从噪声图像中提取数字

Question

Extract digit from noisy image

I want to extract text from an image taken by mobile phone camera. First I try to convert the image to greyscale by using this code:

imgg = Image.open('originale.jpg').convert('LA')

Second i try to threshold the grey image to get image with only black and white with this code::

 retval, threshold = cv2.threshold(grayscaled, 0, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)
cv2.imwrite("threshold.png", threshold)

Third i try to extract text with pytesseract but i have not the correct result with this code.

result5 = pytesseract.image_to_string(Image.open("threshold.png"))

This is the image which I want to extract digits number for example: My expected output is: 111 2 11 4 1 23 2 3 .

and this is my image:

originale.jpg

threshold.png

And this is my full code:

import cv2
import numpy as np
import pytesseract
from PIL import Image
img = cv2.imread('originale.jpg')
grayscaled = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
retval, threshold = cv2.threshold(grayscaled, 0, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)
cv2.imwrite("threshold.png", threshold)
result = pytesseract.image_to_string(Image.open("threshold.png"))
print(result)

Answer 1

You can use Otsu method to determine optimal threshold value to exact your digits.

import cv2

img # this is your original image
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
retval, threshold = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)
cv2.imwrite("threshold.png", threshold)

Result: