OpenCV(Python)的二值化示例

# -*-coding:utf-8-*-
# src： 输入图，只能输入单通道图像，通常来说为灰度图
# - dst： 输出图
# - thresh： 阈值
# - maxval： 当像素值超过了阈值（或者小于阈值，根据type来决定），所赋予的值
# - type：二值化操作的类型，包含以下5种类型： cv2.THRESH_BINARY； cv2.THRESH_BINARY_INV； cv2.THRESH_TRUNC； cv2.THRESH_TOZERO；cv2.THRESH_TOZERO_INV
#
# - cv2.THRESH_BINARY           超过阈值部分取maxval（最大值），否则取0
# - cv2.THRESH_BINARY_INV    THRESH_BINARY的反转
# - cv2.THRESH_TRUNC            大于阈值部分设为阈值，否则不变
# - cv2.THRESH_TOZERO          大于阈值部分不改变，否则设为0
# - cv2.THRESH_TOZERO_INV  THRESH_TOZERO的反转
import cv2
import matplotlib.pyplot as plt
plt.switch_backend("TkAgg")
img=cv2.imread("../Lena.png")
img_gray=cv2.imread("../Lena.png",0)
#ret:阈值
ret, thresh1 = cv2.threshold(img_gray, 127, 255, cv2.THRESH_BINARY)
ret, thresh2 = cv2.threshold(img_gray, 127, 255, cv2.THRESH_BINARY_INV)
ret, thresh3 = cv2.threshold(img_gray, 127, 255, cv2.THRESH_TRUNC)
ret, thresh4 = cv2.threshold(img_gray, 127, 255, cv2.THRESH_TOZERO)
ret, thresh5 = cv2.threshold(img_gray, 127, 255, cv2.THRESH_TOZERO_INV)
 
titles = ['Original Image', 'BINARY', 'BINARY_INV', 'TRUNC', 'TOZERO', 'TOZERO_INV']
images = [img_gray, thresh1, thresh2, thresh3, thresh4, thresh5]
 
for i in range(6):
    plt.subplot(2, 3, i + 1), plt.imshow(images[i], cmap='gray')
    plt.title(titles[i])
    plt.xticks([]), plt.yticks([])
plt.show()