Python - Tophat

import cv2 as cv

import numpy as np

import matplotlib.pyplot as plt

img1 = cv.imread('semillas.jpg',0)

ret,img1 = cv.threshold (img1,0,255,cv.THRESH_OTSU)

kernel = np.ones((6,6),np.uint8)

tophat = cv.morphologyEx(img1,cv.MORPH_TOPHAT,kernel)

plt.imshow(tophat,cmap='gray')