二值化函数Threshold

Threshold函数：

函数的调用方式：

void cvThreshold( const CvArr* src, CvArr* dst, double threshold,                  double max_value, int threshold_type );

函数参数详解：

src 原始数组 (单通道 , 8-bit of 32-bit 浮点数).

 dst 输出数组，必须与 src 的类型一致，或者为 8-bit. threshold 

阈值 max_value 使用 CV_THRESH_BINARY 和 CV_THRESH_BINARY_INV 的最大值.

 threshold_type 阈值类型 

函数 cvThreshold 对单通道数组应用固定阈值操作。该函数的典型应用是对灰度图像进行阈值操作得到二值图像。(cvCmpS 也可以达到此目的) 或者是去掉噪声，例如过滤很小或很大象素值的图像点。本函数支持的对图像取阈值的方法由 threshold_type 确定:

threshold_type=CV_THRESH_BINARY:dst(x,y) = max_value, if src(x,y)>threshold           0, otherwisethreshold_type=CV_THRESH_BINARY_INV:dst(x,y) = 0, if src(x,y)>threshold           max_value, otherwisethreshold_type=CV_THRESH_TRUNC:dst(x,y) = threshold, if src(x,y)>threshold           src(x,y), otherwisethreshold_type=CV_THRESH_TOZERO:dst(x,y) = src(x,y), if (x,y)>threshold           0, otherwisethreshold_type=CV_THRESH_TOZERO_INV:dst(x,y) = 0, if src(x,y)>threshold           src(x,y), otherwise

opencv代码：

#include <opencv2/core/core.hpp>#include <opencv2/highgui/highgui.hpp>#include <opencv2/imgproc/imgproc.hpp>#include <iostream>using namespace std;using namespace cv;int main(){Mat img = imread("d:6.jpg");Mat dst(img.size(),8,1);cvtColor(img, img, CV_BGR2GRAY);threshold(img, img, 100, 255, CV_THRESH_BINARY);/*dilate(img, dst, NULL, Point(-1, -1), 10, BORDER_DEFAULT, Scalar(0, 0, 255));*/namedWindow("shiyan");imshow("shiyan", img);waitKey(0);return 0;}

或者：

#include "opencv2/imgproc/imgproc.hpp"#include "opencv2/highgui/highgui.hpp"#include <stdlib.h>#include <stdio.h>using namespace cv;/// 全局变量定义及赋值int threshold_value = 0;int threshold_type = 3;;int const max_value = 255;int const max_type = 4;int const max_BINARY_value = 255;Mat src, src_gray, dst;char* window_name = "Threshold Demo";char* trackbar_type = "Type: \n 0: Binary \n 1: Binary Inverted \n 2: Truncate \n 3: To Zero \n 4: To Zero Inverted";char* trackbar_value = "Value";/// 自定义函数声明void Threshold_Demo( int, void* );/** * @主函数 */int main( int argc, char** argv ){  /// 读取一副图片，不改变图片本身的颜色类型（该读取方式为DOS运行模式）  src = imread( argv[1], 1 );  /// 将图片转换成灰度图片  cvtColor( src, src_gray, CV_RGB2GRAY );  /// 创建一个窗口显示图片  namedWindow( window_name, CV_WINDOW_AUTOSIZE );  /// 创建滑动条来控制阈值  createTrackbar( trackbar_type,                  window_name, &threshold_type,                  max_type, Threshold_Demo );  createTrackbar( trackbar_value,                  window_name, &threshold_value,                  max_value, Threshold_Demo );  /// 初始化自定义的阈值函数  Threshold_Demo( 0, 0 );  /// 等待用户按键。如果是ESC健则退出等待过程。  while(true)  {    int c;    c = waitKey( 20 );    if( (char)c == 27 )      { break; }   }}/** * @自定义的阈值函数 */void Threshold_Demo( int, void* ){  /* 0: 二进制阈值     1: 反二进制阈值     2: 截断阈值     3: 0阈值     4: 反0阈值   */  threshold( src_gray, dst, threshold_value, max_BINARY_value,threshold_type );  imshow( window_name, dst );}