Solves basic alpha numeric captchas using pytesseract and PIL

captcha_solver.py

"""
Solves basic alpha numeric captchas using pytesseract and PIL
NOTE: This program is written for testing difficulties of captchas generated by captcha generator.
PLEASE, DO NOT USE IT FOR SPAMMING OR, ABUSING SYSTEMS!
Usage: 
>>> get_captcha_text("https://i.imgur.com/4u7PESk.png")
'hWA K n h'

It is also possible to use proxy i.e:
>>> proxies = {"http": "http://104.236.13.100:8888", "https": "http://104.236.13.100:8888"}
>>> get_captcha_text('https://i.imgur.com/4u7PESk.png', proxies=proxies)
'hWA K n h'

"""

__auth__ = "wasi0013"

import os
try:
    import requests
except:
    os.system('pip install requests')
    
# also requires Google's Tesseract-OCR installed and, `tesseract` command must be available on terminal/cmd.
try:
    import pytesseract 
except:
    os.system('pip install pytesseract')
from PIL import Image, ImageEnhance, ImageFilter

def clean_image(captcha_image, chop = 8):
    """
    clean_image(PIL_IMAGE, [optionally chop])

    takes a PIL_IMAGE and, removes all the stripes & grids using 
    the optional parameter `chop`
    the default value of chop is set to 8
    """
    width, height = captcha_image.size
    data = captcha_image.load()
    for y in range(height):
        for x in range(width):
            if data[x, y] > 128:
                continue
            total = 0
            for c in range(x, width):
                if data[c, y] < 128:
                    total += 1
                else:
                    break
            if total <= chop:
                for c in range(total):
                    data[x + c, y] = 255
            x += total
    for x in range(width):
        for y in range(height):
            if data[x, y] > 128:
                continue
            total = 0
            for c in range(y, height):
                if data[x, c] < 128:
                    total += 1
                else:
                    break
            if total <= chop:
                for c in range(total):
                    data[x, y + c] = 255
            y += total
    return True
    
def get_captcha_text(url, proxies = None):
    """
    get_captcha_test(url) -> str

    takes a captcha image url loads it as PIL Image applies various filters & call's clean_image method to remove all the stripes
    & grids (if any left) 
    returns text from the image.
    """
    # proxies = {"http": "http://104.236.13.100:8888",
    #       "https": "http://104.236.13.100:8888"}
    
    image = None
    if proxies:
        image = requests.get(url, proxies=proxies, stream=True).raw
    else: 
        image = requests.get(url, stream=True).raw

    captcha_image = Image.open(image)
    captcha_image = captcha_image.resize((1000, 200), Image.ANTIALIAS)
    # captcha_image.save('captcha.png')
    for i in range(5):
        captcha_image = captcha_image.filter(ImageFilter.MedianFilter())
    
    enhancer = ImageEnhance.Contrast(captcha_image)
    captcha_image = enhancer.enhance(9)
    # captcha_image.save('crap2.png')
    captcha_image = captcha_image.convert('1')
    # captcha_image.save('converted.png')
    
    clean_image(captcha_image)
    
    captcha_image = captcha_image.convert('RGBA')
    enhancer = ImageEnhance.Sharpness(captcha_image)
    captcha_image = enhancer.enhance(0)
    # captcha_image.save('sharp.png')
    
    enhancer = ImageEnhance.Contrast(captcha_image)
    captcha_image = enhancer.enhance(4)
    captcha_image = captcha_image.convert('1')
    clean_image(captcha_image)
    captcha_image.save('captcha.png')
    
    text = pytesseract.image_to_string(Image.open('captcha.png'))    
    text = "".join(i for i in text if i.isalnum() or i == " ")
    return text

url = "https://i.imgur.com/4u7PESk.png"
print(get_captcha_text(url))

Sample url: https://i.imgur.com/4u7PESk.png

Sample output: hWA K n h