opencv-041-基本阈值操作

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知识点

API

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double cv::threshold(
    InputArray src,
    OutputArray dst,
    double thresh,
    double maxval,
    int type
)
其中type表示阈值分割的方法，支持如下五种：
THRESH_BINARY = 0  二值分割
THRESH_BINARY_INV = 1 反向二值分割
THRESH_TRUNC = 2 截断
THRESH_TOZERO = 3 取零
THRESH_TOZERO_INV = 4 反向取零

代码（c++,python）

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#include <iostream>
#include <opencv2/opencv.hpp>

using namespace std;
using namespace cv;

/*
 * 基本阈值操作
 */
int main() {
    Mat src = imread("../images/master.jpg");
    if (src.empty()) {
        cout << "could not load image.." << endl;
    }
    imshow("input", src);

    int T = mean(src)[0];
    Mat gray, binary;
    cvtColor(src, gray, COLOR_BGR2GRAY);
    for (int i = 0; i < 5; ++i) {
//        THRESH_BINARY = 0
//        THRESH_BINARY_INV = 1
//        THRESH_TRUNC = 2
//        THRESH_TOZERO = 3
//        THRESH_TOZERO_INV = 4
        threshold(gray, binary, T, 255, i);
        imshow(format("binary_%d", i), binary);
    }

    waitKey(0);
    return 0;
}
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import cv2 as cv
import numpy as np
#
# THRESH_BINARY = 0
# THRESH_BINARY_INV = 1
# THRESH_TRUNC = 2
# THRESH_TOZERO = 3
# THRESH_TOZERO_INV = 4
#
src = cv.imread("D:/images/master.jpg")
cv.namedWindow("input", cv.WINDOW_AUTOSIZE)
cv.imshow("input", src)

T = 127

# 转换为灰度图像
gray = cv.cvtColor(src, cv.COLOR_BGR2GRAY)
for i in range(5):
    ret, binary = cv.threshold(gray, T, 255, i)
    cv.imshow("binary_" + str(i), binary)

cv.waitKey(0)
cv.destroyAllWindows()

结果

代码地址

github