色度色座标

1. 輻射束(joule/sec)2. 光束/光通量(lumen)3. 光度(Candela, cd)4. 輝度(cd/m 2)5. 照度(Lux)6. 光束發散度(radlux)7. 反射率(reflectivity)8. 電光源效率(power eff.)七、色度與CIE 色度座標色度座標之測定之測定之測定--發光學術語與基本概念發光光度學常用單位與定義電磁波於單位時間內所傳播的輻射能量(J/sec)或Watt F = KΦ (K為視覺度,其大小依波長而異,其最大值為100, F為光束2.光束/光通量(luminous, 單位:流明Lumen)光源所發出的總光量或單位時間內所通過的光量, 可用照度計加以量測3.光度I (Luminous intensity,單位為燭光Cd, candela)一光源在冇一方向所發出光的強度稱之為光度，假設dω為一微小立體角，其包含的光束為dF，則此光源箭頭方向的光度(I)為I = 光束/立體角= dF/dω所以dF= I dω此立體角內所有方向之光度I 則為I =dF/dω對均勻的點光源而言，，F (lumen) = 4πI (單位為燭光)對均勻的點光源而言其中4π為總立體角各種光源的輝度值(nit)太陽165 x 107月亮26 x 102蠟燭1 x 104藍空8 x 103水銀燈14 x 104日光燈6x 103-1x 104納氣燈(200W) 8 x1044. 輝度L (Brightness, 單位為nit 或nt = cd/m 2或stilb (sb), sb = cd/m 2由一特定的光源發出強度相同時由一特定的光源發出強度相同時，，其發光的面積越大者其發光的面積越大者，，則其輝度值越小越小。

某一截面的輝度L (nit)值，為其該方向的光度值I (cd)，以該截面的視面積A (m 2)除得之值除得之值，，以L 表示L = I (cd)/A (m 2) = nit or cd/m 2or stilb5. 照度E (Illumination Intensity,單位為Lux勒克斯)(Spectra colorimeter)380-780 nm(Lux meter)(color analyzer) 測量輝度值與色度值0.2 –999 cd/m2彩色分析儀彩色分析儀--輝亮度輝亮度((cd/m 2)、對比度對比度、、閃爍閃爍、、色度色度(x,y)(x,y)(x,y)值之測定值之測定Anatomy of Human Eyes1虹膜2角膜玻璃體4 Rods5 Cones 3 視網膜6 水晶體.7 瞳孔視神經Cones(解析度高有色彩分析能力) and rods(感光度高對低照暗輻極敏感)The distribution of cones and rods in the retina and where the retina is most sensitive to light (blue graph).Luminosity response of eyes–yellow-green is brighter or stronger response to eyes, than R and B.視網膜(3 types of cones )Providing high accuracy and the ability to measure absolute color, used in research areaSpectrophotometric method Tristimulus method Human eye Problems with difference betweenindividuals and memory characteristicsSmall size and portability, used for colordifference measurements and QC inspection3 sensors Spectral sensorsChromatic Adaptation（色彩的適應性）Chromatic Adaptation (色彩的適應性)Block diagram of basic components of a spectrophotometerA spectrophotometer is a device used to measure the intensity of radiation absorbed at different wavelengths by looking at the spectral reflectance, transmittance or emission.Inventor: Brace DeWitt; In 1935 Arthur Cobb Hardy received a patent for the spectrophotometer .The spectral luminous efficiency curvesScotopic (low light) vision system V’(λ):Driven by rod cells; unable to differentiate different λ’s; provides no saensation of colorsPhototopic (daytime) vision system V(λ) : Driven by cone cells; can differentiatedifferent λ’s: ctreate sensation of colors 507 nm 555 nm視覺函數V(λ), V’(λ)曲線1942與1951年根據亮年根據亮、、暗適應條件下暗適應條件下，，CIE 對200多位觀察者視覺的測定結果位觀察者視覺的測定結果，，分別推薦了標準的明標準的明視覺視覺(V(λ):峰值555 nm ，光譜光效能最高值K m (λ)=683lm/W )與暗視覺(V’(λ);峰值507 nm ，光譜光效能最高值K m ’(λ)1699=lm/W )函數曲線函數曲線。

函數曲線的標準化與K m (λ)、K m ’(λ)值測定值測定，，在全球光度量測上有了統一的基礎!投影片 1818投影片S1 Steven, 2006/5/8Color perception by eye and brainThe human retina has three kinds of cones. The response of each type of cone asa function of l of the incident light.The sensitivity between 700-800 nm is very low, only 380-700 nm is shown.RGB-cones for the RED -GREEN -BLUE sensitivity alsocalled as theSML-cones for Short, Medium and Long wavelengths.The BLUE sensitivity for the B-cones or the S-conesThe GREEN sensitivity for the G-conesor the M-cones The RED sensitivityfor the R-conesor the L-conesThe human retina has three kinds of cones. The response of eachtype of cone as a function of λof the incident light.440545580xzStandard ObserverIn 1931, the CIE originally defined the standard Observer using a 2o fieldof view,hence the name "2o Standard Observer "In 1964, the CIE defined an additional standard Observer, this time basedupon a 10o field of view and this is referred to as the "10o Supplementary Standard Observer “The 2o standard Observer should be used for viewing angles of 1o to 4oand the 10o supplementary standard Observer should be used for viewingangles of more than 4o.An Observer is a person or thing that observes. The sensitivity of each individual's Eye is slightly different; even for people considered to have "normal color vision", there may be some bias toward red and blue. Also, person's eyesight generally changes with age. Because of these factors, colors will appear differently to each observer.1. The human eyes2. The nature of chroma (色度)3. The standard observers (標準觀查者)4.Color space (色域)-chromaticity diagram/coordinates-color temperature七、色度與CIE 色度座標色度座標之測定之測定-specification and measurements of colors http://home.wanadoo.nl/paulschils/10.02.htmCIE 1931 RGB r10(λ),g10(λ),b10(λ)color matching functions The r10(λ)curve is more than 3 times higher than the others because "red" wavelengths have low luminance and moderate tinting strength, so more of the R primary must be used to match the high luminance of the G primary and the high tinting strength of the B primary.Color-matching functions of the CIEStandard Observer based on matchingstimuli of wavelengths700.0 (R), 546.1(G), and 435.8 (B) nm.R G BC R G B≡()+()+()R G B+≡(520 nm)()()+()C R G BR G BC R G B≡−()+()+()were the spectral response curves for the cone-receptors in the human eye . While it is convenient to think of X, Y and Z as red, green and blue, owing to their wide band and substantial overlap (especially of X and Y),this is a crude approximation. XYZ –tristimulus values; x, y, z : tristimulus response of RGBCIE 1931 XYZ standard Color matching functionsfor 2°observerX,zSo the 3 "primary" colors are the virtual colors A, B, and C. Then for a given real color, its components with respect to theprimaries are as follows:x = A/(A+B+C)y = B/(A+B+C)z = C/(A+B+C)Since x + y + z = 1, if x and y are known then z can be determined. The CIE diagram is a plot of x vs. y for all visible colorsCIE Chromaticity Diagram (色品圖色品圖；；色度座標圖)This is an international standard for primary colors established in 1931. It allows all other colors to be defined as weighted sum of the three "primary" colors. 1)There are no real three colors that can be combined to give all possible colors . 2) Therefore, the standard "primary" colors established by CIE don't correspond to real colors.The CIE Color Space•The CIE system characterizescolors by a luminanceparameter Y and two colorcoordinates x and y whichspecify the point on thechromaticity diagram.•the parameters are based onthe spectral powerdistribution of the lightemitted from a colored objectand are factored by sensitivitycurves which have beenmeasured for the human eye.CIE-1931 Chromaticity Coordinates as the Cartesian Coordinates used to define color in the CIE color space. They are designated as x, y and z and are the ratios of each of the tristimulus values X,Y and Z in relation to the sum of the three.z = 1 -( x + y )CIE-1976U.C.S. CHROMATICITY DIAGRAMCIE-1976 Chromaticity Coordinates used to define color in the CIE color space. They are designated as u' and v'u’= u-u o v’= v-v oCIE 色度座標圖飽和度色調CIE(Commission Internationale de l'Éclairage )Additive mixingMixing of Colors of lightMixing paint pigmentsSight of human EyesMixing of Colors of pigmentsMAGENTA, YELLOW and CYAN pigment of proper intensities are known as ”The Subtractive Primary Colors ”.Simple subtractive mixingAdditive color mixtures are always lighter than any of the individual components!Subtractive color mixtures are always darker than the components separately.Additive mixing Simple subtractive mixingApproximate color regions on CIE chromaticity diagram (after Fortner, P. 5, Scien Tech J. 1996)The boundary represents maximum saturation for the spectral colors, and the diagram forms the boundary of all perceivable hues (色調).The C.I.E. Chromaticity DiagramY 2SiO 5Y 2SiO 5YAGYAGYAGP22 CRT phosphors ZnS:Ag (blue)(Zn,Cd)S:Ag (green)Y 2O 3:Eu 3+(red)The boundary of x, y diagram is bounded by the values of monochromatic light, any color in terms of (x, y)Tristimulus Fuilters Used in Defining ColorsThe energy of any spectral curve:E R= Σ(Idλ)R E G= Σ(Idλ)G E B= Σ(Idλ)B1. Take the spectral curves.2. Multiplying by the overlap of each tristimulus curve.3. We obtain Tristimulus Values.x, y, z are the stimulus response of red, green, and blue；而X, Y, Z則稱之為tristimulus valuesBecause each color gives a set of tristimulus values 但each set之間並未有相互correlation因為I R≠I G≠I B (RGB spectral energy are not equal)因此有必要將三刺激值tristimulus values (XYZ) normalized，並且定義一套chromaticity coordinates (x, y, z) Chromaticity coordinates x, y, z 可以定義為x = X/(X+Y+Z) y= Y/(X+Y+Z) z = Z/(X+Y+Z)其中x + y + z= 1(x, y, z) 稱之為色(度)座標(chromaticity coordinates)1) Obtain emission spectrum (利用spectrofluorimeter)Measuring Emissive Colors 之過程(如何將光譜轉換成色度座標如何將光譜轉換成色度座標??)2) 利用energy of RGB spectral curve:E R = Σ(Id λ)R E G = Σ(Id λ)G E B = Σ(Id λ)B等公式等公式，，將(Id λ)積分積分，，以獲得RGB 三原色色光之能量3) 因為X = x ΣI R d λY = y ΣI G d λI B d λ故可以利用求取求取((x,y )值上述x, y, and z 為the stimulus response of red, green, and bluex = y = z = X + Y + Z X + Y + Z X + Y + Z XY Z4) Draw vertical lines on each color function to obtain “weighted functions”to calculate chromaticity coordinatesx: 550-650 nm y: 510-600 nm z: 420-480 nmOne would have a set of lines whose spacing was inversely proportional to peak height.標準光源C Daylight.The northern skylight at 11:30a.m. at Greenwich, England on Oct. 31, 1931.Values Related to Color SpecificationComparison of Energy Distribution of Different Light SourcesD 65An approximation of noon sunlight having a correlated color temperature of approximately 4874 K and obtained by a combination Light Source (A) and a special filter.Light source C Light source ALight source B 2856 K6774 K 6504 K。