如题，我也找到了一个这样的算法（如下），但是与photoshop中的相差甚远
RGB=>Lab
|X| |0.433910 0.376220 0.189860| |R/255|
|Y| = |0.212649 0.715169 0.072182|*|G/255|
|Z| |0.017756 0.109478 0.872915| |B/255|L = 116*Y^1/3 for Y>0.008856
L = 903.3*Y for Y<=0.008856a = 500*(f(X)-f(Y))
b = 200*(f(Y)-f(Z))
其中 f(t)=t^1/3 for t>0.008856
f(t)=7.787*t+16/116 for t<=0.008856
RGB=>Lab
|X| |0.433910 0.376220 0.189860| |R/255|
|Y| = |0.212649 0.715169 0.072182|*|G/255|
|Z| |0.017756 0.109478 0.872915| |B/255|L = 116*Y^1/3 for Y>0.008856
L = 903.3*Y for Y<=0.008856a = 500*(f(X)-f(Y))
b = 200*(f(Y)-f(Z))
其中 f(t)=t^1/3 for t>0.008856
f(t)=7.787*t+16/116 for t<=0.008856
TVector3 = array[1..3] of Double;function LabToRgb(Lab: TVector3): TVector3;
function RgbToLab(Rgb: TVector3): TVector3;implementationtype
TMatrix3 = array[1..3, 1..3] of Double;const
RgbXyz: TMatrix3 = ((1, 0, 0), (0, 1, 0), (0, 0, 1));
XyzRgb: TMatrix3 = ((1, 0, 0), (0, 1, 0), (0, 0, 1)); { CCIR recommended values }
PhosphorX: TVector3 = (0.64, 0.30, 0.15);
PhosphorY: TVector3 = (0.33, 0.60, 0.06);
WhitePoint: TVector3 = (0.95, 1.0000, 1.09);
Gamma: Double = 1 / 0.45;function MultiplyMatrix3ByVector3(const M: TMatrix3;
const V: TVector3): TVector3;
var
I: Integer;
J: Integer;
begin
for I := 1 to 3 do begin
Result[I] := 0.0;
for J := 1 to 3 do
Result[I] := Result[I] + M[I, J] * V[J] end end;function MultiplyMatrix3ByMatrix3(const M1, M2: TMatrix3): TMatrix3;
var
I: Integer;
J: Integer;
K: Integer;
begin
for I := 1 to 3 do
for J := 1 to 3 do begin
Result[I, J] := 0.0;
for K := 1 to 3 do
Result[I, J] := Result[I, J] + M1[I, K] * M2[K, J] end end;function InvertMatrix3(const M: TMatrix3): TMatrix3;
var
I: Integer;
J: Integer;
D: Double; function Next(I: Integer): Integer;
begin
Result := I + 1;
if Result > 3 then
Result := Result - 3 end; function Prev(I: Integer): Integer;
begin
Result := I - 1;
if Result < 1 then
Result := Result + 3 end; begin
D := 0;
for I := 1 to 3 do
D := D + M[1, I] * (M[2, Next(I)] * M[3, Prev(I)] -
M[2, Prev(I)] * M[3, Next(I)]);
FillChar(Result, SizeOf(Result), 0);
for I := 1 to 3
do for J := 1 to 3 do
Result[J, I] := (M[Next(I), Next(J)] * M[Prev(I), Prev(J)] -
M[Next(I), Prev(J)] * M[Prev(I), Next(J)]) / D end;function LabToXyz(const Lab: TVector3): TVector3;
var
LL: Double; function Cube(X: Double): Double;
begin
if X >= (6 / 29) then
Result := X * X * X
else
Result := (108 / 841) * (X - (4 / 29)) end; begin
LL := (Lab[1] + 16) / 116;
Result[1] := WhitePoint[1] * Cube(LL + Lab[2] / 500);
Result[2] := WhitePoint[2] * Cube(LL);
Result[3] := WhitePoint[3] * Cube(LL - Lab[3] / 200) end;function XyzToRgb(const Xyz: TVector3): TVector3;
var
I: Integer;
begin
Result := MultiplyMatrix3ByVector3(XyzRgb, Xyz);
for I := 1 to 3 do
if Result[I] <= 0.0 then
Result[I] := 0
else Result[I] := Exp(Ln(Result[I]) / Gamma) end;function LabToRgb(Lab: TVector3): TVector3;
begin
Result := XyzToRgb(LabToXyz(Lab)) end;function RgbToXyz(const Rgb: TVector3): TVector3;
var
I: Integer;
begin
Result := Rgb;
for I := 1 to 3 do
if Result[I] <= 0.0 then
Result[I] := 0
else Result[I] := Exp(Ln(Result[I]) * Gamma);
Result := MultiplyMatrix3ByVector3(RgbXyz, Result) end;function XyzToLab(const Xyz: TVector3): TVector3;
var
YY: Double; function CubeRoot(X: Double): Double;
begin
if X >= (216 / 24389) then
Result := Exp(Ln(X) / 3)
else
Result := (841 / 108) * X + (4 / 29) end; begin
YY := CubeRoot(Xyz[2] / WhitePoint[2]);
Result[1] := 116 * YY - 16;
Result[2] := 500 * (CubeRoot(Xyz[1] / WhitePoint[1]) - YY);
Result[3] := 200 * (YY - CubeRoot(Xyz[3] / WhitePoint[3])) end;
begin
Result := XyzToLab(RgbToXyz(Rgb)) end;procedure InitTransformationMatrices;
var
I: Integer;
J: Integer;
PhosphorZ: TVector3;
C: TVector3;
CToXyz: TMatrix3;
XyzToC: TMatrix3;
begin
for I := 1 to 3 do begin
CToXyz[1, I] := PhosphorX[I];
CToXyz[2, I] := PhosphorY[I];
CToXyz[3, I] := 1 - PhosphorX[I] - PhosphorY[I] end;
XyzToC := InvertMatrix3(CToXyz);
C := MultiplyMatrix3ByVector3(XyzToC, WhitePoint);
for I := 1 to 3 do
for J := 1 to 3 do
RgbXyz[I, J] := CToXyz[I, J] * C[J];
XyzRgb := InvertMatrix3(RgbXyz) end;initialization
InitTransformationMatrices end.
having the same L value aren't all of the same perceived brightness.
This makes it difficult to do brightness matching. I've put together
some code that uses the CIE's L*,a*,b* system to provide a color
coordinate system that does a much better job of matching the response
of the human visual system.To use the code, take your original RGB value, then divide each value
by 255 so that the resulting numbers range from 0.0 to 1.0. Now feed
these values to the RgbToLab function. This converts the RGB
coordinates to LAB coordinates, where the first coordinate (L) is
scaled from 0 to 100. So now you can modify that L value to change the
brightness of the color, then feed the new LAB values to LabToRgb to
convert back to RGB. Finally, multiply each of the final result values
by 255 and round to the nearest integer.
你说的这个我也试过了，但比那个差得更远，简单算得上离谱
*
* =-----------------------------------------------------------------=
* = ____ _________ =
* = / _ \ \___ __/ =
* = / /_/ / ____ / / =
* = / _ \ ● / _ \ / / =
* = / /_/ // // / / // / =
* = \______//_//_/ /_//_/ =
* = =
* = Copyright (c) BIN Technology studio,2004 =
* = LET'Z BT =
* =-----------------------------------------------------------------=
*
* Author : 周蔚
* Create : 2004-10-14
* LastChange : 2004-10-14 23:40
* History :
*
* Description : RGB=>CIELab
*
********************************************************************}procedure RGB2CIELab(R, G, B: Integer; var L, aa, bb: Integer);
var
X, Y, Z, FL, Fa, Fb: Extended;
begin
X := 0.412453 * R + 0.357580 * G + 0.180423 * B;
Y := 0.212671 * R + 0.715160 * G + 0.072169 * B;
Z := 0.019334 * R + 0.119193 * G + 0.950227 * B;
X := X / 255 / 0.950456;
Y := Y / 255;
Z := Z / 255 / 1.088754;
if Y > 0.008856 then
FL := 116.0 * Power(Y, 1 / 3) - 16
else
FL := 903.3 * Y;
L := Round(FL); if X > 0.008856 then
Fa := Power(X, 1 / 3)
else
Fa := (7.787 * X) + 16 / 116; if Y > 0.008856 then
Fa := Fa - Power(Y, 1 / 3)
else
Fa := Fa - ((7.787 * Y) + 16 / 116); aa := Round(Fa * 500) + 128; if Y > 0.008856 then
Fb := Power(Y, 1 / 3)
else
Fb := (7.787 * Y) + 16 / 116; if Z > 0.008856 then
Fb := Fb - Power(Z, 1 / 3)
else
Fb := Fb - ((7.787 * Z) + 16 / 116); bb := Round(Fb * 200) + 128;
end;
var tmp:single;
begin
tmp:=Y/CieY0;//ciey0=100
result:=iif(tmp>CieK1,116*power(tmp,1/3)-16,
903.3*tmp); //ciek1=8.856E-3 当TEP在0－100之间的时候 cieL=
if result<0 then
result:=0
else if result>100 then
result:=100;
end;
function getCieA(X,Y:single):single;
begin
result:=500*(FX(X)-FY(Y));
if result<-86 then
result:=-86
else if result>100 then
result:=100;
end;function getCieB(Z,Y:single):single;
begin
result:=200*(FY(Y)-FZ(Z));
if result<-108 then
result:=-108
else if result>94 then
result:=94;
end;
function FX(X:single):single;
var tmp:single;
begin
tmp:=X/CieX0; //ciexo=95
result:=iif(tmp>CieK1,power(tmp,1/3),
7.787*tmp+16/116);
end;function FY(Y:single):single;
var tmp:single;
begin
tmp:=Y/CieY0; //ciey0=100
result:=iif(tmp>CieK1,power(tmp,1/3),
7.787*tmp+16/116);
end;function FZ(Z:single):single;
var tmp:single;
begin
tmp:=Z/CieZ0; //ciez0=109
-
result:=iif(tmp>CieK1,power(tmp,1/3),
7.787*tmp+16/116);
end;
你的这个得出的结果和photoshop中的结果也差得很远呀，
To: johnneng(阿能)
你这个是XYZ-->Lab吧，好像也不太对还是多谢两位，还有其它的人有和Photoshop中的结果差不多的算法吗？