void showHist(Mat& img, Mat& dst)
{
//1、创建3个矩阵来处理每个通道输入图像通道。
//我们用向量类型变量来存储每个通道,并用split函数将输入图像划分成3个通道。
vector<Mat>bgr;
split(img, bgr);
//2、定义直方图的区间数
int numbers = 256;
//3、定义变量范围并创建3个矩阵来存储每个直方图
float range[] = { 0,256 };
const float* histRange = { range };
Mat b_hist, g_hist, r_hist;
//4、使用calcHist函数计算直方图
int numbins = 256;
calcHist(&bgr[0], 1, 0, Mat(), b_hist, 1, &numbins, &histRange);
calcHist(&bgr[1], 1, 0, Mat(), g_hist, 1, &numbins, &histRange);
calcHist(&bgr[2], 1, 0, Mat(), r_hist, 1, &numbins, &histRange);
//5、创建一个512*300像素大小的彩色图像,用于绘制显示
int width = 800;
int height = 600;
Mat histImage(height, width, CV_8UC3, Scalar(0, 0, 0));
//6、将最小值与最大值标准化直方图矩阵
normalize(b_hist, b_hist, 0, height, NORM_MINMAX);
normalize(g_hist, g_hist, 0, height, NORM_MINMAX);
normalize(r_hist, r_hist, 0, height, NORM_MINMAX);
//7、使用彩色通道绘制直方图
int binStep = cvRound((float)width / (float)numbins); //通过将宽度除以区间数来计算binStep变量
for (int i = 1; i < numbins; i++)
{
line(histImage,
Point(binStep * (i - 1), height - cvRound(b_hist.at<float>(i - 1))),
Point(binStep * (i), height - cvRound(b_hist.at<float>(i))),
Scalar(255, 0, 0)
);
line(histImage,
Point(binStep * (i - 1), height - cvRound(g_hist.at<float>(i - 1))),
Point(binStep * (i), height - cvRound(g_hist.at<float>(i))),
Scalar(0, 255, 0)
);
line(histImage,
Point(binStep * (i - 1), height - cvRound(r_hist.at<float>(i - 1))),
Point(binStep * (i), height - cvRound(r_hist.at<float>(i))),
Scalar(0, 0, 255)
);
}
dst = histImage;
return;
}
opencv一些基础的代码之直方图绘制
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转载自blog.csdn.net/weixin_63163242/article/details/131683293
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