convert RGB image to HSI color space - visual-studio-2010

Question

I'm trying to convert RGB image to HSI color space using visual c++ express 2010 and open CV 2.3.1 and have compiling error problem with this. Please can anyone help me with this and I need to know how can I use the matrix to save the values of H,S and I. Thanks in advance.
The codes that I use are.
#include "stdafx.h"
#include <cmath>
#include <cstdlib>
#include <iostream>
#include <string>
#include <opencv2/opencv.hpp>
using namespace std;
#include "cxcore.h"
#include "cv.h"
#include <highgui.h>
using namespace cv;
const string openCVpath = string(getenv("ProgramFiles"))+"\\OpenCV-2.3.1\\samples\\c\\";
int main (int, char**) {
//call image
Mat img1 = imread(openCVpath+"image1.jpg");
unsigned char *input = (unsigned char*)(img1.data);
// To get pixel values of i-th row and j-th cloumn,
double R,G,B,min,H,S,I;
int i,j;
const double PI= 3.14;
for(int i = 0;i < img1.rows ;i++){
for(int j = 0;j < img1.cols ;j++){
B = input[img1.step * j + i ] ;
G = input[img1.step * j + i + 1];
R = input[img1.step * j + i + 2];
}
// calculate the values of Hue, Saturation and Intensity
min = R;
if (G < min)
min = G;
if (B < min)
min = B;
I = (R+G+B)/3.0;
S = 1 - min/I;
if (S == 0.0)
{
H = 0.0;
}
else
{
H = ((R-G)+(R-B))/2.0;
H = H/sqrt((R-G)*(R-G) + (R-B)*(G-B));
H = acos(H);
if (B > G)
{
H = 2*PI - H;
}
H = H/(2*PI);
}
}
ifstream f("file.txt"); //...in your routine
//};
imshow("Image",img1);
cvWaitKey(0);
return 0;
};

Answer 1

why don't you use this :
cvtColor(img_rgb,img_hsv,CV_RGB2HSV);
also, see, OpenCV image conversion from RGB to HSV

Answer 2

I do not get a compilation error. But I needed to make the following changes to get your Programm to run:
B = input[img1.step * i + 3*j ] ;
G = input[img1.step * i + 3*j + 1];
R = input[img1.step * i + 3*j + 2];
I had to switch i and j because that is the way opencv organizes the memory. Also, you need to advance 3 bytes per pixel, because of the 3 rgb values.
Move the curly bracket in the next line to the line above ifstream f("file.txt");.
Otherwise you would only compute values for the last row of the image.
remove this line (I am not sure, what it is supposed to do):
ifstream f("file.txt");
And inside the for loops I added the following just to visualize the result, because so far you are not doing anything the computed results:
input[img1.step * i + 3*j ] = 255*H;
input[img1.step * i + 3*j + 1] = 255*S;
input[img1.step * i + 3*j + 2] = I;