RGB to HSI、CMYK的代码实现

前言：

在之前博文的基础上，我使用OpenCV2实现了RGB颜色空间向HIS、CMYK转换的代码。下列链接为各种经典颜色空间的介绍及转换公式的介绍。

http://blog.csdn.net/solomon1558/article/details/43772147

1. RGB to HIS

HSI与RGB颜色空间可以进行相互转换。RGB转换到HSI 的计算公式如下：首先给定RGB颜色空间的值(R,G,B),其中R,G,B∈[ 0,2 5 5]，则转换到HSI  空间的(H,S,I)值的计算如下：设将(R ,G ,B)归一化得(R',G',B')为：

int rgb2hsi(Mat &image,Mat &hsi){

if(!image.data){

cout<

return -1;

}

int nl = image.rows;

int nc = image.cols;

if(image.isContinuous()){

nc = nc*nl;

nl = 1;

}

for(int i = 0;i < nl;i++){

uchar *src = image.ptr(i);

uchar *dst = hsi.ptr(i);

for(int j = 0;j < nc;j++){

float b = src[j*3]/255.0;

float g = src[j*3+1]/255.0;

float r = src[j*3+2]/255.0;

float num = (float)(0.5*((r-g)+(r-b)));

float den = (float)sqrt((r-g)*(r-g)+(r-b)*(g-b));

float H,S,I;

if(den == 0){//分母不能为0

H = 0;

}

else{

double theta = acos(num/den);

if(b <= g)

H = theta/(PI*2);

else

H = (2*PI - theta)/(2*PI);

}

double minRGB = min(min(r,g),b);

den = r+g+b;

if(den == 0)//分母不能为0

S = 0;

else

S = 1 - 3*minRGB/den;

I = den/3.0;

//将S分量和H分量都扩充到[0,255]区间以便于显示;

//一般H分量在[0,2pi]之间，S在[0,1]之间

dst[3*j] = H*255;

dst[3*j+1] = S*255;

dst[3*j+2] = I*255;

}

}

return 0;

}

【注】：

程序中将S分量和H分量都扩充到[0,255]区间以便于显示;

一般H分量在[0,2pi]之间，S在[0,1]之间。

2.   RGB to CMYK

给定RGB颜色空间的值(R,G,B)，其中R,G ,B∈ [0, 2 5 5]，则转换到CMYK 空间的(C,M,Y,K)值的计算如下：

【注】式中，maxG是每个矢量分量的最大允许值(255)；C , M , Y , K ∈ [ 0,255]。

int rgb2cmyk( Mat &image,Mat &cmyk){

if(!image.data){

cout<

return -1;

}

int nl = image.rows;//行数

int nc = image.cols;//列数

if(image.isContinuous()){//没有额外的填补像素

nc = nc*nl;

nl = 1;//It is now a 1D array

}

//对于连续图像，本循环只执行1次

for(int i=0;i

uchar *data = image.ptr(i);

uchar *dataCMYK = cmyk.ptr(i);

for(int j = 0;j < nc;j++){

uchar b = data[3*j];

uchar g = data[3*j+1];

uchar r = data[3*j+2];

uchar c = 255 - r;

uchar m = 255 - g;

uchar y = 255 - b;

uchar k = min(min(c,m),y);

dataCMYK[4*j] = c - k;

dataCMYK[4*j+1] = m - k;

dataCMYK[4*j+2] = y - k;

dataCMYK[4*j+3] = k;

}

}

return 0;

}

3. 完整的工程

#include

#include

#include

#include

#define PI 3.1416

#define min(a,b) (a

using namespace std;

using namespace cv;

int rgb2hsi(Mat &image,Mat &hsi){

if(!image.data){

cout<

return -1;

}

int nl = image.rows;

int nc = image.cols;

if(image.isContinuous()){

nc = nc*nl;

nl = 1;

}

for(int i = 0;i < nl;i++){

uchar *src = image.ptr(i);

uchar *dst = hsi.ptr(i);

for(int j = 0;j < nc;j++){

float b = src[j*3]/255.0;

float g = src[j*3+1]/255.0;

float r = src[j*3+2]/255.0;

float num = (float)(0.5*((r-g)+(r-b)));

float den = (float)sqrt((r-g)*(r-g)+(r-b)*(g-b));

float H,S,I;

if(den == 0){//分母不能为0

H = 0;

}

else{

double theta = acos(num/den);

if(b <= g)

H = theta/(PI*2);

else

H = (2*PI - theta)/(2*PI);

}

double minRGB = min(min(r,g),b);

den = r+g+b;

if(den == 0)//分母不能为0

S = 0;

else

S = 1 - 3*minRGB/den;

I = den/3.0;

//将S分量和H分量都扩充到[0,255]区间以便于显示;

//一般H分量在[0,2pi]之间，S在[0,1]之间

dst[3*j] = H*255;

dst[3*j+1] = S*255;

dst[3*j+2] = I*255;

}

}

return 0;

}

int rgb2cmyk( Mat &image,Mat &cmyk){

if(!image.data){

cout<

return -1;

}

int nl = image.rows;//行数

int nc = image.cols;//列数

if(image.isContinuous()){//没有额外的填补像素

nc = nc*nl;

nl = 1;//It is now a 1D array

}

//对于连续图像，本循环只执行1次

for(int i=0;i

uchar *data = image.ptr(i);

uchar *dataCMYK = cmyk.ptr(i);

for(int j = 0;j < nc;j++){

uchar b = data[3*j];

uchar g = data[3*j+1];

uchar r = data[3*j+2];

uchar c = 255 - r;

uchar m = 255 - g;

uchar y = 255 - b;

uchar k = min(min(c,m),y);

dataCMYK[4*j] = c - k;

dataCMYK[4*j+1] = m - k;

dataCMYK[4*j+2] = y - k;

dataCMYK[4*j+3] = k;

}

}

return 0;

}

int main(){

Mat img = imread("E:\\CV视频处理工作室\\Test_Photo\\lena_1.jpg");

if(!img.data){

cout<

return -1;

}

Mat img_cmyk,img_hsi;

Mat img_hsv;

vector vecRgb,vecHsi,vecHls,vecHsv,vecCmyk;

img_hsv.create(img.rows,img.cols,CV_8UC3);

Mat img_hls;

img_hls.create(img.rows,img.cols,CV_8UC3);

//生成与输入图像尺寸一样的4通道cmyk图像

img_cmyk.create(img.rows,img.cols,CV_8UC4);

img_hsi.create(img.rows,img.cols,CV_8UC3);

rgb2cmyk(img,img_cmyk);

rgb2hsi(img,img_hsi);

cvtColor(img,img_hsv,CV_BGR2HSV);

cvtColor(img,img_hls,CV_BGR2HLS);

split(img_cmyk,vecCmyk);

split(img_hsi,vecHsi);

cout<

for(int i=0;i<3;i++){

cout<(0,0)[i]<

}

cout<

for(int i=0;i<4;i++){

cout<(0,0)[i]<

}

int a = min(min(24,32),16);

cout<

namedWindow("RGB_Image");

namedWindow("CMYK_Image");

//namedWindow("HSV_Image");

//namedWindow("HLS_Image");

namedWindow("HSI_Image");

namedWindow("CMYK_C");

namedWindow("CMYK_M");

namedWindow("CMYK_Y");

namedWindow("CMYK_K");

imshow("CMYK_C",vecCmyk[0]);

imshow("CMYK_M",vecCmyk[1]);

imshow("CMYK_Y",vecCmyk[2]);

imshow("CMYK_K",vecCmyk[3]);

imshow("HSI_H",vecHsi[0]);

imshow("HSI_S",vecHsi[1]);

imshow("HSI_I",vecHsi[2]);

imshow("RGB_Image",img);

imshow("CMYK_Image",img_cmyk);

//imshow("HSV_Image",img_hsv);

//imshow("HLS_Image",img_hls);

imshow("HSI_Image",img_hsi);

waitKey();

return 0;

}