C++ Opencv L*a*b*到RGB的转换产生灰度输出
我被指派使用OpenCV将图片从Lab*颜色空间更改为RGB。为了做到这一点,我使用了提供的信息和 编辑:被指定在不使用OpenCV附带的cvtColor函数的情况下进行编辑 还尝试直接从中实现公式。我还是图像处理的新手,不知道我的结果是否有用。我可以看到每个通道,RGB图像的参数介于0和255之间,但在合并通道时,我会获得灰度图像。我希望在从Lab*转换到RGB后,我会得到原始的彩色图像。这正常吗C++ Opencv L*a*b*到RGB的转换产生灰度输出,c++,opencv,rgb,cielab,C++,Opencv,Rgb,Cielab,我被指派使用OpenCV将图片从Lab*颜色空间更改为RGB。为了做到这一点,我使用了提供的信息和 编辑:被指定在不使用OpenCV附带的cvtColor函数的情况下进行编辑 还尝试直接从中实现公式。我还是图像处理的新手,不知道我的结果是否有用。我可以看到每个通道,RGB图像的参数介于0和255之间,但在合并通道时,我会获得灰度图像。我希望在从Lab*转换到RGB后,我会得到原始的彩色图像。这正常吗 Mat image = imread(argv[1], CV_LOAD_IMAGE_UN
Mat image = imread(argv[1], CV_LOAD_IMAGE_UNCHANGED);
Mat labimage = Mat::zeros(image.size(), image.type()); //Matriz para almacenar imagen LAB.
cvtColor(image, labimage, CV_BGR2Lab); //Conversion automatica RGB to lab.
Mat lchannel = Mat::zeros(image.size(), labimage.type()); //Matriz para almacenar canal b.
Mat achannel = Mat::zeros(image.size(), labimage.type()); //Matriz para almacenar canal g.
Mat bchannel = Mat::zeros(image.size(), labimage.type()); //Matriz para almacenar canal r.
Mat bwchannel = Mat::zeros(image.size(), labimage.type()); //Matriz para almacenar canal r.
for(int x = 0;x < cols;x++){
for(int y = 0;y < rows;y++){
lchannel.at<Vec3b>(y,x)[0] = labimage.at<Vec3b>(y,x)[0];
achannel.at<Vec3b>(y,x)[1] = labimage.at<Vec3b>(y,x)[1];
bchannel.at<Vec3b>(y,x)[2] = labimage.at<Vec3b>(y,x)[2];
}
}
Mat color = Mat::zeros(image.size(), labimage.type());
double X, Y, Z, dX, dY, dZ;
double R, G, B;
double L, a, b;
X = Y = Z = dX = dY = dZ = R = G = B = L = a = b = 0;
for(int x = 0;x < cols;x++){
for(int y = 0;y < rows;y++){
L = (double)(lchannel.at<Vec3b>(y,x)[0] / 255.0) * 100.0; //Rango 0 a 100.
a = (double)(achannel.at<Vec3b>(y,x)[1] / 255) * 128; //Rango -128 a 128.
b = (double)(bchannel.at<Vec3b>(y,x)[2] / 255) * 128; //Rango -128 a 128.
// Lab -> normalized XYZ (X,Y,Z are all in 0...1)
Y = L * (1.0/116.0) + 16.0/116.0;
X = a * (1.0/500.0) + Y;
Z = b * (-1.0/200.0) + Y;
X = X > 6.0/29.0 ? X * X * X : X * (108.0/841.0) - 432.0/24389.0;
Y = L > 8.0 ? Y * Y * Y : L * (27.0/24389.0);
Z = Z > 6.0/29.0 ? Z * Z * Z : Z * (108.0/841.0) - 432.0/24389.0;
// normalized XYZ -> linear sRGB (in 0...1)
R = X * (1219569.0/395920.0) + Y * (-608687.0/395920.0) + Z * (-107481.0/197960.0);
G = X * (-80960619.0/87888100.0) + Y * (82435961.0/43944050.0) + Z * (3976797.0/87888100.0);
B = X * (93813.0/1774030.0) + Y * (-180961.0/887015.0) + Z * (107481.0/93370.0);
// linear sRGB -> gamma-compressed sRGB (in 0...1)
R = R > 0.0031308 ? pow(R, 1.0 / 2.4) * 1.055 - 0.055 : R * 12.92;
G = G > 0.0031308 ? pow(G, 1.0 / 2.4) * 1.055 - 0.055 : G * 12.92;
B = B > 0.0031308 ? pow(B, 1.0 / 2.4) * 1.055 - 0.055 : B * 12.92;
//printf("a0: %d\t L0: %d\t b0: %d\n", achannel.at<Vec3b>(y,x)[1], lchannel.at<Vec3b>(y,x)[0], bchannel.at<Vec3b>(y,x)[2]);
//printf("a: %f\t L: %f\t b: %f\n", a, L, b);
//printf("X: %f\t Y: %f\t Z: %f\n", X, Y, Z);
//printf("R: %f\t G: %f\t B: %f\n", R, G, B);
//cout<<"R: "<<R<<" G: "<<G<<" B: "<<B<<endl;
//string str = type2str(color.type());
//cout<<"Matrix type: "<<str<<endl;
color.at<Vec3b>(y,x)[0] = R*255;
color.at<Vec3b>(y,x)[1] = G*255;
color.at<Vec3b>(y,x)[2] = B*255;
}
}
Mat image=imread(argv[1],CV\u LOAD\u image\u未更改);
Mat labimage=Mat::零(image.size(),image.type())//Matriz para almacenar imagen实验室。
cvtColor(图像、labimage、CV_BGR2Lab)//将RGB自动转换为实验室。
Mat lchannel=Mat::zeros(image.size(),labimage.type())//阿尔马塞纳运河b。
Mat achannel=Mat::zeros(image.size(),labimage.type())//阿拉木图运河g。
Mat bchannel=Mat::zeros(image.size(),labimage.type())//阿尔马塞纳运河r。
Mat bwchannel=Mat::零(image.size(),labimage.type())//阿尔马塞纳运河r。
对于(int x=0;x标准化XYZ(X、Y、Z都在0…1中)
Y=L*(1.0/116.0)+16.0/116.0;
X=a*(1.0/500.0)+Y;
Z=b*(-1.0/200.0)+Y;
X=X>6.0/29.0?X*X*X:X*(108.0/841.0)-432.0/24389.0;
Y=L>8.0?Y*Y*Y:L*(27.0/24389.0);
Z=Z>6.0/29.0?Z*Z*Z:Z*(108.0/841.0)-432.0/24389.0;
//标准化XYZ->线性sRGB(在0…1中)
R=X*(1219569.0/395920.0)+Y*(-608687.0/395920.0)+Z*(-107481.0/197960.0);
G=X*(-80960619.0/87888100.0)+Y*(82435961.0/43944050.0)+Z*(3976797.0/87888100.0);
B=X*(93813.0/1774030.0)+Y*(-180961.0/887015.0)+Z*(107481.0/93370.0);
//线性sRGB->伽马压缩sRGB(在0…1中)
R=R>0.0031308?功率(R,1.0/2.4)*1.055-0.055:R*12.92;
G=G>0.0031308?功率(G,1.0/2.4)*1.055-0.055:G*12.92;
B=B>0.0031308?功率(B,1.0/2.4)*1.055-0.055:B*12.92;
//printf(“a0:%d\t L0:%d\t b0:%d\n”,通道在(y,x)[1],通道在(y,x)[0],通道在(y,x)[2]);
//printf(“a:%f\tl:%f\tb:%f\n”,a,L,b);
//printf(“X:%f\t Y:%f\t Z:%f\n”,X,Y,Z);
//printf(“R:%f\t G:%f\t B:%f\n”,R,G,B);
//cout不要滚动你自己的每像素循环,这是非常无效的
改用
(另外,如果我可以这么说的话,我更喜欢to-SO答案…)没关系。我自己设法解决了它,这是一件非常愉快的事情。对于任何感兴趣的人,如果他们和我有过同样的问题,这里是算法和一些代码:
将CIE Lab*转换为XYZ。这是必要的,因为CIE Lab*不是线性颜色空间,因此没有已知的直接转换为RGB
void CIElabtoXYZ(cv::Mat& image, cv::Mat& output){
float WhitePoint[3] = {0.950456, 1, 1.088754};
Mat fX = Mat::zeros(image.size(), CV_32FC1);
Mat fY = Mat::zeros(image.size(), CV_32FC1);
Mat fZ = Mat::zeros(image.size(), CV_32FC1);
Mat invfX = Mat::zeros(image.size(), CV_32FC1);
Mat invfY = Mat::zeros(image.size(), CV_32FC1);
Mat invfZ = Mat::zeros(image.size(), CV_32FC1);
for(int x = 0;x < image.rows;x++){
for(int y = 0;y < image.cols;y++){
fY.at<float>(x,y) = (image.at<Vec3f>(x,y)[0] + 16.0) / 116.0;
fX.at<float>(x,y) = fY.at<float>(x,y) + image.at<Vec3f>(x,y)[1] / 500.0;
fZ.at<float>(x,y) = fY.at<float>(x,y) - image.at<Vec3f>(x,y)[2] / 200.0;
}
}
invf(fX, invfX);
invf(fY, invfY);
invf(fZ, invfZ);
for(int x = 0;x < image.rows;x++){
for(int y = 0;y < image.cols;y++){
output.at<Vec3f>(x,y)[0] = WhitePoint[0] * invfX.at<float>(x,y);
output.at<Vec3f>(x,y)[1] = WhitePoint[1] * invfY.at<float>(x,y);
output.at<Vec3f>(x,y)[2] = WhitePoint[2] * invfZ.at<float>(x,y);
}
}
}
void invf(cv::Mat& input, cv::Mat& output){
for(int x = 0;x < input.rows;x++){
for(int y = 0;y < input.cols;y++){
output.at<float>(x,y) = pow(input.at<float>(x,y), 3);
if(output.at<float>(x,y) < 0.008856){
output.at<float>(x,y) = (input.at<float>(x,y) - 4.0/29.0)*(108.0/841.0);
}
}
}
}
void CIElabtoXYZ(cv::Mat和图像,cv::Mat和输出){
浮点白点[3]={0.950456,1,1.088754};
Mat fX=Mat::zeros(image.size(),CV_32FC1);
Mat fY=Mat::零(image.size(),CV_32FC1);
Mat fZ=Mat::zeros(image.size(),CV_32FC1);
Mat invfX=Mat::零(image.size(),CV_32FC1);
Mat invfY=Mat::零(image.size(),CV_32FC1);
Mat invfZ=Mat::零(image.size(),CV_32FC1);
对于(int x=0;x
将XYZ转换为RGB
void XYZtoRGB(cv::Mat& input, cv::Mat& output){
float data[3][3] = {{3.240479, -1.53715, -0.498535}, {-0.969256, 1.875992, 0.041556}, {0.055648, -0.204043, 1.057311}};
Mat T = Mat(3, 3, CV_32FC1, &data);
Mat R = Mat::zeros(input.size(), CV_32FC1);
Mat G = Mat::zeros(input.size(), CV_32FC1);
Mat B = Mat::zeros(input.size(), CV_32FC1);
for(int x = 0;x < input.rows;x++){
for(int y = 0;y < input.cols;y++){
R.at<float>(x,y) = T.at<float>(0,0)*input.at<Vec3f>(x,y)[0] + T.at<float>(1,0)*input.at<Vec3f>(x,y)[1] + T.at<float>(2,0)*input.at<Vec3f>(x,y)[2];
G.at<float>(x,y) = T.at<float>(0,1)*input.at<Vec3f>(x,y)[0] + T.at<float>(1,1)*input.at<Vec3f>(x,y)[1] + T.at<float>(2,1)*input.at<Vec3f>(x,y)[2];
B.at<float>(x,y) = T.at<float>(0,2)*input.at<Vec3f>(x,y)[0] + T.at<float>(1,2)*input.at<Vec3f>(x,y)[1] + T.at<float>(2,2)*input.at<Vec3f>(x,y)[2];
}
}
//Desaturate and rescale to constrain resulting RGB values to [0,1]
double RminVal, GminVal, BminVal;
double RmaxVal, GmaxVal, BmaxVal;
Point minLoc;
Point maxLoc;
minMaxLoc( R, &RminVal, &RmaxVal, &minLoc, &maxLoc );
minMaxLoc( G, &GminVal, &GmaxVal, &minLoc, &maxLoc );
minMaxLoc( B, &BminVal, &BmaxVal, &minLoc, &maxLoc );
Mat matMin = Mat::zeros(1, 4, CV_32FC1), matMax = Mat::zeros(1, 4, CV_32FC1);
matMin.at<float>(0,0) = RminVal; matMin.at<float>(0,1) = GminVal; matMin.at<float>(0,2) = BminVal; matMin.at<float>(0,3) = 0;
double min, max;
minMaxLoc( matMin, &min, &max, &minLoc, &maxLoc );
float addWhite = -min;
matMax.at<float>(0,0) = RmaxVal + addWhite; matMax.at<float>(0,1) = GmaxVal + addWhite; matMax.at<float>(0,2) = BmaxVal + addWhite; matMax.at<float>(0,3) = 1;
minMaxLoc( matMax, &min, &max, &minLoc, &maxLoc );
float Scale = max;
for(int x = 0;x < input.rows;x++){
for(int y = 0;y < input.cols;y++){
output.at<Vec3f>(x,y)[2] = (R.at<float>(x,y) + addWhite) / Scale;
output.at<Vec3f>(x,y)[1] = (G.at<float>(x,y) + addWhite) / Scale;
output.at<Vec3f>(x,y)[0] = (B.at<float>(x,y) + addWhite) / Scale;
}
}
imshow("Unscaled RGB", output);
}
void XYZtoRGB(cv::Mat和输入,cv::Mat和输出){
浮动数据[3][3]={{3.240479,-1.53715,-0.498535},{-0.969256,1.875992,0.041556},{0.055648,-0.204043,1.057311};
Mat T=Mat(3、3、CV_32FC1和数据);
Mat R=Mat::zeros(input.size(),CV_32FC1);
Mat G=Mat::zeros(input.size(),CV_32FC1);
Mat B=Mat::zeros(input.size(),CV_32FC1);
for(int x=0;x