JP6774642B2 - Color chart and color chart device - Google Patents

Description

The present disclosure relates to color charts and color chart devices.

Conventionally, in image input devices such as video cameras, still cameras, and scanners, color reproducibility has been evaluated and calibrated using a color chart in order to ensure color reproducibility of the input image. The number of gradations of the conventional color chart is about several tens to one hundred.

By the way, in recent years, a high dynamic range image input device capable of acquiring brightness information of a subject having a large difference in brightness with high resolution has been developed and commercialized.

However, the conventional color chart is not sufficient for evaluation and calibration of an image input device having a high dynamic range due to the limited number of gradations.

From the above background, a technique for superimposing color charts to expand the color gamut has been proposed (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-88226

However, in Patent Document 1, no device is made to increase the number of gradations, and the number of gradations exceeding the gradation resolution of each of the superimposed color charts cannot be obtained. Therefore, the color chart of Patent Document 1 may not be able to properly evaluate and calibrate an image input device having a high dynamic range.

An object to be solved by the present disclosure is to provide a color chart and a color chart device capable of increasing the number of gradations while using an existing material having gradation resolution.

In order to solve the above problems, in one aspect of the present disclosure,
A first chart having a plurality of first translucent regions in which the color density of the same color is gradually changed in a single direction along the first direction on the first translucent substrate.
A second translucent region that is arranged so as to overlap the plurality of first translucent regions on the second translucent substrate that overlaps with the first translucent substrate and extends in the first direction, and the first translucent region. A second chart having a third translucent region, which is arranged adjacent to the second translucent region along a second direction intersecting in one direction and has a predetermined transmittance, is provided.
The second translucent region has the same color density as the maximum color density in the plurality of first translucent regions.
A color chart is provided in which the widths of the second light-transmitting region and the third light-transmitting region in the second direction are narrower than the widths of the plurality of first light-transmitting regions in the second direction, respectively.

The plurality of first translucent regions arranged along the first direction may have equal amounts of different color densities.

The first chart is arranged side by side along the second direction on the first translucent substrate, and m pieces (m is an integer of 2 or more) of different colors are arranged in the plurality of first translucent regions. Have and
The second chart is arranged so as to overlap the m first translucent regions, and extends in the first direction with the m second translucent regions and the second direction. It may have the m third light-transmitting regions arranged adjacent to the second light-transmitting region along the line.

The m plurality of first translucent regions may include the plurality of first translucent regions of cyan, magenta, yellow and black colors, or red, green, blue and black colors.

The third translucent region of the second chart may have the same transmittance as the second translucent substrate.

The third light-transmitting region of the second chart may have the same color density as the minimum color density in the plurality of first light-transmitting regions to be overlapped.

The first translucent substrate and the second translucent substrate may have the same transmittance characteristics with respect to wavelength.

It comprises at least one third chart superimposed on the first chart and the second chart.
The third chart shows a fourth translucent region extending in the first direction so as to overlap the plurality of first transmissive regions, and the fourth along a second direction intersecting the first direction. It has a fifth translucent region, which is arranged adjacent to the translucent region and has a predetermined transmittance.
The width of the fourth translucent region in the second direction is different from the width of the second translucent region in the second direction.
The width of the fifth translucent region in the second direction may be different from the width of the third translucent region in the second direction.

In one aspect of the disclosure,
Sheet-shaped color chart and
A lighting device that is arranged on one sheet surface side of the color chart and emits light that passes through the color chart is provided.
The color chart is
A first chart having a plurality of first translucent regions in which the color density of the same color is gradually changed in a single direction along the first direction on the first translucent substrate.
A second translucent region that is arranged so as to overlap the plurality of first translucent regions on the second translucent substrate that overlaps with the first translucent substrate and extends in the first direction, and the first translucent region. It has a third light-transmitting region arranged adjacent to the second light-transmitting region along a second direction intersecting in one direction and having a predetermined transmittance, and a second chart having.
The second translucent region has the same color density as the maximum color density in the plurality of first translucent regions.
A color chart device is provided in which the widths of the second translucent region and the third translucent region in the second direction are narrower than the widths of the plurality of first translucent regions in the second direction, respectively.

According to the present disclosure, the number of gradations can be increased while using the existing material having gradation resolution.

The figure which shows the 1st chart in the color chart by 1st Embodiment. The figure which shows the 2nd chart in the color chart by 1st Embodiment. The figure which shows the color chart by 1st Embodiment. Sectional drawing of the color chart by 1st Embodiment. In the color chart according to the first embodiment, the figure which shows the color density of the 1st chart and the 2nd chart. The figure which shows the color density of the color chart by 1st Embodiment. The flowchart which shows the manufacturing method of the color chart by 1st Embodiment. The explanatory view for demonstrating the color reproducibility evaluation method using the color chart by 1st Embodiment. The figure which shows the 1st chart in the color chart by 2nd Embodiment. The figure which shows the 2nd chart in the color chart by 2nd Embodiment. The figure which shows the 3rd chart in the color chart by 2nd Embodiment. The figure which shows the color chart by the 2nd Embodiment. In the color chart according to the second embodiment, the figure which shows the color density of the 1st to 3rd charts. The figure which shows the color density of the color chart by 2nd Embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The embodiments do not limit the present disclosure. Further, in the present specification, terms such as "board", "film", and "sheet" are not distinguished from each other based only on the difference in designation. Thus, for example, "board" is a concept that also includes members that can be called films or sheets.

(First Embodiment)
The color chart of the first embodiment is a transmission type color chart in which the transmitted light is used for evaluating and calibrating the color reproducibility of the image input device. The color chart according to the present embodiment is a superposition of the first chart and the second chart.

FIG. 1A is a schematic plan view of the first chart 11. FIG. 1B is a schematic plan view of the second chart 12. FIG. 1C is a schematic plan view of a color chart 1 in which the first chart 11 and the second chart 12 are superimposed. Each numerical value of FIGS. 1A, 1B, and 1C is a numerical value of a gradation value (color density), and is actually displayed in a hue corresponding to the gradation value. 2 is a cross-sectional view taken along line II-II of FIG. 1C. The part with a large numerical value indicates the part with a darker color.

(Chart 1 11)
The first chart 11 has a first translucent substrate 111 that transmits the colors of the color chart 1. The first translucent substrate 111 is, for example, a colorless and transparent resin film. The first translucent substrate 111 may be a colorless and transparent glass plate.

As shown in FIG. 1A, in the first chart 11, four types of first translucent light having different colors are arranged side by side along the Y direction, which is an example of the second direction, on the first translucent substrate 111. It has regions C _{1 to} C _21, M _{1 to} M _21, Y _{1 to} Y _{21, and} K _{1 to} K ₂₁ . Hereinafter, a specific description will be given.

As shown in FIG. 1A, in the first translucent substrate 111, the color density of cyan was changed stepwise as an example of a plurality of first translucent regions in which the color density of the same color was changed stepwise. A plurality of first cyanide regions C _{1 to} C ₂₁ are arranged. In FIG. 1A, the respective color densities are numerically indicated in each of the first cyan regions C _{1 to} C ₂₁ . The color density can be expressed as D ₁₁ of the mathematical formula (4) described later.

The first cyan regions C _{1 to} C ₂₁ are continuously arranged on the end side of the first translucent substrate 111 in the + Y direction along the X direction, which is an example of the first direction. In the example of FIG. 1A, 1 th first cyan region 21 of the cyan region _C 1 _{-C 21} from _{C 1} to 21 th first cyan region _{C 21} having a maximum density with the minimum density is located .. However, the number of the first cyan regions C _{1 to} C ₂₁ is not limited to the example of FIG. 1A, and may be more or less than 21.

In the first cyan region C _{1 to} C ₂₁ , the color density of cyan changes stepwise toward the −X direction, which is an example of a single direction. Specifically, in the first cyan regions C _{1 to} C ₂₁ , the color density gradually increases toward the −X direction. More specifically, the first cyan region C ₁ -C _21, the color density is different by 0.1, which is an example of an equivalent amount. In other words, in the first cyan region C _{1 to} C ₂₁ , the spectral transmittance of light decreases by a constant value toward the −X direction.

The first cyan region _C 1 _{-C 21} of such first chart 11, the second cyan region _{C A} and the third cyan region _{C B} and overlaps it with the color patches _PC 1 ~ of the cyan second chart 12 to be described later It constitutes PC ₄₂ .

FIG. 3 is a diagram showing the color densities of the first chart 11 and the second chart 12 in the color chart 1 according to the first embodiment. The horizontal axis of FIG. 3 is the number of the color patches PC _{1 to} PC ₄₂ , and the vertical axis is the color density. That is, FIG. 3 shows the correspondence between the patch numbers of the color patches CP _{1 to} CP ₄₁ and the color densities of the first cyan regions C _{1 to} C ₂₁ . In the example of FIGS. 1A and 3, except for the first the first cyan region _{C 1,} 2 single color patches _PC 1 _{to PC 41} that is the patch number is assigned to one of the first cyan region _C 1 _{-C 21} There is. Since the first cyan region C ₁ and the 21st first cyan region C ₂₁ have the same color density, one color patch is provided for the first cyan regions C ₁ and C ₂₁ in order to avoid overlapping color densities. Only PC ₁ is assigned. Specifically, when the number of the first cyan region _C 1 _{-C 21} of k to 1 to 21, the first cyan region _C 1 _{-C 21,} in the case of k = 1 only No. 1 patch number Is assigned, and when k ≠ 1, patch numbers k and k + 20 are assigned. For example, the first first-cyan region C ₁ having a minimum density, only the patch number 1 is assigned to the 21 th first cyan region C ₂₁ having a maximum density, the patch number 21 th and 41 th Is assigned. That is, in ascending order of the patch number, the color density of the first cyan region C ₁ -C ₂₁ corresponding to the patch number is increasing gradually. In the example of FIG. 3, the minimum concentration is 0. In the example of FIG. 1A, 1 th first cyan region C ₁ of the minimum density 0 it is realized by transmission of itself first light-transmissive substrate 111.

Further, as shown in FIG. 1A, on the first translucent substrate 111, the color density of magenta is stepped as an example of a plurality of first translucent regions in which the color density of the same color different from cyan is changed stepwise. Twenty-one first magenta regions M _{1 to} M ₂₁ that have been changed in a specific manner are arranged. In FIG. 1A, the respective color densities are shown in the first magenta regions M _{1 to} M ₂₁ . In FIG. 1A, the color densities of the first magenta regions M _{1 to} M ₂₁ match the color densities of the first cyan regions C _{1 to} C ₂₁ , but the present disclosure is not limited to such a configuration. The first magenta region _M 1 _{~M 21} at a position adjacent to the first cyan region _C 1 _{-C 21} in the -Y direction of the first light-transmissive substrate 111, a first cyan region _{C 1} in the X direction ~ C ₂₁ is continuously arranged over the same range. In the first magenta regions M _{1 to} M ₂₁ , the color density increases by an equal amount in the −X direction, that is, the color density changes stepwise. The first magenta region _M 1 _{~M 21} constitutes a second magenta region _{M A} and the third magenta region _M color patches _PM 1 _{Pm 41} magenta by overlapping with _B of the second chart 12 to be described later. Similar to the first cyan regions C _{1 to} C ₂₁ , the first magenta regions M _{1 to} M ₂₁ have a correspondence relationship with the patch number as shown in FIG.

Further, as shown in FIG. 1A, the first translucent substrate 111 has a yellow color density as an example of a plurality of first translucent regions in which the color densities of colors different from cyan and magenta are changed stepwise. Twenty-one first yellow regions Y _{1 to} Y ₂₁ are arranged in which the above is changed stepwise. In FIG. 1A, the respective color densities are shown in the first yellow regions Y _{1 to} Y ₂₁ . The first yellow region _Y 1 _{to Y 21} is in a position adjacent to the first magenta region _M 1 _{~M 21} in the -Y direction of the first light-transmissive substrate 111, a first magenta region along the X direction _{M 1} ~ M ₂₁ is continuously arranged over the same range. The first yellow regions Y _{1 to} Y ₂₁ overlap with the second yellow regions Y _A and Y _{B of} the second chart 12, which will be described later, to form the yellow color patches PY _{1 to} PY ₄₁ . The distribution of the color densities of the first yellow regions Y _{1 to} Y ₂₁ and the correspondence with the patch numbers are the same as those of the first magenta regions M _{1 to} M ₂₁ .

Further, as shown in FIG. 1A, on the first translucent substrate 111, as an example of a plurality of first translucent regions in which the color densities of colors different from cyan, magenta, and yellow are changed stepwise, black is used. Twenty-one first black regions K _{1 to} K _{21 in} which the color density is changed stepwise are arranged. In Figure 1A, each of the color density in each of the first black region _K 1 _{~K 21} is described. The first black region _K 1 _{~K 21} at a position adjacent to the first yellow region _Y 1 _{to Y 21} in the -Y direction of the first light-transmissive substrate 111, a first yellow region _{Y 1} along the X-direction It is continuously arranged over the same range as ~ Y ₂₁ . The first black region _K 1 _{~K 21} constitutes the second black area _{K A} and the third black area _K color patches _PK 1 _{~PK 41} black by overlapping with _B of the second chart 12 to be described later. The distribution of the color densities of the first black regions K _{1 to} K ₂₁ and the correspondence with the patch numbers are the same as those of the first magenta regions M _{1 to} M ₂₁ .

As described above, in the example of FIG. 1A, as an example of the first translucent regions of m pieces, that is, m types (m is an integer of 2 or more), four types of first translucent regions of cyan, magenta, yellow, and black are used. C _{1 to} C _21, M _{1 to} M _21, Y _{1 to} Y _{21, and} K _{1 to} K ₂₁ have been described. The types of colors are not limited to the above-mentioned color combinations, and for example, the m types of first translucent regions may be four types of first translucent regions of red, green, blue, and black. Further, the first chart 11 may be a combination of other colors, the types of colors are not limited to four, and even if the first chart 11 has a first translucent region of a single color. Good.

(2nd chart 12)
The second chart 12 has a second translucent substrate 121 that overlaps the first translucent substrate 111. The second translucent substrate 121 has the same transmittance characteristics with respect to the wavelength of light as the first translucent substrate 111. For example, if the material of the second translucent substrate 121 is the same as the material of the first translucent substrate 111, the transmittance characteristics of the first translucent substrate 111 and the second translucent substrate 112 are matched. be able to. By matching the transmittance characteristics of the first translucent substrate 111 and the second translucent substrate 121, the variation in the transmittance characteristics between the first translucent substrate 111 and the second translucent substrate 121 is taken into consideration. The desired color chart 1 can be easily designed without this.

As shown in FIG. 1B, the second chart 12 overlaps each of the four types of first translucent regions C _{1 to} C _21, M _{1 to} M _21, Y _{1 to} Y _{21, and} K _{1 to} K _21. It arranged four second light transmitting region _{C a, M a, Y a} , K a and four third transmitting region _{C B, M B, Y B} , and a _{K B.} Hereinafter, a specific description will be given.

As shown in FIG. 1B, on the second light-transmissive substrate 121, a second cyan region _{C A} disposed so as to overlap the first cyan region _C 1 _{-C 21} and the third cyan region _{C B} is arranged Has been done. The second cyan region C _A, on the end side of the inner + Y direction of the second light-transmissive substrate 121 is disposed so as to extend in the X direction. Third cyan region C _B are located adjacent to the second cyan region C _A in the Y direction.

As fully overlap the first cyan region _C 1 _{-C 21,} a second cyan region _{C A} and the third cyan region _{C B} is in the range i.e. the corresponding to the entire first cyan region _C 1 _{-C 21} as a whole 1 Cyan region C _{1 to} C ₂₁ are arranged over the same area. In other words, each of the Y-direction of the width of the second cyan region _{C A} and the third cyan region _{C B} is narrower than the Y-direction of the width of the first cyan region _C 1 _{-C 21.}

The second cyan region _{C A,} has the same color density as the maximum color density in the first cyan region _C 1 _{-C 21.} In the example of FIGS. 1A and 1B, the second cyan region _{C A,} has the same color density "2" and 21-th color density of the first cyan region _{C 21.}

The third cyan region C _B has the same transmittance as the second translucent substrate 121 as an example of a predetermined transmittance. In other words, the third cyan region C _B has the same color density as the minimum color density in the first cyan regions C _{1 to} C ₂₁ . In the example of FIGS. 1A and 1B, the third cyan region _{C B} have the same color density "0" and the first first-color density of the cyan region _{C 1.}

Figure 3 is a patch number and the second and third cyan region _C A color patch _CP 1 _{~ CP 41,} the correspondence relationship between color density of _{C B} shown. The second cyan region _{C A,} patch number 22 No. No. to 41 are allocated. The third cyan region _{C B,} the patch number 1 No. to 21 are allocated.

Further, as shown in FIG. 1B, on the second translucent substrate 121, the second magenta region M _A and the third magenta region M _B arranged so as to overlap the first magenta regions M _{1 to} M ₂₁ Is placed. The second magenta region M _A, at a position adjacent to the third cyan region C _B in the -Y direction of the second light-transmissive substrate 121 is disposed so as to extend in the X direction. Third magenta region M _B is disposed adjacent to the second magenta region M _A in the Y direction. As fully overlap the first magenta region _M 1 _{~M 21,} second magenta region _{M A} and the third magenta region _{M B} is arranged over a range corresponding to the entire first magenta region _M 1 _{~M 21} as a whole Has been done. The second magenta region _{M A,} has a 21-th same color density as the color density of the first magenta region _{M 21} is the maximum color density in the first magenta region _M 1 _{~M 21} "2". Third magenta region M _B includes a first first-color density magenta region M ₁ is the minimum color density in the second light-transmissive substrate 121 That same transmittance as the first magenta region M ₁ ~M ₂₁ It has the same color density "0". Second and third magenta region _M A, _{M B} is the cyan region _C A, similarly to _{C B,} has a corresponding relation of Fig. 3 between the patch number.

Further, as shown in FIG. 1B, on the second translucent substrate 121, the second yellow region Y _A and the third yellow region Y _B arranged so as to overlap the first yellow regions Y _{1 to} Y ₂₁ Is placed. The second yellow region Y _A, at a position adjacent to the third Magenta region M _B in the -Y direction of the second light-transmissive substrate 121 is disposed so as to extend in the X direction. Third yellow region Y _B are arranged adjacent in the Y direction to a second yellow region Y _A. As fully overlap the first yellow region _Y 1 _{to Y 21,} the second yellow region _{Y A} and the third yellow region _{Y B} is arranged over a range corresponding to the entire first yellow region _Y 1 _{to Y 21} as a whole Has been done. The second yellow region _{Y A,} has a 21-th same color density as the color density of the first yellow region _{Y 21} is the maximum color density in the first yellow region _Y 1 _{to Y 21} "2". The third yellow region Y _B has the same transmittance as the second translucent substrate 121, that is, the color density of the first first yellow region Y ₁ , which is the minimum color density in the first yellow regions Y _{1 to} Y _21. It has the same color density "0". Second and third yellow region _Y A, _{Y B} are cyan region _C A, similarly to _{C B,} it has a corresponding relation of Fig. 3 between the patch number.

Further, as shown in FIG. 1B, on the second light-transmissive substrate 121, and the second black area _{K A} which is arranged so as to overlap the first black region _K 1 _{~K 21} third black area _{K B} Is placed. The second black area K _A, at a position adjacent to the third yellow region Y _B in the -Y direction of the second light-transmissive substrate 121 is disposed so as to extend in the X direction. The third black region K _B are disposed adjacent to the second black area K _A in the Y direction. As fully overlap the first black region _K 1 _{~K 21,} second black area _{K A} and the third black region _{K B} is arranged over a range corresponding to the entire first black region _K 1 _{~K 21} as a whole Has been done. The second black area _{K A,} has a 21-th same color density as the color density of the first black area _{K 21} is the maximum color density in the first black region _K 1 _{~K 21} "2". The third black region K _B includes a first first-color density of the black region K ₁ is the minimum color density in the same transmittance as the second light-transmissive substrate 121 or first black region K ₁ ~K ₂₁ It has the same color density "0". Second and third black area _K A, _{K B} is the cyan region _C A, similarly to _{C B,} has a corresponding relation of Fig. 3 between the patch number.

(Color chart 1)
As shown in FIGS. 1C and 2, in the color chart 1, the first chart 11 and the second chart 12 overlap in the directions orthogonal to the X direction and the Y direction, that is, in the thickness direction of the translucent substrates 111 and 121. It is composed of. Between the first chart 11 and the second chart 12, the first to third translucent regions of the same color completely overlap each other, and the first to third translucent regions of different colors do not overlap each other.

As shown in FIG. 1C, in the color chart 1, and 21 of the first cyan region _C 1 _{-C 21} of the first chart 11, the second and third cyan region _C A of the second chart 12, and _{C B} By overlapping, 41 cyan color patches PC _{1 to} PC ₄₁ are configured. The first first-cyan region _{C 1} and the second cyan region _{C A} and the overlapping area is 21 th first cyan region _{C 21} and the third cyan region _{C B} 21 th and are overlapped color patches _{PC 21} Since the color density overlaps with, it is excluded from the color patch. This also applies to color patches of other colors. The number of color patches PC _{1 to} PC ₄₁ , that is, the number of gradations, is about twice that of the first cyan region C _{1 to} C ₂₁ .

FIG. 4 is a diagram showing the color density of the color chart 1 according to the first embodiment. FIG 4 is constructed by superimposing the first second and third cyan region _C A of the first cyan region _C 1 _{-C 21} chart 11 and the second chart 12, _{C B,} shown in FIG. 3 The color densities of the cyan color patches PC _{1 to} PC ₄₁ are shown.

As can be seen from FIGS. 1A, 1C and 4, the color density of the cyan color patches PC _{1 to} PC ₄₁ is twice as wide as the color density of the first cyan region C _{1 to} C ₂₁ , and the number is about. It is double. That is, the cyan color patches PC _{1 to} PC ₄₁ have about twice the number of gradations as the first cyan region C _{1 to} C ₂₁ .

Further, in the color patches PC _{1 to} PC ₄₁ , the color density is increased by 0.1, which is an equal amount in ascending order of the patch numbers.

By using the color patches PC _{1 to} PC _{41 in} which the number of gradations is approximately doubled and the color density changes by an equal amount, the color reproducibility of the high dynamic range image input device is appropriately evaluated and calibrated. be able to.

Further, in the color patches PC _{1 to} PC ₄₁ , the maximum color densities of the first cyan regions C _{1 to} C ₂₁ and the first cyan regions C _{1 to} C _{21 in which} the color densities increase by equal amounts in the -X direction and it can be conveniently obtained by the second and third cyan region C _a, superposition of the C _B having a respective minimum color density.

Further, as shown in FIG. 1C, in the color chart 1, the 21 first magenta regions M _{1 to} M _{21 of} the first chart 11 and the second and third magenta regions M _A and M of the second chart 12 are shown. _By overlapping with _B , 41 magenta color patches PM _{1 to} PM ₄₁ are configured. The number of color patches PM _{1 to} PM _{41 and} the number of gradations are about twice that of the first magenta region M _{1 to} M ₂₁ . Similar to the cyan color patches PC _{1 to} PC ₄₁ , the color densities of the magenta color patches PM _{1 to} PM ₄₁ increase by equal amounts in ascending order of the patch numbers.

Further, as shown in FIG. 1C, in the color chart 1, and 21 pieces of yellow region _Y 1 _{to Y 21} of the first chart 11, the second and third yellow region _Y A second chart 12, and _{Y B} By overlapping, 41 yellow color patches PY _{1 to} PY ₄₁ are configured. The number of color patches PY _{1 to} PY _{41 and} the number of gradations are about twice that of the first yellow region Y _{1 to} Y ₂₁ . Similar to the cyan color patches PC _{1 to} PC ₄₁ , the yellow color patches PY _{1 to} PY ₄₁ also have their color densities increased by equal amounts in ascending order of patch numbers.

Further, as shown in FIG. 1C, in the color chart 1, and 21 pieces of black area _K 1 _{~K 21} of the first chart 11, the second and third black region _K A of the second chart 12, and _{K B} By overlapping, 41 black color patches PK _{1 to} PK ₄₁ are configured. The number of color patches PK _{1 to} PK _{41 and} the number of gradations are about twice that of the first black regions K _{1 to} K ₂₁ . Similar to the cyan-based color patches PC _{1 to} PC ₄₁ , the black-based color patches PK _{1 to} PK ₄₁ also increase the color density by equal amounts in ascending order of the patch numbers.

If two identical first charts 11 are superposed to form a color chart, the difference between the maximum color density and the minimum color density, that is, the color density range should be double that of one first chart 11. Can be done. However, in such a color chart, the difference in color density between adjacent color patches becomes larger than the difference in color density between adjacent first translucent regions in chart 1. Therefore, it is not possible to properly evaluate the color density that takes a value between the color densities of adjacent color patches. That is, it is difficult to evaluate the color reproducibility with high accuracy in a color chart intended only for expanding the color gamut.

On the other hand, according to the color chart 1 of the first embodiment, by superimposing the first chart 11 and the second chart 12, not only the color gamut can be expanded from that of the first chart 11, but also the first chart It is possible to obtain about twice the number of gradations of 11. As a result, the color reproducibility of the image input device having a high dynamic range can be evaluated and calibrated with high accuracy, that is, appropriately.

(Manufacturing method of color chart 1)
FIG. 5 is a flowchart showing a method of manufacturing a color chart according to the first embodiment. The color chart 1 of FIGS. 1A to 1C can be manufactured according to, for example, the flowchart of FIG. Specifically, first, the plate-making data of the first chart 11 is created (step S1_1), and the plate-making data of the second chart 12 is created (step S1-2).

In the creation of plate making data, the first charts 11 and 12 are prepared in advance so that a color patch having a desired color arrangement and density arrangement can be obtained when the first chart 11 and the second chart 12 are overlapped. The color arrangement and density arrangement of the 1st to 3rd translucent regions are determined.

Here, the spectral transmittances of the transmitted light at a certain two-dimensional coordinate position of the color chart 1 in which the first chart 11 and the second chart 12 are superimposed with respect to the wavelength λ are T ₁₁ (λ) and T ₁₂ (λ), respectively. To do. The spectral transmittance T ₁ (λ) of the color chart 1 at that position can be expressed by the following equation using T ₁₁ (λ) and T ₁₂ (λ).

T ₁ (λ) = T ₁₁ (λ) × T ₁₂ (λ) (1)

Further, by taking the logarithms of both sides of the formula (1), the following formula is derived.
logT ₁ (λ) = logT ₁₁ (λ) + logT ₁₂ (λ) (2)

Here, according to the international standard ISO-5 / 2, the concentration D is defined by the following equation using the average transmittance _Targ in a specific wavelength region.
D = -log _{10 Targ} (3)

According to the equation (3), log T ₁ (λ) of the equation (2) can be approximately regarded as the density D ₁ of the color chart 1. Further, log T ₁₁ (λ) in the mathematical formula (2) can be approximately regarded as the concentration D ₁₁ in the first chart 11. Further, the log T ₁₂ (λ) of the mathematical formula (2) can be approximately regarded as the concentration D ₁₂ of the second chart 11.

Therefore, the mathematical formula (2) can be approximated to the following equation.
D ₁ = D ₁₁ + D ₁₂ (4)

Then, plate making data in which the density D ₁₁ of the first chart 11 is set as a plurality of values from the minimum color density to the maximum color density and the density D ₁₂ of the second chart 12 is set as two values of the minimum color density and the maximum color density. To create.

After creating the plate-making data of the first chart 11, the created plate-making data is printed on a positive film with a film printer to produce the first chart 11 (step S2_1). Further, after creating the plate-making data of the second chart 12, the created plate-making data is printed on a positive film with a film printer to produce the second chart 12 (step S2_2). At this time, the color density of the first to third translucent regions of the color charts 11 and 12 may be adjusted by the amount of the pigment adhered to the film.

After preparing the first chart 11 and the second chart 12, both charts 11 and 12 are overlapped with each other so that the corresponding first translucent region and the second and third translucent regions completely overlap each other (step S3). .. The overlapping of the charts 11 and 12 may be performed in a holder (not shown) that holds the peripheral edges of the color charts 11 and 12.

According to the manufacturing method of the first embodiment, the color chart 1 having twice the gradation number of the first chart 11 exceeding the limit of the film printer, that is, the output device is referred to as the first chart 11 and the second chart 12. It can be easily manufactured by superimposing. Further, the color density of the first translucent region of the first chart 11 is changed by an equal amount along the −X direction, and the second chart 12 is the second translucent region having the maximum color density of the first chart 11. The color density interval of the first chart 11 can be maintained even after the superposition by configuring the third light-transmitting region having the minimum color density. Therefore, a color chart 1 having a density arrangement suitable for use in evaluation and calibration of color reproducibility can be easily designed.

The color chart 1 of the present disclosure can be produced by using the following three methods. The first method is a method of forming a transmission region on a positive film by a silver halide photography method. The second method is a method of forming the first to third translucent regions on the translucent substrate by printing with an inkjet printer or an electrophotographic printer. The method described in FIG. 5 is an example of this second method. From a productivity standpoint, this second method is optimal. The third method is a method in which the first to third translucent regions are prepared by dyeing gelatin, and the dyed gelatin is sandwiched between films. From the point of view of accuracy, this third method is optimal.

(Color reproducibility evaluation method)
FIG. 6 is an explanatory diagram for explaining a color reproducibility evaluation method using the color chart 1 according to the first embodiment.

FIG. 6 shows an example of evaluating the color reproducibility of the camera 2, which is an example of the image input device, using the color chart 1. In order to evaluate the color reproducibility of the camera 2, first, as shown in FIG. 6, the lighting device 3 is arranged on one surface side of the color chart 1. Further, the camera 2 is arranged on the other side of the color chart 1 on which the translucent region is printed. The lighting device 3 constitutes the color chart device of the first embodiment together with the color chart 1.

Then, while the lighting device 3 illuminates the color chart 1 from one side, the camera 2 takes an image of the color chart 1 from the other side.

After capturing the color chart 1, the arithmetic circuit of the camera 2 compares the color patch on the captured image with the reference color patch data stored in the storage unit of the camera 2 in advance, and determines the color difference between the two. The evaluation value of the color reproducibility of the camera 2 based on this is calculated. The smaller the color difference of the color patch, the better the evaluation value of color reproducibility.

After calculating the evaluation value of the color reproducibility, the color correction circuit of the camera 2 calibrates the camera 2 by correcting the parameters of the camera 2 that correlate with the color reproducibility so that the color difference is minimized.

According to the color reproducibility evaluation method of the first embodiment, the color reproduction of the camera 2 having a high dynamic range is performed by using the color chart 1 simply prepared by superimposing the first chart 11 and the second chart 12. Sex evaluation and calibration can be performed appropriately.

As described above, in the first embodiment, by superimposing the first chart 11 and the second chart 12, the color chart 1 having a wider color gamut than the first chart 11 and a large number of gradations can be produced. .. Since the maximum color density of the second chart is matched with the maximum color density of the first chart, and the second chart has a simple configuration in which color patterns having uniform gradation are arranged separately. It can be easily manufactured by the existing manufacturing method, and there is no possibility that the manufacturing cost will increase.

(Second Embodiment)
In the first embodiment, an example of superimposing two charts 11 and 12 on the first chart 11 has been described, but the number of charts to be superposed is not particularly limited. Hereinafter, as the second embodiment, an example in which three color charts are superimposed to increase the number of gradations as compared with the first embodiment will be described. In the second embodiment, the same reference numerals are used for the configurations corresponding to the first embodiment, and duplicate description will be omitted.

FIG. 7A is a diagram showing the first chart 11 in the color chart 1 according to the second embodiment. FIG. 7A typically shows the first cyan regions C _{1 to} C ₂₁ in the first chart 11. FIG. 7B is a diagram showing the second chart 12. 7B is the second and third cyan region _C A of the second chart 12, it is representatively shown _{C B.} FIG. 7C is a diagram showing the third chart 13. Figure 7C is representatively show a fourth and fifth cyan region _C C, _{C D} of the third chart 13. FIG. 7D is a diagram showing a color chart 1. FIG. 7D typically shows the cyan color patches PC _{1 to} PC ₆₁ in the color chart 1.

Here, the third chart 13 is superimposed on the first chart 11 and the second chart 12. The third chart 13 has a fourth translucent region and a fifth translucent region corresponding to each color of CMYK on the third translucent substrate 131. In FIG. 7C, the fourth cyan region C _C and the fifth cyan region C _D are typically shown. The fourth translucent region extends in the X direction so as to overlap the first translucent region of the same color. The fifth translucent region is arranged adjacent to the fourth translucent region along the Y direction. The third translucent substrate 131 has the same transmittance characteristics as the first translucent substrate 111 and the second translucent substrate 121.

In the first embodiment, by superimposing 21 of the first cyan region _C 1 _{-C 21} of the first chart 11 and the second and third cyan region _C A of the second chart 12, and _{C B,} 41 The color patches PC _{1 to} PC ₄₁ were configured.

In contrast, in the second embodiment, and 21 of the first cyan region _C 1 _{-C 21} of the first chart 11, the second and third cyan region _C A of the second chart 12, and _{C B,} fourth and fifth cyan region _C C of the third chart 13, by overlapping the _{C D,} constitute a 61 color patches _PC 1 _{to PC 61.} Hereinafter, a specific description will be given.

As shown in FIG 7A~ Figure 7C, the whole and first cyan region _C 1 _{-C 21} of the first chart 11, the second and third cyan region _C A of the second chart 12, and the entire _{C B,} the fourth and fifth cyan region C _C 3 chart _13, the entire C _D, the position and extent correspond. Therefore, the cyan regions of each filter completely overlap. The fourth cyan region _{C C} of the second cyan region _{C A} third chart 13 of the second chart 12 are both identical to the maximum color density ie 21 th first cyan region _{C 21} of the first chart 11 Has color density. Further, both the third cyan region C _{B of} the second chart 12 and the fifth cyan region C _D of the third chart 13 have the same color density as the minimum color density of the first chart 11. In other words, the third cyan region C _B and the fifth cyan region C _D have the same transmittance as the translucent substrates 121 and 131.

Further, as shown in FIGS. 7B and 7C, the width of the Y direction of the fourth cyan region C _C is different from the Y direction width of the second cyan region C _A. In the example shown, the width of the Y direction of the fourth cyan region C _C is a half of the width in the Y direction of the second cyan region C _A. Further, the width of the fifth cyan region C _{D in} the Y direction is different from the width of the third cyan region C _{B in} the Y direction. In the illustrated example, the width of the fifth cyan region C _{D in} the Y direction is twice the width of the third cyan region C _{B in} the Y direction.

FIG. 8 is a diagram showing the color densities of the first to third charts 11 to 13 in the color chart 1 according to the second embodiment. As shown in FIG. 8, in the second chart 12, the second cyan transmitting region _{C A,} assigned the patch number 22 No. No. to 61 is, in the third cyan region _{C B,} the patch number 1 to 21 A number is assigned. In the third chart 13, the fourth cyan region _{C C,} assigned the patch number 42 No. No. to 61 is, in the fifth cyan region _{C D,} the patch number 1 No. to 41 are allocated.

FIG. 9 is a diagram showing the color density of the color chart 1 according to the second embodiment. In the second embodiment, a second cyan region _{C A} of the second chart 12, the fourth by superimposing the cyan region _{C C} of the third chart 13, the maximum color of the first cyan region _C 1 _{-C 21} A region having twice the color density can be created. Further, by superimposing the region having twice the color density and the 21st first cyan region C ₂₁ having the maximum color density, the color patch PC having three times the color density of the first cyan region C _{21. 61} can be configured.

That is, as shown in FIGS. 7D and 9, according to the color chart 1 of the second embodiment, by superimposing the three color charts 11, 12, and 13, the number of gradations is larger than that of the first embodiment. 61 cyan color patches PC _{1 to} PC ₆₁ can be configured.

By increasing the number of gradations in the first cyan region C _{1 to} C ₂₁ , the number of gradations in the cyan color patches PC _{1 to} PC ₆₁ can be further increased.

May also be superimposed fourth cyan region C _C and the third chart 13 dimensional ratio in the Y direction of the two or more different respective fifth cyan region C _D sequentially as the first chart 11 and the second Chart 12 .. As a result, the number of gradations can be further increased by a relatively simple configuration.

The configuration of the cyan region as described above is the same in the magenta region, the yellow region, and the black region.

As described above, according to the second embodiment, the number of gradations can be increased as compared with the first embodiment by increasing the number of charts to be superimposed and adjusting the width of the color region of each chart. ..

The aspects of the present disclosure are not limited to the individual embodiments described above, but also include various modifications that can be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the contents described above. That is, various additions, changes and partial deletions are possible without departing from the conceptual idea and purpose of the present disclosure derived from the contents defined in the claims and their equivalents.

1 color chart, 11 1st chart, 111 1st translucent substrate, 12 2nd chart, 121 2nd translucent substrate

Claims (8)

A first chart having a plurality of first translucent regions in which the color density of the same color is gradually changed in a single direction along the first direction on the first translucent substrate.
A second translucent region that is arranged so as to overlap the plurality of first translucent regions on the second translucent substrate that overlaps with the first translucent substrate and extends in the first direction, and the first translucent region. A second chart having a third translucent region, which is arranged adjacent to the second translucent region along a second direction intersecting in one direction and has a predetermined transmittance, is provided.
The second translucent region has the same color density as the maximum color density in the plurality of first translucent regions.
Each of the second width of the second light transmitting region and the third light transmitting region, rather narrower than the second width of the plurality of first light transmitting region,
The third translucent region is a color chart having the same color density as the minimum color density in the plurality of first translucent regions to be overlapped . The color chart according to claim 1, wherein the plurality of first translucent regions arranged along the first direction have equal amounts of different color densities. The first chart is arranged side by side along the second direction on the first translucent substrate, and m pieces (m is an integer of 2 or more) of different colors are arranged in the plurality of first translucent regions. Have and
The second chart is arranged so as to overlap the m first light-transmitting regions, and extends in the first direction with the m second light-transmitting regions and the second direction. The color chart according to claim 1 or 2, further comprising the m third translucent regions arranged adjacent to the second translucent region along the line. According to claim 3, the m plurality of first translucent regions include the plurality of first translucent regions of cyan, magenta, yellow and black colors, or red, green, blue and black colors. Described color chart. The color chart according to any one of claims 1 to 4, wherein the third translucent region of the second chart has the same transmittance as the second translucent substrate. The color chart according to any one of claims 1 to 5 , wherein the first translucent substrate and the second translucent substrate have the same transmittance characteristics with respect to a wavelength of light. It comprises at least one third chart superimposed on the first chart and the second chart.
The third chart shows a fourth translucent region extending in the first direction so as to overlap the plurality of first transmissive regions, and the fourth along a second direction intersecting the first direction. It has a fifth translucent region, which is arranged adjacent to the translucent region and has a predetermined transmittance.
The width of the fourth translucent region in the second direction is different from the width of the second translucent region in the second direction.
Said second width of said fifth light transmitting region, Unlike the second width of the third light transmitting region,
The fourth translucent region has the same color density as the maximum color density in the plurality of first translucent regions.
The color chart according to any one of claims 1 to 6 , wherein the fifth translucent region has the same color density as the minimum color density in the plurality of first translucent regions to be overlapped . Sheet-shaped color chart and
A lighting device that is arranged on one sheet surface side of the color chart and emits light that passes through the color chart is provided.
The color chart is
A first chart having a plurality of first translucent regions in which the color density of the same color is gradually changed in a single direction along the first direction on the first translucent substrate.
A second translucent region that is arranged so as to overlap the plurality of first translucent regions on the second translucent substrate that overlaps with the first translucent substrate and extends in the first direction, and the first translucent region. It has a second chart having a third translucent region, which is arranged adjacent to the second translucent region along a second direction intersecting in one direction and has a predetermined transmittance.
The second translucent region has the same color density as the maximum color density in the plurality of first translucent regions.
Each of the second width of the second light transmitting region and the third light transmitting region, rather narrower than the second width of the plurality of first light transmitting region,
The third translucent region is a color chart device having the same color density as the minimum color density in the plurality of first translucent regions to be overlapped .

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