opencv 中去除阈值 TEXT 图片的噪声

Question

I have these images:

I want to remove the noise from the background(ie make the background white in 1st and 3rd and black in 2nd) in all these images, I tried this method: Remove noise from threshold image opencv python but it didn't work, how can I do it?

PS This is the original image that I am trying to enhance.

Answer 1

You can use adaptive threshold on your original image in Python/OpenCV

Input:

import cv2
import numpy as np

# read image
img = cv2.imread("writing.jpg")

# convert img to grayscale
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

# do adaptive threshold on gray image
thresh = cv2.adaptiveThreshold(gray, 255, cv2.ADAPTIVE_THRESH_MEAN_C, cv2.THRESH_BINARY, 21, 10)

# write results to disk
cv2.imwrite("writing_thresh.jpg", thresh)

# display it
cv2.imshow("thresh", thresh)
cv2.waitKey(0)
cv2.destroyAllWindows()

Result: