OpenCV显示RGB直方图的代码实现

//frame为视频流cap出来的帧
split(frame, image);
Mat matRGB[3];
split(frame, matRGB);
int Channels[] = { 0 };
int nHistSize[] = { 256 };
float range[] = { 0, 255 };
const float* fHistRanges[] = { range };
Mat histR, histG, histB;
// 计算直方图
calcHist(&matRGB[0], 1, Channels, Mat(), histB, 1, nHistSize, fHistRanges, true, false);
calcHist(&matRGB[1], 1, Channels, Mat(), histG, 1, nHistSize, fHistRanges, true, false);
calcHist(&matRGB[2], 1, Channels, Mat(), histR, 1, nHistSize, fHistRanges, true, false);

// 创建直方图画布
int nHistWidth = 800;
int nHistHeight = 600;
int nBinWidth = cvRound((double)nHistWidth / nHistSize[0]);
Mat matHistImage(nHistHeight, nHistWidth, CV_8UC3, Scalar(255, 255, 255));
// 直方图归一化
normalize(histB, histB, 0.0, matHistImage.rows, NORM_MINMAX, -1, Mat());
normalize(histG, histG, 0.0, matHistImage.rows, NORM_MINMAX, -1, Mat());
normalize(histR, histR, 0.0, matHistImage.rows, NORM_MINMAX, -1, Mat());
// 在直方图中画出直方图
for (int i = 1; i < nHistSize[0]; i++)
{
line(matHistImage,
Point(nBinWidth * (i - 1), nHistHeight - cvRound(histB.at<float>(i - 1))),
Point(nBinWidth * (i), nHistHeight - cvRound(histB.at<float>(i))),
Scalar(255, 0, 0),