CN117073841A - Color code data generation method for high dynamic range color management of imaging system - Google Patents
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Abstract
The invention discloses a color code data generation method for high dynamic range color management of an imaging system, which is applied to the technical fields of color science and display and comprises the following steps: collecting the spectral reflectivity of the color card and the relative spectral power distribution of the light source, and simulating the brightness transformation of various light sources by setting a reference light source and the reference reflectivity to obtain various spectral brightness; further combining the color matching function and the luminosity calibration coefficient to obtain a high dynamic range tristimulus value of the CIE XYZ color space; calibrating the spectral sensitivity and the radiation response coefficient of the color imaging system, and generating three-channel response data with high dynamic range under the RGB color space of the imaging system under different parameters based on the same target color block; according to the high dynamic range data under the same target color block spectrum brightness matching XYZ and RGB color space, the high dynamic range color code data set corresponding to the two color spaces is generated, and an effective data generation method is provided for the high dynamic range color management related research.
Description
Technical Field
The invention relates to the technical field of color science and display, in particular to a color code data generation method for high dynamic range color management of an imaging system.
Background
Color scale data is directed to color information management of color imaging devices including digital cameras, printers, projectors, displays, and the like. The current color code data generation method mainly comprises the following steps:
in 2021, liu et al measured tristimulus values (CIE XYZ) of 96 non-neutral colors of the ColorChecker SG color card using a QTC-600-7 standard color box D65 as a light source, using a PR715 spectrometer (Photo Research), and photographed three channel response values of the color patches corresponding to the ColorChecker SG color card using a Canon EOS 1000D to obtain color patch data, which was a method that achieved only low dynamic range color patch data acquisition.
In 2023, qin Yan et al, the western applied optical institute measured the tristimulus values of the gretag macbeth24 color chart using a CS-2000 spectroradiometer, photographed the gretag macbeth24 color chart using nikon D5300 at different exposure times, and further fused the chart images to generate high dynamic range images, thereby obtaining a high dynamic range calibration data pair.
In 2016, university of Zhejiang Fang Jingyu et al, under GretagMacbeth SpectraLight III standard lamp box and color control adjustable LED lamp box environment of JUSTNormlight, change lighting environment by changing 4 color temperatures and 7 illuminations of the lamp box light source, measure the reflection spectrum of GretagMacbeth DC 237 color card, X-Rite ColorChecker Digital SG 140 color card and X-Rite ColorChecker Classic 24 color card by using X-Rite SP64 spectrophotometer, shoot the above different color cards under different exposure time and different light source brightness by using different model digital cameras; the method realizes target color change by setting 28 illumination environments, color space sampling of the method is limited by experimental hardware, meanwhile, the response range of an imaging system is changed by camera imaging parameters (gain, integration time), a target color block cannot change color due to the change of the camera parameters, and a large amount of sampling of the CIEXYZ color space with high dynamic range cannot be realized, namely, the camera changing imaging parameters (gain, integration time and the like) only expands sampling in the imaging system color space, and cannot be paired with a color scene one by one.
The generation method of the color code data is mainly obtained by actual measurement of an instrument, the adopted instrument device comprises a lamp box, a color card, a spectroradiometer and the like, and the current generation method has the following problems:
1. the dynamic range of the scene corresponding to the color card matching illumination environment is smaller, and the color code data with a larger range and high density can not be obtained;
2. the color card and the lamp box are subject to hardware equipment such as a color card and the lamp box, have strict requirements on the equipment, and have more requirements on the type of light source of the equipment;
3. the cost of setting the lighting environment with high dynamic range and the required color card is high;
4. the experimental process is complicated, the required experimental process is time-consuming and has large workload, and the practical experiment is complex.
Because the setting range of the standard color card and the light source equipment of the standard lamp box is limited, the color code data has smaller brightness range, low sampling density and larger difference with the actual color dynamic range in the nature, and is difficult to be applied to color management of high dynamic range images.
Therefore, how to obtain high-dynamic-range and high-density color code data for color information management provides a color code data generation method for high-dynamic-range color management of an imaging system with sufficient color sample data and large dynamic range, which is a problem to be solved by those skilled in the art.
Disclosure of Invention
In view of this, the present invention proposes a color patch data generation method for high dynamic range color management of an imaging system. The combined data generation of RGB and XYZ under different brightness is realized through light source brightness simulation by measuring the light source relative spectral power distribution, combining a color matching function and brightness data calibration based on a visual mechanism, and the spectral sensitivity of an imaging system and a system radiation calibration coefficient.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the color code data generation method for the high dynamic range color management of the imaging system comprises the following steps:
collecting spectral reflectance data of the color card and relative spectral power distribution of the light source, converting the brightness of the light source through simulation, and calculating to obtain relative spectral brightness data reflected by the color card;
according to a visual mechanism, combining spectral brightness data and a color matching function, and obtaining high dynamic range tristimulus value data under CIE standard XYZ color space based on brightness calibration data;
performing radiation calibration on the color imaging system, wherein the radiation calibration comprises measuring spectral sensitivity data and a radiation response coefficient, converting spectral brightness data into spectral illuminance data, and generating three-channel response data with high dynamic range under RGB color space by combining the spectral illuminance data and imaging system radiation calibration data;
and generating high dynamic range color code data sets corresponding to the two color spaces according to the high dynamic range tristimulus value data of the spectrum brightness matching XYZ color space of the same target color card and the high dynamic range three-channel response data under the RGB color space.
Optionally, based on the spectral reflectance data of the color chart and the relative spectral power distribution of the light source, the brightness of the light source is transformed through simulation, and the spectral brightness data reflected by the color chart is obtained through calculation, as follows:
L(λ)＝k(P(λ)r(λ))；
wherein L (lambda) is the spectral brightness of the object reflection; k is a light source brightness adjustment factor,i is the brightness adjustment coefficient of the light source, i=1.. n; n=k 1 R, n is the brightness adjustment times, R is the reflectivity of the white color block, and the reflectivity of the reference white color block is taken as 1; k (k) 1 To use the photometric calibration coefficient, k, of the light source relative to a reference light source 1 ＝L 0 L is the brightness of the light source, L 0 Is the brightness of the reference light source; p (λ) is the relative spectral power distribution of the light source used; r (lambda) is the color chip color lump spectral reflectance.
Optionally, the data in the non-normalized XYZ color space is obtained by a color matching function as follows:
wherein X is a 、Y a 、Z a Is data in an unremoved XYZ color space, Y a Is brightness data;is a color matching function; l (λ) is the spectral brightness of the object reflection; lambda (lambda) 1 、λ 2 Is the visual spectral range.
Optionally, the normalization coefficient is introduced to convert the data in XYZ color space into color data in xyY color space as follows:
Y＝k 0 ·Y a ；
wherein x and y are chromaticity coordinates in an xyY color space; k (k) 0 In order to normalize the coefficients of the coefficients, P 0 (lambda) is the relative spectral power distribution of the reference light source. Y is the obtained stimulus value of the color block Y;
optionally, the spectral luminance data is converted into spectral luminance data as follows:
wherein E (lambda) is the spectral illuminance;A det detecting the element area for a camera detector; θ is the angle between the light entering the system and the main optical axis; f is the F number of the imaging system; l (λ) is the spectral luminance reflected by the color chip. When the F number is changed, the detector plane illumination is converted to the same F number parameter, and the change exposure time and the ISO sensitivity are linearly changed to a certain parameter according to the energy linear relation.
Optionally, the color imaging system is subjected to radiation calibration, the spectral brightness data is converted into spectral illuminance data, and the spectral illuminance data and the imaging system radiation calibration data are combined to generate three channel response data with high dynamic range under RGB color space, as follows:
wherein R, G, B isThree channel response values in RGB color space; k (k) R 、k G 、k B Scaling coefficients under different channels; r is R r (λ)、R g (λ)、R b (lambda) is the spectral sensitivity under different channels; e (lambda) is the spectral illuminance lambda 1 、λ 2 The spectral range is detected for the imaging system.
Optionally, generating the high dynamic range color scale data set corresponding to the two color spaces according to the high dynamic range tristimulus value data of the same target color card spectrum brightness matching XYZ color space and the high dynamic range three-channel response data under the RGB color space, further includes: neutral color data in the high dynamic range data in the XYZ color space and the RGB color space is removed.
Compared with the prior art, the color code data generation method for the high dynamic range color management of the imaging system is provided. The spectrum reflectivity of the ColorChecker SG color card, the light source and other instruments and the color imaging system are selected, spectrum sensitivity data of a Canon EOS600D camera are measured, CIE standard illumination relative to the spectrum power distribution is introduced, the spectrum brightness reflected by the color card under the high dynamic range brightness is generated in a simulation mode, and RGB data are acquired through the spectrum sensitivity of the camera; and combining the spectral brightness reflected by the color card sample with a human visual color matching function and a human eye tone response curve to obtain XYZ data, and generating combined data of RGB and XYZ under different brightness by light source brightness simulation to generate the color code data with high dynamic range of an imaging system. The invention obtains high dynamic range color imaging data and visual tristimulus value data by simulating and changing the brightness of the light source based on the relative spectral power distribution of the light source, the spectral reflectivity of the color card and the spectral sensitivity measurement of the camera, and displays the color code data required by supporting the color management of the high dynamic color image. The method makes up the current generation mode of color code data and provides an effective data generation method for the related research of high dynamic range color management.
Compared with the currently known high dynamic range color code data generation method, the high dynamic range color code data generation method for color information management has the advantages that:
1. the dynamic range of the color code is large, and the brightness of the light source can be digitally regulated by a simulation generation method, so that the dynamic data of the color code with a larger range is obtained;
2. the device is not limited by hardware devices such as a color card, a lamp box and the like, and the brightness of the light source can be digitally regulated due to a simulation experiment, so that an instrument light source does not need to be replaced as required;
3. the problems of high cost for producing the lamps with high dynamic range and the required color cards are solved, and the simulation experiment only needs the common dynamic data of part of the color cards, and the problems of various color cards and adjusting the equipment light source are not needed to be considered; 4. the experimental process is simple, the experimental type is a simulation experiment, and the implementation is very convenient.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of the method of the present invention.
FIG. 2 is a graph showing spectral reflectance data collected by the present invention.
Fig. 3 is a graph of the relative spectral power distribution of the D65 light source of the experimental light box.
Fig. 4 is a relative spectral power distribution of the a light source of the experimental light box.
FIG. 5 is a schematic representation of color data in xyY color space according to the present invention.
Fig. 6 is a graph of high dynamic range tristimulus data in XYZ color space according to the present invention.
Fig. 7 is a schematic diagram of collected camera spectral sensitivity data according to the present invention.
Fig. 8 is a diagram of high dynamic range three channel response value data in RGB color space according to the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1:
the embodiment 1 of the invention discloses a color code data generation method for high dynamic range color management of an imaging system, which comprises the following steps as shown in fig. 1:
and collecting spectral reflectance data of a ColorChecker SG color card experimental sample and relative spectral power distribution of D65 and A light sources of the lamp box, converting the brightness of the light sources through simulation, and calculating to obtain spectral brightness data of color card reflection.
Spectral reflectance data of ColorChecker SG color card experimental samples were collected, as shown in fig. 2, specifically:
selecting test samples including 96 non-neutral color blocks of a ColorChecker SG color card, gretagMacbeth 24-color non-neutral color blocks and the like, wherein the 96 non-neutral color blocks of the ColorChecker SG color card are selected in the embodiment;
selecting a spectral reflectance measuring instrument including an X-Rite7000A spectrophotometer and the like;
and (3) using a spectral reflectance measuring instrument X-Rite7000A spectrophotometer to place the color card to be measured in a specular reflection component exclusion (SCE) optical trap of the instrument, and measuring the spectral reflectance of the color card.
The CIE standard illuminant relative spectral power distribution and various light source relative power distributions were introduced, and the present example used the D65, a light source data of the light box. Based on the spectral reflectance data of the color card and the relative spectral power distribution of the light source, the brightness of the light source is converted through simulation, and the spectral brightness data reflected by the color card is obtained through calculation, wherein the spectral reflectance data are as follows:
L(λ)＝k(P(λ)r(λ))；
wherein L (lambda) is the spectral brightness of the object reflection; k is a light source brightness adjustment factor,i is the brightness adjustment coefficient of the light source, i=1.. n; n=k 1 R, n is the brightness adjustment times, R is the reflectivity of the white color block, and the reflectivity of the reference white color block is taken as 1; k (k) 1 To use the photometric calibration coefficient, k, of the light source relative to the D65 light source 1 ＝L 0 L is the brightness of the light source, L 0 Taking the brightness of a D65 light source as the brightness of the light source with the maximum brightness value in the experiment; p (λ) is the relative spectral power distribution of the light source used; r (lambda) is the color chip color lump spectral reflectance.
According to the visual mechanism, spectrum brightness data and a color matching function are combined, and based on data calibration, high dynamic range tristimulus value data under CIE standard XYZ color space is obtained, specifically:
based on the simulation of a color vision formation mechanism, calculating a vision tristimulus value of a color card sample under the irradiation of a light source, namely, a tristimulus value of a visual response formed by human eyes by spectrum brightness formed by spectrum reflection of spectrum power of the light source through the surface of the color card, wherein the tristimulus value specifically comprises:
the data in the non-normalized XYZ color space are obtained by the color matching function as follows:
wherein X is a 、Y a 、Z a Is data in an unremoved XYZ color space, Y a Is brightness data;is a color matching function; l (λ) is the spectral brightness of the object reflection; lambda (lambda) 1 、λ 2 Is the visual spectral range.
The relative spectral power distribution of the D65 and A light sources of the QTC-600-7 lamp box is selected, the spectrum of the lamp is measured through a shared FX2000 optical fiber spectrometer, the relative value of the spectral power at 560nm of the relative wavelength of the spectral power in the visible spectrum section is calculated according to the relative spectral power distribution, the relative value is the same as the relative spectral brightness distribution, and r (lambda) is the spectral reflectivity of the color card; k is a light source brightness adjusting factor, a high dynamic range scene corresponds to a large radiation brightness range, namely, a high brightness light source and a low brightness light source respectively irradiate surfaces with different reflectivities, the surface reflectivity information of the method is provided by a color card, the sample distribution of the scene reflection brightness range is increased by changing the superposition of the light source brightness ranges, so that the light source brightness adjusting factor k is further introduced, the brightness range of the light source is adjusted in a simulation mode by setting the light source brightness adjusting factor k, tristimulus value of the color card in an XYZ color space is calculated based on the steps, tristimulus value data of the color card in different light source brightness ranges are obtained, and the brightness (Y) value of all color blocks in the color card is ensured to be changed in a large range, so that the tristimulus value data of a high dynamic range color sample in an XYZ color space under the initial condition is obtained. Regarding the collected sample color card spectral reflectivity data, the reflection relation exists between the color card and the light source, so that the reflection factor and brightness interval relation is considered in a simulation experiment, and therefore the light source brightness adjustment factor k is as follows:
wherein i is a light source brightness adjustment coefficient, i=1, …, n; n=k 1 R, n is the number of brightness adjustment times, 10 times in this embodiment; r is the reflectivity of a white color block, wherein the reflectivity of a reference white color block is taken as 1; k (k) 1 To use the photometric calibration coefficient, k, of the light source relative to a reference light source 1 ＝L 0 L, L is the brightness of the light source used, L 0 As the brightness of the reference light source, the present embodiment uses light sources including two kinds of a light source and D65 light source,taking a D65 light source as a reference light source; because part of the light sources have higher brightness, direct measurement is difficult; in this example, the photometric calibration coefficient is obtained by the ratio of the CS2000 measurement values of the color patch reflected brightness.
Since the high dynamic range color sample tristimulus value data simulation is obtained under the condition of changing the brightness of a light source, in order to ensure that the brightness is taken as a unique variable, the calculation is performed in an xyY color space, and chromaticity x, Y and initial brightness Y are obtained; the relative spectral power distribution of the two light sources is shown in fig. 3 and 4, and the visual response brightness Y values of all color blocks of the color card are obtained by scaling with CS2000 spectrophotometry data, so as to generate high dynamic range color sample data in xyY color space, and the data are further converted into XYZ color space, so that high dynamic range color data in XYZ color space are obtained. The method comprises the following steps:
the data in the XYZ color space is converted into color data in the xyY color space based on the normalization coefficient, as shown in fig. 5, as follows:
Y＝k 0 ·Y a ；
wherein x and y are chromaticity coordinates in an xyY color space; k (k) 0 In order to normalize the coefficients of the coefficients, P 0 (lambda) is the relative spectral power distribution of the D65 light source. Y is the obtained stimulus value of the color block Y; further conversion to tristimulus values is shown in fig. 6.
And carrying out radiation calibration on the color imaging system, wherein the radiation calibration comprises measuring spectral sensitivity data and radiation response coefficients of color imaging system equipment of a camera image, converting spectral brightness data into spectral illuminance data, and generating three channel response data with high dynamic range under RGB color space by combining the spectral illuminance data.
Spectral sensitivity data of a color imaging system device for measuring camera images, in this embodiment, corresponds to Canon EOS600D, as shown in FIG. 7, specifically:
selecting imaging system spectral sensitivity measuring instruments including 71SW151 monochromator, PR-715 spectrophotometer and the like;
selecting a measuring environment, wherein the measuring environment is in a darkroom, and selecting an instrument light source;
the spectral sensitivity of the camera is obtained by adopting the following flow, a 71SW151 monochromator of OFN is used for generating monochromatic light, and a 71LX150A spherical xenon lamp is used as a light source for OFN; the monochromatic light is output within the range of 380nm-780nm, and the spectrum interval is 10nm; the exposure time and ISO sensitivity coefficient of the camera are adjusted, a certain F number is set unchanged, the proper exposure of the camera is ensured, and different exposure times and ISO are converted into the condition that the imaging system responds to a certain parameter. A typical setting is an F number of 5.6, exposure time and ISO adjusted with the shooting scene; when the F number is changed, the change is carried out under the same F number parameter according to the detection illumination, and the change exposure time and the ISO sensitivity are linearly changed under a certain parameter according to the energy linear relation; performing brightness measurement on the light source to obtain RGB three-channel response values of the camera; the three-channel response value is divided by the brightness value of the input monochromatic light to obtain the ratio of the two different monochromatic light spectrums, and the maximum value of the ratio under the green channel of the camera is further normalized to be 1, so that the spectral sensitivity can be obtained. The spectral sensitivity can be measured by brightness, flux and illuminance, and the spectral sensitivity obtained by the three measurements under different parameters of the camera is completely consistent because absolute magnitude is not introduced.
Because the experiment needs to calibrate the energy relation, different parameters of the imaging system need to calibrate the illumination value of the detector plane, the F number of the system is considered to be introduced, the input brightness is required to be converted into the illumination of the detector plane for operation, the spectral brightness data is converted into the spectral illumination data, and the conversion can be used for carrying out data conversion of different F numbers as follows:
wherein E (λ is spectral illuminance;normalizing coefficients for low dynamic imaging; a is that det Detecting the element area for a camera detector; θ is the angle between the light entering the system and the main optical axis, and is 0 because it is parallel to the main optical axis during measurement; f is the F number of the imaging system and is a parameter representing the light transmission capacity of the lens; l (λ) is the spectral luminance reflected by the color chip.
Performing radiation calibration on a color imaging system, converting spectral brightness data into spectral illuminance data, and generating three-channel response data with high dynamic range under RGB color space by combining spectral sensitivity and imaging system radiation calibration data, wherein the three-channel response data comprises the following specific steps: the spectral illuminance and the camera spectral sensitivity data are integrated, three channel response values of the color card sample surface under the irradiation of the light source are simulated by combining the calibration coefficients, namely, the spectral illuminance formed by converting the light source relative spectral power after passing through the spectral reflection of the color card surface is obtained, three channel response value data of the camera spectral sensitivity are obtained by combining the calibration coefficients, and as shown in fig. 8, the three channel response values correspond to a calculation formula as follows:
wherein R, G, B is the three channel response value in the device dependent color space; k (k) R 、k G 、k B Scaling for different channelsCoefficients; r is R r (λ)、R g (λ)、R b (lambda) is the spectral sensitivity under different channels; e (lambda) is the spectral luminance,and setting a light source brightness adjustment factor k similar to the XYZ color space, and simulating and adjusting the brightness range of the light source, and obtaining color tristimulus value data of the color card under different light source brightness ranges based on the calculated spectral reflectivity of the color card and the spectral power distribution of the light source, so as to ensure that the brightness of all color blocks in the color card is changed in a large range, namely obtaining three-channel response values of a high dynamic range color sample under the initial condition under the RGB color space.
And removing neutral color data in the high dynamic range data in the XYZ color space and the RGB color space, and generating high dynamic range color code data sets corresponding to the two color spaces according to the spectrum brightness of the same target color card, matching the high dynamic range tristimulus value data in the CIE1931XYZ color space and the high dynamic range three-channel response data in the RGB color space.
The embodiment of the invention discloses a color code data generation method for high dynamic range color management of an imaging system. The method comprises the steps of selecting a ColorChecker SG color card, a light source, a spectrophotometer and other instruments and a color imaging system, measuring spectral reflectivity of the ColorChecker SG color card and spectral sensitivity data of a Canon EOS600D camera, introducing light source relative spectral power distribution, simulating to generate spectral brightness reflected by the color card under high dynamic range brightness, and acquiring RGB data through camera spectral sensitivity; and then matching the spectrum brightness reflected by the color card sample with a human visual color matching function, combining calibration data to obtain XYZ data, and generating combined data of RGB and XYZ under different brightness by light source brightness simulation to generate the color code data with high dynamic range of an imaging system. The invention obtains high dynamic range color imaging data and visual tristimulus value data by simulating and changing the brightness of the light source based on the relative spectral power distribution of the light source, the spectral reflectivity of the color card and the spectral sensitivity measurement of the camera, and displays the color code data required by supporting the color management of the high dynamic color image. The method makes up the current generation mode of color code data and provides an effective data generation method for the related research of high dynamic range color management.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (7)
1. The color code data generation method for the high dynamic range color management of the imaging system is characterized by comprising the following steps of:
collecting spectral reflectance data of the color card and relative spectral power distribution of the light source, converting the brightness of the light source through simulation, and calculating to obtain relative spectral brightness data reflected by the color card;
according to a visual mechanism, combining the relative spectrum brightness data, the color matching function and the brightness calibration coefficient of the comparison of the measured values of the spectrum photometer, and obtaining high dynamic range tristimulus value data under CIE standard XYZ color space;
performing radiometric calibration on a color imaging system, the radiometric calibration comprising measuring a radiometric response coefficient and a spectral sensitivity, converting the relative spectral luminance data into spectral luminance data, and combining the spectral luminance data and imaging system radiometric calibration data to generate high dynamic range three-channel response data in an RGB color space;
and generating high dynamic range color code data sets corresponding to the two color spaces according to the high dynamic range tristimulus value data of the XYZ color space and the high dynamic range three-channel response data of the RGB color space which are matched by the spectrum brightness of the same target color card.
2. The method for generating color scale data for high dynamic range color management of imaging system according to claim 1, wherein the relative spectral brightness data of the color card reflection is calculated by converting the brightness of the light source through simulation based on the spectral reflectance data of the color card and the relative spectral power distribution of the light source, as follows:
L(λ)＝k(P(λ)r(λ))；
wherein L (lambda) is the spectral brightness of the object reflection; k is a light source brightness adjustment factor,i is the brightness adjustment coefficient of the light source, i=1.. n; n=k 1 R, n is the brightness adjustment times, R is the reflectivity of the white color block, and the reflectivity of the reference white color block is taken as 1; k (k) 1 To use the photometric calibration coefficient, k, of the light source relative to a reference light source 1 ＝L 0 L is the brightness of the light source, L 0 Is the brightness of the reference light source; p (λ) is the relative spectral power distribution of the light source used; r (lambda) is the color chip color lump spectral reflectance.
3. The method for generating color patch data for high dynamic range color management of an imaging system according to claim 1, wherein the data in the non-normalized XYZ color space is obtained by a color matching function as follows:
wherein X is a 、Y a 、Z a Is data in an unremoved XYZ color space, Y a Is brightness data;is a color matching function; l (λ) is the spectral brightness of the object reflection; lambda (lambda) 1 、λ 2 Is the visual spectral range.
4. The method of claim 1, wherein the color scale data generating for high dynamic range color management of an imaging system,
converting the data in the non-normalized XYZ color space to color data in the xyY color space based on the normalization coefficient as follows:
Y＝k 0 ·Y a ；
wherein x and y are chromaticity coordinates in an xyY color space; k (k) 0 In order to normalize the coefficients of the coefficients, P 0 (lambda) is the relative spectral power distribution of the reference light source, Y is the obtained color patch Y stimulus value.
5. The method of claim 1, wherein converting the spectral luminance data into spectral luminance data is performed as follows:
wherein E (lambda) is the spectral illuminance;A det detecting the element area for a camera detector; θ is the angle between the light entering the system and the main optical axis; f is the F number of the imaging system; l (λ) is the spectral luminance.
6. The imaging system high dynamic range color management oriented color scale data generating method of claim 1, wherein the color imaging system is radiometrically calibrated, the spectral luminance data is converted into spectral luminance data, and the spectral luminance data and imaging system radiometrically calibrated data are combined to generate high dynamic range three-channel response data in RGB color space, as follows:
wherein R, G, B is the imaging system three channel response value in RGB color space; k (k) R 、k G 、k B Imaging system for different channelsScaling coefficients; r is R r (λ)、R g (λ)、R b (lambda) is the spectral sensitivity under different channels; e (lambda) is the spectral illuminance.
7. The method of claim 1, wherein generating the two color space corresponding high dynamic range color patch data sets by matching the high dynamic range tristimulus value data of the XYZ color space and the high dynamic range three-channel response data of the RGB color space according to the spectral luminance of the same target color card, further comprises: neutral color data in the high dynamic range data in the XYZ color space and the RGB color space is removed.
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