【opencv函数】阈值处理函数threshold()详解

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数字图像处理中，阈值操作占有非常重要的地位，例如图像的二值化可以使图像中数据量大为减少，从而能凸显出目标的轮廓。opencv中提供了函数cv::threshold()用于图像的阈值操作。

函数原型

double cv::threshold(InputArray src, OutputArray dst, double thres, double maxval, int type)

参数说明

src：源图像，可以为8位的灰度图，也可以为32位的彩色图像；

dst：输出图像；

thresh：阈值；

maxval：二值图像中灰度最大值；

type：阈值操作类型，具体的阈值操作实现如下图所示：

测试代码

	//全局二值化int th = 100;cv::Mat threshold1, threshold2, threshold3, threshold4, threshold5, threshold6, threshold7, threshold8;cv::threshold(gray, threshold1, th, 255, cv::THRESH_BINARY);cv::threshold(gray, threshold2, th, 255, cv::THRESH_BINARY_INV);cv::threshold(gray, threshold3, th, 255, cv::THRESH_TRUNC);cv::threshold(gray, threshold4, th, 255, cv::THRESH_TOZERO);cv::threshold(gray, threshold5, th, 255, cv::THRESH_TOZERO_INV);cv::threshold(gray, threshold7, th, 255, cv::THRESH_OTSU);cv::threshold(gray, threshold8, th, 255, cv::THRESH_TRIANGLE);cv::imshow("gray", gray);cv::imshow("THRESH_BINARY", threshold1);cv::imshow("THRESH_BINARY_INV", threshold2);cv::imshow("THRESH_TRUNC", threshold3);cv::imshow("THRESH_TOZERO", threshold4);cv::imshow("THRESH_TOZERO_INV", threshold5);cv::imshow("THRESH_OTSU", threshold7);cv::imshow("THRESH_TRIANGLE", threshold8);

测试结果对比