#include <cv.h>

#include <highgui.h>

# include <math.h>

#define M_PI 3.1415

void RGB_to_HSI(IplImage *src, IplImage *dst);

int main(void)

{

    IplImage * oo  = cvLoadImage   ("6013202130.jpg", );

    IplImage * xx  = cvCreateImage  (cvGetSize(oo), , );

    RGB_to_HSI(oo, xx);

    cvNamedWindow("原图", );

    cvNamedWindow("HSI", );

    cvShowImage("原图", oo);

    cvShowImage("HSI" , xx);

    cvWaitKey();

    cvReleaseImage(&xx);

    cvReleaseImage(&oo);

    return ;

}

void RGB_to_HSI(IplImage *src, IplImage *dst)

{

    int i, j;

    double b, g, r, numm, den, min, theta, H, S, I;

    CvScalar s0;

    for (i = ; i<src->height; i++)

    for (j = ; j<src->width; j++)

    {

        s0 = cvGet2D(src, i, j);

        b = s0.val[] / ;//rgb归一化

        g = s0.val[] / ;

        r = s0.val[] / ;

        //几何推导法转换

        numm = 0.5*((r - g) + (r - b));

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

        if (den == )

            H = ;

        else

        {

            theta = acos(numm / den);

            if (b>g)

                H = ( * M_PI - theta) / ( * M_PI);

            else

                H = theta / ( * M_PI);

        }

        min = (b>g) ? g : b;

        min = (min>r) ? r : min;

        den = r + g + b;

        if (den == )

            S = ;

        else

            S =  -  * min / den;

        I = (r + g + b) / ;

        cvSet2D(dst, i, j, cvScalar(H * , S * , I * ));

    }

}