[Python] Remove background text and noise from a CAPTCHA using image processing with OpenCV

I have these images





For which I want to remove the text in the background. Only the captcha characters should remain(i.e K6PwKA, YabVzu). The task is to identify these characters later using tesseract.

This is what I have tried, but it isn't giving much good accuracy.

import cv2
import pytesseract

pytesseract.pytesseract.tesseract_cmd = r"C:\Users\HPO2KOR\AppData\Local\Tesseract-OCR\tesseract.exe"
img = cv2.imread("untitled.png")
gray_image = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
gray_filtered = cv2.inRange(gray_image, 0, 75)
cv2.imwrite("cleaned.png", gray_filtered)


How can I improve the same?

Note : I tried all the suggestion that I was getting for this question and none of them worked for me.

EDIT : According to Elias, I tried finding the color of the captcha text using photoshop by converting it to grayscale which came out to be somewhere in between [100, 105]. I then threshold the image based on this range. But the result which I got did not give satisfactory result from tesseract.

gray_filtered = cv2.inRange(gray_image, 100, 105)
cv2.imwrite("cleaned.png", gray_filtered)
gray_inv = ~gray_filtered
cv2.imwrite("cleaned.png", gray_inv)
data = pytesseract.image_to_string(gray_inv, lang='eng')


Output :

'KEP wKA'


Result :



EDIT 2 :

def get_text(img_name):
lower = (100, 100, 100)
upper = (104, 104, 104)
img = cv2.imread(img_name)
img_rgb_inrange = cv2.inRange(img, lower, upper)
neg_rgb_image = ~img_rgb_inrange
cv2.imwrite('neg_img_rgb_inrange.png', neg_rgb_image)
data = pytesseract.image_to_string(neg_rgb_image, lang='eng')
return data


gives :



and the text as

GXuMuUZ


Is there any way to soften it a little

Continue reading...