JP6390737B2 - Transparent color calibration chart - Google Patents

Description

  The present invention relates to a transmission color calibration chart (hereinafter sometimes abbreviated as a color chart) for imaging apparatuses, and in particular, pathological imaging apparatuses.

In the field of imaging equipment, higher resolution of output images is being promoted, and high color reproducibility that faithfully reproduces color tone is also demanded for colors.
In order to display an output image with a correct reproduction color, the imaging device uses, for example, a color chart disclosed in Patent Document 1 to compare the reproduction color on the imaging device with the reproduction color on the color chart. If there is a difference in the reproduction color, calibration is performed based on the color chart.

  A color chart used for color calibration is composed of color bars of arbitrary colors. For example, a color bar of three primary colors of red, green, and blue may be used, and the type of color bar may be abbreviated as a color gamut that can be reproduced by an imaging device (hereinafter simply referred to 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 of the XYZ color system (CIE1931-XYZ color system) defined by the CIE (International Lighting Commission). It can be represented using a chromaticity diagram. In the xy chromaticity diagram, the color gamut can be indicated by a triangle in which chromaticity coordinates that are the vertices of each color of R, G, and B are defined and connected with straight lines.
The color gamut is conventionally defined by various color gamut standards, and examples thereof include sRGB standard and NTSC standard. The sRGB standard is an international standard established by the International Electrotechnical Commission (IEC), and the NTSC standard is an analog television standard color gamut standard created by the US National Television Standards Committee. Recently, new standards such as the Adobe RGB standard and the digital cinema standard projector (D-Cinema Ref.PJ) standard have been developed to cover a wider color gamut.
The imaging device is designed to be compatible with these color gamut standards, and can reproduce a pointer color included in the color gamut of the imaging device when outputting an image. Pointer color refers to colorimetric data representing the color gamut of the actual surface color. When an image output with accurate and uniform color reproducibility is required as in a pathological imaging device, it is necessary to have a wider color gamut so as to include many pointer colors.

International Publication No. 2004/044639

  A color chart used for color calibration has a color bar group composed of a plurality of color bars. In order to accurately perform color calibration of the imaging device, it is necessary to align the brightness of each color bar that constitutes the color bar group. Conventionally, for example, a gray scale is used as an image captured by the imaging device. A method of uniformly adjusting the brightness of each color bar is known. However, in the method of adjusting the brightness of each color bar using the gray scale, there arises a problem that the configuration of the color chart is complicated, for example.

  In addition, the imaging device usually has an IR cut filter in the camera. The IR cut filter has a different wavelength range to be cut depending on its type. For this reason, the color chart used for color calibration of the imaging device has a problem that the color tone differs depending on the type of IR cut filter provided in the camera, and as a result, accurate color calibration of the imaging device becomes difficult. Arise.

  The present invention has been made in view of the above problems, and by making the brightness of the color bar group uniform and suppressing the influence of the IR cut filter provided in the camera of the imaging device, the accuracy of the imaging device is improved. It is a main object of the present invention to provide a transmission color calibration chart capable of performing accurate color calibration.

  In order to solve the above-mentioned problems, the inventors of the present invention have conducted intensive research. As a result, the transmission spectrum of the color bars constituting the color bar group has, for example, a mountain waveform as shown in FIG. In other words, the inventors have found that the brightness of the color bar is higher than the brightness of other color bars. In addition, when the transmission spectrum of the color bar does not have a chevron waveform, the wavelength range to be cut changes depending on the type of the IR cut filter, so the color tone of the color bar depends on the type of the IR cut filter. I got the knowledge that it would be affected. Therefore, the inventors of the present invention can 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 mountain-shaped waveform. In addition, the present invention has provided a transmission color calibration chart that can suppress the influence on the color tone caused by the IR cut filter and can perform accurate color calibration of the imaging device.

  That is, the present invention includes a transparent substrate and a color bar group formed on the transparent substrate, and the color bar group includes a plurality of color bars including at least a first color and a second color. The coordinate points of the first color are (0.351, 0.649), (0.547, 0.453), (0.380) on the xy chromaticity diagram. , 0.506), (0.433, 0.464), and the second color coordinate point is (0.125, 0...) On the xy chromaticity diagram. 489), (0.112, 0.229), (0.270, 0.407), and (0.224, 0.242). The spectrum and the transmission spectrum of the second color bar have separate peak tops. A transmissive color calibration chart is provided.

Of the colors in the color bar, red, green, and blue may be referred to as “(three) primary colors”. In addition, each color may be represented by an abbreviation in parentheses.
The chromaticity coordinates on the xy chromaticity diagram may be simply referred to as “color coordinates” or “coordinates”.
Further, 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, since the transmission spectrum of the first color bar and the transmission spectrum of the second color bar have the peak tops separated from each other, the transmission spectra of the first color bar and the second color bar are obtained. It can be a chevron waveform. Accordingly, it is possible to perform accurate color calibration of the imaging device by making the brightness of the color bar group uniform and suppressing the influence of the IR cut filter provided in the camera 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 a separated peak top. The transmission spectrum of the five color bars excluding white can be a mountain-shaped waveform. This makes it 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. Because.

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. The pointer color coverage is preferably 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 the pointer color, so that the colors in the visible light region can be sufficiently covered. Thereby, the imaging device calibrated using the color chart of the present invention can reproduce the existing object color with high accuracy and sufficient.

  Furthermore, the present invention has a transparent substrate and a color bar group formed on the transparent substrate, and the color bar group includes at least one of red, green, blue, first color, second color, and white. Six color bars are arranged in a pattern in random order, and the coordinate points of the first color are (0.351, 0.649), (0.547, 0.00) on the xy chromaticity diagram. 453), (0.380, 0.506), (0.433, 0.464), and the second color coordinate point is on the xy chromaticity diagram. (0.125, 0.489), (0.112, 0.229), (0.270, 0.407), and (0.224, 0.242) in the region 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 color 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 second color A transmission color calibration chart is provided in which the peak wavelength of the transmission spectrum of the bar is in the range of 470 nm to 515 nm.

  In other words, the present invention includes a transparent substrate and a color bar group formed on the transparent substrate, and the color bar group includes red (R), green (G), blue (B), yellow (Ye), cyan (Cy), and white (W) at least six color bars are arranged in a random pattern, and the peak wavelength of the transmission spectrum of the R color bar is in 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 The transmission color calibration chart is characterized in that the peak wavelength of the transmission spectrum of the Cy color bar is in the range of 470 nm to 515 nm. To.

  According to the present invention, the five color bars excluding white have the peak wavelength of the transmission spectrum at a predetermined position, so that the minimum six colors necessary to include the desired pointer color in the xy chromaticity diagram. The colors in the visible light region can be covered, and the colors in the visible light region can be reproduced uniformly. Thereby, the color calibration of the imaging device can be accurately performed using the color chart of the present invention.

In the 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, and the reference wavelength. The wavelength at which the relative transmittance when the transmittance at 100% is 50% is in the range of 435 nm to 465 nm, and the transmission spectrum of the NIR color bar has a wavelength of 730 nm as a reference wavelength, The wavelength at which the relative transmittance is 50% when the transmittance is 100% is preferably in the range of 630 nm to 730 nm.
The color chart of the present invention can sufficiently cover colors in the visible light region by further including violet and near-infrared two color bars showing a predetermined transmission spectrum. Color can be reproduced uniformly. This is because the accuracy of color calibration of the imaging device using the color chart of the present invention can be increased.

Moreover, in the said invention, it is preferable that the said color bar group contains an orange (O) color bar, and the peak wavelength of the transmission spectrum of the said O color bar exists in the range of 575 nm -620 nm.
The color chart of the present invention further includes an orange color bar showing a predetermined transmission spectrum, so that an intermediate color between yellow and red having a wide peak wavelength interval can be compensated, and colors in the visible light region can be balanced. This is because the color calibration can be performed in more detail and with high accuracy because it can be sufficiently covered.

In the above invention, the color bars of at least five of R, G, B, the first color, and the second color are included in a pentagon that connects the chromaticity coordinates on the xy chromaticity diagram with a straight line. The pointer color coverage is preferably 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 the pointer color, so that the colors in the visible light region can be sufficiently covered. Thereby, the imaging device calibrated using the color chart of the present invention can reproduce the existing object color with high accuracy and sufficient.

  In the above invention, the color bar group preferably further includes a magenta (Mg) color bar. White is obtained by mixing red and cyan, or blue and yellow, which are symmetrical and in position (complementary color relationship) 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 in a complementary color relationship at an appropriate ratio. As described above, the color chart of the present invention can perform white calibration more accurately by adjusting the same white according to three criteria using complementary colors.

  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, W (D65) coordinate). It is preferable that it exists on the extension line of the line which ties. In the xy chromaticity diagram, by setting the position of the Mg coordinate on the extension line of the line connecting the W (D65) coordinate and the G coordinate, red and cyan, blue and yellow, and green and magenta, which are complementary colors, respectively. It is possible to reproduce white that becomes D65 by mixing these combinations at an appropriate ratio. Thereby, the color chart of the present invention can perform white calibration and white balance adjustment 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, 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 m to 540 nm. It is preferable that the half 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 width is 80 nm or less.
Since the transmission spectrum of the color bars of the three primary colors has the spectral characteristics as described above, a color gamut defined by a triangle formed by connecting the chromaticity coordinates of the three primary colors with a straight line on the xy chromaticity diagram is represented by BT. The color gamut defined by the coordinates of the three primary colors in the 2020 standard can be approached. Therefore, the color chart of the present invention is BT. This is because it is possible to cope with color calibration of an imaging device to which the 2020 standard is applied. Further, 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, This is because the color chart can ensure the color reproducibility by the transmission spectrum.

In the above invention, the chromaticity coordinate on the xy chromaticity diagram of the second color bar is a line connecting the chromaticity coordinate on the xy chromaticity diagram of the R color bar and the W (D65) coordinate. On the extension line and BT. The chromaticity coordinates on the xy chromaticity diagram of the first color bar located on the outer periphery of the color gamut prescribed by the 2020 standard or outside the color gamut are on the xy chromaticity diagram of the B color bar. On the extension line of the line connecting the chromaticity coordinates at W and the W (D65) coordinates, and BT. It is preferably located on the outer periphery of the color gamut defined by the 2020 standard or on the outside of the color gamut.
On the xy chromaticity diagram, the position of the second color coordinate is an extension of the line connecting the W (D65) coordinate and the R coordinate, and the position of the first color coordinate is the line connecting the W (D65) coordinate and the B coordinate. By using the extended line, the combination of cyan and red or yellow and blue, which are complementary colors, can be mixed at an appropriate ratio to reproduce D65 white, and the white balance can be adjusted. It is. Also, the positions of the second color coordinates and the first color coordinates are set to BT. This is because, by being positioned on the outer periphery of the color gamut defined by the 2020 standard or on the outer side of the color gamut, the color gamut capable of color reproduction can be expanded using the color chart of the present invention.

  The transmission color calibration chart according to the present invention makes the brightness of the color bar group uniform and suppresses the influence on the color tone caused by the IR cut filter provided in the camera of the imaging device, thereby preventing the accurate color of the imaging device. There exists an effect that calibration can be performed.

It is a schematic plan view which shows an example of the chart for transmissive color calibration of this invention. It is an image graph which shows an example of the spectral transmission spectrum which the transmission type color calibration chart of this invention shows. It is an xy chromaticity diagram showing an example of the color gamut of the transmission color calibration chart of the present invention. It is explanatory drawing explaining the prescription | regulation method of the peak wavelength of a transmission spectrum, and a reference wavelength. It is a schematic plan view which shows an example of the chart for transmissive color calibration of this invention. It is an image graph which shows the other example of the spectral transmission spectrum which the chart for transmission type color calibration of this invention shows. It is an xy chromaticity diagram showing another example of the color gamut of the transmission color calibration chart of the present invention. It is a schematic plan view which shows an example of the chart for transmissive color calibration of this invention. It is an image graph which shows the other example of the spectral transmission spectrum which the chart for transmission type color calibration of this invention shows. It is an xy chromaticity diagram for explaining the positions of chromaticity coordinates of Cy, Ye, and Mg in the color gamut of the transmission color calibration chart of the present invention. It is an xy chromaticity diagram explaining a color gamut.

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

I. First Embodiment The color chart of the first embodiment will be described in detail. The color chart of this aspect includes a transparent substrate and a color bar group formed on the transparent substrate, and the color bar group includes a plurality of color bars including at least a first color and a second color. The coordinate points of the first color are (0.351, 0.649), (0.547, 0.453), (0...) On the xy chromaticity diagram. 380, 0.506) and (0.433, 0.464), and the second color coordinate point is (0.125, 0) on the xy chromaticity diagram. .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 have separate peak tops. It is characterized by that.

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

  Conventionally, for example, as a method of uniformly adjusting the brightness of each color bar, a method using a gray scale is known. However, in the method of adjusting the brightness of each color bar using the gray scale, there arises a problem that the configuration of the color chart is complicated, for example. In addition, the imaging device usually has an IR cut filter in the camera. The IR cut filter has a different wavelength range to be cut depending on its type. For this reason, the color chart used for color calibration of the imaging device has a problem that the color tone differs depending on the type of IR cut filter provided in the camera, and as a result, accurate color calibration of the imaging device becomes difficult. Arise.

  Therefore, the inventors of the present aspect have determined that the luminance of the color bar is not a mountain-shaped waveform as shown in FIG. 4C, which will be described later, for example. The knowledge that it becomes high compared with the brightness | luminance of other color bars was acquired. In addition, when the transmission spectrum of the color bar does not have a chevron waveform, the wavelength range to be cut changes depending on the type of the IR cut filter, so the color tone of the color bar depends on the type of the IR cut filter. I got the knowledge that it would be affected. This aspect has been made on the basis of such knowledge, and is characterized in that the transmission spectrum of the first color bar and the transmission spectrum of the second color bar each have a separated peak top. Thereby, in this aspect, the brightness of the color bar group can be made uniform, and the influence on the color tone by the IR cut filter provided in the camera of the imaging device can be suppressed. Therefore, in this aspect, accurate color calibration of the imaging device can be performed.

  Further, according to this aspect, by adding the first color bar and the second color bar exhibiting a predetermined color to the conventional color bar group, the colors in the visible light region can be covered, The color in the visible light region can be reproduced uniformly. Thereby, the color calibration of an imaging device can be accurately performed using the color chart of this aspect.

In the following description, “having a separated peak top” is a so-called mountain waveform in which the external shape of the transmission spectrum is a mountain shape, for example, a shape as shown in FIG. Point to. Here, “the external shape is a mountain shape” means that it is a mountain shape when the entire transmission spectrum in at least the visible region is observed. For example, the transmittance (%) is within a range of several percent. Waveforms created when moving up and down do not have a chevron shape.
Further, in the case of “having separated peak tops”, the transmission spectrum has one convex portion that is a mountain shape of an external shape, as in the transmission spectrum of each color bar shown in FIG. Alternatively, two or more may be provided as in the transmission spectrum of a magenta color bar shown in FIG. 9 to be described later. However, in this aspect, the outer shape is a mountain shape at least in the visible region. It is preferable to have one convex part.
Therefore, “the transmission spectrum of each color bar has a separate peak top” means, for example, that each color transmission spectrum has an independent chevron waveform as shown in FIG. To do.

  Hereafter, each structure of the color chart of this aspect is demonstrated.

A. Color Bar Group The color bar group in this embodiment is formed on a transparent substrate.
The color bar group includes a plurality of color bars including at least a first color and a second color arranged in a pattern in random order. The color bar group in this aspect is preferably configured by arranging, for example, at least six color bars of R, G, B, Ye, Cy, and W in random order.
“Five colors excluding (excluding) W” means five colors of R, G, B, Ye, and Cy. In this specification, “5-color bar” means the above-mentioned 5-color bar unless otherwise specified. The “six-color bar” means a total of six color bars of the above-mentioned five colors and W unless otherwise specified. As will be described later, the same applies to the case of including color bars of other colors.

1. Transmission spectrum The transmission spectrum of the first color bar and the transmission spectrum of the second color bar each have a separate peak top, and can have a chevron waveform. In general, the transmission spectra of the R, G, and B color bars also have separate peak tops, and can have a mountain-shaped waveform.

(1) Method for defining peak wavelength The transmission spectrum of the five color bars excluding W has a peak wavelength or a reference wavelength according to the waveform. In addition, about the specific definition method of a peak wavelength, it is the same as the content described in the section of "II. 2nd embodiment A. Color bar group 1. Transmission spectrum (1) Definition method of peak wavelength" mentioned later. 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 transparency to red light in a light source.
The transmission spectrum of the R color bar preferably has a separated peak top. That is, it is preferable that the transmission spectrum of the R color bar has an angle 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 in the range of 600 nm to 680 nm, particularly preferably in the range of 610 nm to 680 nm, and particularly preferably in the range of 625 nm to 680 nm. This is because when the peak wavelength is not within the above range, when the transmission spectra of five colors excluding W are arranged in a well-balanced manner, the separation of peak tops is not clear, and the interpolated color effect is difficult to occur.

  For other detailed description of the R color bar, see “II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (a) Red (R) color bar” described later. Since it can be the same as the content described in the section, the description here is omitted.

(B) Green (G) color bar The G color bar has selective transparency to green light in the light source.
The transmission spectrum of the G color bar preferably has a separated peak top. That is, it is preferable that the transmission spectrum of the G color bar has an angle 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 in the range of 495 nm to 570 nm, and more preferably in the range of 505 nm to 550 nm, particularly in the range of 510 nm to 540 nm. This is because when the peak wavelength is not within the above range, when the transmission spectra of five colors excluding W are arranged in a well-balanced manner, the separation of peak tops is not clear, and the interpolated color effect is difficult to occur.

  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. Since it can be the same as the content described in the section, the description here is omitted.

(C) Blue (B) color bar The B color bar has selective permeability to blue light in a light source.
The transmission spectrum of the B color bar preferably has a separated peak top. That is, it is preferable that the transmission spectrum of the B color bar has an angle 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 example, the peak wavelength of the transmission spectrum of the B color bar is preferably in the range of 430 nm to 490 nm, and more preferably in the range of 435 nm to 475 nm, and particularly preferably in the range of 450 nm to 470 nm. This is because when the peak wavelength is not within the above range, when the transmission spectra of five colors excluding W are arranged in a well-balanced manner, the separation of peak tops is not clear, and the interpolated color effect is difficult to occur.

  Other detailed description of the B color bar will be described later in “II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (c) Blue (B) color bar” Since it can be the same as the content described in the section, the description here is omitted.

(D) First color bar In the first color bar in this aspect, the coordinate points on the xy chromaticity diagram are (0.351, 0.649), (0.547, 0.453), ( 0.380, 0.506) and (0.433, 0.464), which are within the region surrounded by four points, among which (0.417, 0.583), (0.490, 0.510) ), (0.387, 0.501), (0.421, 0.474), preferably within a region surrounded by four points, in particular, (0.435, 0.565), (0. 472, 0.528), (0.402, 0.504), and (0.421, 0.489).

Further, the transmission spectrum of the first color bar has a separated peak top. That is, the transmission spectrum of the first color bar is a mountain waveform. This makes it 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. Because.
Hereinafter, the first color bar may be referred to as a Ye color bar.

  Other detailed description of the Ye color bar is described later in “II. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (d) Yellow (Ye) color bar” Since it can be the same as the content described in the section, the description here is omitted.

(E) Second color bar In the second color bar in this aspect, the coordinate points on the xy chromaticity diagram are (0.125, 0.489), (0.112, 0.229), ( 0.270, 0.407) and (0.224, 0.242), but in the region surrounded by four points, (0.123, 0.437), (0.115, 0.296) , (0.254, 0.350), and (0.240, 0.297) are preferably within a region surrounded by four points, and in particular, (0.133, 0.384), (0.130 , 0.320), (0.239, 0.341), and (0.231, 0.312) are preferably in a region surrounded by four points.

Further, the transmission spectrum of the second color bar has a separated peak top. That is, the transmission spectrum of the second color bar is a mountain waveform. This makes it 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. Because.
Hereinafter, the second color bar may be referred to as a Cy color bar.

  Other detailed description of the Cy color bar will be described later in “II. Second Embodiment A. Color Bar Group 1. Transmission Spectrum (2) Spectral Characteristics of Each Color Bar (e) Cyan Color (Cy) Color Bar” Since it can be the same as the content described in the section, the description is omitted here.

(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. Second embodiment A. Color bar group 1. Transmission spectrum (2) Spectral characteristics of each color bar (f) White (W) color bar”. Since it can be the same as the contents, description thereof is omitted here.

(G) Arbitrary color bar In addition to the above-mentioned six color bars, the color bar group further includes two color bars of violet (V) and near infrared (NIR) having a predetermined transmission spectrum. It is preferable. By including the V color bar and NIR color bar showing a predetermined transmission spectrum in addition to the five color bars excluding W, the color chart of this embodiment can sufficiently cover the colors in the visible light region. The color in the visible light region can be reproduced uniformly. Thereby, the precision of the color calibration of the imaging device using the color chart of this aspect can be improved.

  The color bar group preferably further includes an orange (O) color bar having a predetermined transmission spectrum in addition to the above-described six color bars. The color chart of this aspect further includes an O color bar showing a predetermined transmission spectrum, so that an intermediate color between yellow and red having a wide peak wavelength interval can be supplemented, and the color in the visible light region is sufficiently balanced. Therefore, more detailed and highly accurate color calibration is possible.

  Hereinafter, the configuration when an arbitrary color bar is included will be described later in “II. Second Embodiment A. Color Bar Group 1. Transmission Spectrum (2) Spectral Characteristics of Each Color Bar (g) Arbitrary Color Bar”. Since it can be the same as the description using FIGS. 5 to 9 described in the section, description thereof is omitted here.

  Hereinafter, the color bar of each color that can be included in the color chart of this embodiment will be described.

(I) Violet color (V) color bar Since the transmission spectrum of the V color bar has selective transmission with respect to light shorter than blue light among short wavelength light in the light source, the transmission spectrum of B color bar Is also located on the short wavelength side, and a part thereof preferably overlaps the transmission spectrum of the B color bar.

  The transmission spectrum of the V color bar preferably has a separated peak top. That is, it is preferable that the transmission spectrum of the V color bar has an angle 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. .

  Other detailed description of the V color bar will be described later in “II. Second Embodiment A. Color Bar Group 1. Transmission Spectrum (2) Spectral Characteristics of Each Color Bar (i) Violet Color (V) Color Bar” Since it can be the same as the content described in the section, the description is omitted here.

(Ii) Near-infrared (NIR) color bar Since the transmission spectrum of the NIR color bar has selective transmission with respect to light having a longer wavelength than red light among long-wavelength light in the light source, transmission through the R color bar. It is preferably located on the shorter wavelength side than the spectrum, and part of it overlaps with the transmission spectrum of the B color bar.

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

(Iii) Orange (O) color bar Since the transmission spectrum of the O color bar has selective transmission with respect to light shorter than red light among long wavelength light in the light source, the transmission spectrum of the Ye color bar It is preferably located between the transmission spectrum of the R color bar.
Since the peak wavelength interval between the transmission spectrum of the Ye color bar and the transmission spectrum of the R color bar is wide, the intermediate color between Ye and R is compensated by the peak wavelength of the transmission spectrum of the O color bar being located at the above position. And the intermediate color can be reproduced.

  The transmission spectrum of the O color bar preferably has a separated peak top. That is, the transmission spectrum of the O color bar is preferably 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. .

  Other detailed description of the O color bar will be described later. “II. Second Embodiment A. Color Bar Group 1. Transmission Spectrum (2) Spectral Characteristics of Each Color Bar (iii) Orange (O) Color Bar” Since it can be the same as the content described in the section, the description is omitted here.

(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 aspect, 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 taking into account the positional relationship between the Mg coordinate and the Mg coordinate, the position of the W coordinate 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, there is an advantage that the position of the W (65) coordinate can be accurately adjusted by using the color chart of this aspect including the Mg color bar.

The Mg color bar has selective permeability for red light 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 a first peak wavelength) near the peak wavelength of the transmission spectrum 22 (R) of the R color bar. ) And a second transmission peak (hereinafter referred to as a second peak wavelength) in the vicinity of 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 separated peak top. That is, it is preferable that the first transmission peak and the second transmission peak of the O color bar have a mountain-shaped 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. .

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

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

2. xy chromaticity diagram Next, the xy chromaticity diagram shown in the color chart of this aspect by the color bar group will be described. Note that the xy chromaticity diagram in this aspect can be the same as that described in the section “II. Second Embodiment A. Color Bar Group 2. xy Chromaticity Diagram” described later. Is omitted.

3. Structure of Color Bar and Color Bar Group Each color bar may be a member showing a desired transmission spectrum, and for example, a band pass filter or a dye substrate can be used. In addition, about the structure of the color bar and color bar group in this aspect, it is the same as the content described in the section of “II. Second embodiment A. Color bar group 3. Structure of color bar and color bar group” described later. The description here is omitted.

B. Light Shielding Part In the color chart of this embodiment, a light shielding part is usually provided on the outer periphery of the color bar group on the transparent substrate. In addition, about the light-shielding part in this aspect, since it can be made to be the same as that of the content described in the term of "II. 2nd embodiment B. Light-shielding part" mentioned later, description here is abbreviate | omitted.

C. Transparent substrate In this embodiment, the transparent substrate is not particularly limited as long as it can support the color bar group and the light-shielding portion and has a desired light transmittance, and a transparent substrate used in a conventionally known color chart The same can be said. In addition, about the transparent substrate in this aspect, since it can be the same as that of the content described in the term of "II. 2nd embodiment C. transparent substrate" mentioned later, description here is abbreviate | omitted.

D. Others The color chart of this aspect 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, and the like in addition to the above-described configuration. In addition, about the other structure in this aspect, since it can be made to be the same as that of the content described in the term of "II. 2nd embodiment D. Others" mentioned later, description here is abbreviate | omitted.

E. Applications The color chart of this aspect can be used for imaging devices, video devices, and peripheral devices that require color calibration. Among these, it can be suitably used for an imaging device for pathology.

II. Second Embodiment The color chart of the second embodiment will be described in detail. The color chart of this aspect includes a transparent substrate and a color bar group formed on the transparent substrate, and the color bar group includes red, green, blue, first color, second color, and white. At least six color bars are arranged in a pattern in random order, and the coordinate points of the first color are (0.351, 0.649), (0.547, 0) on the xy chromaticity diagram. .453), (0.380, 0.506), and (0.433, 0.464) are within a region surrounded by four points, and the coordinate point of the second color is on the xy chromaticity diagram. , (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, and the transmission spectrum of the green color bar is The peak wavelength of the spectrum 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 second The peak wavelength of the transmission spectrum of the 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, higher resolution of output images has been promoted, and high color reproducibility that faithfully reproduces color tone is also demanded for colors.
Among them, the imaging device for pathology is required to accurately reproduce the color of the output image with a color close to the real thing because it observes a human body tissue and performs a pathological diagnosis based on an image captured through a microscope. In addition, when photographing the same sample using different imaging devices, uniform results can be obtained in pathological diagnosis of the same sample based on the output image if there is a difference in the reproduced color due to the difference in spectral sensitivity characteristics of the imaging device. There may not be. Therefore, the reproduced color of the output image needs to be the same regardless of the type and manufacturer of the imaging device.

  In order to increase the color reproducibility of the output image in the imaging device, it is necessary to make the color gamut reproducible by the imaging device wide.

  In order to display an output image with a correct reproduction color, the imaging device uses, for example, a color chart disclosed in Patent Document 1 to compare the reproduction color on the imaging device with the reproduction color on the color chart. If there is a difference in the reproduction color, calibration is performed based on the color chart. As described above, since pathological imaging devices are required to output images with accurate and uniform color reproducibility, color charts used for color calibration of output images also have a wider color gamut. It is required to have.

  By the way, as the color gamut of the imaging device expands, the number of reproducible colors also increases, so it is necessary to reproduce the pointer color more accurately. In the conventional color chart, all colors in the visible light region are displayed. There are colors that cannot be fully covered and cannot be reproduced when color-calibrating an output image by an imaging device, particularly a pathological imaging device. For this reason, there is a problem that the color calibration of the imaging device cannot be performed accurately, and the imaging device cannot achieve high color reproducibility of the output image.

On the other hand, in order to reproduce a wide color gamut in displays, etc., the so-called “single-peak” spectrum that reduces color mixing with adjacent colors by reducing the overlap of RGB primary colors with a color filter or backlight. Technical development of the shape is underway.
Also in the color chart, in order to widen the color gamut, in principle, it is necessary to develop the three primary colors so that the distribution width of the transmission spectrum is narrow and has a unimodal spectrum shape, similar to a display or the like.
In addition, in the development of color charts, in addition to the three primary colors, the colors in the wavelength range between B and G and R and R in addition to the three primary colors can be improved by improving the chart function. However, the color arrangement and transmission spectrum must be examined.

  Among them, the pathological imaging device particularly requires high color reproducibility for the output image as described above, and uniform color reproducibility is required regardless of the type of the imaging device. A color chart used for an imaging device for pathology needs to sufficiently cover colors in the visible light region and is required to be able to reproduce colors in the visible light region uniformly.

  This aspect has been made in view of the above-described problems, and can fully reproduce colors uniformly in the visible light region and accurately perform color calibration of an imaging device. The main objective is to provide a possible transmissive color calibration chart.

In this aspect, the transmission spectrum of each color bar excluding W constituting the color bar group is arranged in a balanced manner with peaks at desired intervals in the visible light region. That is, as shown in FIG. 2, the color chart of this embodiment is such that the peak wavelength of the transmission spectrum 22 (R) of the R color bar is in the range of 600 nm to 680 nm, and the peak wavelength of the transmission spectrum 22 (G) of the G color bar. 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 five color bars excluding white have the peak wavelength of the transmission spectrum at a predetermined position, so that the minimum six colors necessary to include the desired pointer color in the xy chromaticity diagram. The colors in the visible light region can be covered, and the colors in the visible light region can be reproduced uniformly. Thereby, the color calibration of an imaging device can be accurately performed using the color chart of this aspect.

In this embodiment, the visible light region means a wavelength region of 380 nm to 780 nm. What is described as “within the range of Anm to Bnm (A and B are numerical values)” in the wavelength range defined in this specification may be rephrased as “Anm to Bnm (A and B are numerical values)”. it can.
Further, in this embodiment, the “xy chromaticity diagram” refers to an xy chromaticity diagram of the CIE 1931-XYZ color system.

  In the following description, “separation of peak tops” means to suppress overlapping of peak tops of transmission spectra of respective colors. Further, “spectrum separation” means to suppress the occurrence of color mixing due to overlapping of transmission spectra of a plurality of colors.

The color chart of this aspect will be described with reference to the drawings. FIG. 1 is a schematic plan view showing an example of the color chart of this aspect. FIG. 2 is an image graph showing an example of the spectral transmission spectrum shown 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.
The color chart 10 of this embodiment includes a transparent substrate 1 and a color bar group 2 formed on the transparent substrate 1. A color bar holding frame 4 is provided on the outer periphery of the color bar group 2.
The color bar group 2 is a pattern in which 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 are arranged in any order. It is arranged in a shape. The white color bar 12W is usually 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 a spectral transmission spectrum characteristic as shown in FIG. 2, and as shown in FIG. 3, it is a pentagon in which the coordinates of five colors excluding W on the xy chromaticity diagram are connected by straight lines. 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 surface is dispersed according to the selective transmission of the five color bars excluding W constituting the color bar group. In the visible light region, in order from the short wavelength side, Transmission spectra of each of the B color bar, Cy color bar, G color bar, Ye color bar, and R color bar appear.

In this aspect, the transmission spectrum of each color bar excluding W constituting the color bar group is arranged in a balanced manner with peaks at desired intervals in the visible light region. That is, as shown in FIG. 2, the color chart of this embodiment is such that the peak wavelength of the transmission spectrum 22 (R) of the R color bar is in the range of 600 nm to 680 nm, and the peak wavelength of the transmission spectrum 22 (G) of the G color bar. 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 the color chart of this aspect, the chromaticity coordinates of the five color bars excluding W are distributed as shown in FIG. 3 on the xy chromaticity diagram. The color chart of this aspect can reproduce and calibrate the color of the pointer color included in the color gamut L1 surrounded by the pentagon in which the coordinates of the five colors are connected by 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), y_ (λ) for the color matching functions in the XYZ color system adopted in 1931 by the CIE. , Z_ (λ), and S_ (λ) as the spectral distribution of the light source,
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.
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 the white indicated by the white coordinate is referred to as “D65 white” in this specification.

  According to this aspect, the five color bars excluding white have the peak wavelength of the transmission spectrum at a predetermined position, so that the minimum six colors necessary to include the desired pointer color in the xy chromaticity diagram. The colors in the visible light region can be covered, and the colors in the visible light region can be reproduced uniformly. Thereby, the color calibration of an imaging device can be accurately performed using the color chart of this aspect.

  Hereafter, each structure of the color chart of this aspect is demonstrated.

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 at least six color bars of R, G, B, Ye, Cy, and W in a random pattern.
“Five colors excluding (excluding) W” means five colors of R, G, B, Ye, and Cy. In this specification, “5-color bar” means the above-mentioned 5-color bar unless otherwise specified. The “six-color bar” means a total of six color bars of the above-mentioned five colors and W unless otherwise specified. As will be described later, the same applies to the case of including color bars of other colors.

1. Transmission spectrum The transmission spectrum of the five color bars excluding W has a peak wavelength at a predetermined position.
In the spectral transmission spectrum of the color chart of this embodiment, the transmission spectrum of each color bar appears in a balanced manner so as to cover a desired wavelength region in the visible light region. Further, adjacent transmission spectra partially overlap, and the spectral transmission spectrum of the color chart can cover the entire visible light region.

(1) Method for defining peak wavelength The transmission spectrum of the five color bars excluding W has a peak wavelength or a reference wavelength according to the waveform. In other words, the transmission spectrum of the five color bars excluding W shows a mountain-shaped waveform as shown in FIG. 4A and has a peak wavelength λ _P indicating high transmittance. As shown in FIG. 4A, the peak wavelength λ _P has a relative transmittance of 50 when the maximum value T _max of the measured transmittance of the transmission spectrum is specified and the transmittance of the maximum value T _max is 100%. % Wavelengths λ ₁ and λ ₂ are specified and set as the center wavelength in the wavelength region from wavelength λ ₁ to wavelength λ ₂ . The measured transmittance T at the peak wavelength λ _P is referred to as “transmittance at the peak wavelength (hereinafter sometimes referred to as peak transmittance)”.
Note that the term “transmittance” simply refers to the measured transmittance, and the term “relative transmittance” refers to the transmittance obtained by converting the measured transmittance at a specific wavelength as 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 using Olympus Co., Ltd., microspectrophotometer OSP-SP200, with a colorless (transparent) white color bar as the background. . In addition, when calculating the coordinates of each color on the xy chromaticity diagram, data of the known D65 light source spectrum is used.
The same applies to any color bar 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 transparency to red light in a light source.
The peak wavelength of the transmission spectrum of the R color bar may be in the range of 600 nm to 680 nm, preferably in the range of 610 nm to 680 nm, particularly in the range of 625 nm to 680 nm. This is because when the peak wavelength is not within the above range, when the transmission spectra of five colors excluding W are arranged in a well-balanced manner, the separation of peak tops is not clear, and the interpolated color effect is difficult to occur.

Further, the half-value 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, and particularly preferably in the range of 30 nm to 80 nm. In addition, the lower limit of the half width can be set to 10 nm.
When the half width is not within the above range, there is an overlap region with the transmission spectrum of the color bars of other colors, and it may be difficult to sufficiently widen the red region of the color gamut of the color chart of this aspect, This is because the saturation of reproducible colors may be reduced.
The half-value width of the transmission spectrum refers to the wavelength interval at which the peak transmittance of the transmission spectrum becomes half value, and is calculated from the measurement result obtained by measuring the transmission spectrum (using Olympus Microspectroscope OSP-SP200) described above. can do. The same applies to the color bars of other colors.

In addition, the transmission spectrum of the R color bar is BT. It is preferably equivalent to the red transmission spectrum defined by the 2020 standard. That is, the peak wavelength of the transmission spectrum of the R color bar is preferably in the range of 620 nm to 680 nm and the half width is preferably 100 nm or less, and the peak wavelength is in 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 more preferably 70 nm or less.
By setting the peak wavelength and half-value 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 can be changed to BT. It can be matched or approximated with the red coordinates defined in the 2020 standard. This is because it can be expanded to the red region defined by the 2020 standard.

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

Also, 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 with 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, and particularly preferably in the range of 30 nm to 60 nm. In addition, the lower limit of the half width can be set to 10 nm.
If the full width at half maximum is not within the above range, there is an overlap region with the transmission spectrum of the color bars of other colors, and it may be difficult to sufficiently widen the green region of the color gamut of the color chart of this aspect. This is because the saturation of reproducible colors may be reduced.

The transmission spectrum of the G color bar is BT. It is preferably equivalent to the green transmission spectrum defined by the 2020 standard. That is, the peak wavelength of the transmission spectrum of the G color bar is preferably in the range of 510 nm to 540 nm and the half width is preferably 80 nm or less, and the peak wavelength is in the range of 515 nm to 538 nm and the half width is 60 nm or less. More preferably, the peak wavelength is in the range of 520 nm to 535 nm, and the half width is more preferably 40 nm or less.
By setting the peak wavelength and full width at half maximum 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 can be changed to BT. It can be matched or approximated with the green coordinates defined in the 2020 standard, and the green area of the color gamut of the color chart of this aspect is represented by BT. This is because it is possible to expand to the green region defined by the 2020 standard.

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

In addition, the half-value width of the transmission spectrum of the B color bar is not limited as long as the transmission spectrum of the B color bar can show a waveform that can 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, and particularly preferably in the range of 25 nm to 55 nm. In addition, the lower limit of the half width can be set to 10 nm.
If the full width at half maximum is not within the above range, there is an overlap region with the transmission spectrum of the color bars of other colors, and it may be difficult to sufficiently widen the blue region of the color gamut of the color chart of this aspect. This is because the saturation of reproducible colors may be reduced.

The transmission spectrum of the B color bar is BT. It is preferable to be equivalent to the blue transmission spectrum defined by the 2020 standard. That is, the peak wavelength of the transmission spectrum of the B color bar is preferably in the range of 450 nm to 472 nm and the half width is preferably 80 nm or less, and the peak wavelength is in the range of 455 nm to 470 nm and the half width is 60 nm or less. More preferably, the peak wavelength is in the range of 458 nm to 468 nm, and the half width is more preferably 40 nm or less.
By setting the peak wavelength and half-value 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 can be changed to BT. It is possible to match or approximate the blue coordinates defined in the 2020 standard. This is because it is possible to extend to the blue region defined by the 2020 standard.

(D) Yellow (Ye) color bar The Ye color bar has selective permeability to short wavelength light and long wavelength light in the light source.
Further, 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 in the range of 540 nm to 595 nm, and in particular, it is preferably in the range of 545 nm to 585 nm, particularly in the range of 560 nm to 575 nm. This is because when the peak wavelength is not within the above range, when the transmission spectra of five colors excluding W are arranged in a well-balanced manner, the separation of peak tops is not clear, and the interpolated color effect is difficult to occur.

The half-value width of the transmission spectrum of the Ye color bar is not limited as long as the transmission spectrum of the Ye color bar can show a waveform that can 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, and particularly preferably in the range of 30 nm to 70 nm. In addition, the lower limit of the half width can be set to 10 nm.
This is because when the half width is not within the above range, an overlapping area with the transmission spectrum of the color bar of another color increases.

(E) Cyan (Cy) color bar The Cy color bar has selective transparency to short wavelength light and medium wavelength light in the light source.
The transmission spectrum of the Cy color bar is located 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 only needs to be in the range of 470 nm to 515 nm, and in particular, it is preferably in the range of 480 nm to 505 nm, particularly in the range of 490 nm to 500 nm. When the peak wavelength of the transmitted light of the Cy color bar is not within the above range, when the transmission spectra of five colors except W are arranged in a well-balanced manner, the separation of the peak tops is not clear, and the interpolated color effect is hardly produced Because it becomes.

As for the half width of the transmission spectrum of the Cy color bar, it is possible that the transmission spectrum of the Cy color bar shows a waveform that can partially overlap the transmission spectrum of the G color bar and the transmission spectrum of the B color bar. That's fine. Specifically, the half width is preferably 150 nm or less, more preferably in the range of 20 nm to 130 nm, and particularly preferably in the range of 30 nm to 80 nm. In addition, the lower limit of the half width can be set to 10 nm.
When the half width is not within the above range, the overlapping region with the transmission spectrum of the color bars of other colors increases. In particular, B and G may be different colors on the color coordinates in the xy chromaticity diagram. This is because 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 described later.
In order to enable brightness adjustment, an achromatic W color bar (for example, an ND filter) designed so as to be able to uniformly absorb light in a visible range may be disposed on a transparent substrate. It may be used as a transparent substrate.

(G) Arbitrary color bar In addition to the above-mentioned six color bars, the color bar group further includes two color bars of violet (V) and near infrared (NIR) having a predetermined transmission spectrum. It is preferable. By including the V color bar and NIR color bar showing a predetermined transmission spectrum in addition to the five color bars excluding W, the color chart of this embodiment can sufficiently cover the colors in the visible light region. The color in the visible light region can be reproduced uniformly. Thereby, the precision of the color calibration of the imaging device using the color chart of this aspect can be improved.

  The color bar group preferably further includes an orange (O) color bar having a predetermined transmission spectrum in addition to the above-described six color bars. The color chart of this aspect further includes an O color bar showing a predetermined transmission spectrum, so that an intermediate color between yellow and red having a wide peak wavelength interval can be supplemented, and the color in the visible light region is sufficiently balanced. Therefore, more detailed and highly accurate color calibration is possible.

  The group of color bars may be composed of a total of eight colors including the above-described six color bars and two colors of a V color bar and a NIR color bar having a predetermined transmission spectrum. It may be composed of a total of seven colors including a color bar and an O color bar. Further, it may be composed of a total of nine colors including the above-mentioned six color bars and a total of three 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. In addition to the six color bars 12R, 12G, 12B, 12Ye, 12Cy, and 12W shown in FIG. A total of nine color bars including 12V, a near-infrared color bar 12NIR, and an orange color bar 12O have a color bar group 2 that is arranged in a random pattern. The color chart shown in FIG. 5 has spectral transmission spectrum characteristics as shown in FIG.
Further, the chromaticity coordinates of the eight color bars excluding W in the color chart shown in FIG. 5 are distributed as shown in FIG. 7 on the xy chromaticity diagram, and the coordinates of the eight colors are connected by a straight line. The color of the pointer color included in the color gamut L3 surrounded by the octagon can be reproduced and calibrated.

When the color bar group is composed of a total of eight colors including a V color bar and a NIR color bar having a predetermined transmission spectrum in addition to the six color bars described above, the color chart of this aspect is Of the spectral transmission spectrum shown in FIG. 6, the spectral transmission spectrum excluding the transmission spectrum 22 (O) of the O color bar is shown.
Further, when the color bar group is composed of a total of seven colors including O color bars having a predetermined transmission spectrum in addition to the six color bars described above, the color chart of this aspect is shown in FIG. Of the spectral transmission spectrum, the spectral transmission spectrum excluding the transmission spectrum 22 (NIR) of the NIR color bar and the transmission spectrum 22 (V) of the V color bar is 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 and in position (with a complementary color relationship) with respect to the W coordinate on the xy chromaticity diagram. By including the Mg color bar in the bar group, W can also be obtained by mixing G and Mg having a complementary color relationship at an appropriate ratio. Thus, the color chart of this aspect is because white can be calibrated more accurately by adjusting the same white according to three criteria using complementary colors.

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

FIG. 8 is a schematic plan view showing another example of the color chart of this aspect, in addition to the nine color bars 12R, 12G, 12B, 12Ye, 12Cy, 12W, 12V, 12NIR, and 12O shown in FIG. Thus, a total of 10 color bars including the magenta color bar 12Mg have the color bar group 2 configured in a random pattern. The color chart shown in FIG. 8 has spectral transmission spectrum characteristics as shown in FIG.
Further, 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. 7, and the chromaticity coordinates of Mg are the above except for Mg. It is included in a color gamut L3 surrounded by an eight shape in which the coordinates of the eight colors are connected by straight lines.

  When the color bar group is composed of a total of seven colors including the above-described six color bars and Mg color bar, the color chart of this aspect is the NIR color bar in the spectral transmission spectrum shown in FIG. The spectral transmission spectrum excluding the transmission spectrum 22 (NIR), the transmission spectrum 22 (V) of the V color bar, and the transmission spectrum 22 (O) of the O color bar is shown.

  Hereinafter, the color bar of each color that can be included in the color chart of this embodiment will be described.

(I) Violet color (V) color bar Since the transmission spectrum of the V color bar has selective transmission with respect to light shorter than blue light among short wavelength light in the light source, the transmission spectrum of B color bar Is also located on the short wavelength side, and a part thereof preferably overlaps the transmission spectrum of the B color bar.

The transmission spectrum of the V color bar has a waveform that shows a transmittance equal to or higher than a predetermined transmittance at a certain wavelength or less, as shown in FIG. 4B, in addition to the mountain-shaped waveform as shown in FIG. It may not be a chevron waveform. Therefore, for the transmission spectrum of the V color bar, as shown in FIG. 4B, the wavelength 415 nm is the reference wavelength λ _s, and the measured transmittance T at the reference wavelength λ _s is expressed as “transmittance at the reference wavelength”. (Hereafter, it may be referred to as a reference transmittance).
The transmission spectrum of the V color bar has a wavelength (relative wavelength) λ ₃ of 435 nm to 465 nm at which the relative transmittance is 50% when 415 nm is the reference wavelength λ _s and the transmittance at the reference wavelength λ _s is 100%. In particular, it is preferable to be in the range of 435 m to 460 nm, particularly in 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 the wavelength region longer than the reference wavelength, and to overlap the transmission spectrum of the B color bar with the 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 of the transmission spectrum of the B color bar and the peak top, so that the short wavelength side of the visible light region can be evaluated without omission. Because it can.

  In the transmission spectrum of the V color bar, it is preferable that the transmittance is equal to or higher than a predetermined value in a wavelength region shorter than the reference wavelength. The “shorter wavelength region than the reference wavelength” refers to a wavelength region having a wavelength of 380 nm or more, which is the lower limit of the visible light region, and smaller than the reference wavelength of 415 nm. The transmission spectrum of the V color bar shows a transmittance of a predetermined value or more in a shorter wavelength region than the reference wavelength. Specifically, the transmittance in the shorter wavelength region than the reference wavelength when the reference transmittance is 100%. The relative transmittance 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 shorter wavelength region 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 wavelength region of the transmission spectrum of the V color bar exceeds the above-mentioned range, it is difficult to separate the spectrum from the transmission spectrum of the color bars of other colors on the spectral transmission spectrum, and the xy color. This is because there is a high possibility that the reproducibility with respect to the color coordinates in the degree diagram is extremely low.

(Ii) Near-infrared (NIR) color bar Since the transmission spectrum of the NIR color bar has selective transmission with respect to light having a longer wavelength than red light among long-wavelength light in the light source, transmission through the R color bar. It is preferably located on the shorter wavelength side than the spectrum, and part of it overlaps with the transmission spectrum of the B color bar.

As shown in FIG. 4 (c), 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. For this reason, as shown in FIG. 4C, the NIR color bar transmission spectrum has a wavelength 730 nm as the reference wavelength λ _t, and the measured transmittance T at the reference wavelength λ _t is _expressed as “transmittance at the reference wavelength”. (Hereafter, it may be referred to as a reference transmittance).
The transmission spectrum of the NIR color bar has a wavelength (relative wavelength) λ _{4 at} which the relative transmittance is 50% when the reference wavelength λ _t is 730 nm and the transmittance at the reference wavelength λ _t is 100%. It is preferably within the range of 730 nm, and particularly preferably within the range of 640 nm to 710 nm, and 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 the shorter wavelength region than the reference wavelength, and to overlap the transmission spectrum of the R color bar with the desired wavelength region. As a result, the transmission spectrum of the NIR color bar can maintain the overlap of the peak itself while maintaining the separation of the transmission spectrum of the R color bar and the peak top, so the high wavelength side of the visible light region should be evaluated without omission. Because you can.

  Further, it is preferable that the transmittance of the NIR color bar shows a transmittance of a certain value or longer in the wavelength region longer than the reference wavelength. The “longer wavelength region than the reference wavelength” refers to a wavelength region that is larger than the reference wavelength of 730 nm and has a wavelength of 780 nm or less that is the upper limit of the visible light region. The transmission spectrum of the NIR color bar shows a transmittance of a certain value or longer in the wavelength region longer than the reference wavelength. Specifically, in the wavelength region longer than the reference wavelength when the reference transmittance is 100%. The relative transmittance is preferably 30% or more, more preferably 50% or more, and still more preferably 80% or more. This is because it is possible to reproduce colors in a wavelength region longer 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. . If 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 spectrum of the color bar of other colors on the spectral transmission spectrum, as well as the xy color. This is because there is a high possibility that the reproducibility with respect to the color coordinates in the degree diagram is extremely low.

(Iii) Orange (O) color bar Since the transmission spectrum of the O color bar has selective transmission with respect to light shorter than red light among long wavelength light in the light source, the transmission spectrum of the Ye color bar It is preferably located between the transmission spectrum of the R color bar.
Since the peak wavelength interval between the transmission spectrum of the Ye color bar and the transmission spectrum of the R color bar is wide, the intermediate color between Ye and R is compensated by the peak wavelength of the transmission spectrum of the O color bar being located at the above position. And the intermediate color can be reproduced.

  The peak wavelength of the transmission spectrum of the O color bar is preferably in the range of 575 nm to 620 nm, more preferably in the range of 580 nm to 615 nm, and particularly preferably in the range of 585 nm to 610 nm. This is because, when the peak wavelength is not within the above range, when the transmission spectra of 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 hardly generated.

As for the half width of the transmission spectrum of the O color bar, it is possible to show a waveform in which the transmission spectrum of the O color bar can partially overlap with the transmission spectrum of the Ye color bar and the transmission spectrum of the R color bar. That's fine. Specifically, the half width is preferably 120 nm or less, more preferably in the range of 20 nm to 100 nm, and particularly preferably in the range of 20 nm to 70 nm. In addition, the lower limit of the half width can be set to 10 nm.
When the full width at half maximum is not within the above range, the overlapping area with the transmission spectrum of the color bars of other colors increases. In particular, Ye, R, and NIR are different colors on the color coordinates in the xy chromaticity diagram. This is because spectral separation on the spectral transmission spectrum becomes difficult.

The transmission spectrum of the O color bar preferably has a relative transmittance of 10% or less at a wavelength of 550 nm or less and 680 nm or more, with a peak transmittance of 100%, particularly 5% or less, particularly 3% or less. Preferably there is.
When the relative transmittance of the transmission spectrum of the O color bar exceeds the above range, the overlapping area with the transmission spectrum of the color bars of other colors increases, and the spectral separation on the spectral transmission spectrum is reduced. This is because it may be difficult. Moreover, it is because the color reproduction accuracy of O by the color chart of this aspect may fall.

(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 aspect, 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 taking into account the positional relationship between the Mg coordinate and the Mg coordinate, the position of the W coordinate 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, there is an advantage that the position of the W (65) coordinate can be accurately adjusted by using the color chart of this aspect including the Mg color bar.

The Mg color bar has selective permeability for red light 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 a first peak wavelength) in the vicinity of the peak wavelength of the transmission spectrum 22 (R) of the R color bar. ) And a second transmission peak (hereinafter referred to as a second peak wavelength) in the vicinity of 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, particularly preferably in the range of 590 nm to 710 nm, and particularly preferably in the range of 610 nm to 680 nm.
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, and 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, white that is D65 is obtained at any mixing ratio when white is reproduced by mixing magenta and green having a complementary color relationship. This is because it becomes difficult. In addition, it is difficult to fall into 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, the adjacent transmission spectra in the visible light region partially overlap so that the mixing ratio of each color component included in the color mixture can be accurately specified. Further, the color reproduction accuracy and color calibration accuracy of mixed colors can be improved.

2. xy chromaticity diagram Next, the xy chromaticity diagram shown in the color chart of this aspect by the color bar group will be described. In the color chart of this aspect, the chromaticity coordinates of the five color bars excluding W are distributed on the xy chromaticity diagram as shown in FIG.
As coordinates (x, y) of R, G, B, Ye, and Cy on the xy chromaticity diagram shown in FIG. 3, for example, R (0.708, 0.291), G (0.187, 0.751), B (0.137, 0.049), Ye (0.448, 0.538), Cy (0.141, 0.339).

  The color chart of this aspect can reproduce and calibrate a pointer color included in a color gamut surrounded by a pentagon in which coordinates of five colors are connected by straight lines on the xy chromaticity diagram. According to this aspect, since each color bar which comprises a color bar group shows the above-mentioned transmission spectrum, it can have a color gamut wider than the conventional color chart.

  In this aspect, the coverage rate of the pointer color included in the pentagon obtained by connecting the coordinates on the xy chromaticity diagram of the five color bars excluding white with a straight line is, for example, 90.3% or more. In particular, it is preferably 99.9% or more, more preferably 100%, that is, it is preferable that all the pointer colors are included in the pentagon. The pentagon in which the coordinates of five colors except white are connected by straight lines is the color gamut of the color chart of this embodiment, and the color gamut sufficiently covers the colors in the visible light region by sufficiently including the pointer color. be able to. This is because the actual object color can be reproduced more accurately, and 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.
As the coordinates (x, y) of V, NIR, and O on the xy chromaticity diagram shown in FIG. 7, for example, V (0.164, 0.013), NIR (0.724, 0.272) ), O (0.647, 0.352).

The color chart of this aspect can expand the range of the color gamut on the xy chromaticity diagram in accordance with 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 the 6 color bars, the color chart of this aspect is represented as W on the xy chromaticity diagram. It is possible to reproduce and calibrate a pointer color included in a color gamut surrounded by a heptagon obtained by connecting the coordinates of the seven colors except for.
In addition, when the color bar group is composed of a total of seven colors including an O color bar in addition to the six color bars, the color chart of this aspect has six colors excluding W on the xy chromaticity diagram. It is possible to reproduce and calibrate a pointer color included in a color gamut surrounded by a hexagon in which the coordinates of each are connected by a straight line.
Furthermore, when the color bar group is composed of a total of nine colors including a V color bar, an NIR color bar, and an O color bar in addition to the six color bars, the color chart of this aspect has an xy chromaticity diagram. In the above, it is possible to reproduce and calibrate the pointer color included in the color gamut surrounded by the octagon in which the coordinates of the eight colors except W are connected by a straight line.
In this way, a wider color gamut can be achieved by increasing the color types of the color bars constituting the color bar group.
When the color bar group is composed of the above-described 7 colors, 8 colors, or 9 colors, the coverage rate of the pointer color included in the polygon connecting the coordinates on the xy chromaticity diagram with a straight line is 5 It can be the same as the coverage ratio of the pointer color included in the pentagon by the color bar of the color.

  As described above, in the spectral transmission spectrum of the color chart of this embodiment, it is preferable that the peak wavelength and the half width of the transmission spectrum of each color bar of R, G, and B are within a predetermined range. A color gamut (L2 in FIG. 3) defined by a triangle formed by connecting the coordinates of the three primary colors on the xy chromaticity diagram of the color chart of this embodiment with a straight line is represented by BT. It can be close to the color gamut defined by the coordinates of the three primary colors in the 2020 standard. This is because it is possible to cope with color calibration of an imaging device to which the 2020 standard is applied. Moreover, 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, This is because the color chart can ensure the color reproducibility by 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) are the coordinates (R coordinate) of the R color bar on the xy chromaticity diagram and W ( 65) is an extension of the line connecting the coordinates, and BT. The coordinates on the xy chromaticity diagram of the Ye color bar (hereinafter referred to as the Ye coordinate) located on the outer periphery of the color gamut defined by the 2020 standard or outside the color gamut are referred to as the B color bar. is an extension of the line connecting the coordinates (B coordinates) and W (D65) coordinates on the xy chromaticity diagram, and BT. It is preferably located on the outer periphery of the color gamut defined by the 2020 standard or on the outside of 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, each combination of cyan and red or yellow and blue, which are complementary colors, can be mixed at an appropriate ratio to reproduce white that is D65, and white balance can be adjusted with high accuracy. It is. The positions of the Cy coordinate and Ye coordinate are BT. In addition to the outer periphery of the color gamut defined by the 2020 standard, it may be located outside the above color gamut, so that the color gamut capable of color reproduction can be expanded using the color chart of this embodiment.

Among them, the Cy coordinate is the intersection of the extension line of the line connecting the R coordinate and the W coordinate and the side of the triangle, and the Ye coordinate is the extension line of the line connecting the B coordinate and the W coordinate and the side of the triangle. An intersection is preferred.
On the xy chromaticity diagram, when the Cy coordinate is on the triangle, cyan obtained by mixing green and blue at an appropriate mixing ratio is the same as cyan indicated by the Cy color bar of the color chart of this embodiment. It is possible to verify whether white obtained by mixing cyan and red is white of D65.
Similarly, for Ye, when the Ye coordinate is on the triangle on the xy chromaticity diagram, yellow obtained by mixing green and red at an appropriate mixing ratio and the Ye color bar of the color chart of this embodiment. It is possible to verify whether the yellow color indicated by is the same as the yellow color, and whether the white color obtained by mixing yellow and blue is D65 white.
As described above, the color chart of this embodiment has the same white obtained by mixing cyan and red, and yellow and blue, respectively, by having the Cy coordinate and Ye coordinate on the xy chromaticity diagram in the above position. Can be calibrated to D65 white.

Further, when the color bar group includes the Mg color bar, the coordinates on the xy chromaticity diagram of the Mg color bar (hereinafter referred to as Mg coordinates) are the xy chromaticity diagram of the G color bar. It is preferable to be on an extension line of a line connecting the coordinates (G coordinate) and the W coordinate. Above all, it is preferable to be on the extension line and on the side of the triangle.
In the xy chromaticity diagram, by setting the position of the Mg coordinate on the extension line of the line connecting the W (D65) coordinate and the G coordinate, red and cyan, blue and yellow, and green and magenta, which are complementary colors, respectively. It is possible to reproduce white that becomes D65 by mixing these combinations at an appropriate ratio. This is because the color chart of this aspect can perform white calibration and white balance adjustment more accurately.
When the Mg color bar is included, the Mg coordinate is not included as each color coordinate defining the color gamut.

The transmission spectrum of each color bar of Cy, Ye, and Mg is designed by appropriately adjusting the peak wavelength position and half-value width according to the position of each coordinate of Cy, Ye, and Mg on the xy chromaticity diagram. can do. The transmission spectrum of the Cy color bar includes an extension line obtained by drawing a straight line from the color coordinate position of W (D65) to the target Cy color coordinate and the outer periphery of the xy chromaticity diagram in order to adjust the Cy coordinate. The point where the wavelength position along the curve intersects can be used as a guide for the peak position. Further, the half width of the transmission spectrum of the Cy color bar can be set so as not to interfere with the peak position of another adjacent transmission spectrum. Since the saturation is higher as the half width is smaller and the saturation is lower as the half width is larger, the half width can be changed according to the target coordinate position of Cy. The same applies to 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 coordinate on the xy chromaticity diagram. The first peak and the second peak of the transmission spectrum of the Mg color bar can be set at the wavelength positions, 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 showing a desired transmission spectrum, and for example, a band pass filter or a dye substrate can be used.
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 above silver salt emulsion is coated on a chip substrate such as a glass plate. It can be formed by desilvering from a silver salt photographic plate obtained by drying and dyeing with a dye corresponding to the color of the color bar. The dye substrate can also be formed by mixing a dye in advance with gelatin (solution) and applying a predetermined color 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 the color bar and its forming method.
For example, if a dyed substrate using one kind of dye is used as the color bar, the peak wavelength of the transmission spectrum of the color bar can be adjusted by adjusting the concentration of the dye.
If 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. it can. Specifically, if it is a G color bar, it can be formed by a dyeing method using two types of yellow dyes and blue dyes, but when shifting the peak wavelength to the longer wavelength side, When the blending ratio is increased and shifted to the short wavelength side, the peak wavelength position can be adjusted by increasing the blending ratio of the blue dye.

  The size and the like of the color bar are not particularly limited, and can be appropriately designed so as to easily achieve a desired effect according to the use of the color chart of this aspect.

In the color bar group, the color bars are arranged in a pattern in random order. As an arrangement pattern of each color bar, as illustrated in FIG. 1, it may be arranged in a line pattern in a line, or although not illustrated, it may be arranged in a lattice pattern or a circle.
Further, the order of arrangement of the color bars is not particularly limited, and can be appropriately designed so that a desired effect can be easily achieved according to the use of the color chart of this aspect.

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, or an ink jet method. Since the method for forming the color bar by the dyeing method has been described above, the description thereof is omitted here.
The color bar group can be formed, for example, by arranging each color bar formed by the above-described method in a desired pattern on one side of the transparent substrate described later and sandwiching the transparent substrate and the cover glass. .

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

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

D. Others The color chart of this aspect 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, and the like in addition to the above-described configuration.
The recognition code can be, for example, a code in which information on a test chart is recorded. The alignment mark may be a mark in which position information is recorded, but may further function as a recognition code in which information on a test chart or the like is recorded. These may be provided on a transparent protective plate with a light shielding part.

Moreover, the color chart of this aspect may have an IR cut filter. When each color carver is formed by a dyeing method, due to the characteristics of the dye, the transmission spectrum tends to transmit light in a wavelength region of 650 nm or more, and the light transmittance is high. In particular, dyes used for Ye, O, and R color bars tend not to absorb light on the long wavelength side from around 650 nm. For this reason, the transmission spectra of the respective colors overlap in the long wavelength region.
On the other hand, by combining an IR cut filter that removes a predetermined area with the color bar, the transmission spectrum of each color can be separated, and color mixing can be prevented.
The IR cut filter can be selected in consideration of the wavelength region to be blocked in accordance with the transmission spectral 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 applied captured image. 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 a pathological imaging device, a color bar having a size corresponding to the magnification of the objective lens of the microscope It can be set as the color chart for micro imaging in which the group was formed.
In addition, when the color chart of this aspect is used for color evaluation and color correction of an output image of a measurement sample imaged at an equal magnification by an imaging device, for example, a color bar group having a size corresponding to the captured image size is formed. In addition, a color chart for macro imaging can be obtained.

E. Applications The color chart of this aspect can be used for imaging devices, video devices, and peripheral devices that require color calibration. Among these, it can be suitably used for an imaging device for pathology.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  The following examples illustrate the present invention in more detail.

[Example 1]
A transmission type color calibration chart comprising six color bars of R, G, B, Ye, Cy, and W and showing the spectral spectrum of FIG. 2 and the xy chromaticity diagram of FIG. 3 was prepared.
The five color bars other than W are prepared by applying a silver salt emulsion prepared by adding a solution of potassium bromide and silver nitrate to gelatin on a glass plate, and then desilvering the dried silver salt photographic plate. A dyed substrate was used in which the substrate was dyed with a dye corresponding to each color. As the dye, an acid dye that is generally used according to the color of each color bar was used. In addition, the dyeing method is similar to a generally popular production method. First, a dyeing solution in which an acid dye and an auxiliary agent are mixed is prepared, the substrate is immersed in the dyeing solution, and dyeing proceeds to a predetermined concentration. The substrate was taken out and washed with water.
The transmission color calibration chart was formed by laminating a surface to be recognized by the device as an upper surface, and from the uppermost surface in order of a transparent protective plate with a light-shielding portion, each color bar, and a transparent substrate. Each color bar (dyed substrate) was arranged on a transparent substrate (glass substrate) in the order of arrangement of B, Cy, G, Ye, R, and W. For the W color bar, a glass substrate serving as a transparent substrate was disposed.
Further, the color bars other than W were arranged on the transparent substrate through an IR cut filter. The B, Cy, and G color bars use the A type (half-value T = 50% 620 nm) as the IR cut filter, and the Ye and R color bars use the B type (half value T = 50% 665 nm) as the IR cut filter. ) Was used.
Table 1 shows the peak wavelength of each color bar.

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

[Example 3]
In addition to the nine color bars of Example 2, Mg was added to form a total of 10 color bars, and a transmission type color calibration chart showing the spectral 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 the color bars of other colors in Example 1.
The transmission type color calibration chart was formed in the same manner as in Example 1. Each color bar was arranged in the arrangement order of V, B, Cy, G, Ye, O, R, Mg, NIR, and W on the transparent substrate.
In addition, color bars other than NIR and W were arranged on a transparent substrate through an IR cut filter. For the V, B, Cy, and G color bars, the A type (half-value T = 50% 620 nm) is used as the IR cut filter. For the Ye, O, R, and Mg color bars, the B type ( 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.

  In the xy chromaticity diagrams of the transmission type color calibration charts obtained in Examples 1 to 3, Table 3 shows the inclusion rates of pointer colors included in the color gamut. The color gamut is shown in FIG. 3 as a pentagon connecting the coordinates of five colors excluding W, and in FIGS. 7 and 10 an octagon connecting the coordinates of eight colors excluding W and Mg.

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

Claims (10)

A transparent substrate;
A group of color bars formed on the transparent substrate;
Have
The color bar group is configured by arranging a plurality of color bars including at least a first color and a second color in a random 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 each have a separated peak top;
The color bar group further includes two color bars of violet and near infrared,
The transmission spectrum of the violet color bar has a wavelength of 435 nm to 465 nm at which the relative transmittance is 50% when the wavelength is 415 nm and the transmittance at the reference wavelength is 100%.
The transmission spectrum of the near-infrared color bar has a wavelength at which the relative transmittance is 50% when the wavelength is 730 nm as a reference wavelength and the transmittance at the reference wavelength is 100%. A transmissive color calibration chart characterized by the above. The color bar group further includes the color bars of three colors of red, green, and blue,
The transmission 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 a separated peak top.   Inclusion of pointer colors included in a pentagon in which 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 connected by a straight line. The transmission color calibration chart according to claim 2, wherein the rate is 74.4% or more. A transparent substrate;
A group of color bars formed on the transparent substrate;
Have
The color bar group is configured by arranging at least six color bars of red, green, blue, first color, second color, and white in a random 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 in the range of 470 nm to 515 nm,
The color bar group further includes two color bars of violet and near infrared,
The transmission spectrum of the violet color bar has a wavelength of 435 nm to 465 nm at which the relative transmittance is 50% when the wavelength is 415 nm and the transmittance at the reference wavelength is 100%.
The transmission spectrum of the near-infrared color bar has a wavelength at which the relative transmittance is 50% when the wavelength is 730 nm as a reference wavelength and the transmittance at the reference wavelength is 100%. A transmissive color calibration chart characterized by the above.   Inclusion of pointer colors included in a pentagon in which 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 connected by a straight line. The transmission color calibration chart according to claim 4, wherein the rate is 90.3% or more. The peak wavelength of the transmission spectrum of the red color bar is in the range of 620 nm to 680 nm, and the half width is 100 nm or less,
The peak wavelength of the transmission spectrum of the green color bar is in the range of 510 m to 540 nm, and the half width is 80 nm or less,
6. The transmission type according to claim 2, wherein a peak wavelength of a transmission spectrum of the blue color bar is in a range of 450 nm to 472 nm and a half width is 80 nm or less. Color calibration chart. The chromaticity coordinates on the xy chromaticity diagram of the second color bar are an extension of the line connecting the chromaticity coordinates on the xy chromaticity diagram of the red color bar and the white coordinates of D65; and , BT. Located on the outer periphery of the color gamut prescribed by the 2020 standard or outside the color gamut,
The chromaticity coordinate on the xy chromaticity diagram of the first color bar is an extension of a line connecting the chromaticity coordinate on the xy chromaticity diagram of the blue color bar and the white coordinate; and BT. The transmissive color calibration chart according to any one of claims 2 to 6, wherein the chart is located on an outer periphery of a color gamut defined by the 2020 standard or on an outer side of the color gamut.   The color bar group further includes an orange color bar, and a peak wavelength of a transmission spectrum of the orange color bar is in a range of 575 nm to 620 nm. The transmission type color calibration chart according to claim 1.   The transmissive color calibration chart according to any one of claims 1 to 8, wherein the color bar group further includes a magenta color bar. The color bar group further includes a magenta color bar,
A chromaticity coordinate on the xy chromaticity diagram of the magenta color bar is on an extension of a line connecting the chromaticity coordinate on the xy chromaticity diagram of the green color bar and the white coordinate of D65. The transmission type color calibration chart according to any one of claims 2 to 7 .

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