实现opencv阈值操作函数threshold

下面直接贴代码

//灰度的阈值变换，实现opencv的threshold函数#include<opencv2/opencv.hpp>#include<iostream>#include<cassert>namespace mycv {    enum ThresholdType
    {        //详情参考https://docs.opencv.org/3.4.3/d7/d1b/group__imgproc__misc.html#gaa9e58d2860d4afa658ef70a9b1115576
        THRESH_BINARY = 0,
        THRESH_BINARY_INV = 1,
        THRESH_TRUNC = 2,
        THRESH_TOZERO = 3,
        THRESH_TOZERO_INV = 4
    };    void threshold(cv::Mat& input, cv::Mat& output, const uchar thresh = 128, const uchar max_val = 255, int type = 0);

}//mycvint main(){
    cv::Mat img = cv::imread("lena.jpg", 0);    if (img.empty()) return -1;
    cv::Mat dst;
    
    mycv::threshold(img, dst);
    cv::imwrite("dst.bmp", dst);
    cv::imshow("img", img);
    cv::imshow("dst", dst);
    cv::waitKey(0);    return 0;
}void mycv::threshold(cv::Mat& input, cv::Mat& output, const uchar thresh, const uchar max_val, int type)
{
    assert(1 == input.channels());
    output = input.clone();    const int rows = input.rows;//行
    const int cols = input.cols;//列

    switch (type)//五种操作方式
    {    case 0:        for(int i = 0; i < rows; ++i)            for (int j = 0; j < cols; ++j)
            {                //THRESH_BINARY
                if (input.at<uchar>(i, j) > thresh)
                    output.at<uchar>(i, j) = max_val;                else
                    output.at<uchar>(i, j) = 0;
            }        break;    case 1:        for (int i = 0; i < rows; ++i)            for (int j = 0; j < cols; ++j)
            {                //THRESH_BINARY_INV
                if (input.at<uchar>(i, j) < thresh)
                    output.at<uchar>(i, j) = max_val;                else
                    output.at<uchar>(i, j) = 0;
            }        break;    case 2:        for (int i = 0; i < rows; ++i)            for (int j = 0; j < cols; ++j)
            {                //THRESH_TRUNC
                if (input.at<uchar>(i, j) > thresh)
                    output.at<uchar>(i, j) = thresh;                else
                    output.at<uchar>(i, j) = input.at<uchar>(i, j);
            }        break;    case 3:        for (int i = 0; i < rows; ++i)            for (int j = 0; j < cols; ++j)
            {                //THRESH_TOZERO
                if (input.at<uchar>(i, j) < thresh)
                    output.at<uchar>(i, j) = input.at<uchar>(i, j);                else
                    output.at<uchar>(i, j) = 0;
            }        break;    case 4:        for (int i = 0; i < rows; ++i)            for (int j = 0; j < cols; ++j)
            {                //THRESH_TOZERO_INV
                if (input.at<uchar>(i, j) > thresh)
                    output.at<uchar>(i, j) = input.at<uchar>(i, j);                else
                    output.at<uchar>(i, j) = 0;
            }        break;    default:
        assert(false);
    }
}//threshold

作者：芒果浩明
链接：https://www.jianshu.com/p/313fd08dfc12