Seuillage Tozero

import cv2
import matplotlib.pyplot as plt
import matplotlib.image as mpimg
 
def threshold_tozero(img):
    ret1, thresh1 = cv2.threshold(img, 127, 255, cv2.THRESH_TOZERO)
 
    ret2, thresh2 = cv2.threshold(img, 127, 255, cv2.THRESH_TOZERO_INV)
 
    return thresh1, thresh2
 
 
if __name__ == '__main__':
 
    imgfile = 'cat-threshimages.jpg'
    try:
        img = cv2.imread(imgfile)
        img = cv2.cvtColor(img, cv2.COLOR_RGB2GRAY)
    except cv2.error:
        print("Add image to args or in the code.")
        exit()
 
    binary_image1, binary_image2 = img > threshold_tozero(img)
    plt.imshow(binary_image1, cmap='gray')
    plt.axis('off')
    plt.show()
 
    mpimg.imsave('CatTozeroThresholding.jpg', binary_image1, cmap='gray')
 
    plt.imshow(binary_image2, cmap='gray')
    plt.axis('off')
    plt.show()
 
    mpimg.imsave('CatTozeroInvThresholding.jpg', binary_image2, cmap='gray')