https://blog.csdn.net/weixin_38570251/article/details/82079080

threshold：固定阈值二值化，

ret, dst = cv2.threshold(src, thresh, maxval,type)

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

官方文档的示例代码：

importcv2

importnumpyasnp

frommatplotlibimportpyplotasplt

img = cv2.imread('gradient.png',0)

ret,thresh1 = cv2.threshold(img,127,255,cv2.THRESH_BINARY)

ret,thresh2 = cv2.threshold(img,127,255,cv2.THRESH_BINARY_INV)

ret,thresh3 = cv2.threshold(img,127,255,cv2.THRESH_TRUNC)

ret,thresh4 = cv2.threshold(img,127,255,cv2.THRESH_TOZERO)

ret,thresh5 = cv2.threshold(img,127,255,cv2.THRESH_TOZERO_INV)

titles = ['Original Image','BINARY','BINARY_INV','TRUNC','TOZERO','TOZERO_INV']

images = [img, thresh1, thresh2, thresh3, thresh4, thresh5]

foriinxrange(6):

plt.subplot(2,3,i+1),plt.imshow(images[i],'gray')

    plt.title(titles[i])

    plt.xticks([]),plt.yticks([])

plt.show()