将RGB转换为YCbCr - C代码

Question

我需要将RGB转换为YCbCr以用于我的最终项目,并且我尝试这样做(我在C中编程):

/* Autor: Vinicius Garcia
 * Data : 09.ago.2011
 * 
 * Função que converte um pixel RGB em YCbCr
 * 
 * param : int R valor do pixel no canal red
 * param : int G valor do pixel no canal green
 * param : int B valor do pixel no canal blue
 * return: int* vetor de inteiros com os valores H, S e V calculados - nesta ordem
 */
int* converter_RGB_para_YCbCr(int R, int G, int B){
    int* YCbCr = (int*) malloc(3 * sizeof(int));

    double delta = 128.0; //Constante necessaria para o calculo da conversão de cor
    double Y  = (0.299 * R + 0.587 * G + 0.114 * B);
    double Cb = ((B - Y) * 0.564 + delta);
    double Cr = ((R - Y) * 0.713 + delta);

    YCbCr[0] = (int) Y;
    YCbCr[1] = (int) Cb;
    YCbCr[2] = (int) Cr;
    return YCbCr;
}

但它对我不起作用!

我正在与cvCvtColor(来自OpenCv库)进行比较,结果不匹配:

            R = 88,  G  = 76,   B = 78
cvCvtColor: Y = 80,  Cb = 127, Cr = 134
myfunction: Y = 382, Cb = 132, Cr = 132 (cr and cr are always equal!)

我真的需要这方面的帮助,我试着做了很长时间,但我无法找到任何答案.

---

你们认为我的RGB值是错误的吗？我是这样做的:

uchar B = CV_IMAGE_ELEM(img_RGB, uchar, linha, coluna * 3);
uchar G = CV_IMAGE_ELEM(img_RGB, uchar, linha, coluna * 3 + 1);
uchar R = CV_IMAGE_ELEM(img_RGB, uchar, linha, coluna * 3 + 2);

然后我用这种方式调用我的转换函数:

converter_RGB_para_YCbCr(R, G, B);

我的函数需要int R,int G,int B但是我传递了uchar B,uchar G,uchar R.它还好吗？

Answer 1

int y  = (int)( 0.299   * R + 0.587   * G + 0.114   * B);
int cb = (int)(-0.16874 * R - 0.33126 * G + 0.50000 * B);
int cr = (int)( 0.50000 * R - 0.41869 * G - 0.08131 * B);