【opencv】閾值處理函數threshold()詳解

原創

ingy

2020-06-04 07:45

參考opencv的思想，使用C++重新實現圖像的閾值操作，代碼詳見：代碼

數字圖像處理中，閾值操作佔有非常重要的地位，例如圖像的二值化可以使圖像中數據量大爲減少，從而能凸顯出目標的輪廓。opencv中提供了函數cv::threshold()用於圖像的閾值操作。

函數原型

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

參數說明

src：源圖像，可以爲8位的灰度圖，也可以爲32位的彩色圖像；

dst：輸出圖像；

thresh：閾值；

maxval：二值圖像中灰度最大值；

type：閾值操作類型，具體的閾值操作實現如下圖所示：

測試代碼

	//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);

測試結果對比