CN101527108B - Measuring method for colorimetric parameters of LED display screen - Google Patents

Abstract

The invention relates to a measuring method for colorimetric parameters of an LED display screen. According to the luminescent characteristics of the LED display screen, the method creates and stipulates the measuring steps of color domain coverage ratio, non-uniformity of white field chromaticity and color reproduction of the LED display screen and a calculating method, provides a method for improving the accuracy of measuring and debugging the value and the range of the white field chromaticity and improving the accuracy of measuring primary wavelength of base color, and carries out necessary discrimination to peak wavelength of an LED tube and primary wavelength of an LED screen from scientific concept. A 1980 color luminance meter which conforms to spetral tristimulus values and contains four groups of filter plates is adopted to measure the colorimetric parameters of the LED display screen accurately; by adopting the method, the accuracy of measurement can meet the technical requirements to the standard color luminance meter. A 1980 spectroradiometer with spectral bandwidth and the sampling interval of 1nm can accurately measure the peak wavelength of the LED tube. In the debugging process, a multiturn potentiometer is adopted to achieve the purpose of finely selecting the resistance value of a resistor. The core technology is the necessary premise and key of debugging and manufacturing the LED display screen with excellent color reproduction.

Description

The measuring method of LED display colorimetric parameter

Technical field

The present invention relates to a kind of measuring method of LED display, particularly a kind of measuring method of LED display colorimetric parameter.

Background technology

At present, along with LED display is applied to various important events, people have higher requirement to the LED display quality of colour; And the application and the use value of LED display will be constantly widened in improving constantly of LED display quality of colour again.

But the measurement project that lacks LED display colour gamut coverage rate in the existing LED display measuring method lacks the LED display measurement project of a colourity unevenness in vain; In the existing LED display measuring method error method for expressing of color analyzer existed that wrong (colourity error not percent utilization is represented; The application absolute value representation) the LED display industry is ignored the important hints of national authority mechanism at present; Itself just introduces considerable error employed colorimeter instrument; And most instruments do not possess the implementing method of eliminating error; This can cause the grade of errors that can't accurately confirm primary colours predominant wavelength, also the debugging of the white colourity of actual influence LED display and definite.

For example:

1. point out in country of national authority mechanism television-quality inspection center peace " colour television set performance measurement principle and method " book that one-tenth etc. is write forever: the instrument of three optical filters, to compare with the spectral tristimulus value of human vision organ, it has no idea to simulate X ₁Effect (λ) has brought certain error to measurement; And the X of color luminance meters such as the 1980A of produced in usa, 1980B in simulating respectively by four groups of optical filters ₁(λ), X ₂(λ), the response curve of Y (λ) and Z (λ).Color luminance meter is a kind of color measurement instrument the most frequently used in the LED display colour measurement, and the detector after color luminance meter color filter and the photomultiplier combination should be tried one's best and accurately met spectral tristimulus value curve X (λ), Y (λ) and Z (λ).X (λ) has two crest X at short-wave band and long-wave band ₁(λ), X ₂(λ).

2. present, to colourity error prescriptive procedure existing problems (the colourity error is used absolute value representation, and percent utilization is not represented), there is excessive error in actual instrument commonly used in the LED industry standard.

The following work of a China National Measuring Science Research Inst. job is therewith paid close attention to about being worth our, should use the photo-multiplier tube type spectral radiometer.

According to the Yin Yu of optics place of China National Measuring Science Research Inst. Zhe, Ma Yu, Zhou Qingguo, Gui Kangnian and Beijing Institute of Technology's photoelectric project is to confirm in " construction of light source colourity country disjunction mark standard apparatus system " literary composition of writing of people such as Zheng Yang, Hou Sufang, Lu Hansheng: " spectral distribution of FPD light source all belongs to the spectral line type; the intensity difference between each spectral line often reaches more than three one magnitude; CCD spectral type photometry color measurement instrument commonly used; the PR650/705 of Photo Research etc. for example, the calibration needs that can not provide enough dynamic ranges to satisfy colour measurement.Therefore, must use the color measurement instrument of HDR, will adopt photodiode array (PDA) at least, or even the photometry color measurement instrument that photomultiplier (PMT) is made detector just can satisfy the demands.”

Instrument such as the CS-100 and the BM-7 etc. of LED display industry use at present are not photo-multiplier tube type all, on spectral response, have only three parts, can't well simulate X ₁Effect (λ) brings error to measurement.Do not have calibration function, when measuring red, green, blue, can't use the error when measuring white simply to replace.Three groups of high-grade sheet color luminance meters, like BM-5, no corresponding standard light source also can't be worked.

3. should select the receiving device of photomultiplier when measure spectrum distributes and get little sample interval and do the transmission benchmark.

Confirm in " about several problems of colour temperature measurement " literary composition that the Liu Hui of optics place of China National Measuring Science Research Inst., Xiao Wenbin write: " the wavelength interval Δ λ that is adopted in the relative spectral power measuring process will directly influence precision of calculation results; λ is more little for Δ; measuring accuracy is high more; but the Measuring Time increase should be selected different SI Δ λ for use according to the difference of kind.For the SI of selecting 5nm for use in the actual colour temperature 18W fluorescent light measuring process that is 6520K, then recording colour temperature is 7539K, if select for use the SI of Δ λ=2nm, then recording colour temperature is 6520K.And, in the SI of selecting Δ λ=5nm for use, just can guarantee the correctness of measurement result for the incandescent lamp of continuous spectrum.”

PR-650 spectral bandwidth 8nm, sample interval 4nm as with CCD spectral type apparatus measures LED displays such as PR-650, the problem of pointing out in the above-mentioned several pieces of articles then can occur.

Shenzhen illumination can setting up in 20 anniversary collected works " the illuminating LED optical property detects principle and the method " literary composition in Chinese illumination of Xue's ability also be pointed out: " because the spectrum of LED comprises line-spectra; for improving accuracy of detection, the monochromator step interval is answered≤1nm.”

Selecting suitable color luminance meter according to the LED luminescent properties, carry out intensive scientific and technological work, is the key of formulating white color standard of LED and tolerant scope, also is the important prerequisite of measuring and differentiate other photochromic index of LED display.

As pointed problem in the article that China National Measuring Science Research Inst. delivers can appear in the PR650, the SR-3A that use the CCD device.The task of surveying instrument is that accurate measurements and calculations go out X ₁, X ₂, Y, four components of Z get final product.We all can calculate x, y through the simple mathematical conversion, u, v, u ', v ' etc.Otherwise, if instrument accurately measurements and calculations go out X ₁, X ₂, Y, four components of Z, functions such as calculating u ', v ' are but arranged on the contrary, can bring considerable error in the same old way.

To foundation be provided for design, the manufacturing that improves LED to the light of LED display, the experimental result that look is measured, in order to adapt to the application of LED display, light, look measuring technique should have new breakthrough.

All evaluations and objective measurement all should be carried out under the distance of implementation space mixed color effect, and the light probe acquisition range must not be less than 16 neighbors in measuring the white chromaticity coordinate of display screen.Because the physical points spacing of various display screens is different with phsyical density, therefore adjustable nitometer of visual field solid angle and color luminance meter should be used, and field angle greatly such as 2 °, 3 ° should be contained, its working range should reach more than several thousand nits.

The spacing of LED screen pixels physical points is much larger than CTT CRT and LCD TV LCD, plasm TV PDP, and the phsyical density of unit plane pixel is much smaller than above-mentioned three.Therefore could produce spacing color mixed effect at a distance.

We can be edified from the general character of adjacent field progress on the one hand, carry out necessary measurement and evaluation based on the characteristic of LED screen again on the one hand, and the quality of colour of LED screen constantly is improved.In order to guarantee enough big survey area, eliminate measuring error, should use the color luminance meter of adjustable visual field solid angle.Under same distance, the different fields of view solid angle has different test area, can satisfy the technical requirement of variety classes display screen.

Therefore, a kind of measuring method of LED display colorimetric parameter reasonable in design, widely used being provided, is one of the current urgency in this field difficult problem to be solved.

Summary of the invention

The objective of the invention is to overcome the weak point of prior art, a kind of measuring method of LED display colorimetric parameter is provided.

Following for realizing the embodiment that above-mentioned purpose the present invention adopted:

A kind of measuring method of LED display colorimetric parameter is characterized in that implementation step is following:

At first selecting measuring equipment is that four groups of sheet 1980A color intensities meeting the human eye spectral tristimulus value are taken into account spectral bandwidth and the sample interval is the 1980B spectral radiometer of 1nm; In debug process, adopt multiturn potentiometer, promptly each corresponding physical points spacing place of LED display circuit is connected with the many circles adjustable potentiometer that is used to carry out the colorimetric parameter debugging respectively by three the tunnel;

Color luminance meter is a kind of color measurement instrument the most frequently used in the LED display colour measurement, and the detector after color luminance meter color filter and the photomultiplier combination will accurately meet spectral tristimulus value curve X (λ), Y (λ) and Z (λ); X (λ) has two crest X at short-wave band and long-wave band ₁(λ), X ₂(λ);

Can try to achieve the suitable colour correction factor of 1980A by following formula

$C_1=\frac{x_0}{y_0}\frac{p_0}{(\mathrm{Xr}+\mathrm{Xb})}\·\·\·\·\·\·\·\·\·\left(1\right)$

$C_2=\frac{(1-x_0-y_0)}{y_0}\·\frac{p_0}{z_0}$

Wherein: p ₀, X _r, X _b, z ₀Be four groups of output datas in 1980A measurement standard light source, look source; x ₀, y ₀Be the chromaticity coordinate that same standard sources, look source are measured by China National Measuring Science Research Inst. of national authority mechanism, formula can be extrapolated white colour correction factor C respectively according to this ₁, C ₂, Red Square colour correction factor C ₁, C ₂, green colour correction factor C ₁, C ₂, blue corresponding colour correction factor C ₁, C ₂

P, x _r, x _b, z is the output data of 1980 color luminance meters actual measurements LED display; When measuring the white field of LED display, red primary field, green primary field, blue fundamental color field respectively with corresponding colour correction factor C ₁, C ₂In the substitution formula:

$x=\frac{(x_r+x_b)c_1}{(x_r+x_b)c_1+p+z{c}_2}\·\·\·\·\·\·\·\·\·\left(2\right)$

$y=\frac{p}{(x_r+x_b)c_1+p+z{c}_2}$

Can obtain and the consistent chromaticity coordinate of national metrological service accuracy, can reach technical requirement fully the standard color luminance meter; Primary colours predominant wavelength and grade of errors that the formula of utilization the present invention regulation and implementation step can accurately be evaluated LED display;

Measure the peak wavelength that LED manages like needs, should use spectral bandwidth and sample interval all can be accurate to 1980 spectral radiometers of 1nm;

Measurement contents and concrete steps are:

(1) measurement of LED display colour gamut coverage rate and calculating

The colour gamut coverage rate characterizes primary colours R, G, B in the uniform colour space coordinate, the leg-of-mutton area tolerance of the corresponding colour developing of institute;

(1.1) definition of colour gamut coverage rate: the CIE1976 uniform color space (u '; V '), and the gamut area that display device shows (be three primary colours R, G; The leg-of-mutton area of B) with the percentage that accounts for (u ', v ') the whole spectrum of chrominance space (from 380-780nm) areas (0.1952);

(1.2) measurement of colour gamut coverage rate

Respectively with full Red Square, full Lv Chang and complete blue test signal input; With red, green, blue screen center's point chromaticity coordinate (u of the color luminance meter difference measurements and calculations that meet above-mentioned requirements _r', v _r'), (u _g', v _g'), (u _b', v _b'); Its accuracy of measurement, degree of accuracy can be synchronous with national level, and the chromaticity coordinate when China National Measuring Science Research Inst. provides respective standard look source can realize that promptly country is to correction factor C red, green, blue field ₁, C ₂Transmission of quantity value;

(1.3) calculating of colour gamut coverage rate

Calculate CIE-1976L by formula ^*, u ^*, v ^*Chromaticity coordinate u ', v ' value

$\left.\begin{array}{c}{u}^{\′}=\frac{4X}{X+15Y+3Z}\\ v^{\′}=\frac{9Y}{X+15Y+3Z}\end{array}\right\}\·\·\·\·\·\·\·\·\·\left(3\right)$

Gamut area=0.5 [(u _r'-u _b') (v _g'-v _b')-(u _g'-u _b') (v _r'-v _b')] ... (4)

Colour gamut coverage rate=gamut area ÷ 0.1952 * 100%,

The colour gamut coverage rate characterizes the leg-of-mutton area tolerance of the corresponding colour developing of primary colours (R, G, B) institute in the uniform colour space coordinate;

The colour gamut coverage rate is that the chromaticity coordinate of three kinds of colors of examination RGB surrounds leg-of-mutton size on chromaticity diagram, and any point color can be synthetic by the RGB three primary colours in triangle, and the color that the big more explanation of area can cover is wide more;

(1.4) scope of color monitor Color reproduction

Input end at display adds the monochrome signal suitable with R, G, the B of colour signal, measures in the vertical direction of picture with color luminance meter, and the chromaticity coordinate during with input R signal is decided to be x _R, y _R, the chromaticity coordinate during with input G signal is decided to be x _G, y _G, the chromaticity coordinate during with input B signal is decided to be x _B, y _B, and be depicted on the chromatic diagram, each point is connected with straight line, express the color reproduction scope; By can reproducing color therewith in the triangle scope that straight line surrounded;

(2) measurement of LED display reference white and colourity unevenness

Measure the P of screen center ₀The point chromaticity coordinate can be represented reference white; Measure the difference of image chroma between screen center and the surrounding edge and represent the colourity unevenness; Measure P ₀To P ₈Chromaticity coordinate be (x ₀, y ₀) (u ' ₀, v ' ₀) to (x ₈, y ₈) (u ' ₈, v ' ₈)

Colour difference by these points of computes

Δx＝x _i-x ₀，Δy＝y _i-y ₀， ………………(5)

Δu’＝u _i’-u ₀’Δv’＝v _i’-v ₀’ ………………(6)

Δc＝[(u‘ _i-u‘ ₀) ²+(v’ _i-v‘ ₀) ²] ^1/2；?………………(7)

(3) measurement of each primary colours predominant wavelength of display screen and peak wavelength

Respectively with full Red Square, full Lv Chang and complete blue test signal input; With red, green, the blue screen center's point chromaticity coordinate of color luminance meter difference measurements and calculations that meets above-mentioned requirements;

Its accuracy of measurement, degree of accuracy can be synchronous with national level, and the chromaticity coordinate when China National Measuring Science Research Inst. provides respective standard look source can realize that promptly country is to correction factor C red, green, blue field ₁, C ₂Transmission of quantity value;

Computing method is according to connecting with reference to light source E (x on the chromatic diagram ₀, y ₀) and sample spot (x, the slope (x-x of straight line y) ₀)/(y-y ₀) and (y-y ₀)/(x-x ₀), by one group of little acquisition of tabling look-up of absolute value, tabling look-up to obtain predominant wavelength; X wherein ₀=y ₀=0.333;

The correct key that obtains predominant wavelength is that correct measurement goes out X1, X2, Y, Z; Should use photomultiplier as receiving device according to the scientific research result that China National Measuring Science Research Inst. obtained, confirm to measure the color luminance meter that tristimulus values should be used four groups of optical filters according to the scientific research result of national television-quality inspection center;

(4) measurement of colored reproduction

Because varying with each individual appears in color evaluation sometimes,, when conditions being possessed, can increase the measurement of colored reproduction when hard case that great difference can't be made conclusion occurring;

(4.1) spectral distribution of the common look of measurement large nature is calculated its chromaticity coordinate, represents common look with the complete colour atla of colour gamut;

(4.2) measure the chromaticity coordinates of object with same color luminance meter;

(4.3) measure the chromaticity coordinates that reproduces look on different white the chromatic value LED displays;

(4.4) the colourity error between calculating object and the reproduction look; The colourity reproduction difference of different white the shooting-imaging systems that the chromatic value LED display is formed of research is analyzed comparison;

Carry out four groups of sheet color luminance meters that this need of work has measurement light source look, object color function to have both, need the complete colour atla of colour gamut, need white chromatic value display screen of colored well behaved video camera of reproduction and satisfactory difference;

Measure the cie color parameter of object colour atla primary colors and reproduction look with the PR-1980 color luminance meter; By the u ' that can calculate the object colour atla in the even chromaticity formula of CIE 1976 UCS respectively _o, v ' ₀Value; U ', v ' value are represented the reproduction look of display;

$u^{\′}=\frac{4x}{-2x+12y+3}\·\·\·\·\·\·\·\·\·\left(8\right)$

$v^{\′}=\frac{9y}{-2x+12y+3}$

Can calculate colourity reproduction error by formula (2)

$\mathrm{\ΔC}=\frac{\sqrt{{(u^{\′}-u_o^{\′})}^2+{(v^{\′}-v_o^{\′})}^2}}{0.00384}\·\·\·\·\·\·\·\·\·\left(9\right).$

The invention has the beneficial effects as follows: the measuring method that the present invention relates to a kind of LED display colorimetric parameter; LED display colour gamut coverage rate, white measuring process and the computing method that colourity unevenness, colour reappear are created and stipulated to the characteristics that this method is luminous according to LED display; Accuracy, the raising measurement primary colours predominant wavelength method of accuracy of raising measurement and white chromatic value of debugging and scope have been proposed; LED pipe peak wavelength and LED screen predominant wavelength have been carried out necessary differentiation from scientific concept.Measure the colorimetric parameter of LED display with meeting 1980 color luminance meters that spectral tristimulus value contains four groups of optical filters accurately, comprehensively; By this measuring method; Its accuracy of measurement can reach the highest level of national regulation, promptly reaches the technical requirement to the standard color luminance meter.Use spectral bandwidth and sample interval can accurately measure the peak wavelength of LED pipe as 1980 spectral radiometers of 1nm.Set according to the present invention; In debug process, adopt multiturn potentiometer to replace the fixed resistance in the prior art scheme; To reach the purpose of meticulous selection resistance, these core technologies are debugging and make the indispensable prerequisite of outstanding color rendering LED display with crucial.

Embodiment

Below in conjunction with preferred embodiment, to according to embodiment provided by the invention, details are as follows for characteristic:

1. select suitable surveying instrument and formulate measuring method according to the characteristics of LED display

All evaluations and objective measurement all should be carried out under the distance of implementation space mixed color effect, and the light probe acquisition range must not be less than 16 neighbors in measuring the white chromaticity coordinate of display screen.Because the physical points spacing of various display screens is different with phsyical density, therefore adjustable nitometer of visual field solid angle and color luminance meter should be used, and field angle greatly such as 2 °, 3 ° should be contained, its working range should reach more than several thousand nits.

The spacing of LED screen pixels physical points is much larger than CTT CRT and LCD TV LCD, plasm TV PDP, and the phsyical density of unit plane pixel is much smaller than above-mentioned three.Therefore could produce spacing color mixed effect at a distance.

We can be edified from the general character of adjacent field progress on the one hand, carry out necessary measurement and evaluation based on the characteristic of LED screen again on the one hand, and the quality of colour of LED screen constantly is improved.In order to guarantee enough big survey area, eliminate measuring error, should use the color luminance meter of adjustable visual field solid angle.In same distance down, the different fields of view solid angle has different test area, can satisfy the technical requirement of variety classes display screen, and table one has been listed under 0.1 °, 0.2 °, 1 °, 2 °, field angle the measurement diameter with the relation of tested distance,

Table one (unit: mm dia)

The color luminance meter that contains 2 °, 3 ° big field angle has bigger test area under same measuring distance, help to eliminate the unevenness in the sampling.Point out " degree of accuracy higher brightness meter has the eyepiece modular system; functions such as the visual field solid angle is interchangeable " in China Measuring Press's " photometric measurement technology and instrument " book; Present your CS-100 and some luminance meters such as PR-650 and BM-7 of reaching of display screen industry U.S. commonly used by contrast; Do not have the interchangeable function of visual field solid angle; 1 ° of visual field solid angle is only arranged, bring unnecessary sampling and measure error easily.

2. the spectral response of color luminance meter

Color luminance meter is a most important color measurement instrument in the LED display colour measurement, and the detector after color luminance meter color filter and the photomultiplier combination should be tried one's best and accurately met spectral tristimulus value curve X (λ), Y (λ) and Z (λ).X (λ) has two crest X at short-wave band and long-wave band ₁(λ), X ₂(λ).

Instrument such as the CS-100 and the BM-7 etc. of LED display industry use at present have only three parts on spectral response, can't well simulate X ₁Effect (λ) does not possess calibration function yet, brings the error that can't overcome to measurement.

Select suitable color luminance meter for use, three primary colours degree value X, Y, Z and chromaticity coordinate x, the y that accurately measures LED display is the key of confirming white chromaticity coordinate of LED display and tolerant scope.After measuring the chromaticity coordinate of primary colours,, table look-up and read primary colours predominant wavelength through calculating.

For debugging with produce the LED display of outstanding color rendering, the equipment that the present invention adopts is: four groups of sheet 1980A color intensities that meet the human eye spectral tristimulus value take into account spectral bandwidth and the sample interval is the 1980B spectral radiometer of 1nm.

Color luminance meter is a kind of color measurement instrument the most frequently used in the LED display colour measurement, and the detector after color luminance meter color filter and the photomultiplier combination should be tried one's best and accurately met spectral tristimulus value curve X (λ), Y (λ) and Z (λ).X (λ) has two crest X at short-wave band and long-wave band ₁(λ), X ₂(λ),

Can try to achieve the suitable colour correction factor of 1980A by following formula

$C_1=\frac{x_0}{y_0}\frac{p_0}{(\mathrm{Xr}+\mathrm{Xb})}\·\·\·\·\·\·\·\·\·\left(1\right)$

$C_2=\frac{(1-x_0-y_0)}{y_0}\·\frac{p_0}{z_0}$

Wherein: p ₀, X _r, X _b, z ₀Be four groups of output datas in 1980A measurement standard light source, look source; x ₀, y ₀Be the chromaticity coordinate that same light source, look source are measured by China National Measuring Science Research Inst. of national authority mechanism, formula can be extrapolated white colour correction factor C respectively according to this ₁, C ₂, Red Square colour correction factor C ₁, C ₂, green colour correction factor C ₁, C ₂, blue corresponding colour correction factor C ₁, C ₂

P, x _r, x _b, z is the output data of 1980 color luminance meters actual measurements LED display.When measuring the white field of LED display, red primary field, green primary field, blue fundamental color field respectively with corresponding colour correction factor C ₁, C ₂In the substitution formula:

$x=\frac{(x_r+x_b)c_1}{(x_r+x_b)c_1+p+z{c}_2}\·\·\·\·\·\·\·\·\·\left(2\right)$

$y=\frac{p}{(x_r+x_b)c_1+p+z{c}_2}$

Can obtain and the consistent chromaticity coordinate of national metrological service accuracy, can reach technical requirement fully the standard color luminance meter.Equipment, method and the implementation step of utilization the present invention regulation can accurately be evaluated the primary colours predominant wavelength and the grade of errors of LED display.

After above-mentioned correction, its instrument chromaticity coordinate error can reach country to the technical requirement of standard color luminance meter (color luminance meter branch standard, one-level, secondary, three grades)

Measure the peak wavelength that LED manages like needs, should use spectral bandwidth and sample interval all can be accurate to 1980 spectral radiometers of 1nm.

1980A, 1980B meet above-mentioned requirements; Can realize and China National Measuring Science Research Inst. of state supremacy prestige mechanism dialogue, red, green, blue transmission of quantity value; Have five adjustable field angle simultaneously, have 3 ° of big field angle and be applicable to that LED display need be at the chromatic value of measuring under the large tracts of land collection under the high brightness.

Selecting suitable color luminance meter according to the LED luminescent properties, carry out intensive scientific and technological work, is the key of formulating white chromaticity coordinate of LED and tolerant scope, also is the important prerequisite of measuring and differentiate other photochromic index of LED display.

Measurement contents and concrete steps are:

(1) measurement of LED display colour gamut coverage rate and calculating

The colour gamut coverage rate characterizes the leg-of-mutton area tolerance of the corresponding colour developing of primary colours (R, G, B) institute in the uniform colour space coordinate.

(1.1) definition of colour gamut coverage rate: the CIE1976 uniform color space (u '; V '), and the gamut area that display device shows (be three primary colours R, G; The leg-of-mutton area of B) with the percentage that accounts for (u ', v ') the whole spectrum of chrominance space (from 380-780nm) areas (0.1952).

(1.2) measurement of colour gamut coverage rate

Respectively with full Red Square, full Lv Chang and complete blue test signal input.With red, green, blue screen center's point chromaticity coordinate (u of the color luminance meter difference measurements and calculations that meet above-mentioned requirements _r', v _r'), (u _g', v _g'), (u _b', v _b').

Its accuracy of measurement, degree of accuracy can be synchronous with national level, and the chromaticity coordinate when China National Measuring Science Research Inst. provides respective standard look source can realize that promptly country is to correction factor C red, green, blue field ₁, C ₂Transmission of quantity value.

(1.3) calculating of colour gamut coverage rate

Calculate CIE-1976L by formula ^*, u ^*, v ^*Chromaticity coordinate u ', v ' value

$\left.\begin{array}{c}{u}^{\′}=\frac{4X}{X+15Y+3Z}\\ v^{\′}=\frac{9Y}{X+15Y+3Z}\end{array}\right\}\·\·\·\·\·\·\·\·\·\left(3\right)$

Gamut area=0.5 [(u _r'-u _b') (v _g'-v _b')-(u _g'-u _b') (v _r'-v _b')] ... (4)

Colour gamut coverage rate=gamut area ÷ 0.1952 * 100%;

The colour gamut coverage rate characterizes the leg-of-mutton area tolerance of the corresponding colour developing of primary colours (R, G, B) institute in the uniform colour space coordinate.

The colour gamut coverage rate is that the chromaticity coordinate of three kinds of colors of examination RGB surrounds leg-of-mutton size on chromaticity diagram, and any point color can be synthetic by the RGB three primary colours in triangle, and the color that the big more explanation of area can cover is wide more.

Flat-panel monitor has expanded to LCD, LED, PDP, DLP and other display at present; The luminophor of various displays has nothing in common with each other; And constantly development, should be increased in standard observation position measurement colour gamut coverage rate, with the ability of examination display colour reproduction for this reason.The colour gamut coverage rate leg-of-mutton area of representing to develop the color accounts for the number percent of ligulate area.

(1.4) scope of color monitor Color reproduction

Input end at display adds the monochrome signal suitable with R, G, the B of colour signal, measures in the vertical direction of picture with color luminance meter, and the chromaticity coordinate during with input R signal is decided to be x _R, y _R, the chromaticity coordinate during with input G signal is decided to be x _G, y _G, the chromaticity coordinate during with input B signal is decided to be x _B, y _B, and be depicted on the chromatic diagram, each point is connected with straight line, express the color reproduction scope.By can reproducing color therewith in the triangle scope that straight line surrounded.

We have tested CRT, LCD, LED, DLP, PDP at P ₀The primary colours coordinate of point, and calculated the colour gamut coverage rate respectively.

Table two CRT three primary colours degree coordinate (colour gamut coverage rate=33.2%)

	x 0	y 0	u 0’	v 0’
					R	0.649	0.322	0.466	0.521
G	0.308	0.593	0.130	0.569
					B	0.142	0.071	0.159	0.179

Table three LCD three primary colours degree coordinate (colour gamut coverage rate=32.9%)

	x 0	y 0	u 0’	v 0’
					R	0.634	0.325	0.450	0.519
G	0.286	0.575	0.123	0.556
					B	0.139	0.062	0.161	0.159

Table four DLP three primary colours degree coordinate (colour gamut coverage rate=23.9%)

	x 0	y 0	u 0’	v 0’
					R	0.612	0.318	0.438	0.512
G	0.351	0.545	0.159	0.555
					B	0.146	0.095	0.152	0.222

Table five PDP three primary colours degree coordinate (colour gamut coverage rate=38.45%)

	x 0	y 0	u 0’	v 0’
					R	0.668	0.321	0.484	0.524
G	0.284	0.643	0.112	0.570
					B	0.140	0.062	0.162	0.161

Table six LED three primary colours degree coordinate (colour gamut coverage rate=41%)

	x 0	y 0	u 0’	v 0’
					R	0.709	0.288	0.483	0.441
G	0.177	0.701	0.064	0.571
					B	0.136	0.063	0.157	0.163

Plasma color monitor colour gamut coverage rate is superior to CRT monitor and LCD color monitor.

By finding out in the table, flat-panel monitor will replace the position of CRT in the demonstration field, and colour gamut can not be lower than CRT, and brightness will be higher than CRT.LCD display has had sizable improvement in recent years on the colour gamut coverage rate, the LCD display colour gamut coverage rate that has also is higher than above-mentioned data, and is on a par on this index with CRT; But the DLP color sense is obviously not enough, and bright-coloured inadequately, the colour gamut coverage rate is more much lower than CRT and LCD.

By the table in can find out that the colour gamut coverage rate of LED is superior to various displays, and the red LED light intensity is the highest can be near 10; (common product is greater than 1, and 000mcd), the green LED luminous intensity is the highest can be near 8 for 000mcd; 000mc, blue look LED luminous intensity has also obtained large increase recently.Therefore reach 5,000cd/m for outdoor full-color screen brightness is general equal ²More than.And LCD TV (LCD), plasm TV (PDP) and kinescope TV (CRT) maximum brightness can only reach hundreds of cd/m ², the brightness of DLP is lower.And LED display also has the reliability height, and driving voltage is low, and the life-span is long, and response speed is fast etc.Therefore to be used for outdoor giant-screen be that other display device is incomparable to LED, and the colour gamut coverage rate of LED can reach more than 40%, is higher than above-mentioned various color monitor, has embodied it and has been used for the vitality of backlight and display screen.The colour gamut coverage rate that the different LED pipe is formed can be different, and the measurement through the domain coverage ratio of checking colors can help to be chosen in the outstanding LED pipe of chromatic rendition.

(2) measurement of LED display reference white and colourity unevenness

Measure the P of screen center ₀The point chromaticity coordinate can be represented reference white.Measure the difference of image chroma between screen center and the surrounding edge and represent the colourity unevenness.Measure P ₀To P ₈Chromaticity coordinate be (x ₀, y ₀) (u ' ₀, v ' ₀) to (x ₈, y ₈) (u ' ₈, v ' ₈)

Colour difference by these points of computes

Δx＝x _i-x ₀，Δy＝y _i-y ₀， ………………(5)

Δu’＝u _i’-u ₀’Δv’＝v _i’-v ₀’ ………………(6)

Δc＝[(u‘ _i-u‘ ₀) ²+(v’ _i-v‘ ₀) ²] ^1/2………………(7)

Measurement result is with representing

If predominant wavelength, colour gamut coverage rate depend primarily on LED made and tube-making process, some is the work of preceding two industries; Then white chromatic value of LED screen and tolerance are the work of LED display industry fully.This work need be carried out a large amount of scientific experiments especially, establishes rich scientific and technical basis and reintroduces revision.

White chromaticity coordinates scope in the SJ/T11281-2003 standard

The x coordinate	0.28	0.47	0.37	0.33
					The y coordinate	0.25	0.30	0.33	0.37

Four groups of data existing problems in the table, the basic ellipse that formed does not have any rule yet on the CIE1931 chromatic diagram; And these four groups of data considerably beyond on the chromatic diagram white scope; What form is regional excessive, as making display screen by these four groups of data, can cause the obvious distortion of color, or dimness or colour cast.

By formula

$\left.\begin{array}{c}{u}^{\′}=\frac{4X}{X+15Y+3Z}\\ v^{\′}=\frac{9Y}{X+15Y+3Z}\end{array}\right\}\·\·\·\·\·\·\·\·\·\left(3\right)$

U ' coordinate	0.206	0.333	0.238	0.195
					V ' coordinate	0.414	0.477	0.478	0.492

Or by formula

$\left.\begin{array}{c}u=\frac{4X}{X+15Y+3Z}\\ v=\frac{6Y}{X+15Y+3Z}\end{array}\right\}\·\·\·\·\·\·\·\·\·\left(10\right)$

The u coordinate	0.206	0.333	0.238	0.195
					The v coordinate	0.276	0.318	0.478	0.492

On 1960UCS coordinate system and 1976u ' v ' chromatic diagram, also all formed not the figure of approaching circle.

Though SJ/T11281-2007 revises the apparent error of SJ/T11281-2003, changes 0.27 into 0.47

The x coordinate	0.28	0.27	0.37	0.33
					The y coordinate	0.25	0.30	0.33	0.37

But this of this standard clause requires in practice and in theory still, to have problems, and need carry out after scientific experiment and the scientific and technological work this clause being made revision or being reformulated a national standard " LED display colour measurement method and quality of colour evaluation ".

SJ/T11281-2007 and SJ/T11281-2003 are defined in theory the error of color analyzer and in fact equal existing problems.

(3) measurement of each primary colours predominant wavelength of display screen and peak wavelength

Respectively with full Red Square, full Lv Chang and complete blue test signal input.Measure red, green, blue screen center's point chromaticity coordinate respectively with the color luminance meter that meets above-mentioned requirements.

Its accuracy of measurement, degree of accuracy can be synchronous with national level, and the chromaticity coordinate when China National Measuring Science Research Inst. provides respective standard look source can realize that promptly country is to correction factor C red, green, blue field ₁, C ₂Transmission of quantity value.

We think to need to do the notion of predominant wavelength at this and offer some clarification on: according to the regulation in the colorimetry with a certain spectral color by a certain percentage with a definite sample look that mixes mutually to match with reference to light source, the wavelength of this spectrum colour is exactly the predominant wavelength of sample.

Computing method is according to connecting with reference to light source E (x on the chromatic diagram ₀, y ₀) and sample spot (x, the slope (x-x of straight line y) ₀)/(y-y ₀) and (y-y ₀)/(x-x ₀), by one group of little acquisition of tabling look-up of absolute value.Computing method is more accurate than graphing method, and can be accurate to 1nm.Table look-up and to obtain predominant wavelength, wherein x ₀=y ₀=0.333.

The correct key that obtains predominant wavelength is that correct measurement goes out X1, X2, Y, Z.Should use photomultiplier as receiving device according to the scientific research result that China National Measuring Science Research Inst. obtained, confirm to measure the color luminance meter that tristimulus values should be used four groups of optical filters according to the scientific research result of national television-quality inspection center.

The predominant wavelength (dominant wave length) that requires in the standard to confirm is distinguished with the peak wavelength in the semiconductor material to some extent, and predominant wavelength is psychophysical quantity; Peak wavelength is physical quantity, radiant quantity.Different chip materials sends the light of different wave length, and this is because the energy that free electron discharges when dropping into the lower valence band of energy by the high energy valence band is different.Theory and practice proves that the peak wavelength λ of light that LED sends is relevant with the used semiconductor material energy gap of luminescence chip Eg, i.e. λ ≈ 1240/Eg (nm); Eg unit is an electron-volt (ev) in the formula; Gallium arsenide Eg=1.43ev for example, peak value is in the near-infrared region, and gallium phosphide Eg=2.26ev; Luminescence peak is in the Green Zone; For semiconductor material or their interwoven crystal GaAsP such as GaAs, the corresponding emission wavelength of its energy gap just in time is in the visible region of 380nm～780nm, thereby has opened up wide space with using for the development of LED.When carrying out this work, should use spectral bandwidth and sample interval all can be accurate to the spectral radiometer of 1nm, like 1980B.

(4) measurement of colored reproduction

Because varying with each individual appears in color evaluation sometimes,, when conditions being possessed, can increase the measurement of colored reproduction when hard case that great difference can't be made conclusion occurring;

(4.1) spectral distribution of the common look of measurement large nature is calculated its chromaticity coordinate, represents common look with the complete colour atla of colour gamut;

(4.2) measure the chromaticity coordinates of object with same color luminance meter (avoiding introducing the individual difference between the surveying instrument).

(4.3) measure the chromaticity coordinates that reproduces look on different white the chromatic value LED displays;

(4.4) the colourity error between calculating object and the reproduction look; The colourity reproduction difference of different white the shooting-imaging systems that the chromatic value LED display is formed of research is analyzed comparison.Measurement and the research of carrying out above-mentioned a whole set of colored reproduction will make the ideal chroma of white of display be based upon more on the accurate science basis.The measurement of colored reproduction can be got rid of in the subjective assessment all " subjectivity " factors fully, possesses repeatability, objectivity, accuracy and credibility with the colored reproduction of instrument objective measurement error.

The bright lattice in Germany scientist glycolylurea Vichy (Heinwig Lang) are also pointed out in authoritative works " colorimetry and CTV ": pursuing on the video screen chromaticity coordinate consistent as far as possible with the object chromaticity coordinate is the target that colour reappears.

For the ideal chroma that makes white of LED display is based upon on the more tight scientific basic, we have carried out the measurement of colored reproduction again.

Four groups of sheet color luminance meters that carrying out this need of work has measurement light source look, object color function to have both need the complete colour atla of colour gamut, and white chromatic value display screen of satisfactory difference.Need the well behaved colour TV camera of colored reproduction.

Table seven is listed corresponding white the colorimetric parameter of these two displays.

Table seven color monitor white field chroma data

Colour atla: from Japanese Color Atlar 5510, selected ten colour atlas to represent main colour gamut, table eight has been listed the cie color parameter of measuring ten colour atlas with the PR-1980B color luminance meter.

Table eight is measured the CIE parameter of colour atla with 1980 color luminance meter spectrum radiation gauges

Tested the cie color parameter of ten colour atlas at colour reproduction look with the PR-1980 color luminance meter, table nine has been listed the cie color data of reproduction look on two kinds of white chromatic value displays.

By the u ' that can calculate the object colour atla in the even chromaticity formula of CIE 1976 UCS respectively _o, v ' ₀Value.U ', v ' value are represented the reproduction look of display.

$u^{\′}=\frac{4x}{-2x+12y+3}\·\·\·\·\·\·\·\·\·\left(8\right)$

$v^{\′}=\frac{9y}{-2x+12y+3}$

Can calculate colourity reproduction error by formula (2)

$\mathrm{\ΔC}=\frac{\sqrt{{(u^{\′}-u_o^{\′})}^2+{(v^{\′}-v_o^{\′})}^2}}{0.00384}\·\·\·\·\·\·\·\·\·\left(9\right)$

The first eight look of colour atla in table eight, the table nine is represented the human colour of skin and is master's colour gamut with the common look of indoor scene, and back dichromatism is sky blue and fruit green.

Table nine, measure the colour reproduction error with 1980 color luminance meters

We can find out the data of analytical table nine: the colourity reproduction error delta C=3.894j.n.d that the display that 6500K is white is to the first eight look average, the first eight look average chrominance reproduction error delta C=9.964j.n.d of the display that 9300K is white.Is 5.446j.n.d containing outdoor scenery blue sky, fruit green at interior ten look average chrominance reproduction error 6500K, and 9300K is 11.19j.n.d.By contrast, the display color distortion of white of 9300K is obviously greater than the display of white of 6500K.

Accurately measuring the white chromatic value of display is debugging and the most important science and technology basis of making outstanding color rendering LCD display with other colorimetric parameters, also for the correct LED pipe of selecting experimental basis accurately is provided.Points for attention are following:

1, with the instrument SPECTRA PR1TCHARD PHOTOMETER1980 debugging LED screen model machine that meets the technical requirement of national metrological service.

1.1,1980 receiving device is photomultiplier, (PR650, PR704, BM-7, SR-3A receiving device are CCD).

1.2,1980 contain five field angle, wherein brightness (the Candelas/Meter up to 10,000 nits can be measured in 3 ° of big visual fields ²), BM-52 ° of visual field highest measurement brightness is 1.999 * 10 ³Nit, the highest measurement brightness of 2 ° of visual fields of SR-3A is 3,000 nits.

1980 can test and debug by meeting to surpass under the condition of 16 pixels.

1.3,1980 be four groups of optical filter color luminance meters, meet comrade such as one-tenths grade pointed technical requirement of publishing an article forever of national television-quality inspection center peace.

1.4, through extrapolating C ₁, C ₂Can make 1980 to keep in full accord, carry out national metering transmission satisfactorily with the colour examining result of China metering institute.

2, with the LED display model machine after 1980 debugging common look (or standard rating band) is done evaluation.

2.1, the evaluation of the common look of LED display should carry out (cannot see carrying out at a distance under the red, green, blue color dot condition) under the colour mixture condition of implementation space.

2.2, can to combine the characteristics of LED display industry to make technical work simultaneously with reference to the center of white chromatic value of other color monitor industry screen.

2.3, the tolerant scope of white the chromatic value of LED display should approach ellipse on the CIE1931 chromatic diagram, on CIE1960 even color figure, will approach circle.

2.4, should be noted that colour temperature be very narrow, very the limitation notion, it only can express the color table of heat radiation light source such as incandescent lamp.The color table of nonthermal radiation light source such as fluorescent light, high-pressure mercury lamp and LED should not described with colour temperature; Because their spectral power distribution and blackbody radiation differ greatly; Chromaticity coordinate does not drop on the black body locus, and correlated colour temperature can only be expressed the color of glow discharge spot lamp cursorily.Each point isochrome not can't definitely show its relevant position with the colour temperature one-dimensional data on the experimental result proof isotemperature line on the gamut map plane, should use its position in gamut map of chromaticity coordinate two-dimensional data exact expression.In the time must using colour temperature one speech, should be simultaneously at relevant place dated chromaticity coordinate or and the distance of Planckian locus.

3, also calculate with the predominant wavelength of 1980 test LED displays.

4, also calculate with the colour gamut coverage rate of 1980 test LED displays.

Accomplish above-mentioned work and need use following equipment:

(1) SPECTRA PR1TCHARD PHOTOMETER 1980 color luminance meters;

(2)PHILIPS?PM5539?TV?ANALYSER?MADE?IN?DENMARK；

(3)PM?5519?COLOUR?PATTERN?GENERATOR?MADE?IN?GERMANY；

(4)WHITE?STANDARD?6500K?MURAKAMI?COLOR?RESEARCH?LABORATURY。

What particularly point out is: in debug process, adopt multiturn potentiometer, promptly each corresponding physical points spacing place of LED display circuit is connected with the many circles adjustable potentiometer that is used to carry out the colorimetric parameter debugging respectively by three the tunnel.Wherein, the light emitting diode positive pole links to each other with positive source, and negative pole links to each other with the constant current source chip for driving; The multiturn potentiometer that adopts be metal wire around adjustable potentiometer, an end links to each other with the constant current source chip for driving, an end links to each other with power cathode.Said constant current source chip for driving, an end links to each other with light emitting diode, and an end links to each other with adjustable potentiometer.Three multiturn potentiometers that adjusting is provided with can be controlled the size of constant current source electric current, thereby make the brightness of light emitting diode three primary colours reach white balance.

Above-mentioned detailed description of the measuring method of LED display colorimetric parameter being carried out with reference to embodiment is illustrative rather than determinate, therefore in the variation and the modification that do not break away under the general plotting of the present invention, should belong within protection scope of the present invention.

Claims (1)

1. the measuring method of a LED display colorimetric parameter is characterized in that implementation step is following:

At first selecting measuring equipment is that four groups of sheet 1980A color intensities meeting the human eye spectral tristimulus value are taken into account spectral bandwidth and the sample interval is the 1980B spectral radiometer of 1nm; In debug process, adopt multiturn potentiometer, promptly each corresponding physical points spacing place of LED display circuit is connected with the many circles adjustable potentiometer that is used to carry out the colorimetric parameter debugging respectively by three the tunnel;

Color luminance meter is a kind of color measurement instrument in the LED display colour measurement, and the detector after color luminance meter color filter and the photomultiplier combination will accurately meet spectral tristimulus value curve X (λ), Y (λ) and Z (λ); X (λ) has two crest X at short-wave band and long-wave band ₁(λ), X ₂(λ);

Can try to achieve the suitable colour correction factor of 1980A by following formula

Wherein: p ₀, X _r, X _b, z ₀Be four groups of output datas in 1980A measurement standard light source, look source; x ₀, y ₀Be the chromaticity coordinate of measuring same standard sources, look source, formula can be extrapolated white colour correction factor C respectively according to this ₁, C ₂, Red Square colour correction factor C ₁, C ₂, green colour correction factor C ₁, C ₂, blue corresponding colour correction factor C ₁, C ₂

P, x _r, x _b, z is the output data of 1980 color luminance meters actual measurements LED display; When measuring the white field of LED display, red primary field, green primary field, blue fundamental color field respectively with corresponding colour correction factor C ₁, C ₂In the substitution formula:

Equipment, method and the implementation step of utilization the present invention regulation can accurately be evaluated the primary colours predominant wavelength and the grade of errors of LED display;

Measure the peak wavelength that LED manages like needs, should use spectral bandwidth and sample interval all can be accurate to 1980 spectral radiometers of 1nm;

Measurement contents and concrete steps are:

(1) measurement of LED display colour gamut coverage rate and calculating

The colour gamut coverage rate characterizes primary colours R, G, B in the uniform colour space coordinate, the leg-of-mutton area tolerance of the corresponding colour developing of institute;

(1.1) definition of colour gamut coverage rate: at CIE1976 uniform color space (u ', v '), gamut area that display device shows and the percentage that accounts for (u ', v ') whole spectrum areas of chrominance space;

(1.2) measurement of colour gamut coverage rate

Respectively with full Red Square, full Lv Chang and complete blue test signal input; With red, green, blue screen center's point chromaticity coordinate (u of the color luminance meter difference measurements and calculations that meet above-mentioned requirements _r', v _r'), (u _g', v _g'), (u _b', v _b'); Promptly can realize correction factor C to red, green, blue ₁, C ₂Transmission of quantity value;

(1.3) calculating of colour gamut coverage rate

Calculate CIE-1976L by formula ^*, u ^*, v ^*Chromaticity coordinate u ', v ' value

Gamut area=0.5 [(u _r'-u _b') (v _g'-v _b')-(u _g'-u _b') (v _r'-v _b')] ... (4)

Colour gamut coverage rate=gamut area ÷ 0.1952 * 100%,

The colour gamut coverage rate characterizes the leg-of-mutton area tolerance of the corresponding colour developing of primary colours institute in the uniform colour space coordinate;

The colour gamut coverage rate is that the chromaticity coordinate of three kinds of colors of examination RGB surrounds leg-of-mutton size on chromaticity diagram, and any point color can be synthetic by the RGB three primary colours in triangle, and the color that the big more explanation of area can cover is wide more;

(1.4) scope of color monitor Color reproduction

Input end at display adds the monochrome signal suitable with R, G, the B of colour signal, measures in the vertical direction of picture with color luminance meter, and the chromaticity coordinate during with input R signal is decided to be x _R, y _R, the chromaticity coordinate during with input G signal is decided to be x _G, y _G, the chromaticity coordinate during with input B signal is decided to be x _B, y _B, and be depicted on the chromatic diagram, each point is connected with straight line, express the color reproduction scope; By can reproducing color therewith in the triangle scope that straight line surrounded;

(2) measurement of LED display reference white and colourity unevenness

Measure the P of screen center ₀The point chromaticity coordinate can be represented reference white; Measure the difference of image chroma between screen center and the surrounding edge and represent the colourity unevenness; Measure P ₀To P ₈Chromaticity coordinate be (x ₀, y ₀) (u ' ₀, v ' ₀) to (x ₈, y ₈) (u ' ₈, v ' ₈)

Colour difference by these points of computes

Δx＝x _i-x0，Δy＝y _i-y ₀， ………………(5)

Δu’＝u _i’-u ₀’Δv’＝v _i’-v ₀’ ………………(6)

Δc＝[(u‘ _i-u‘ ₀) ²+(v’ _i-v‘ ₀) ²] ^1/2；………………(7)

(3) measurement of each primary colours predominant wavelength of display screen and peak wavelength

Respectively with full Red Square, full Lv Chang and complete blue test signal input; Measure red, green, blue screen center's point chromaticity coordinate respectively with the color luminance meter that meets above-mentioned requirements;

Promptly can realize correction factor C to red, green, blue ₁, C ₂Transmission of quantity value;

Computing method is according to connecting with reference to light source E (x on the chromatic diagram ₀, y ₀) and sample spot (x, the slope (x-x of straight line y) ₀)/(y-y ₀) and (y-y ₀)/(x-x ₀), by one group of little acquisition of tabling look-up of absolute value, tabling look-up to obtain predominant wavelength; X wherein ₀=y ₀=0.333;

The correct key that obtains predominant wavelength is that correct measurement goes out X1, X2, Y, Z; Should use photomultiplier as receiving device, confirm to measure the color luminance meter that tristimulus values should be used four groups of optical filters;

(4) measurement of colored reproduction

Because varying with each individual appears in color evaluation sometimes,, when conditions being possessed, can increase the measurement of colored reproduction when hard case that great difference can't be made conclusion occurring;

(4.1) spectral distribution of the common look of measurement large nature is calculated its chromaticity coordinate, represents common look with the complete colour atla of colour gamut;

(4.2) measure the chromaticity coordinates of object with same color luminance meter;

(4.3) measure the chromaticity coordinates that reproduces look on different white the chromatic value LED displays;

(4.4) the colourity error between calculating object and the reproduction look; The colourity reproduction difference of different white the shooting-imaging systems that the chromatic value LED display is formed of research is analyzed comparison;

Carry out four groups of sheet color luminance meters that this need of work has measurement light source look, object color function to have both, need the complete colour atla of colour gamut, need white chromatic value display screen of colored well behaved video camera of reproduction and satisfactory difference;

Measure the cie color parameter of object colour atla primary colors and reproduction look with the PR-1980 color luminance meter; By the u ' that can calculate the object colour atla in the even chromaticity formula of CIE 1976 UCS respectively ₀, v ' ₀Value; U ', v ' value are represented the reproduction look of display;

Can calculate colourity reproduction error by formula (2)