色彩标准转换-Color-SPACE.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Light source:,角度,(,),輝度,(cd/m),色温度,(K),0,150,000,5,600,60,125,000,5,100,70.5,100,000,4,700,75.5,80,000,4,400,78.5,65,000,4,100,Sunlight,Sunlight spectrum,Relative spectral power distribution curves of daylight typical of various weather condi-tions as received on a nearly vertical surface facing towards the sun.O:overcast;C:clear;LC:light cloud;H:hazy(Condit and Grum,1964).,Relative spectral power distribution curves of daylight with clear sky for various solar altitudes,as received on a nearly vertical surface facing towards the sun(Condit and Grum,1964).,CIE Standard Illuminants,Illuminant,X,Y,Z,Wx,Wy,A,109.85,100,35.58,0.448,0.407,B,99.09,100,85.31,0.348,0.352,C,98.07,100,118.23,0.310,0.316,D50,96.42,100,82.49,0.346,0.359,D55,95.68,100,92.14,0.332,0.347,D65,95.04,100,108.89,0.313,0.329,D75,94.96,100,122.61,0.299,0.315,E,0.333,0.333,CIE Standard Illuminants spectrum,Light source:,fluorescent lamp,Light source:,Flash Light,Source,Kelvins,Mireds,Typical north-sky light,7500,133,Typical average daylight,6500,154,Artificial Daylight fluorescent lamps (*1),6500,154,Xenon(electronic flash or continuous),6000,167,Typical sunlight plus skylight5500,182,Blue flash-bulbs,5500,182,Carbon arc(for projectors),5000,200,Sunlight at solar altitude 20,4700,213,Cool White fluorescent lamps (*2),4300,233,Sunlight at solar altitude 10,4000,250,Clear flash-bulbs,3800,263,White fluorescent lamps (*3),3500,286,Photo-flood tungsten lamps,3400,294,Tungsten-halogen lamps,3300,303,Projection tungsten lamps,3200,312,Studio tungsten lamps,3200,312,Warm White fluorescent lamps,3000,333,Floodlighting tungsten lamps,3000,333,Domestic tungsten lamps(100 to 200 W.),2900,345,Domestic tungsten lamps(40 to 60 W.),2800,357,Sunlight at sunset,2000,500,Candle flame,1900,526,*1 Sometimes called North-light or Colour Matching lamps,*2 Sometimes called Daylight lamps,*3 Sometimes called Natural lamps,Correlated colour temperatures of,Commercial Lights,Color model,Munsell,RGB(Red,Green,Blue)based,CMY(K)(Cyan,Magenta,Yellow,Black)based,Luminance-Chrominance based,Munsell,Hue_Value/Chroma,RGB/CMY color,*,Red,Green,and Blue,Black,(0,0,0),Cyan,(0,1,1),Green,(0,1,0),Yellow,(1,1,0),Red,(1,0,0),Magenta,(1,0,1),Blue,(0,0,1),White,(1,1,1),One of the simplest color models.Cartesian coordinates for each color;an axis is each assigned to the three primary colors red(R),green(G),and blue(B).,Corresponds to the principles of additive colors.,Other colors are represented as an additive mix of R,G,and B.,Ideal for use in computers.,RGB Image Data,Red Channel,Green Channel,Full Color Image,Blue Channel,CMY Image Data,Cyan Image(1-R),Magenta Image(1-G),Yellow Image(1B),Full Color Image,Color Matching Experiment,Color matching experimental setup,Test Light,Tristimulus values,Primary,Mixture,Observer views a split screen of pure white(100%reflectance).,On one half,a test lamp casts a pure spectral color on the screen.,On the other,three lamps emitting variable amounts of red,green,and blue light are adjusted to match the color of the test light.,The amounts of red,green and blue light used to match the pure colors were recorded when an identical match was obtained.,The RGB tristimulus values for each distinct color was obtained this way.,700(RO),546.1(GO),and 435.8 nm(BO),with units such that equal amounts of the three stimuli are required to match light from the equi-energy illuminant Se,CIE 1931 Standard Observer(r,g,b),The following color matching functions were obtained.,There were problems with the r,g,b color matching functions.,Negative values meant that the color had to be added to the test light before the two halves could be balanced.,380,480,580,680,780,Wavelength(nm),Tristimulus values,0.3,0.2,0.1,0.0,-0.1,0.4,r,g,b,1931 standard observer(2,observer).,*CIE:,Commission Internationale de lEclairage,Color-matching function,for 1931 Standard Observer:spectrum with primaries of Bo=435.8nm,Go=546.1 nm,and Ro=700 nm,each wavelength of the equal energy,the average of 17 color-normal observers having matched on a bipartite 2 field,surrounded by darkness.,Special properties of X,Y,Z:-Imaginary(non-physical)primary.,All luminance information is contributed by Y.Linearly related to R,G,B.Non-negative values for all tristimulus values.,The positions of the matching stimuli X,Y,and Z in the Standard Observer colour triangle Ro Go Bo,380,480,580,680,780,Wavelength(nm),2.0,1.5,1.0,0.5,0.0,Tristimulus values,z,x,y,1931 standard observer(2,observer).,Standard Observer,:,2,vs,10,in xy,The colour-matching functions for the CIE matching stimuli X,Y,and Z.Full lines:for the 2 Standard Observer,using X,Y,Z;,broken lines:for the 10 Standard Observer,using X10,Y10,Z10.,The x,y triangle for the 2 Standard Observer(full line)and,for the 10 Standard Observer(broken line)using x10,y10.,Comparison of the results for the 2 and 10 field-size measurements showed that signific-ant differences did occur between them,and 10 Standard Observer data have been adopted for use when large field sizes(greater than 4)are involved(CIE,1960 and 1964).However,in colour reproductions,the interest generally lies much more in patches of colour of about 2 angular size than 10,and the 1931 CIE data may therefore be used with confidence.,CIE 1931,xyY,Chromaticity Diagram,Each point on,xy,corresponds to many points in the original 3D CIE XYZ space.,Color is usually described by,xyY,coordinates,where Y is the luminance,or lightness component of color.,Y,starts at 0 from the,white spot,(D65)on the,xy,plane,and extends perpendicularly to 100.,As the,Y,increases,the colors become lighter,and the range of colors,or gamut,decreases.,2,D projection of 3D CIE XYZ color space onto X+Y+Z=1 plane.,The chromaticity of a color is determined by(,x,y,).,Inadequacies in the,xy,Chromaticity Diagram,Each line in the diagram represents a color difference of equal proportion.,The lines vary in length,sometimes greatly,depending on what part of the diagram theyre in.,The differences in line length indicates the amount of distortion between parts of the diagram.,Visually equal chromaticity steps at constant luminance on the CIE x,y&CIE u v triangle,CIE1931 xy vs CIE1964 uv,CIE 1964,u,v,Chromaticity Diagram,To correct for the deformities in the 1931 xy diagram,a number of uniform chromaticity scale(UCS)diagrams were proposed.,The following formula transforms the XYZ values or x,y coordinates to a set of u,v values,which present a visually more accurate 2D model.,CIE 1976,u,v,Chromaticity Diagram,But the 1964,uv,diagram was still unsatisfactory.,In 1975,CIE modified the,u,v,diagram and by supplying new(,u,v,)values.This was done by multiplying the,v,values by 1.5.,Thus in the new diagram,u,=,u,and,v,=1.5,v,.,The following formulas allow transformation between,uv,and,xy,coordinates.,Each line in the diagram represents a color difference of equal proportion.,While the representation is not perfect(it can never be),the,u,v,diagram offers a much better visual uniformity than the,xy,diagram.,CIE1976 L*u*v*Color Space,Replaces uniform lightness scale Y with L*,an visually linear scale.,Equations are as follows:where u,n,and v,n,refer the the reference white light or light source.,the lightness or grayscale axis(L*):from 0(black)to 100(white).,a-a axis:+a values indicate amounts of red,-a values indicate amounts of green.,b-b axis,+b indicates amounts of yellow;-b values indicates amounts of blue.,For both two color axes(a*,b*)axes to specify a color,zero is neutral gray,Color difference,E*,ab,is between two points,+a,-a,-b,+b,100,0,L*,CIE L*a*b*color axes,(L,1,*,a,1,*,b,1,*),(L,2,*,a,2,*,b,2,*),Xn,Yn,Zn:Reference White,CIE 1976 L*a*b*Color Space,CIE1976 L*u*v*vs,L*a*b*,Color transfer function:,The chromaticities of Planckian radiators,The series D40 to D250 refers to the CIE standard D illuminants having correlated,colour temperatures from 4000 K to 25 000 K.,black body locus,Color Temperature(Tcp),A black body(perfect radiant body)is an ideal object that absorbs all energy,changes its color from red through yellow to white as its temperature increases.,the relationship between the temperature and color by a locus,Color Space Models,CCIR:Comite Consultatif International des Radiocommunications,brightness,-the human sensation by which an area exhibits more or less light.,lightness,-the sensation of an areas brightness relative to a reference white in the scene.,luma,-Luminance component corrected by a gamma function and often noted Y.,chroma,-the colorfulness of an area relative to the brightness of a reference white.,saturation,-the colorfulness of an area relative to its brightness.,29,29,RGB Gray Scale Transformations,The luminancy component,Y,of each color is summed to create the gray scale value.,ITU-R Rec.601-1*Gray scale:Y=0.299R+0.587G+0.114B,ITU-R Rec.709 D65 Gray scale Y=0.2126R+0.7152G+0.0722B,ITU standard D65 Gray scale(Very close to Rec 709)Y=0.222R+0.707G+0.071B,*.ITU:International Telecommunication Union,*,601-1:Based on an old television(NTSC)standard,*709:Based on High Definition TV colorimetric(Contemporary CRT phosphors),Comparison with color gamuts,X,=,0.4124,0.3576,0.1805,R,Y,0.2126,0.7152,0.0722,G,Z,0.0193,0.1192,0.9505,B,R,=,3.2410,-1.5374,-0.4986,X,G,-0.9692,1.8760,0.0416,Y,B,0.0556,-0.2040,1.0570,Z,Use the following matrices to transform between,CIE XYZ and Rec.709 RGB(with its D65 white).,sRGB :CIE XYZ,D65,-RGB,Rec.709,Use the following matrices to transform between,CIE XYZ and Rec.601-1 RGB(with its C white).,X,=,0.6067,0.1736,0.2001,R,Y,0.2988,0.5868,0.1144,G,Z,0.0000,0.0661,11149,B,R,=,1.9105,-0.5326,-0.2883,X,G,-0.9843,1.9985,-0.0283,Y,B,0.0584,-0.1185,0.8986,Z,NTSC :CIE XYZ,C,-RGB,Rec.601-1,Von Kries adaptation,Light Color Temperature transfer:,XYZ,D65,-XYZ,D50,Transformations,If the illuminant is changed from D50 to D65,the observed color will also change.,The following matrices enable transformations between XYZ,D65,and XYZ,D50,.,ITU-R:Y Cb Cr,Y =0255,Ey=0.299R+0.587G+0.114B,Cb=0255,Ecb=0.564(B-Ey)=-0.169R-0.331G+0.500B,Cr=0255,Ecr=0.713(R-Ey)=0.500R-0.419G-0.081B,Y,=,0.2990,0.5870,0.1140,R,+,0,Cb,-0.1687,-0.3313,0.5000,G,128,Cr,0.5000,-0.4187,-0.0813,B,128,R1.0000,0.0000,1.4020,Y,-,0,G,1.0000,-0.3441,-0.7141,Cb,128,B,1.0000,1.7720,0.0000,Cr,128,Adobe(24-bit):CIE XYZ,D65,-RGB,Adobe,ICC profiles,Color Management:,Color matching via ICC profiles,www.color.org,*,ICC:International Color Consortium,Wide Gamut Color Space,HDMI color,Deep Color,xvYCC color space:,1.Deep color:30-bit/36-bit/48-bit,2.Wide color gamut:,sYCC standard(IEC 61966-2-1),xvYCC standard(IEC 61966-2-4),sYCC:CIE XYZ-RGB,sYCC,xvYCC standard(IEC 61966-2-4),January 2006,expands the color gamut by introducing negative color signal values for these video signals.,This standard encompasses xvYCC709,which is upwardly compatible with the B7.709 standard,and xvYCC601,which is upwardly compatible with BT.601.,The chromaticity coordinates of RGB primary colors and the reference white(D65)are the same as for the existing BT.709 standard.,The opto-electric transfer characteristics of signals not less than 0 and not greater than 1 are defined using the same formula as for BT.709,and signals above 1 are also defined using the same formula.Signals below 0 are defined to produce a transfer curve with origin symmetry.,The conversion matrix from RGB(color signals)to YCC(luminance/color-difference signals)for xvYCC709 is the same as for BT.709,and that for xvYCC601 is the same as for BT.601.,With 8-bit quantization of luminance and color-difference signals,definition formula are set and the color gamut is expanded by using values between 1 and 15 and between 241 and 254 as picture signals.,Definitions over 8 bits are also used to support precise gradation.,Chromaticity coordinate of RGB primary colors and reference white:Unchanged RGB(ITU-R BT.709)+white point(D65),Opto-electric transfer characteristics:existing definitions extendedtransfer curve defined in ITU-R BT.709 extended beyond range(same within 0-1 range),xvYCC Color Space,3,原色擴展演算,:,從,12bit(4081,階調,),中自動選擇最佳的,8bit(256,階調,),輸出，提供正確的,gamma,校正,Wide Gamut Design,RGB-YCC conversion matrix:Unchanged SD:ITU-R BT.601 matrix usedHD:ITU-R BT.709 matrix used,Quantization:Unchanged,Defined over 8 bitsFollowing formulae used for 8 bits YxvYCC(8)=219 x Y+16CbxvYCC(8)=224 x Cb+128 CrxvYCC(8)=224 x Cr+128,Colour Compensating Filters,Kodak Colour Compensating Filters required to correct the colour of various phases of daylight for colour photography.,*B:Sun behind camera.C:Sun in front of camera,Weather,Sunny,Sunny,CloudyCloudy,Direction,B,C,B,C,Solar altitude,10,15,20B+,5C,None,10B+,5C,5B+,5C,15,20,10B,“,10B,5C,20,30,5B,5Y,5B,None,30,40,None,10Y,None,“,40,50,“,10Y,“,“,50,60,“,15Y,“,5Y,CIE:,Commission Internationale de lEclairage,CIE,是,International Commission on Illumination,的简称，中文名称是“国际照明委员会”（,CIE,源于法语,Commission Internationale de lEclairage,），它成立于,1913,年是一个国际非盈利性组织，它主要致力于关于光源的科学技术与艺术的国际间的信息交流与合作。它的任务是：为各成员国提供关于光源和照明的国际论坛；在光源和照明领域开发基本的标准和度量程序；为开发关于光源的国际国家标准及其应用提供帮助；发布标准、报告和其它出版物；和其它相关的国家组织保持联系和技术交流。,CIE,分为八个分部，各种技术活动是在各个分部中展开，这八个分部为视觉和颜色、光线和辐射的测量、内部环境和照明设计、传输交通中的照明和信号、外部照明及其它应用、光源的外貌（,1999,年撤销）、图像技术。在各分部内，根据具体的技术问题，还成立了技术委员会，比如在第一分部（视觉和颜色）成立了,TC1-55,，主要研究“用于工业色差评价的均匀颜色空间”（,Uniform Colour Space for Industrial Colour Difference Evaluation,）。,www.cie.co.at/,CIE 1931 RGB,真实三原色表色系统,混色系统是基于三原色光能混出的色彩所归纳的系统。,理论根据：任何色彩都可以由色光三原色混合而成。,转盘实验,:,特点：简单快捷，精度低；属于视觉器官外的颜色混合，属先后混合；多用于颜色匹配的示意。,色光匹配实验,:,特点：,精度高；属于视觉器官内的颜色混合，属同时混合；,CIE,-XYZ,1931,匹配光谱三刺激值的,(X),、,(Y),、,(Z),的数量，称为,“,CIE 1931,标准色度观察者光谱三刺激值,”,，也叫做,“,CIEl931,标准色度观察者颜色匹配函数,”,。,规定函数,与明视觉光谱光效率函,V(),一致，即,三原色匹配光谱色的,匹配颜色,实验,吉尔德,:,红,(,630nm,),绿,(,542nm,),蓝,(,460nm,),由,7,名观察者作颜色实验，,以三原色色光匹配色温为,4800K,的白光为条件,莱特,:,红,(,650nm,),绿,(,530nm,),蓝,(,460nm,),由,10,名观察者在,2,视场,莱特,(,1928,1929,),规定：,相等数量的红和绿刺激匹配，获得,582.5nm,的黄色，,相等数量的蓝和绿刺激匹配，获得,494.0nm,的蓝绿色。,为匹配,460,530nm,的光谱色，原色红的刺激值是负值，说明必须将少量的红加到光谱色一侧，以降低光谱色的饱和度，才能使原色绿和蓝的混合色与之匹配。,在,510nm,处，原色红的负值最大。,CIE1931XYZ,使光谱三刺激值,R,、,G,、,B,和色度坐标,r,、,g,、,b,均变为正值。,CIE,三原色匹配光谱,红、绿、蓝三原色的波长分别为,700nm,、,546.1nm,、,435.8nm,，,当这三原色光的相对亮度比例为,1.0000,：,4.5907,：,0.0601,时就能匹配出等能白光，,所以,CIE,选取这一比例作为红、绿、蓝三原色的单位量，即,(R):(G):(B)=1:1:1,。,尽管这时三原色的亮度值并不等，但,CIE,却把每一原色的亮度值作为一个单位看待，,所以色光加色法中红、绿、蓝三原色光等比例混合结果为白光，即,（,R,）,+,（,G,）,+,（,B,）,=,（,W,）,。,CIE,三原色匹配光谱色的,匹配颜色,实验,0.00000,0.20317,0.03914,0.00000,0.00410,700,0.00549,-0.07101,530,0.14494,-0.04939,480,光谱三刺激值,入,(mm),等能光谱色,C(),CIE 1931,xy,Chromaticity Diagram,For color C,where,C,0.5,X,+,0.4,Y+,0.1,Z,Color C is represented as(0.5,0.4)on the Chromaticity diagram.,(0.5,0.4),CIE 1964 XYZ,(,10,视场,),人眼观察物体细节时的分辨力与观察时视场的大小有关。,人眼对色彩的分辨力也受视场大小的影响。,实验表明：人眼用小视场（,4,）观察颜色时辨别差异的能力较低，,当观察视场从,2,增大至,10,时，颜色匹配的精度和辨别色差的能力都有增高；,但视场再进一步增大时，则颜色匹配的精度提高就不大了。,1931CIE XYZ,系统是在,2,视场下实验的结果。因此，只适用于,4,的视场范围。,1964,年,CIE,又补充规定了一种,10,视场的表色系统，称为,“,CIE1964,补充色度学系统,”,。,这两种系统中的三刺激值和色度坐标的概念完全相似，只是数值不同。,CIE1931(,2,)vs CIE1964(,10,),视场,三刺激值曲线,视场,xy,色度坐标图,CIE 1931,xy,Y,色度图,颜色三角形中心,E,处是等能白光，又三原色各,1/3,产生，其色度坐标为：,x=0.33,，,y=0.33,，,z=0.33,。,