Threshold operation

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

src: Input diagram , Only single channel images can be input , Generally, grayscale image is used
dst: Output chart
thresh: threshold
maxval: When the pixel value exceeds the threshold （ Or less than the threshold , according to type To decide ）, The value assigned to
type: The type of binarization operation , Contains the following 5 Type in the ：
cv2.THRESH_BINARY: The part exceeding the threshold is taken as maxval（ Maximum ）, Otherwise take 0
cv2.THRESH_BINARY_INV:cv2.THRESH_BINARY The reversal of
cv2.THRESH_TRUNC: The part greater than the threshold value is set as the threshold value , Otherwise unchanged
cv2.THRESH_TOZERO: Parts greater than the threshold remain unchanged , Otherwise, it is set to 0
cv2.THRESH_TOZERO_INV:cv2.THRESH_TOZERO The reversal of

import cv2
image = cv2.imread('sample.jpg')
img_Gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
ret1,thresh1 = cv2.threshold(img_Gray, 127, 255, cv2.THRESH_BINARY)
ret2,thresh2 = cv2.threshold(img_Gray, 127, 255, cv2.THRESH_BINARY_INV)
ret3,thresh3 = cv2.threshold(img_Gray, 127, 255, cv2.THRESH_TRUNC)
ret4,thresh4 = cv2.threshold(img_Gray, 127, 255, cv2.THRESH_TOZERO)
ret5,thresh5 = cv2.threshold(img_Gray, 127, 255, cv2.THRESH_TOZERO_INV)

title = ['Original Image', 'BINARY', 'BINARY_INV', 'TRUNC', 'TOZERO', 'THRESH_TOZERO_INV']
images = [image, thresh1,thresh2, thresh3, thresh4, thresh5]

for i in range(6):
    cv2.imshow(title[i],images[i])

cv2.waitKey(0)
cv2.destroyAllWindows()