colorimetric data representing the color gamut of surface colors that actually exist. When image output with accurate and uniform color reproducibility is required, as in pathological imaging equipment, it is necessary to have a wider color gamut to include many of the pointer colors.

WO2004/044639

A color chart used for color calibration has a color bar group composed of a plurality of color bars. In order to accurately calibrate the color of the imaging device, it is necessary to match the brightness of each color bar that constitutes the color bar group. A method of uniformly adjusting the brightness of each color bar is known. However, in the case of the method of adjusting the brightness of each color bar using a grayscale, problems arise, such as the configuration of the color chart becoming complicated.

Also, imaging equipment usually has an IR cut filter in the camera. The IR cut filter cuts different wavelength ranges depending on its type. As a result, color charts used for color calibration of imaging equipment have different color tones depending on the type of IR cut filter provided in the camera, and as a result, there is a problem that accurate color calibration of imaging equipment becomes difficult. occur.

The present invention has been made in view of the above problems. A main object of the present invention is to provide a transmissive color calibration chart that enables accurate color calibration.

In order to solve the above problems, the inventors of the present invention conducted extensive research, and found that the transmission spectrum of the color bars constituting the color bar group is, for example, a chevron waveform as shown in FIG. 4C described later. The inventors have found that the brightness of the color bar becomes higher than the brightness of the other color bars unless . In addition, when the transmission spectrum of the color bar does not have a chevron waveform, the cut wavelength range changes depending on the type of IR cut filter, so the color tone of the color bar varies depending on the type of IR cut filter. I have learned that I am affected. Therefore, the inventors of the present invention made it possible to make the brightness of the color bar group uniform without using a gray scale by making the transmission spectrum of each color bar constituting the color bar group a chevron waveform. In addition, it is possible to suppress the influence of the IR cut filter on the color tone, and to provide a transmissive color calibration chart capable of performing accurate color calibration of imaging equipment.

That is, the present invention has a transparent substrate and a color bar group formed on the transparent substrate, and the color bar group includes color bars of a plurality of colors including at least a first color and a second color, Arranged in a pattern in random order, the coordinate points of the first color are (0.351, 0.649), (0.547, 0.453), and (0.380) on the xy chromaticity diagram. , 0.506) and (0.433, 0.464). 489), (0.112, 0.229), (0.270, 0.407), (0.224, 0.242). Provided is a transmissive color calibration chart characterized in that the spectrum and the transmission spectrum of the second color bar each have separate peak tops.

Among the colors of the color bar, red, green, and blue may be referred to as "(three) primary colors". In addition, each color may be indicated by an abbreviation in parentheses.
Also, the chromaticity coordinates on the xy chromaticity diagram may be simply referred to as “color coordinates” or “coordinates”.
Furthermore, the first color may be referred to as yellow (Ye), and the second color may be referred to as cyan (Cy).

According to the present invention, the transmission spectrum of the first color bar and the transmission spectrum of the second color bar have separate peak tops, so that the transmission spectra of the first color bar and the second color bar are It can be a chevron waveform. As a result, the brightness of the color bar group is made uniform, and the influence of the IR cut filter provided in the camera of the imaging device is suppressed, thereby enabling accurate color calibration of the imaging device.

In the above invention, the color bar group further includes the three color bars of red, green, and blue, and the transmission spectrum of the red color bar, the transmission spectrum of the green color bar, and the transmission spectrum of the blue color bar are respectively It is preferable to have separate peak tops. The transmission spectra of five color bars excluding white can be made into chevron waveforms. This makes it possible to make the brightness of the color bar group more uniform and further suppress the influence of the IR cut filter provided in the camera of the imaging device, thereby enabling accurate color calibration of the imaging device. It is from.

In the above invention, the chromaticity coordinates on the xy chromaticity diagram of the color bar of at least five colors of red, green, blue, the first color, and the second color are included in a pentagon connecting straight lines. It is preferable that the coverage ratio of the pointer color used is 74.4% or more.
In the color chart of the present invention, the color gamut defined by the coordinates of the five colors sufficiently includes pointer colors, so that colors within the visible light region can be sufficiently covered. This is because an imaging device calibrated using the color chart of the present invention can sufficiently reproduce the colors of an existing object with high accuracy.

Further, the present invention has a transparent substrate and a group of color bars formed on the transparent substrate, wherein the group of color bars comprises at least one of red, green, blue, a first color, a second color and white. Color bars of six colors are arranged in random order in a pattern. 453), (0.380, 0.506), and (0.433, 0.464). (0.125, 0.489), (0.112, 0.229), (0.270, 0.407), (0.224, 0.242) within the area surrounded by the four points, The peak wavelength of the transmission spectrum of the red color bar is in the range of 600 nm to 680 nm, the peak wavelength of the transmission spectrum of the green color bar is in the range of 495 nm to 570 nm, and the peak wavelength of the transmission spectrum of the blue color bar is in the range of 430 nm to 490 nm. , the peak wavelength of the transmission spectrum of the first color bar is in the range of 540 nm to 595 nm, and the peak wavelength of the transmission spectrum of the second color bar is in the range of 470 nm to 515 nm. provide a chart.

In other words, the present invention has a transparent substrate and a group of color bars formed on the transparent substrate, wherein the group of color bars includes red (R), green (G), blue (B), and yellow. At least six color bars of (Ye), cyan (Cy), and white (W) are arranged in random order in a pattern, and the peak wavelength of the transmission spectrum of the R color bar is within the range of 600 nm to 680 nm, The peak wavelength of the transmission spectrum of the G color bar is in the range of 495 nm to 570 nm, the peak wavelength of the transmission spectrum of the B color bar is in the range of 430 nm to 490 nm, and the peak wavelength of the transmission spectrum of the Ye color bar is in the range of 540 nm to 595 nm. , and a Cy color bar having a transmission spectrum peak wavelength in the range of 470 nm to 515 nm.

According to the present invention, the five color bars excluding white have the peak wavelengths of the transmission spectrum at predetermined positions, so that the minimum six colors required to encompass the desired pointer color in the xy chromaticity diagram , the colors in the visible light range can be covered, and the colors in the visible light range can be reproduced uniformly. As a result, the color chart of the present invention can be used to accurately perform color calibration of imaging equipment.

In the above invention, the color bar group further includes two color bars of violet (V) and near infrared (NIR), and the transmission spectrum of the V color bar has a wavelength of 415 nm as a reference wavelength. The wavelength at which the relative transmittance is 50% when the transmittance at 100% is in the range of 435 nm to 465 nm. The wavelength at which the relative transmittance is 50% when the transmittance is 100% is preferably within the range of 630 nm to 730 nm.
The color chart of the present invention further includes two color bars, violet and near-infrared, which show predetermined transmission spectra, so that colors within the visible light range can be sufficiently covered. Colors can be reproduced uniformly. This is because the accuracy of color calibration of imaging equipment using the color chart of the present invention can be improved.

Further, in the above invention, it is preferable that the color bar group further includes an orange (O) color bar, and the transmission spectrum of the O color bar has a peak wavelength in the range of 575 nm to 620 nm.
The color chart of the present invention further includes an orange color bar that exhibits a predetermined transmission spectrum, so that it is possible to compensate for intermediate colors between yellow and red, which have wide intervals between peak wavelengths, and to achieve well-balanced colors in the visible light region. This is because it is possible to perform more detailed and highly accurate color calibration because it is possible to cover sufficiently.

In the above invention, the chromaticity coordinates on the xy chromaticity diagram of the color bar of at least five colors of R, G, B, the first color, and the second color are included in a pentagon connecting straight lines. It is preferable that the pointer color coverage rate is 90.3% or more.
In the color chart of the present invention, the color gamut defined by the coordinates of the five colors sufficiently includes pointer colors, so that colors within the visible light region can be sufficiently covered. This is because an imaging device calibrated using the color chart of the present invention can sufficiently reproduce the colors of an existing object with high accuracy.

In the above invention, the color bar group preferably further includes a magenta (Mg) color bar. White can be obtained by mixing red and cyan, or blue and yellow, which are symmetrical (complementary colors) with respect to the W coordinate on the xy chromaticity diagram. By including the Mg color bar in the bar group, white can also be obtained by mixing green and magenta, which are complementary colors, in an appropriate ratio. In this way, the color chart of the present invention can calibrate white more accurately by adjusting the same white using three references that utilize complementary color relationships.

In the case of the above invention, the chromaticity coordinates on the xy chromaticity diagram of the Mg color bar are the chromaticity coordinates on the xy chromaticity diagram of the G color bar and the white coordinate of D65 (hereinafter referred to as W (D65) coordinate It is preferable that it is on the extension line of the line connecting On the xy chromaticity diagram, the position of the Mg coordinate is on the extension line of the line connecting the W (D65) coordinate and the G coordinate, so that red and cyan, blue and yellow, green and magenta, which are complementary colors can be mixed at an appropriate ratio to reproduce white of D65. This is because the color chart of the present invention enables white calibration and white balance adjustment to be performed more accurately.

In the above invention, the peak wavelength of the transmission spectrum of the R color bar is in the range of 620 nm to 680 nm and the half width is 100 nm or less, and the peak wavelength of the transmission spectrum of the G color bar is in the range of 510 nm to 540 nm. It is preferable that the half value width is 80 nm or less, the peak wavelength of the transmission spectrum of the B color bar is in the range of 450 nm to 472 nm, and the half value width is 80 nm or less.
Since the transmission spectra of the color bars of the three primary colors have the spectral characteristics as described above, the color gamut defined by a triangle connecting the chromaticity coordinates of the three primary colors with a straight line on the xy chromaticity diagram is called BT. It is possible to approximate the color gamut defined by the coordinates of the three primary colors in the 2020 standard. Therefore, the color chart of the present invention is BT. This is because it is possible to cope with color calibration of imaging equipment to which the 2020 standard is applied. In addition, since the waveform of the transmission spectrum can have various waveform shapes for each color coordinate, by setting the half-value width together with the position of the peak wavelength of the transmission spectrum for each color, the present invention can be achieved. This is because the color chart can ensure color reproducibility based on the transmission spectrum.

In the above invention, the chromaticity coordinates of the second color bar on the xy chromaticity diagram is the line connecting the chromaticity coordinates of the R color bar on the xy chromaticity diagram and the W (D65) coordinate. is an extension, and BT. 2020 standard on the outer periphery of the color gamut or outside the color gamut, and the chromaticity coordinates on the xy chromaticity diagram of the first color bar are on the xy chromaticity diagram of the B color bar and the W (D65) coordinate, and BT. It is preferably located on the outer periphery of the color gamut defined by the 2020 standard or outside the color gamut.
On the xy chromaticity diagram, the position of the second color coordinate is on the extension line of the line connecting the W (D65) coordinate and the R coordinate, and the position of the first color coordinate is on the line connecting the W (D65) coordinate and the B coordinate. By making it on the extension line of , it is possible to reproduce the white of D65 by mixing each combination of cyan and red or yellow and blue, which are complementary colors, at an appropriate ratio, and it is possible to adjust the white balance. is. Also, the positions of the second color coordinates and the first color coordinates are determined by BT. This is because the color gamut in which colors can be reproduced using the color chart of the present invention can be widened by being positioned on the outer periphery of the color gamut defined by the 2020 standard or outside the color gamut.

The transmissive color calibration chart of the present invention uniforms the brightness of the color bar group and suppresses the influence of the IR cut filter provided in the camera of the imaging device on the color tone, so that the accurate color of the imaging device can be obtained. There is an effect that calibration can be performed.

1 is a schematic plan view showing an example of a transmissive color calibration chart of the present invention; FIG. 4 is an image graph showing an example of a spectral transmission spectrum indicated by the transmission type color calibration chart of the present invention. FIG. 4 is an xy chromaticity diagram showing an example of the color gamut of the transmissive color calibration chart of the present invention; FIG. 4 is an explanatory diagram illustrating a method of defining a peak wavelength and a reference wavelength of a transmission spectrum; 1 is a schematic plan view showing an example of a transmissive color calibration chart of the present invention; FIG. 4 is an image graph showing another example of the spectral transmission spectrum indicated by the transmission type color calibration chart of the present invention. FIG. 5 is another exemplary xy chromaticity diagram of the color gamut of the transmissive color calibration chart of the present invention; 1 is a schematic plan view showing an example of a transmissive color calibration chart of the present invention; FIG. 4 is an image graph showing another example of the spectral transmission spectrum indicated by the transmission type color calibration chart of the present invention. 4 is an xy chromaticity diagram illustrating positions of chromaticity coordinates of Cy, Ye, and Mg in the color gamut of the transmissive color calibration chart of the present invention; FIG. It is an xy chromaticity diagram explaining a color gamut.

The color chart of the present invention will be described separately for a first embodiment and a second embodiment.

I. First Embodiment The color chart of the first embodiment will be described in detail. The color chart of this aspect has a transparent substrate and a color bar group formed on the transparent substrate, and the color bar group includes color bars of a plurality of colors including at least a first color and a second color. , arranged in random order in a pattern, and the coordinate points of the first color are (0.351, 0.649), (0.547, 0.453), (0. 380, 0.506) and (0.433, 0.464), and the coordinate point of the second color is (0.125, 0 .489), (0.112, 0.229), (0.270, 0.407), and (0.224, 0.242). The transmission spectrum and the transmission spectrum of the second color bar are characterized by having separate peak tops.

A color chart of this embodiment will be described with reference to the drawings. FIG. 1 is a schematic plan view showing an example of a color chart of this embodiment. FIG. 2 is an image graph showing an example of the spectral transmission spectrum indicated by the color chart of this embodiment. 1 and 2 can be the same as the contents described in the section "II. Second embodiment" described later, so the description here is omitted.

Conventionally, for example, a method using a grayscale is known as a method of uniformly adjusting the brightness of each color bar. However, in the case of the method of adjusting the brightness of each color bar using a grayscale, problems arise, such as the configuration of the color chart becoming complicated.
Also, imaging equipment usually has an IR cut filter in the camera. The IR cut filter cuts different wavelength ranges depending on its type. As a result, color charts used for color calibration of imaging equipment have different color tones depending on the type of IR cut filter provided in the camera, and as a result, there is a problem that accurate color calibration of imaging equipment becomes difficult. occur.

Therefore, the inventors of this embodiment have found that when the transmission spectrum of the color bars constituting the color bar group does not have a chevron waveform, for example, as shown in FIG. We have found that the luminance is higher than that of other color bars. In addition, when the transmission spectrum of the color bar does not have a chevron waveform, the cut wavelength range changes depending on the type of IR cut filter, so the color tone of the color bar varies depending on the type of IR cut filter. I have learned that I am affected. This aspect has been made based on such findings, and is characterized in that the transmission spectrum of the first color bar and the transmission spectrum of the second color bar have separate peak tops. Accordingly, in this aspect, the brightness of the color bar group can be made uniform, and the influence of the IR cut filter provided in the camera of the imaging device on the color tone can be suppressed. Therefore, in this aspect, it is possible to perform accurate color calibration of the imaging device.

Further, according to this aspect, by adding color bars of the first color and the second color that newly exhibit a predetermined color to the conventional color bar group, it is possible to cover the colors in the visible light region, Colors within the visible light range can be reproduced uniformly. Thereby, the color chart of this aspect can be used to accurately calibrate the color of the imaging device.

In the following description, "having a separated peak top" refers to a so-called chevron waveform in which the apparent shape of the transmission spectrum is chevron, for example, a shape as shown in FIG. 4(a) described later. point to Here, the phrase "the external shape is mountain-shaped" means that the transmission spectrum in the visible region is at least mountain-shaped when observed as a whole. Waveforms created when moving up and down should not be chevron-shaped.
In addition, in the case of "having a separated peak top", the transmission spectrum has, for example, one convex part that is a chevron shape in appearance, like the transmission spectrum of each color bar shown in FIG. 2 to be described later. Alternatively, it may have two or more like the transmission spectrum of the magenta color bar shown in FIG. 9, which will be described later. It is preferable to have one protrusion.
Therefore, "the transmission spectrum of each color bar has a separate peak top" means that the transmission spectrum of each color has an independent chevron waveform, as shown in FIG. 2, which will be described later. do.

Each configuration of the color chart of this embodiment will be described below.

A. Color Bar Group The color bar group in this embodiment is formed on a transparent substrate.
The color bar group is configured by arranging color bars of a plurality of colors including at least a first color and a second color in random order in a pattern. The color bar group in this aspect preferably comprises at least six color bars of R, G, B, Ye, Cy and W arranged in a pattern in random order.
"Five colors excluding (excluding) W" means five colors of R, G, B, Ye and Cy.
In this specification, the term "five-color bar" refers to the five-color bar unless otherwise specified. In addition, unless otherwise specified, the term "6-color bar" refers to a color bar of a total of 6 colors, ie, the 5 colors and W described above. As will be described later, the same applies even when color bars of other colors are included.

1. Transmission Spectrum The transmission spectrum of the first color bar and the transmission spectrum of the second color bar each have separate peak tops and can be chevron waveforms. Also, normally, the transmission spectra of the R, G, and B color bars also have separate peak tops, and can be formed into chevron waveforms.

(1) Defining Method of Peak Wavelength The transmission spectra of the five color bars excluding W have peak wavelengths or reference wavelengths according to waveforms. The specific method for defining the peak wavelength is the same as the content described in the section “II. Therefore, the description is omitted here.

(2) Spectral Characteristics of Each Color Bar The spectral characteristics of each color bar constituting the color bar group will be described below.

(a) Red (R) color bar The R color bar has selective transmission to red light in the light source.
The transmission spectrum of the R color bar preferably has discrete peak tops. That is, it is preferable that the transmission spectrum of the R color bar has a chevron waveform. This is because it is possible to perform accurate color calibration of the imaging device by making the brightness of the color bar group more uniform and further suppressing the influence of the IR cut filter provided in the camera of the imaging device. .

The peak wavelength of the transmission spectrum of the R color bar is, for example, preferably within the range of 600 nm to 680 nm, more preferably within the range of 610 nm to 680 nm, particularly preferably within the range of 625 nm to 680 nm. This is because, if the peak wavelength is not within the above range, the separation of the peak tops will not be clear when the transmission spectra of the five colors excluding W are arranged in a well-balanced manner, and the interpolated color effect will be difficult to obtain.

For other detailed description of the R color bar, refer to "II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (a) Red (R) color bar" described later. The description here is omitted because it can be the same as the content described in Section 1.

(b) Green (G) Color Bar The G color bar has selective transmission to green light in the light source.
The transmission spectrum of the G color bar preferably has discrete peak tops. That is, it is preferable that the transmission spectrum of the G color bar has a chevron waveform. This is because it is possible to perform accurate color calibration of the imaging device by making the brightness of the color bar group more uniform and further suppressing the influence of the IR cut filter provided in the camera of the imaging device. .

The peak wavelength of the transmission spectrum of the G color bar is, for example, preferably within the range of 495 nm to 570 nm, more preferably within the range of 505 nm to 550 nm, particularly preferably within the range of 510 nm to 540 nm. This is because, if the peak wavelength is not within the above range, the separation of the peak tops will not be clear when the transmission spectra of the five colors excluding W are arranged in a well-balanced manner, and the interpolated color effect will be difficult to obtain.

For other detailed description of the G color bar, refer to "II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (b) Green (G) color bar" described later. The description here is omitted because it can be the same as the content described in Section 1.

(c) Blue (B) color bar The B color bar has selective transmission to blue light in the light source.
The transmission spectrum of the B color bar preferably has discrete peak tops. That is, it is preferable that the transmission spectrum of the B color bar has a chevron waveform. This is because it is possible to perform accurate color calibration of the imaging device by making the brightness of the color bar group more uniform and further suppressing the influence of the IR cut filter provided in the camera of the imaging device. .

The peak wavelength of the transmission spectrum of the B color bar is, for example, preferably within the range of 430 nm to 490 nm, more preferably within the range of 435 nm to 475 nm, particularly preferably within the range of 450 nm to 470 nm. This is because, if the peak wavelength is not within the above range, the separation of the peak tops will not be clear when the transmission spectra of the five colors excluding W are arranged in a well-balanced manner, and the interpolated color effect will be difficult to obtain.

For other detailed description of the B color bar, refer to "II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (c) Blue (B) color bar" described later. The description here is omitted because it can be the same as the content described in Section 1.

(d) First Color Bar The first color bar in this aspect has coordinate points on the xy chromaticity diagram of (0.351, 0.649), (0.547, 0.453), ( 0.380, 0.506), (0.433, 0.464), among which (0.417, 0.583), (0.490, 0.510) ), (0.387, 0.501), and (0.421, 0.474), especially (0.435, 0.565), (0.474). 472, 0.528), (0.402, 0.504), and (0.421, 0.489).

Also, the transmission spectrum of the first color bar has a discrete peak top. That is, the transmission spectrum of the first color bar is a chevron waveform. This makes it possible to make the brightness of the color bar group more uniform and further suppress the influence of the IR cut filter provided in the camera of the imaging device, thereby enabling accurate color calibration of the imaging device. It is from.
Hereinafter, the first color bar may be referred to as the Ye color bar in some cases.

For other detailed description of the Ye color bar, refer to "II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (d) Yellow (Ye) color bar" described later. The description here is omitted because it can be the same as the content described in Section 1.

(e) Second Color Bar The second color bar in this embodiment has coordinate points on the xy chromaticity diagram of (0.125, 0.489), (0.112, 0.229), ( 0.270, 0.407) and (0.224, 0.242), among which (0.123, 0.437) and (0.115, 0.296) , (0.254, 0.350), (0.240, 0.297). , 0.320), (0.239, 0.341), and (0.231, 0.312).

Also, the transmission spectrum of the secondary color bar has a discrete peak top. That is, the transmission spectrum of the second color bar is a chevron waveform. This makes it possible to make the brightness of the color bar group more uniform and to further suppress the influence of the IR cut filter provided in the camera of the imaging device, thereby enabling accurate color calibration of the imaging device. It is from.
Hereinafter, the second color bar may be referred to as a Cy color bar in some cases.

For other detailed description of the Cy color bar, refer to "II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (e) Cyan (Cy) color bar" described later. Since it can be the same as the content described in the section, the description here is omitted.

(f) White (W) Color Bar The W color bar is colorless and translucent and is used as a blank. The W color bar will be described later in the section “II. Since it can be the same as the content, the description here is omitted.

(g) Arbitrary color bar In addition to the six color bars described above, the color bar group further includes two color bars, violet (V) and near-infrared (NIR), having predetermined transmission spectra. is preferred. By including a V color bar and an NIR color bar showing a predetermined transmission spectrum in addition to five color bars excluding W, the color chart of this embodiment can sufficiently cover colors in the visible light region. , can uniformly reproduce colors in the visible light region. As a result, it is possible to improve the accuracy of color calibration of imaging equipment using the color chart of this aspect.

Also, the color bar group preferably further includes an orange (O) color bar having a predetermined transmission spectrum in addition to the six color bars described above. The color chart of this embodiment further includes an O color bar that exhibits a predetermined transmission spectrum, so that it is possible to compensate for intermediate colors between yellow and red, which have wide intervals between peak wavelengths, and sufficiently balance colors in the visible light region. can be covered, more detailed and highly accurate color calibration is possible.

Hereinafter, the configuration when an arbitrary color bar is included is described later in "II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (g) Arbitrary color bar". 5 to 9 described in Section 1, so the description here is omitted.

The color bars of each color that can be included in the color chart of this embodiment will be described below.

(i) Violet color (V) color bar The transmission spectrum of the V color bar is more selective than the transmission spectrum of the B color bar because it has selective transmittance for light on the short wavelength side of blue light among the short wavelength light in the light source. is also on the short wavelength side and partly overlaps the transmission spectrum of the B color bar.

Also, the transmission spectrum of the V color bar preferably has separate peak tops. That is, it is preferable that the transmission spectrum of the V color bar has a chevron waveform. This is because it is possible to perform accurate color calibration of the imaging device by making the brightness of the color bar group more uniform and further suppressing the influence of the IR cut filter provided in the camera of the imaging device. .

For other detailed description of the V color bar, refer to "II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (i) Violet color (V) color bar" described later. Since it can be the same as the content described in the section, the description here is omitted.

(ii) Near-infrared (NIR) color bar The transmission spectrum of the NIR color bar has selective transmittance for light on the longer wavelength side than red light among the long wavelength light from the light source, so the transmission of the R color bar is It is preferably located on the shorter wavelength side of the spectrum and partially overlaps the transmission spectrum of the B color bar.

For other detailed explanations of NIR color bars, refer to "II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (ii) Gold infrared (NIR) color Since it can be the same as the content described in the section “Bar”, the description here is omitted.

(iii) Orange (O) color bar Since the transmission spectrum of the O color bar has selective transmittance for light on the short wavelength side of the red light among the long wavelength light in the light source, it is the transmission spectrum of the Ye color bar. It is preferably located between the transmission spectrum of the R color bar.
Since the distance between the peak wavelengths of the transmission spectrum of the Ye color bar and the transmission spectrum of the R color bar is wide, the peak wavelength of the transmission spectrum of the O color bar is located at the above position to compensate for the intermediate color between Ye and R. This makes it possible to reproduce the intermediate colors.

Also, the transmission spectrum of the O color bar preferably has discrete peak tops. That is, it is preferable that the transmission spectrum of the O color bar has a chevron waveform. This is because it is possible to perform accurate color calibration of the imaging device by making the brightness of the color bar group more uniform and further suppressing the influence of the IR cut filter provided in the camera of the imaging device. .

For other detailed explanations of the O color bar, refer to "II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (iii) Orange (O) color bar" described later. Since it can be the same as the content described in the section, the description here is omitted.

(iv) Magenta (Mg) Color Bar The color bar group preferably includes a magenta (Mg) color bar.
On the xy chromaticity diagram based on the color chart of this embodiment, the position of the W coordinate can be specified by the positional relationship between the R coordinate and the Cy coordinate, and the positional relationship between the B coordinate and the Ye coordinate. By considering the positional relationship between , and the Mg coordinates, the position of the W coordinates of D65, which is the reference color, can be specified more accurately. In particular, even when a light source other than the D65 light source is used, the use of the color chart of this embodiment including the Mg color bar has the advantage that the position of the W(65) coordinate can be adjusted accurately.

The Mg color bar has selective transmission to red and blue light in the light source.
As shown in FIG. 9, the transmission spectrum 22 (Mg) of the Mg color bar has a first transmission peak (hereinafter referred to as the first peak wavelength) near the peak wavelength of the transmission spectrum 22 (R) of the R color bar. ) and has a second transmission peak (hereinafter referred to as a second peak wavelength) near the peak wavelength of the transmission spectrum 22(B) of the B color bar.

The transmission spectrum of the Mg color bar preferably has discrete peak tops.
That is, it is preferable that the first transmission peak and the second transmission peak of the O color bar are chevron waveforms. This is because it is possible to perform accurate color calibration of the imaging device by making the brightness of the color bar group more uniform and further suppressing the influence of the IR cut filter provided in the camera of the imaging device. .

For other detailed description of the Mg color bar, refer to "II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (iv) Magenta (Mg) color bar" described later. Since it can be the same as the content described in the section, the description here is omitted.

(h) Others In the spectral transmission spectrum of the color chart of this embodiment, adjacent transmission spectra partially overlap in the visible light region, so that the mixing ratio of each color component included in the color mixture can be accurately specified. , the color reproduction accuracy and color calibration accuracy of mixed colors can be improved.

2. xy Chromaticity Diagram Next, the xy chromaticity diagram indicated by the color chart of this embodiment using the color bar group will be described. Note that the xy chromaticity diagram in this aspect can be the same as the content described in the section "II. Second embodiment A. Color bar group 2. xy chromaticity diagram" to be described later. is omitted.

3. Structure of Color Bar and Color Bar Group Each color bar may be a member that exhibits a desired transmission spectrum, and may be a band-pass filter or a dyed substrate, for example. The structure of the color bar and color bar group in this embodiment is the same as the content described in the section "II. Second embodiment A. Color bar group 3. Structure of color bar and color bar group" described later. Therefore, the description here is omitted.

B. Light Shielding Portion The color chart of this aspect is usually provided with a light shielding portion around the color bar group on the transparent substrate. It should be noted that the light shielding part in this aspect can be the same as the content described in the section "II. Second embodiment B. Light shielding part" described later, so the description is omitted here.

C. Transparent Substrate The transparent substrate in this embodiment is not particularly limited as long as it can support the color bar group and the light shielding portion and has the desired light transmittance. can be the same. It should be noted that the transparent substrate in this aspect can be the same as that described in the section "II. Second Embodiment C. Transparent substrate" described later, so the description is omitted here.

D. Others The color chart of this embodiment may have an alignment mark, a recognition code, a cover glass, a color bar holding frame, a transparent protective plate with a light shielding portion, etc., in addition to the above-described configuration. Other configurations in this aspect can be the same as those described in the section "II. Second Embodiment D. Others" to be described later, so descriptions thereof will be omitted here.

E. Uses The color chart of this embodiment can be used for general imaging equipment, video equipment, and peripheral equipment that require color calibration. Among others, it can be suitably used for pathological imaging equipment.

II. Second Embodiment A color chart of the second embodiment will be described in detail. A color chart of this aspect has a transparent substrate and a group of color bars formed on the transparent substrate, and the group of color bars includes red, green, blue, a first color, a second color and white. At least six color bars are arranged in random order in a pattern, and the coordinate points of the first color are (0.351, 0.649), (0.547, 0 .453), (0.380, 0.506), and (0.433, 0.464). , (0.125, 0.489), (0.112, 0.229), (0.270, 0.407), (0.224, 0.242) , the peak wavelength of the transmission spectrum of the red color bar is in the range of 600 nm to 680 nm, the peak wavelength of the transmission spectrum of the green color bar is in the range of 495 nm to 570 nm, and the peak wavelength of the transmission spectrum of the blue color bar is in the range of 430 nm to 490 nm. Among them, the peak wavelength of the transmission spectrum of the first color bar is in the range of 540 nm to 595 nm, and the peak wavelength of the transmission spectrum of the second color bar is in the range of 470 nm to 515 nm.

2. Description of the Related Art Conventionally, in the field of imaging equipment, the resolution of output images has been increasing, and high color reproducibility that faithfully reproduces color tones has been demanded.
In particular, pathological imaging equipment is required to accurately reproduce the colors of the output image with colors that are close to the real thing, since human tissues are observed and pathologically diagnosed based on images captured through a microscope. In addition, when imaging the same sample using different imaging devices, differences in reproduced colors due to differences in the spectral sensitivity characteristics of the imaging devices may result in uniform results in pathological diagnosis of the same sample based on output images. sometimes not. Therefore, regardless of the type and manufacturer of imaging equipment, the reproduced color of the output image should be the same.

In order to improve the color reproducibility of an output image in an imaging device, it is necessary to widen the color gamut reproducible by the imaging device.

In order to display an output image with correct reproduced colors, the imaging device uses, for example, a color chart as disclosed in Patent Document 1, and compares the colors reproduced by the imaging device with the reproduced colors on the color chart. If there is a difference in the reproduced color, it is calibrated based on the above color chart.
As described above, pathological imaging equipment is required to output images with accurate and uniform color reproducibility. required to have

By the way, as the color gamut of imaging equipment expands, the number of colors that can be reproduced increases, so it is necessary to reproduce pointer colors more accurately. There are colors that are not well covered and cannot be reproduced during color calibration of output images from imaging equipment, especially pathological imaging equipment. For this reason, there is a problem that the imaging equipment cannot be accurately calibrated, and the imaging equipment cannot achieve high color reproducibility of the output image.

On the other hand, in order to reproduce a wide color gamut in displays, etc., a so-called "single peak" spectrum is used to reduce the overlapping of the three primary colors of RGB with color filters and backlights, thereby reducing color mixing with adjacent colors. Shape technology development is underway.
In order to widen the color gamut of the color chart, in principle, it is necessary to develop the three primary colors to have a narrow transmission spectrum distribution width and a unimodal spectral shape, like a display.
In addition, in the development of the color chart, in addition to the three primary colors, in order to improve the chart function and make it possible to calibrate the color of the image sensor of the imaging device, we have developed the color of the wavelength range between B and G and between G and R in addition to the three primary colors. Also, consideration must be given to the arrangement of colors and the transmission spectrum.

In particular, pathological imaging equipment particularly requires high color reproducibility for output images as described above, and uniform color reproducibility is required regardless of the type of imaging equipment. Color charts used for pathological imaging equipment are required to sufficiently cover colors within the visible light range and to be capable of uniformly reproducing colors within the visible light range.

This aspect has been made in view of the above-mentioned problems, and can sufficiently cover colors in the visible light range, reproduce colors uniformly, and accurately perform color calibration of imaging equipment. The main object is to provide a possible transmissive color calibration chart.

This aspect is characterized in that the transmission spectra of the color bars excluding W constituting the color bar group have peaks at desired intervals within the visible light region and are arranged in a well-balanced manner. That is, as shown in FIG. 2, in the color chart of this embodiment, the peak wavelength of the transmission spectrum 22(R) of the R color bar is within the range of 600 nm to 680 nm, and the peak wavelength of the transmission spectrum 22(G) of the G color bar is within the range of 600 nm to 680 nm. is in the range of 495 nm to 570 nm, and the peak wavelength of the transmission spectrum 22(B) of the B color bar is in the range of 430 nm to 490 nm.
The peak wavelength of the transmission spectrum 22 (Ye) of the Ye color bar is in the range of 540 nm to 595 nm, and the peak wavelength of the transmission spectrum 22 (Cy) of the Cy color bar is in the range of 470 nm to 515 nm.

According to this aspect, the color bars of five colors excluding white have the peak wavelengths of the transmission spectrum at predetermined positions, so that the minimum six colors required to include the desired pointer color in the xy chromaticity diagram , the colors in the visible light range can be covered, and the colors in the visible light range can be reproduced uniformly. Thereby, the color chart of this aspect can be used to accurately calibrate the color of the imaging device.

In this aspect, the visible light region refers to a wavelength region of 380 nm to 780 nm. The wavelength range defined in this specification, which is expressed as “within the range of Anm to Bnm (A and B are numerical values)”, can be rephrased as “Anm or more and Bnm or less (A and B are numerical values)”. can.
Further, in this aspect, the “xy chromaticity diagram” refers to the xy chromaticity diagram of the CIE1931-XYZ color system.

In the following description, "separation of peak tops" means suppression of overlapping of peak tops of transmission spectra of respective colors. Also, "spectrum separation" means suppressing the occurrence of color mixture due to overlap of transmission spectra of a plurality of colors.

A color chart of this embodiment will be described with reference to the drawings. FIG. 1 is a schematic plan view showing an example of a color chart of this embodiment. FIG. 2 is an image graph showing an example of the spectral transmission spectrum indicated by the color chart of this embodiment, and FIG. 3 is an xy chromaticity diagram showing the color gamut of the color chart of this embodiment.
A color chart 10 of this embodiment has a transparent substrate 1 and a color bar group 2 formed on the transparent substrate 1 . A color bar holding frame 4 is provided around the color bar group 2 .
The color bar group 2 includes at least six color bars of a red color bar 12R, a green color bar 12G, a blue color bar 12B, a yellow color bar 12Ye, a cyan color bar 12Cy, and a white color bar 12W in random order. are arranged in a pattern. The white color bar 12W is normally transparent. A light shielding portion 3 is provided around each color bar on the transparent substrate 1 .
The color chart 10 of this embodiment has spectral transmission spectrum characteristics as shown in FIG. 2, and as shown in FIG. It has an enclosed color gamut L1. Note that L2 in FIG. 3 indicates a color gamut surrounded by a triangle connecting the coordinates of the three colors R, G, and B on the xy chromaticity diagram with straight lines. The same shall apply hereinafter.

In the color chart of this aspect, the light incident from the back is dispersed according to the selective transmittance of the five color bars excluding W that constitute the color bar group, and in the visible light region, from the short wavelength side, The transmission spectrum of each color of B color bar, Cy color bar, G color bar, Ye color bar, and R color bar appears respectively.

This aspect is characterized in that the transmission spectra of the color bars excluding W constituting the color bar group have peaks at desired intervals within the visible light region and are arranged in a well-balanced manner. That is, as shown in FIG. 2, in the color chart of this embodiment, the peak wavelength of the transmission spectrum 22(R) of the R color bar is within the range of 600 nm to 680 nm, and the peak wavelength of the transmission spectrum 22(G) of the G color bar is within the range of 600 nm to 680 nm. is in the range of 495 nm to 570 nm, and the peak wavelength of the transmission spectrum 22(B) of the B color bar is in the range of 430 nm to 490 nm.
The peak wavelength of the transmission spectrum 22 (Ye) of the Ye color bar is in the range of 540 nm to 595 nm, and the peak wavelength of the transmission spectrum 22 (Cy) of the Cy color bar is in the range of 470 nm to 515 nm.

In addition, the chromaticity coordinates of the five color bars excluding W in the color chart of this embodiment are distributed as shown in FIG. 3 on the xy chromaticity diagram. The color chart of this embodiment can reproduce and calibrate the colors of the pointer colors contained within the color gamut L1 surrounded by a pentagon that connects the coordinates of the five colors with straight lines on the xy chromaticity diagram. .
The chromaticity coordinates of the color bar on the xy chromaticity diagram are P(λ) for the spectral spectrum of the color bar, and x_(λ) and y_(λ) for the color matching functions in the XYZ color system adopted by the CIE in 1931. , z_(λ), and the spectral distribution of the light source as S_(λ),
X = ∫ (380nm to 780nm) P(λ) * x_(λ) * S_(λ) dλ/∫ (380nm to 780nm) y_(λ) * S_(λ) dλ
Y = ∫ (380nm to 780nm) P(λ) * y_(λ) * S_(λ) dλ/∫ (380nm to 780nm) y_(λ) * S_(λ) dλ
Z = ∫ (380nm to 780nm) P(λ) * z_(λ) * S_(λ) dλ/∫ (380nm to 780nm) y_(λ) * S_(λ) dλ
x = X / (X + Y + Z)
y = Y / (X + Y + Z)
z = 1-x-y ( = Z / (X + Y + Z))
are the coordinates calculated by The above formula is defined in JIS Z8701.
Also, here, the spectral distribution S_(λ) of the light source is based on the D65 light source. W (D65) in FIG. 3 is the white coordinate of D65, and white indicated by the white coordinate is referred to as "white of D65" in this specification.

According to this aspect, the color bars of five colors excluding white have the peak wavelengths of the transmission spectrum at predetermined positions, so that the minimum six colors required to include the desired pointer color in the xy chromaticity diagram , the colors in the visible light range can be covered, and the colors in the visible light range can be reproduced uniformly. Thereby, the color chart of this aspect can be used to accurately calibrate the color of the imaging device.

Each configuration of the color chart of this embodiment will be described below.

A. Color Bar Group The color bar group in this embodiment is formed on a transparent substrate.
The color bar group is composed of at least six color bars of R, G, B, Ye, Cy and W arranged in random order in a pattern.
"Five colors excluding (excluding) W" means five colors of R, G, B, Ye and Cy.
In this specification, the term "five-color bar" refers to the five-color bar unless otherwise specified. In addition, unless otherwise specified, the term "6-color bar" refers to a color bar of a total of 6 colors, ie, the 5 colors and W described above. As will be described later, the same applies even when color bars of other colors are included.

1. Transmission Spectra The transmission spectra of the five color bars, excluding W, have peak wavelengths at predetermined positions.
In the spectral transmission spectrum of the color chart of this embodiment, the transmission spectrum of each color bar appears in a well-balanced manner so as to cover the desired wavelength range within the visible light range. In addition, adjacent transmission spectra partly overlap, so that the spectral transmission spectrum of the color chart can cover the entire visible light region.

(1) Defining Method of Peak Wavelength The transmission spectra of the five color bars excluding W have peak wavelengths or reference wavelengths according to waveforms. That is, the transmission spectra of the five color bars excluding W show a chevron waveform as shown in FIG. 4(a) and have a peak wavelength λ _P indicating high transmittance. As shown in FIG. 4A, the peak wavelength λ _P is determined by specifying the maximum value T _max of the actually measured transmittance of the transmission spectrum, and when the transmittance of the maximum value T _max is 100%, the relative transmittance is 50%. The wavelengths λ ₁ and λ ₂ are specified and set as the center wavelength of the wavelength region from the wavelength λ ₁ to the wavelength λ ₂ . Also, the measured transmittance T at the peak wavelength λ _P is defined as "the transmittance at the peak wavelength (hereinafter sometimes referred to as the peak transmittance)".
Note that the term “transmittance” simply means the measured transmittance, and the term “relative transmittance” means the transmittance obtained by converting the actually measured transmittance at a specific wavelength to 100%.

The transmission spectrum of each color bar is obtained by measuring the transmittance in the visible light region of 380 nm to 780 nm with a colorless (transparent) white color bar as a background using a microscopic spectrophotometer OSP-SP200 manufactured by Olympus Corporation. . Further, when calculating the coordinates of each color on the xy chromaticity diagram, the known D65 light source spectrum data is used.
Hereinafter, the same applies to color bars of arbitrary colors other than the above five colors.

(2) Spectral Characteristics of Each Color Bar The spectral characteristics of each color bar constituting the color bar group will be described below.

(a) Red (R) color bar The R color bar has selective transmission to red light in the light source.
The peak wavelength of the transmission spectrum of the R color bar may be within the range of 600 nm to 680 nm, preferably within the range of 610 nm to 680 nm, particularly within the range of 625 nm to 680 nm. This is because, if the peak wavelength is not within the above range, the separation of the peak tops will not be clear when the transmission spectra of the five colors excluding W are arranged in a well-balanced manner, and the interpolated color effect will be difficult to obtain.

The half width of the transmission spectrum of the R color bar is preferably 120 nm or less, more preferably in the range of 20 nm to 100 nm, particularly preferably in the range of 30 nm to 80 nm. Further, the lower limit of the half-value width can be set to 10 nm.
If the half width is not within the above range, the transmission spectrum of the color bars of other colors has an overlapping region, and it may be difficult to sufficiently widen the red region of the color gamut of the color chart of this embodiment. , the saturation of reproducible colors may decrease.
The half-value width of the transmission spectrum refers to the wavelength interval at which the peak transmittance of the transmission spectrum is half the value, and is calculated from the measurement result of the above-mentioned transmission spectrum measurement (using Olympus Co., Ltd. OSP-SP200 microscopic spectrophotometer). can do. Hereinafter, the same applies to color bars of other colors.

In addition, the transmission spectrum of the R color bar is also shown in BT. It is preferably equivalent to the red transmission spectrum defined in the 2020 standard. That is, it is preferable that the peak wavelength of the transmission spectrum of the R color bar is within the range of 620 nm to 680 nm and the half width is 100 nm or less, and the peak wavelength is within the range of 630 nm to 670 nm and the half width is 80 nm or less. More preferably, the peak wavelength is in the range of 630 nm to 660 nm and the half width is 70 nm or less.
By setting the peak wavelength and half width of the transmission spectrum of the R color bar within the above range, the coordinates of the R color bar on the xy chromaticity diagram are set to BT. 2020 standard, and the red region of the color gamut of the color chart of this embodiment is defined by BT. This is because it is possible to expand the red area defined by the 2020 standard.

(b) Green (G) Color Bar The G color bar has selective transmission to green light in the light source.
The peak wavelength of the transmission spectrum of the G color bar may be within the range of 495 nm to 570 nm, preferably within the range of 505 nm to 550 nm, particularly preferably within the range of 510 nm to 540 nm. This is because, if the peak wavelength is not within the above range, the separation of the peak tops will not be clear when the transmission spectra of the five colors excluding W are arranged in a well-balanced manner, and the interpolated color effect will be difficult to obtain.

In addition, as the half width of the transmission spectrum of the G color bar, it is possible to show a waveform in which the transmission spectrum of the G color bar can partially overlap the transmission spectrum of the Cy color bar and the transmission spectrum of the Ye color bar. If it is Specifically, the half width is preferably 100 nm or less, more preferably in the range of 20 nm to 80 nm, particularly preferably in the range of 30 nm to 60 nm. Further, the lower limit of the half-value width can be set to 10 nm.
If the half-value width is not within the above range, it may be difficult to sufficiently widen the green region of the color gamut of the color chart of this embodiment, because the transmission spectra of the color bars of other colors have overlapping regions. , the saturation of reproducible colors may decrease.

Also, the transmission spectrum of the G color bar is that of BT. It is preferably equivalent to the green transmission spectrum defined in the 2020 standard. That is, the transmission spectrum of the G color bar preferably has a peak wavelength of 510 nm to 540 nm and a half width of 80 nm or less, and preferably has a peak wavelength of 515 nm to 538 nm and a half width of 60 nm or less. More preferably, the peak wavelength is in the range of 520 nm to 535 nm and the half width is 40 nm or less.
By setting the peak wavelength and half width of the transmission spectrum of the G color bar within the above range, the coordinates of the G color bar on the xy chromaticity diagram are set to BT. 2020 standard, and the green color region of the color gamut of the color chart of this embodiment is defined by the BT. This is because it is possible to extend the green area defined by the 2020 standard.

(c) Blue (B) color bar The B color bar has selective transmission to blue light in the light source.
The peak wavelength of the transmission spectrum of the B color bar may be within the range of 430 nm to 490 nm, preferably within the range of 435 nm to 475 nm, particularly preferably within the range of 450 nm to 470 nm. This is because, if the peak wavelength is not within the above range, the separation of the peak tops will not be clear when the transmission spectra of the five colors excluding W are arranged in a well-balanced manner, and the interpolated color effect will be difficult to obtain.

Also, the half-value width of the transmission spectrum of the B color bar may be any waveform that allows the transmission spectrum of the B color bar to partially overlap the transmission spectrum of the Cy color bar. Specifically, the half width is preferably 100 nm or less, more preferably in the range of 20 nm to 85 nm, particularly preferably in the range of 25 nm to 55 nm. Further, the lower limit of the half-value width can be set to 10 nm.
If the half width is not within the above range, the transmission spectrum of the color bars of other colors has an overlapping region, and it may be difficult to sufficiently widen the blue region of the color gamut of the color chart of this embodiment. , the saturation of reproducible colors may decrease.

Also, the transmission spectrum of the B color bar is BT. It is preferably equivalent to the blue transmission spectrum defined in the 2020 standard. That is, the transmission spectrum of the B color bar preferably has a peak wavelength of 450 nm to 472 nm and a half width of 80 nm or less, and preferably has a peak wavelength of 455 nm to 470 nm and a half width of 60 nm or less. More preferably, the peak wavelength is in the range of 458 nm to 468 nm and the half width is 40 nm or less.
By setting the peak wavelength and half width of the transmission spectrum of the R color bar within the above range, the coordinates of the R color bar on the xy chromaticity diagram are set to BT. 2020 standard, and the blue region of the color gamut of the color chart of this embodiment is defined by the BT. This is because it is possible to extend the blue color range defined by the 2020 standard.

(d) Yellow (Ye) Color Bar The Ye color bar has selective transmission to short and long wavelength light in the light source.
Also, the transmission spectrum of the Ye color bar is located between the transmission spectrum of the G color bar and the transmission spectrum of the R color bar.

The peak wavelength of the transmission spectrum of the Ye color bar may be within the range of 540 nm to 595 nm, preferably within the range of 545 nm to 585 nm, particularly preferably within the range of 560 nm to 575 nm. This is because, if the peak wavelength is not within the above range, the separation of the peak tops will not be clear when the transmission spectra of the five colors excluding W are arranged in a well-balanced manner, and the interpolated color effect will be difficult to obtain.

The half-value width of the transmission spectrum of the Ye color bar may be any waveform that allows the transmission spectrum of the Ye color bar to partially overlap the transmission spectrum of the G color bar. Specifically, the half width is preferably 180 nm or less, more preferably in the range of 20 nm to 170 nm, particularly preferably in the range of 30 nm to 70 nm.
Further, the lower limit of the half-value width can be set to 10 nm.
This is because if the half-value width is not within the above range, the overlapping region with the transmission spectra of the color bars of other colors increases.

(e) Cyan (Cy) color bar The Cy color bar has selective transmission to short and medium wavelength light in the light source.
The transmission spectrum of the Cy color bar lies between the transmission spectrum of the G color bar and the transmission spectrum of the B color bar.

The peak wavelength of the transmission spectrum of the Cy color bar may be within the range of 470 nm to 515 nm, preferably within the range of 480 nm to 505 nm, particularly preferably within the range of 490 nm to 500 nm. If the peak wavelength of the transmitted light of the Cy color bar is not within the above range, when the transmission spectra of the five colors excluding W are arranged in a well-balanced manner, the separation of the peak tops is not clear, and the interpolation color effect is difficult to achieve. Because it will be.

As the half width of the transmission spectrum of the Cy color bar, the transmission spectrum of the Cy color bar can show a waveform that can partially overlap the transmission spectrum of the G color bar and the transmission spectrum of the B color bar. Just do it. Specifically, the half width is preferably 150 nm or less, more preferably in the range of 20 nm to 130 nm, particularly preferably in the range of 30 nm to 80 nm. Further, the lower limit of the half-value width can be set to 10 nm.
If the half-value width is not within the above range, the overlapping region with the transmission spectrum of the color bar of other colors increases. , spectral separation on the spectral transmission spectrum becomes difficult.

(f) White (W) Color Bar The W color bar is colorless and translucent and is used as a blank. The W color bar can be a transparent substrate, which will be described later.
In addition, in order to enable brightness adjustment, an achromatic W color bar (for example, an ND filter, etc.) designed to evenly absorb light in the visible range may be placed on the transparent substrate. It may be used as a transparent substrate.

(g) Arbitrary color bar In addition to the six color bars described above, the color bar group further includes two color bars, violet (V) and near-infrared (NIR), having predetermined transmission spectra. is preferred. By including a V color bar and an NIR color bar showing a predetermined transmission spectrum in addition to five color bars excluding W, the color chart of this embodiment can sufficiently cover colors in the visible light region. , can uniformly reproduce colors in the visible light region. As a result, it is possible to improve the accuracy of color calibration of imaging equipment using the color chart of this aspect.

Also, the color bar group preferably further includes an orange (O) color bar having a predetermined transmission spectrum in addition to the six color bars described above. The color chart of this embodiment further includes an O color bar that exhibits a predetermined transmission spectrum, so that it is possible to compensate for intermediate colors between yellow and red, which have wide intervals between peak wavelengths, and sufficiently balance colors in the visible light region. can be covered, more detailed and highly accurate color calibration is possible.

The color bar group may be composed of a total of eight colors including the six color bars described above and two colors of a V color bar and an NIR color bar having a predetermined transmission spectrum. It may be composed of a total of seven colors including the color bar and the O color bar. Further, it may be composed of a total of 9 colors including the 6 color bars described above and 3 colors of the V color bar, the NIR color bar and the O color bar.

FIG. 5 is a schematic plan view showing another example of the color chart of this embodiment, and in addition to the six color bars 12R, 12G, 12B, 12Ye, 12Cy, and 12W shown in FIG. 12V, a near-infrared color bar 12NIR, and an orange color bar 12O. The color chart shown in FIG. 5 has spectral transmission spectrum characteristics as shown in FIG.
The chromaticity coordinates of the color bars of eight colors excluding W in the color chart shown in FIG. 5 are distributed on the xy chromaticity diagram as shown in FIG. The colors of the pointer colors contained within the octagonal color gamut L3 can be reproduced and calibrated.

In addition, when the color bar group is composed of a total of eight colors including a V color bar and an NIR color bar having a predetermined transmission spectrum in addition to the six color bars described above, the color chart of this aspect is as follows: 7 shows a spectral transmission spectrum excluding a transmission spectrum 22(O) of an O color bar from the spectral transmission spectrum shown in FIG.
Further, when the color bar group is composed of a total of seven colors including an O color bar having a predetermined transmission spectrum in addition to the six color bars described above, the color chart of this embodiment is shown in FIG. Of the spectral transmission spectra, the spectral transmission spectra excluding the transmission spectrum 22 (NIR) of the NIR color bar and the transmission spectrum 22 (V) of the V color bar are shown.

The color bar group preferably includes a magenta (Mg) color bar in addition to the six color bars described above. White is obtained by mixing R and Cy, or B and Ye, which are symmetrical (complementary colors) with respect to the W coordinate on the xy chromaticity diagram. By including an Mg color bar in the bar group, W can also be obtained by mixing complementary colors G and Mg in an appropriate ratio. In this manner, the color chart of this aspect can calibrate white more accurately by adjusting the same white using three references that utilize complementary color relationships.

The color bar group may be composed of a total of seven colors including the above six color bars and the Mg color bar, and the above six color bars and a V color bar and NIR color bar having a predetermined transmission spectrum. It may be composed of a total of nine colors including two color bars and an Mg color bar. Alternatively, it may be composed of a total of eight colors including the six color bars described above, an O color bar having a predetermined transmission spectrum, and an Mg color bar.
Furthermore, the color bar group is a total of 10 colors including the above-mentioned 6 color bars, 3 colors of V color bar, NIR color bar, and O color bar having a predetermined transmission spectrum, and Mg color bar. may be configured.

FIG. 8 is a schematic plan view showing another example of the color chart of this embodiment, and in addition to the nine color bars 12R, 12G, 12B, 12Ye, 12Cy, 12W, 12V, 12NIR, and 12O shown in FIG. has a color bar group 2 in which a total of 10 color bars including a magenta color bar 12Mg are arranged in random order in a pattern. The color chart shown in FIG. 8 has spectral transmission spectrum characteristics as shown in FIG.
The chromaticity coordinates of the nine color bars excluding W in the color chart shown in FIG. 8 are distributed on the xy chromaticity diagram as shown in FIG. It is included in the color gamut L3 surrounded by an 8 shape connecting the coordinates of the 8 colors with straight lines.

When the color bar group is composed of a total of seven colors, the six color bars and the Mg color bar, the color chart of this embodiment is the NIR color bar among the spectral transmission spectra shown in FIG. The transmission spectrum 22 (NIR) of the V color bar, the transmission spectrum 22 (V) of the V color bar, and the transmission spectrum 22 (O) of the O color bar are shown.

The color bars of each color that can be included in the color chart of this embodiment will be described below.

(i) Violet color (V) color bar The transmission spectrum of the V color bar is more selective than the transmission spectrum of the B color bar because it has selective transmittance for light on the short wavelength side of blue light among the short wavelength light in the light source. is also on the short wavelength side and partly overlaps the transmission spectrum of the B color bar.

The transmission spectrum of the color bar of V has, in addition to the chevron waveform shown in FIG. A chevron waveform may not be obtained. Therefore, regarding the transmission spectrum of the color bar of V, as shown in FIG. 4(b), the wavelength 415 nm is set as the reference wavelength λ _s , and the measured transmittance T at the reference wavelength λ _s is defined as the "transmittance at the reference wavelength (Hereinafter, it may be referred to as a reference transmittance.)”.
The transmission spectrum of the V color bar has a reference wavelength λ _s of 415 nm and a wavelength (relative wavelength) λ ₃ at which the relative transmittance is 50% when the transmittance at the reference wavelength λ _s is 100% is 435 nm to 465 nm. preferably within the range of 435 nm to 460 nm, particularly preferably within the range of 440 nm to 455 nm.
By setting the relative wavelength within the above range, it is possible to suppress the spread of the spectrum waveform in a wavelength region longer than the reference wavelength and overlap the transmission spectrum of the B color bar in a desired wavelength region. As a result, the transmission spectrum of the V color bar can maintain the overlap of the peak itself while maintaining the separation between the transmission spectrum of the B color bar and the peak top, so it is possible to evaluate the short wavelength side of the visible light region without omission. Because you can.

It is preferable that the transmission spectrum of the V color bar exhibits a transmittance equal to or higher than a predetermined value in a wavelength region shorter than the reference wavelength. “A region of wavelengths shorter than the reference wavelength” refers to a wavelength region of 380 nm or more, which is the lower limit of the visible light region, and shorter than the reference wavelength of 415 nm. Specifically, when the transmission spectrum of the V color bar exhibits a transmittance of a predetermined value or more in a wavelength region shorter than the reference wavelength, when the reference transmittance is 100%, in a wavelength region shorter than the reference wavelength is preferably 5% or more, more preferably 8% or more, and even more preferably 10% or more. This is because it is possible to reproduce colors in a wavelength region shorter than the reference wavelength of the transmission spectrum of the V color bar.

The transmission spectrum of the V color bar preferably has a relative transmittance of 5% or less at a wavelength of 490 nm or more when the reference transmittance is 100%, more preferably 3% or less, particularly preferably 1% or less. . If the relative transmittance in the above wavelength region of the transmission spectrum of the V color bar exceeds the above range, it becomes difficult to separate the spectrum from the transmission spectra of the color bars of other colors on the spectral transmission spectrum. This is because there is a high possibility that the reproducibility of the color coordinates in the degree diagram will be extremely low.

(ii) Near-infrared (NIR) color bar The transmission spectrum of the NIR color bar has selective transmittance for light on the longer wavelength side than red light among the long wavelength light from the light source, so the transmission of the R color bar is It is preferably located on the shorter wavelength side of the spectrum and partially overlaps the transmission spectrum of the B color bar.

As shown in FIG. 4C, the transmission spectrum of the NIR color bar has a waveform indicating a transmittance equal to or higher than a predetermined transmittance at a certain wavelength or more, and may not be a chevron waveform. Therefore, regarding the transmission spectrum of the _NIR color bar, as _shown in FIG. (Hereinafter, it may be referred to as a reference transmittance.)”.
In the transmission spectrum of the NIR color bar, the reference wavelength λ _t is 730 nm, and the wavelength (relative wavelength) λ ₄ at which the relative transmittance is 50% when the transmittance at the reference wavelength λ _t is 100% is 630 nm to 630 nm. It is preferably within the range of 730 nm, more preferably within the range of 640 nm to 710 nm, particularly preferably within the range of 650 nm to 700 nm.
By setting the relative wavelength within the above range, it is possible to suppress the spread of the spectrum waveform in a wavelength region shorter than the reference wavelength and overlap the transmission spectrum of the R color bar in a desired wavelength region. As a result, the transmission spectrum of the NIR color bar maintains the separation of the transmission spectrum and the peak top of the R color bar, while maintaining the overlap of the peaks themselves. This is because

Further, it is preferable that the transmission spectrum of the NIR color bar exhibits a transmittance of a certain value or more in a wavelength region longer than the reference wavelength. The term “longer wavelength region than the reference wavelength” refers to a wavelength region longer than the reference wavelength of 730 nm and equal to or less than the wavelength of 780 nm, which is the upper limit of the visible light region. Specifically, when the transmission spectrum of the NIR color bar exhibits a certain value or more of transmittance in a wavelength region longer than the reference wavelength, when the reference transmittance is 100%, in a wavelength region longer than the reference wavelength is preferably 30% or more, more preferably 50% or more, and even more preferably 80% or more. This is because it is possible to reproduce colors in a longer wavelength range than the reference wavelength of the transmission spectrum of the NIR color bar.

The transmission spectrum of the NIR color bar preferably has a relative transmittance of 5% or less at a wavelength of 620 nm or less when the reference transmittance is 100%, more preferably 2% or less, particularly preferably 1% or less. . When the relative transmittance in the above wavelength region of the transmission spectrum of the NIR color bar exceeds the above range, it becomes difficult to separate the spectrum from the transmission spectra of the color bars of other colors on the spectral transmission spectrum. This is because there is a high possibility that the reproducibility of the color coordinates in the degree diagram will be extremely low.

(iii) Orange (O) color bar Since the transmission spectrum of the O color bar has selective transmittance for light on the short wavelength side of the red light among the long wavelength light in the light source, it is the transmission spectrum of the Ye color bar. It is preferably located between the transmission spectrum of the R color bar.
Since the distance between the peak wavelengths of the transmission spectrum of the Ye color bar and the transmission spectrum of the R color bar is wide, the peak wavelength of the transmission spectrum of the O color bar is located at the above position to compensate for the intermediate color between Ye and R. This makes it possible to reproduce the intermediate colors.

The peak wavelength of the transmission spectrum of the O color bar is preferably within the range of 575 nm to 620 nm, more preferably within the range of 580 nm to 615 nm, particularly preferably within the range of 585 nm to 610 nm. This is because, if the peak wavelength is not within the above range, when the transmission spectra of the eight colors excluding W are arranged in a well-balanced manner, the separation of the peak tops is not clear, and the interpolated color effect is difficult to obtain.

As the half width of the transmission spectrum of the O color bar, it is possible to show a waveform that allows the transmission spectrum of the O color bar to partially overlap the transmission spectrum of the Ye color bar and the transmission spectrum of the R color bar. Just do it. Specifically, the half width is preferably 120 nm or less, more preferably in the range of 20 nm to 100 nm, particularly preferably in the range of 20 nm to 70 nm. Further, the lower limit of the half-value width can be set to 10 nm.
If the half width is not within the above range, the overlapping region with the transmission spectrum of the color bars of other colors increases, and in particular Ye, R and NIR are different colors on the color coordinates in the xy chromaticity diagram. This is also because spectral separation on the spectral transmission spectrum becomes difficult.

In the transmission spectrum of the O color bar, the relative transmittance at wavelengths of 550 nm or less and 680 nm or more is preferably 10% or less, especially 5% or less, particularly 3% or less, when the peak transmittance is 100%. Preferably.
When the relative transmittance in the above wavelength region of the transmission spectrum of the O color bar exceeds the above range, the overlapping region with the transmission spectra of the color bars of other colors increases, and the spectral separation on the spectral transmission spectrum increases. This is because it can be difficult. Moreover, it is because the color reproduction accuracy of O by the color chart of this aspect may deteriorate.

(iv) Magenta (Mg) Color Bar The color bar group preferably includes a magenta (Mg) color bar.
On the xy chromaticity diagram based on the color chart of this embodiment, the position of the W coordinate can be specified by the positional relationship between the R coordinate and the Cy coordinate, and the positional relationship between the B coordinate and the Ye coordinate. By considering the positional relationship between , and the Mg coordinates, the position of the W coordinates of D65, which is the reference color, can be specified more accurately. In particular, even when a light source other than the D65 light source is used, the use of the color chart of this embodiment including the Mg color bar has the advantage that the position of the W(65) coordinate can be adjusted accurately.

The Mg color bar has selective transmission to red and blue light in the light source.
As shown in FIG. 9, the transmission spectrum 22 (Mg) of the Mg color bar has a first transmission peak (hereinafter referred to as the first peak wavelength) near the peak wavelength of the transmission spectrum 22 (R) of the R color bar. ) and has a second transmission peak (hereinafter referred to as a second peak wavelength) near the peak wavelength of the transmission spectrum 22(B) of the B color bar.

The transmission spectrum of the Mg color bar preferably has a first peak wavelength in the range of 567 nm to 780 nm, more preferably in the range of 590 nm to 710 nm, particularly preferably in the range of 610 nm to 680 nm.
Also, the second peak wavelength is preferably in the range of 380 nm to 495 nm, more preferably in the range of 400 nm to 485 nm, particularly preferably in the range of 430 nm to 470 nm. When each peak wavelength of the transmission spectrum of the Mg color bar is not within the above range, when reproducing white by mixing magenta and green, which is in a complementary color relationship, white of D65 is obtained at any mixing ratio. This is because it becomes difficult to In addition, it is difficult to fall within the specified color coordinates on the xy chromaticity diagram regardless of the half width of the transmission spectrum of the Mg color bar.

(h) Others In the spectral transmission spectrum of the color chart of this embodiment, adjacent transmission spectra partially overlap in the visible light region, so that the mixing ratio of each color component included in the color mixture can be accurately specified. , the color reproduction accuracy and color calibration accuracy of mixed colors can be improved.

2. xy Chromaticity Diagram Next, the xy chromaticity diagram indicated by the color chart of this embodiment using the color bar group will be described. In the color chart of this embodiment, the chromaticity coordinates of the five color bars excluding W are distributed as shown in FIG. 3 on the xy chromaticity diagram.
Coordinates (x, y) of R, G, B, Ye, and Cy on the xy chromaticity diagram shown in FIG. 0.751), B (0.137, 0.049), Ye (0.448, 0.538), Cy (0.141, 0.339).

The color chart of this embodiment can reproduce and calibrate pointer colors contained within a color gamut surrounded by a pentagon in which coordinates of five colors are connected by straight lines on an xy chromaticity diagram.
According to this aspect, since each color bar constituting the color bar group exhibits the above-described transmission spectrum, it is possible to have a wider color gamut than the conventional color chart.

In this aspect, the coverage rate of the pointer color included in the pentagon connecting the coordinates of the above five color bars on the xy chromaticity diagram with straight lines is, for example, 90.3% or more. Among them, it is preferably 99.9% or more, and more preferably 100%, that is, it is preferable that all the pointer colors are contained within the pentagon. The color gamut of the color chart of this embodiment is the inside of the pentagon connecting the coordinates of the five colors excluding white with straight lines, and the color gamut sufficiently includes the pointer colors, thereby sufficiently covering the colors within the visible light region. be able to. This is because the color of the object that actually exists can be reproduced more accurately, so that the color calibration of the imaging device can be performed with high accuracy.

When the color chart of this embodiment includes the V color bar, the NIR color bar and the O color bar in the color bar group, the chromaticity coordinates of the eight color bars excluding W are shown in FIG. 7 on the xy chromaticity diagram. distributed as shown.
The coordinates (x, y) of V, NIR, and O on the xy chromaticity diagram shown in FIG. ), O(0.647, 0.352).

The color chart of this aspect can extend the range of the color gamut on the xy chromaticity diagram according to the number of colors included in the color bar group.
For example, when the color bar group is composed of a total of 8 colors including a V color bar and an NIR color bar in addition to 6 color bars, the color chart of this embodiment has W It is possible to reproduce and calibrate the pointer colors contained within the color gamut bounded by a heptagon formed by connecting the coordinates of the seven colors with straight lines.
Further, when the color bar group is composed of a total of 7 colors including an O color bar in addition to the 6 color bars, the color chart of this embodiment has 6 colors except W on the xy chromaticity diagram. It is possible to reproduce and calibrate pointer colors contained within the color gamut bounded by the hexagons drawn by connecting the coordinates of .
Furthermore, when the color bar group is composed of a total of 9 colors including a V color bar, an NIR color bar and an O color bar in addition to the 6 color bars, the color chart of this embodiment is an xy chromaticity diagram Above, the pointer colors contained within the color gamut bounded by the octagon drawn by straight lines connecting the coordinates of each of the eight colors, excluding W, can be reproduced and calibrated.
In this way, by increasing the number of types of colors of the color bars forming the color bar group, it is possible to have a wider color gamut.
When the color bar group is composed of 7, 8, or 9 colors as described above, the coverage rate of pointer colors included in polygons connecting the coordinates on the xy chromaticity diagram with straight lines is 5. It can be similar to the coverage of pointer colors contained within a pentagon by a color bar of colors.

As described above, in the spectral transmission spectrum of the color chart of this embodiment, the peak wavelength and half width of the transmission spectrum of each color bar of R, G, and B are preferably within a predetermined range. The color gamut (L2 in FIG. 3) defined by a triangle connecting the coordinates of the three primary colors with straight lines on the xy chromaticity diagram of the color chart of this embodiment is referred to as BT. 2020 standard, the color gamut can be approximated by the coordinates of the three primary colors, and the BT. This is because it is possible to cope with color calibration of imaging equipment to which the 2020 standard is applied. In addition, since the waveform of the transmission spectrum can have various waveform shapes for each color coordinate, by setting the half-value width together with the position of the peak wavelength of the transmission spectrum for each color, the This is because the color chart can ensure color reproducibility based on the transmission spectrum.

As shown in FIG. 10, the coordinates of the Cy color bar on the xy chromaticity diagram (hereinafter referred to as Cy coordinates) correspond to the coordinates of the R color bar on the xy chromaticity diagram (R coordinates) and W ( 65) is on an extension of the line connecting the coordinates and BT. 2020 standard on the outer periphery of the color gamut or outside the color gamut, and the coordinates on the xy chromaticity diagram of the Ye color bar (hereinafter referred to as Ye coordinates) are the coordinates of the B color bar It is on the extension line of the line connecting the coordinate (B coordinate) on the xy chromaticity diagram and the W (D65) coordinate, and BT. It is preferably located on the outer periphery of the color gamut defined by the 2020 standard or outside the color gamut.
On the xy chromaticity diagram, the position of the Cy coordinate is on the extension line of the line connecting the W (D65) coordinate and the R coordinate, and the position of the Ye coordinate is on the extension line of the line connecting the W (D65) coordinate and the B coordinate. By doing so, it is possible to reproduce white of D65 by mixing each combination of cyan and red or yellow and blue, which are in a complementary color relationship, at an appropriate ratio, and it is possible to adjust the white balance with high accuracy. is. In addition, the positions of the Cy and Ye coordinates are based on the BT. In addition to being located on the outer periphery of the color gamut defined by the 2020 standard, it may be positioned outside the above color gamut, thereby expanding the color gamut in which colors can be reproduced using the color chart of this embodiment.

Among them, the Cy coordinate is the intersection of the extension of the line connecting the R coordinate and the W coordinate and the side of the triangle, and the Ye coordinate is the intersection of the extension of the line connecting the B coordinate and the W coordinate and the side of the triangle. A point of intersection is preferred.
On the xy chromaticity diagram, when the Cy coordinates are on the triangle, the cyan obtained by mixing green and blue at an appropriate mixing ratio is the same as the cyan indicated by the Cy color bar of the color chart of this embodiment. and whether the white obtained by mixing cyan and red is D65 white.
Similarly, with respect to Ye, if the Ye coordinate is on the triangle on the xy chromaticity diagram, yellow obtained by mixing green and red in an appropriate mixing ratio and the Ye color bar of the color chart of this embodiment is the same as the yellow indicated by , and it is possible to verify whether the white obtained by mixing yellow and blue is the white of D65.
In this way, the color chart of this embodiment has the Cy coordinates and Ye coordinates on the xy chromaticity diagram at the above positions, so that the same white obtained by mixing cyan and red, and yellow and blue, respectively, It can be calibrated to D65 white.

Furthermore, when the color bar group includes an Mg color bar, the coordinates of the Mg color bar on the xy chromaticity diagram (hereinafter referred to as Mg coordinates) are the coordinates of the G color bar on the xy chromaticity diagram. It is preferably on the extension line of the line connecting the coordinate (G coordinate) and the W coordinate, and more preferably on the extension line and on the side of the triangle.
On the xy chromaticity diagram, the position of the Mg coordinate is on the extension line of the line connecting the W (D65) coordinate and the G coordinate, so that red and cyan, blue and yellow, green and magenta, which are complementary colors can be mixed at an appropriate ratio to reproduce white of D65. This is because the color chart of the present embodiment can thereby perform white calibration and white balance adjustment more accurately.
When the Mg color bar is included, the Mg coordinates are not included as each color coordinate defining the color gamut.

The transmission spectra of the color bars of each color of Cy, Ye, and Mg are designed by appropriately adjusting the position of the peak wavelength and the half-value width according to the position of each coordinate of Cy, Ye, and Mg on the xy chromaticity diagram. can do. In order to adjust the Cy coordinates, the transmission spectrum of the Cy color bar is obtained by drawing a straight line from the W (D65) color coordinate position to the target Cy color coordinates and the outer circumference of the xy chromaticity diagram. The intersection with the wavelength position along the curve can be used as a measure of the peak position. Also, the half width of the transmission spectrum of the Cy color bar can be set so as not to interfere with the peak positions of other adjacent transmission spectra. The smaller the half-value width, the higher the saturation, and the larger the half-value width, the lower the saturation. Therefore, it is possible to change the half-value width according to the target coordinate position of Cy. The same is true for the transmission spectrum of the Ye color bar.
Regarding Mg, the peak wavelength position of the B color bar or V color bar and the peak of the R color bar or NIR color bar that can draw a straight line passing through the target Mg coordinates on the xy chromaticity diagram The wavelength positions can be set to the first and second peaks of the transmission spectrum of the Mg color bar, respectively. The half width of the transmission spectrum of the Mg color bar can be changed according to the target coordinate position of Mg.

3. Structure of Color Bar and Color Bar Group Each color bar may be a member that exhibits a desired transmission spectrum, and may be a band-pass filter or a dyed substrate, for example.
The dyed substrate can be formed by a dyeing method. For example, a silver salt emulsion prepared by adding a solution of potassium bromide and silver nitrate to gelatin is used, and the silver salt emulsion is coated on a chip substrate such as a glass plate. , can be formed by desilvering from a dry silver salt photographic plate obtained by drying and dyeing with a dye corresponding to the color of the color bar. Alternatively, the dyed substrate can be formed by mixing a gelatin (solution) with a dye in advance to obtain a predetermined color, and applying the material to a chip substrate such as a glass plate.

When forming each color bar, the peak wavelength position of the transmission spectrum of the color bar can be adjusted according to the type of color bar and its forming method.
For example, if a dyed substrate using one kind of dye is used as a color bar, the peak wavelength of the transmission spectrum of the color bar can also be adjusted by adjusting the concentration of the dye.
Further, when a dyed substrate formed by blending two or more dyes is used as a color bar, the peak wavelength of the transmission spectrum of the color bar can be adjusted by changing the blending ratio of the two dyes. can. Specifically, if it is a G color bar, it can be formed by a dyeing method using two kinds of yellow dye and blue dye. The peak wavelength position can be adjusted by increasing the compounding ratio and shifting to the short wavelength side by increasing the compounding ratio of the blue dye.

The size and the like of the color bar are not particularly limited, and can be appropriately designed according to the application of the color chart of the present embodiment so that the desired effect can be easily exhibited.

In the color bar group, each color bar is arranged in a pattern in random order. As the arrangement pattern of the color bars of each color, they may be arranged in a line pattern as illustrated in FIG. 1, or may be arranged in a grid pattern or a circle although not illustrated.
Also, the arrangement order of the color bars of each color is not particularly limited, and can be appropriately designed so as to easily produce the desired effect according to the application of the color chart of this embodiment.

Each color bar can be formed using a conventionally known method such as a vapor deposition method, a dyeing method, a printing method, a transfer method, and an inkjet method. Since the method of forming the color bar by the dyeing method has been described above, the explanation is omitted here.
Further, the color bar group can be formed, for example, by arranging the color bars of each color formed by the method described above in a desired pattern on one side of a transparent substrate described later and sandwiching the transparent substrate and the cover glass. .

B. Light Shielding Portion The color chart of this aspect is usually provided with a light shielding portion around the color bar group on the transparent substrate.
The light-shielding part may be any material having a desired light-shielding property, and examples thereof include a metal film such as a chromium thin film, and a printed layer formed with black ink.
As for the method of forming the light shielding portion, a conventionally known method can be used depending on the material to be used.

C. Transparent Substrate The transparent substrate in this embodiment is not particularly limited as long as it can support the color bar group and the light shielding portion and has the desired light transmittance. can be the same. Specifically, an inorganic substrate such as a glass substrate or a resin substrate can be used. The resin substrate may be in the form of a plate, a film, or a sheet.

D. Others The color chart of this embodiment may have an alignment mark, a recognition code, a cover glass, a color bar holding frame, a transparent protective plate with a light shielding portion, etc., in addition to the above-described configuration.
The recognition code can be, for example, a code in which test chart information or the like is recorded. Further, the alignment mark can be a mark in which position information is recorded, but may also function as a recognition code in which test chart information or the like is recorded. These may be provided on a transparent protective plate with a light shielding portion.

Moreover, the color chart of this aspect may have an IR cut filter. When each color cover is formed by a dyeing method, the dye tends to transmit light in a wavelength range of 650 nm or more, resulting in high light transmittance. In particular, the dyes used for the Ye, O, R color bars tend to absorb less light on the long wavelength side from around 650 nm. Therefore, in the long wavelength region, the transmission spectrum of each color overlaps.
On the other hand, by combining an IR cut filter that removes a predetermined region with the color bar, it is possible to separate the transmission spectrum of each color and prevent color mixture.
The IR cut filter can be selected by examining the wavelength region to be blocked according to the transmission spectrum characteristics of each color bar. A conventionally known IR cut filter can be used.

The size of the color chart of this aspect can be designed according to the captured image to which it is applied. For example, when the color chart of this embodiment is used for color evaluation and color correction of an output image of a measurement sample imaged through a microscope of pathological imaging equipment, a color bar having a size corresponding to the magnification of the objective lens of the microscope It can be a grouped color chart for micro imaging.
Further, when the color chart of this aspect is used, for example, for color evaluation and color correction of an output image of a measurement sample imaged by an imaging device at 1:1 magnification, a group of color bars having a size corresponding to the size of the imaged image is formed. It can be a color chart for macro imaging.

E. Uses The color chart of this embodiment can be used for general imaging equipment, video equipment, and peripheral equipment that require color calibration. Among others, it can be suitably used for pathological imaging equipment.

The present invention is not limited to the above embodiments. The above embodiment is an example, and any device that has substantially the same configuration as the technical idea described in the claims of the present invention and produces similar effects is the present invention. It is included in the technical scope of the invention.

EXAMPLES The present invention will be described in more detail below with reference to examples.

[Example 1]
A transmissive color calibration chart consisting of six color bars of R, G, B, Ye, Cy and W and showing the spectrum of FIG. 2 and the xy chromaticity diagram of FIG. 3 was prepared.
Five color bars other than W were obtained by desilvering from a silver salt photographic dry plate coated with a silver salt emulsion prepared by adding a solution of potassium bromide and silver nitrate to gelatin on a glass plate and drying. As a substrate, a dyed substrate obtained by dyeing the substrate with a dye corresponding to each color was used. As for the dyes, acid dyes that are commonly used are used according to the color of each color bar. In addition, the dyeing method is the same as the commonly used manufacturing method. First, a dyeing solution is prepared by mixing an acid dye and an auxiliary agent, the substrate is immersed in the dyeing solution, and the dyeing progresses to a predetermined concentration. The substrate was taken out and washed with water.
The transmissive color calibration chart was formed by laminating a transparent protective plate with a light shielding portion, color bars of each color, and a transparent substrate in this order from the uppermost surface, with the surface to be recognized by the device facing up. Each color bar (dyed substrate) was arranged in the order of B, Cy, G, Ye, R, W on a transparent substrate (glass substrate). For the W color bar, a glass substrate serving as a transparent substrate was arranged.
Color bars other than W were arranged on a transparent substrate via an IR cut filter.
For B, Cy, and G color bars, A type (half value T = 50% 620 nm) was used as an IR cut filter, and for Ye and R color bars, B type (half value T = 50% 665 nm) was used as an IR cut filter. ) was used.
Table 1 shows the peak wavelength of the color bar for each color.

[Example 2]
In addition to the 6 color bars of Example 1, it is composed of a total of 9 color bars with the addition of 3 colors of V, NIR, and O, and shows the spectral spectrum in FIG. 6 and the xy chromaticity diagram in FIG. A transmissive color calibration chart was created. Three color bars of V, NIR, and O were obtained in the same manner as the color bars of other colors in Example 1.
A transmissive color calibration chart was formed in the same manner as in Example 1. Each color bar (dyed substrate) was arranged in the order of V, B, Cy, G, Ye, O, R, NIR, W on a transparent substrate (glass substrate). For the W color bar, a glass substrate serving as a transparent substrate was arranged.
Color bars other than NIR and W were arranged on a transparent substrate via an IR cut filter. For the V, B, Cy, and G color bars, an A type IR cut filter (half value T = 50% 620 nm) was used, and for the Ye, O, and R color bars, a B type IR cut filter (half value T = 50% 665 nm) was used.

[Example 3]
In addition to the 9 color bars of Example 2, a total of 10 color bars with Mg were added, and a transmissive color calibration chart showing the spectrum of FIG. 9 and the xy chromaticity diagram of FIG. 10 was created. . The Mg color bar was obtained by the same method as the method for forming color bars of other colors in Example 1.
A transmissive color calibration chart was formed in the same manner as in Example 1. Each color bar was arranged in the order of V, B, Cy, G, Ye, O, R, Mg, NIR, and W on the transparent substrate.
Color bars other than NIR and W were arranged on a transparent substrate via an IR cut filter. For the V, B, Cy, and G color bars, an A type IR cut filter (half value T = 50% 620 nm) was used, and for the Ye, O, R, and Mg color bars, a B type IR cut filter ( half value T=50% 665 nm) was used.

The relative wavelengths of the V and NIR color bars and the peak wavelengths of the O and Mg color bars are shown in Table 2.

Table 3 shows the inclusion rate of the pointer color included in the color gamut in the xy chromaticity diagram of the transmissive color calibration charts obtained in Examples 1-3. The color gamut is defined within the pentagon connecting the coordinates of the five colors excluding W in FIG. 3, and the octagon connecting the coordinates of the eight colors excluding W and Mg in FIGS.

DESCRIPTION OF SYMBOLS 1... Transparent substrate 2... Color bar group 3... Light shielding part 4... Color bar holding frame 12... Color bar 10... Transmissive color calibration chart (color chart)

Claims (10)

a transparent substrate;
a group of color bars formed on the transparent substrate;
has
The color bar group is configured by arranging color bars of a plurality of colors including at least a first color and a second color in random order in a pattern,
The coordinate points of the first color are (0.351, 0.649), (0.547, 0.453), (0.380, 0.506), (0.433, 0.464) within the area surrounded by four points,
The coordinate points of the second color are (0.125, 0.489), (0.112, 0.229), (0.270, 0.407), (0.224) on the xy chromaticity diagram. , 0.242) within the area surrounded by four points,
The transmission spectrum of the first color bar and the transmission spectrum of the second color bar have separate peak tops,
The color bar group further includes a magenta color bar, and the transmission spectrum of the magenta color bar has two separate peak tops in the visible light region,
A transmissive color calibration chart , wherein the separated peak top exhibits a chevron-shaped waveform in which the apparent shape of a transmission spectrum is chevron-shaped . The color bar group further includes the three color bars of red, green and blue,
2. The transmissive color calibration chart according to claim 1, wherein the transmission spectrum of the red color bar, the transmission spectrum of the green color bar, and the transmission spectrum of the blue color bar each have separate peak tops. Inclusion of a pointer color contained within a pentagon connecting straight lines chromaticity coordinates on the xy chromaticity diagram of the color bar of at least five colors of red, green, blue, the first color, and the second color 3. The transmissive color calibration chart according to claim 2, wherein the ratio is 74.4% or more. a transparent substrate;
a group of color bars formed on the transparent substrate;
has
The color bar group comprises at least six color bars of red, green, blue, first color, second color and white arranged in random order in a pattern,
The coordinate points of the first color are (0.351, 0.649), (0.547, 0.453), (0.380, 0.506), (0.433, 0.464) within the area surrounded by four points,
The coordinate points of the second color are (0.125, 0.489), (0.112, 0.229), (0.270, 0.407), (0.224) on the xy chromaticity diagram. , 0.242) within the area surrounded by four points,
The peak wavelength of the transmission spectrum of the red color bar is in the range of 600 nm to 680 nm,
The peak wavelength of the transmission spectrum of the green color bar is in the range of 495 nm to 570 nm,
The peak wavelength of the transmission spectrum of the blue color bar is in the range of 430 nm to 490 nm,
the peak wavelength of the transmission spectrum of the first color bar is in the range of 540 nm to 595 nm,
The peak wavelength of the transmission spectrum of the second color bar is within the range of 470 nm to 515 nm,
The color bar group further includes a magenta color bar, and the transmission spectrum of the magenta color bar has two separate peak tops in the visible light region,
A transmissive color calibration chart , wherein the separated peak top exhibits a chevron-shaped waveform in which the apparent shape of a transmission spectrum is chevron-shaped . Inclusion of a pointer color contained within a pentagon connecting straight lines chromaticity coordinates on the xy chromaticity diagram of said color bar of at least five colors of red, green, blue, said first color, and said second color 5. The transmissive color calibration chart according to claim 4, wherein the ratio is 90.3% or more. The transmission spectrum of the red color bar has a peak wavelength in the range of 620 nm to 680 nm and a half width of 100 nm or less,
The transmission spectrum of the green color bar has a peak wavelength in the range of 510 nm to 540 nm and a half width of 80 nm or less,
The transmission type according to any one of claims 2 to 5, wherein the peak wavelength of the transmission spectrum of the blue color bar is in the range of 450 nm to 472 nm and the half width is 80 nm or less. Chart for color calibration. The chromaticity coordinates of the second color bar on the xy chromaticity diagram are on an extension of a line connecting the chromaticity coordinates of the red color bar on the xy chromaticity diagram and the white coordinates of D65, and , BT. Located on the outer periphery of the color gamut defined by the 2020 standard or outside the color gamut,
The chromaticity coordinates of the first color bar on the xy chromaticity diagram are on an extension of a line connecting the chromaticity coordinates of the blue color bar on the xy chromaticity diagram and the white coordinates, and BT. 7. The transmissive color calibration chart according to any one of claims 2 to 6, which is located on the outer periphery of the color gamut defined by the 2020 standard or outside the color gamut. 8. Any one of claims 1 to 7, wherein the color bar group further includes an orange color bar, and the transmission spectrum of the orange color bar has a peak wavelength within a range of 575 nm to 620 nm. The transmission type color calibration chart according to claim 1. Claims 1 to 8, wherein the magenta color bar has a first peak wavelength in the range of 567 nm to 780 nm and a second peak wavelength in the range of 380 nm to 495 nm. The transmissive color calibration chart according to any one of claims 1 to 3. The chromaticity coordinates of the magenta color bar on the xy chromaticity diagram are on an extension of a line connecting the chromaticity coordinates of the green color bar on the xy chromaticity diagram and the white coordinates of D65. The transmissive color calibration chart according to any one of claims 2 to 7.

Images