我目前正在尝试在RGB（红色，绿色，蓝色）色彩空间和Lαβ色彩空间之间转换颜色，基于此paper中的详细信息。
我的困难在于扭转转换过程。当结果与初始RGB Mat不同时。我想我在Mats之间的类型铸件中遗漏了一些东西，但我不知道它是什么！
这是我的代码：
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Mat DetectTrackFace::RGB2LAlphBeta(Mat &src)
{
Mat dest;
Mat L_AlphBeta(src.rows, src.cols, CV_32FC3);
//cvtColor(src,dest,CV_BGR2XYZ);
float X,Y,Z,L,M,S,_L,Alph,Beta;
int R,G,B;
for(int i = 0; i < src.rows; i++)
{
for(int j = 0; j < src.cols; j++)
{
B = src.at<Vec3b>(i, j)[0];
G = src.at<Vec3b>(i, j)[1];
R = src.at<Vec3b>(i, j)[2];
X = ( 0.4124 * R ) + ( 0.3576 * G ) + ( 0.1805 * B);
Y = ( 0.2126 * R ) + ( 0.7152 * G ) + ( 0.0722 * B);
Z = ( 0.0193 * R ) + ( 0.1192 * G ) + ( 0.9505 * B);
L = (0.3897 * X) + (0.6890 * Y) + (-0.0787 * Z);
M = (-0.2298 * X) + (1.1834* Y) + (0.0464 * Z);
S = (0.0000 * X) + (0.0000 * Y) + (1.0000 * Z);
//for handling log
if(L == 0.0000) L=1.0000;
if(M == 0.0000) M = 1.0000;
if( S == 0.0000) S = 1.0000;
//LMS to Lab
_L = (1.0 / sqrt(3.0)) *((1.0000 * log10(L)) + (1.0000 * log10(M)) + (1.0000 * log10(S)));
Alph =(1.0 / sqrt(6.0)) * ((1.0000 * log10(L)) + (1.0000 * log10(M)) + (-2.0000 * log10(S)));
Beta = (1.0 / sqrt(2.0)) * ((1.0000 * log10(L)) + (-1.0000 * log10(M)) + (-0.0000 * log10(S)));
L_AlphBeta.at<Vec3f>(i, j)[0] = _L;
L_AlphBeta.at<Vec3f>(i, j)[1] = Alph;
L_AlphBeta.at<Vec3f>(i, j)[2] = Beta;
}
}
return L_AlphBeta;
}
Mat DetectTrackFace::LAlphBeta2RGB(Mat &src)
{
Mat XYZ(src.rows, src.cols, src.type());
Mat BGR(src.rows, src.cols, CV_8UC3);
float X,Y,Z,L,M,S,_L,Alph,Beta, B,G,R;
for(int i = 0; i < src.rows; i++)
{
for(int j = 0; j < src.cols; j++)
{
_L = src.at<Vec3f>(i, j)[0]*1.7321;
Alph = src.at<Vec3f>(i, j)[1]*2.4495;
Beta = src.at<Vec3f>(i, j)[2]*1.4142;
/*Inv_Transform_logLMS2lab =
0.33333 0.16667 0.50000
0.33333 0.16667 -0.50000
0.33333 -0.33333 0.00000*/
L = (0.33333*_L) + (0.16667 * Alph) + (0.50000 * Beta);
M = (0.33333 * _L) + (0.16667 * Alph) + (-0.50000 * Beta);
S = (0.33333 * _L) + (-0.33333 * Alph) + (0.00000* Beta);
L = pow(10 , L);
if(L == 1) L=0;
M = pow(10 , M);
if(M == 1) M=0;
S = pow(10 , S);
if(S == 1) S=0;
/*Inv_Transform_XYZ2LMS
1.91024 -1.11218 0.20194
0.37094 0.62905 0.00001
0.00000 0.00000 1.00000*/
X = (1.91024 *L ) + (-1.11218 * M ) +(0.20194 * S);
Y = (0.37094 * L ) + (0.62905 * M ) +(0.00001 * S);
Z = (0.00000 * L) + (0.00000 * M ) +(1.00000 * S);
/*Inv_Transform_RGB2XYZ
3.240625 -1.537208 -0.498629
-0.968931 1.875756 0.041518
0.055710 -0.204021 1.056996*/
R = ( 3.240625 * X) + ( -1.537208 * Y) + ( -0.498629 * Z);
G = ( -0.968931 * X) + ( 1.875756 * Y) + ( 0.041518 * Z);
B = ( 0.055710 * X) + ( -0.204021 * Y) + ( 1.056996 * Z);
if(R>255) R = 255;
if(G>255) G = 255;
if(B>255) B = 255;
if(R<0) R = 0;
if(G<0) G = 0;
if(B<0) B = 0;
if(R > 255 || G > 255 || B > 255 || R < 0 || G < 0 || B<0)
cout<<"R = "<<R<<" G = "<<G <<" B = "<<B<<endl;
BGR.at<Vec3b>(i, j)[0] = (uchar)B;
BGR.at<Vec3b>(i, j)[1] = (uchar)G;
BGR.at<Vec3b>(i, j)[2] = (uchar)R;
}
}
//normalize(BGR,BGR, 255, 0, NORM_MINMAX, CV_8UC3 );
return BGR;
}
答案 0 :(得分：0)
此处float函数中有uchar到LAlphBeta2RGB个截断错误：
BGR.at<Vec3b>(i, j)[0] = (uchar)B;
BGR.at<Vec3b>(i, j)[1] = (uchar)G;
BGR.at<Vec3b>(i, j)[2] = (uchar)R;
您可以使用以下方法解决此问题：
BGR(i, j)[0] = uchar(cvRound(B));
BGR(i, j)[1] = uchar(cvRound(G));
BGR(i, j)[2] = uchar(cvRound(R));
但是，您不应该明确地处理转换问题。您可以使用saturate_cast为您处理此问题。您可以将R,G,B变量声明为uchar：
uchar B, G, R;
并执行以下转换：
R = saturate_cast<uchar>((3.240625 * X) + (-1.537208 * Y) + (-0.498629 * Z));
G = saturate_cast<uchar>((-0.968931 * X) + (1.875756 * Y) + (0.041518 * Z));
B = saturate_cast<uchar>((0.055710 * X) + (-0.204021 * Y) + (1.056996 * Z));
然后分配为：
BGR(i, j)[0] = B;
BGR(i, j)[1] = G;
BGR(i, j)[2] = R;
或者完全避免使用R,G,B：
BGR(i, j)[2] = saturate_cast<uchar>((3.240625 * X) + (-1.537208 * Y) + (-0.498629 * Z));
BGR(i, j)[1] = saturate_cast<uchar>((-0.968931 * X) + (1.875756 * Y) + (0.041518 * Z));
BGR(i, j)[0] = saturate_cast<uchar>((0.055710 * X) + (-0.204021 * Y) + (1.056996 * Z));
这里是完整的代码。我冒昧地使用Mat_而不是Mat作为函数参数，以避免使用at<type>()来访问像素值。实际上，您已经假设您的函数输入分别为CV_8UC3和CV_32FC3。
#include <opencv2\opencv.hpp>
#include <iostream>
using namespace std;
using namespace cv;
Mat RGB2LAlphBeta(Mat3b &src)
{
Mat3f L_AlphBeta(src.rows, src.cols);
//cvtColor(src,dest,CV_BGR2XYZ);
float X, Y, Z, L, M, S, _L, Alph, Beta;
int R, G, B;
for (int i = 0; i < src.rows; i++)
{
for (int j = 0; j < src.cols; j++)
{
B = src(i, j)[0];
G = src(i, j)[1];
R = src(i, j)[2];
X = (0.4124 * R) + (0.3576 * G) + (0.1805 * B);
Y = (0.2126 * R) + (0.7152 * G) + (0.0722 * B);
Z = (0.0193 * R) + (0.1192 * G) + (0.9505 * B);
L = (0.3897 * X) + (0.6890 * Y) + (-0.0787 * Z);
M = (-0.2298 * X) + (1.1834* Y) + (0.0464 * Z);
S = (0.0000 * X) + (0.0000 * Y) + (1.0000 * Z);
//for handling log
if (L == 0.0000) L = 1.0000;
if (M == 0.0000) M = 1.0000;
if (S == 0.0000) S = 1.0000;
//LMS to Lab
_L = (1.0 / sqrt(3.0)) *((1.0000 * log10(L)) + (1.0000 * log10(M)) + (1.0000 * log10(S)));
Alph = (1.0 / sqrt(6.0)) * ((1.0000 * log10(L)) + (1.0000 * log10(M)) + (-2.0000 * log10(S)));
Beta = (1.0 / sqrt(2.0)) * ((1.0000 * log10(L)) + (-1.0000 * log10(M)) + (-0.0000 * log10(S)));
L_AlphBeta(i, j)[0] = _L;
L_AlphBeta(i, j)[1] = Alph;
L_AlphBeta(i, j)[2] = Beta;
}
}
return L_AlphBeta;
}
Mat LAlphBeta2RGB(Mat3f &src)
{
Mat3f XYZ(src.rows, src.cols);
Mat3b BGR(src.rows, src.cols);
float X, Y, Z, L, M, S, _L, Alph, Beta;
for (int i = 0; i < src.rows; i++)
{
for (int j = 0; j < src.cols; j++)
{
_L = src(i, j)[0] * 1.7321;
Alph = src(i, j)[1] * 2.4495;
Beta = src(i, j)[2] * 1.4142;
/*Inv_Transform_logLMS2lab =
0.33333 0.16667 0.50000
0.33333 0.16667 -0.50000
0.33333 -0.33333 0.00000*/
L = (0.33333*_L) + (0.16667 * Alph) + (0.50000 * Beta);
M = (0.33333 * _L) + (0.16667 * Alph) + (-0.50000 * Beta);
S = (0.33333 * _L) + (-0.33333 * Alph) + (0.00000* Beta);
L = pow(10, L);
if (L == 1) L = 0;
M = pow(10, M);
if (M == 1) M = 0;
S = pow(10, S);
if (S == 1) S = 0;
/*Inv_Transform_XYZ2LMS
1.91024 -1.11218 0.20194
0.37094 0.62905 0.00001
0.00000 0.00000 1.00000*/
X = (1.91024 *L) + (-1.11218 * M) + (0.20194 * S);
Y = (0.37094 * L) + (0.62905 * M) + (0.00001 * S);
Z = (0.00000 * L) + (0.00000 * M) + (1.00000 * S);
/*Inv_Transform_RGB2XYZ
3.240625 -1.537208 -0.498629
-0.968931 1.875756 0.041518
0.055710 -0.204021 1.056996*/
BGR(i, j)[2] = saturate_cast<uchar>((3.240625 * X) + (-1.537208 * Y) + (-0.498629 * Z));
BGR(i, j)[1] = saturate_cast<uchar>((-0.968931 * X) + (1.875756 * Y) + (0.041518 * Z));
BGR(i, j)[0] = saturate_cast<uchar>((0.055710 * X) + (-0.204021 * Y) + (1.056996 * Z));
}
}
//normalize(BGR,BGR, 255, 0, NORM_MINMAX, CV_8UC3 );
return BGR;
}
int main()
{
Mat3b img = imread("path_to_image");
Mat3f labb = RGB2LAlphBeta(img);
Mat3b rgb = LAlphBeta2RGB(labb);
Mat3b diff;
absdiff(img, rgb, diff);
// Check if all pixels are equals
cout << ((sum(diff) == Scalar(0, 0, 0, 0)) ? "Equals" : "Different");
return 0;
}