OpenCV第六篇：阈值函数

       阈值的作用是根据设定的值处理图像的灰度值，比如灰度大于某个数值像素点保留。通过阈值以及有关算法可以实现从图像中抓取特定的图形，比如去除背景等。实例图片：

 1.普通阈值函数：threshold(像素矩阵,起始阈值,最大值,算法类型)-->retval, threshold

import cv2

if __name__ == '__main__':
    img = cv2.imread('1.png')
    retval, threshold = cv2.threshold(img, 12, 255, cv2.THRESH_BINARY)
    cv2.imshow('original', img)
    cv2.imshow('threshold', threshold)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

 使用图片的灰度图试试：

import cv2

if __name__ == '__main__':
    img = cv2.imread('1.png')
    # 灰度图
    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    retval, threshold = cv2.threshold(gray, 12, 255, cv2.THRESH_BINARY)
    cv2.imshow('original', img)
    cv2.imshow('threshold', threshold)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

2.自适应阈值函数：adaptivthreshold()

import cv2

if __name__ == '__main__':
    img = cv2.imread('1.png')
    # 灰度图
    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    threshold = cv2.adaptiveThreshold(gray, 255, cv2.ADAPTIVE_THRESH_GAUSSIAN_C, cv2.THRESH_BINARY, 115, 1)
    cv2.imshow('original', img)
    cv2.imshow('threshold', threshold)
    cv2.waitKey(0)
    cv2.destroyAllWindows()