pytesseract无法识别图像中的文本

Question

以下是示例图片：

我在Python中将图片输入了pytesseract.image_to_string()，但返回的是空白。

更新：这是我尝试过的最新代码，它会为某些验证码返回正确的文本。

import time

import pytesseract
import cv2
import numpy as np
import sys
import os

import argparse

try:
    import Image
except ImportError:
    from PIL import Image
from subprocess import check_output

def solve(path):
    print(path)
    img = cv2.imread(path, 0)
    # cv2.imshow("same", img)
    # cv2.waitKey(0)

    # crop image
    start_width = img.shape[1] // 4
    end_width = img.shape[1] - start_width
    crop_img = img[0:img.shape[0], start_width:end_width]
    # cv2.imshow("crop", crop_img)
    # cv2.waitKey(0)

    # resize image
    scale_percent = 500  # percent of original size
    width = int(crop_img.shape[1] * scale_percent / 100)
    height = int(crop_img.shape[0] * scale_percent / 100)
    dim = (width, height)
    resized = cv2.resize(crop_img, dim, interpolation=cv2.INTER_CUBIC)
    cv2.imshow("Resized image", resized)
    pytesseract_config = "-c tessedit_char_whitelist=0123456789abcdefghijklmnopqrstuvwxyz --oem 1 --psm 8"
    captcha = pytesseract.image_to_string(resized, config=pytesseract_config)
    print("after resized: " + captcha)
    cv2.waitKey(0)

    # blur = cv2.medianBlur(resized, 3)
    # blur = cv2.GaussianBlur(resized,(3,3),0)
    blur = cv2.bilateralFilter(resized,9,100,100)
    cv2.imshow("blur", blur)
    captcha = pytesseract.image_to_string(blur, config=pytesseract_config)
    print("after blur:    " + captcha)
    cv2.waitKey(0)

    ret, thresh_img = cv2.threshold(blur, 0, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)
    cv2.imshow('thresh_img', thresh_img)
    captcha = pytesseract.image_to_string(thresh_img, config=pytesseract_config)
    print("after thresh_img: " + captcha)
    cv2.waitKey(0)

    rows, cols = thresh_img.shape
    horizontalsize = int(cols / 100)
    kernel = cv2.getStructuringElement(cv2.MORPH_RECT, (horizontalsize, 3))
    erode_img = cv2.erode(thresh_img, kernel)
    cv2.imshow("erode_img", erode_img)
    captcha = pytesseract.image_to_string(erode_img, config=pytesseract_config)
    print("after erode_img: " + captcha)
    cv2.waitKey(0)

    morph_img = cv2.morphologyEx(erode_img, cv2.MORPH_CLOSE, kernel)
    cv2.imshow("morph_img", morph_img)
    captcha = pytesseract.image_to_string(morph_img, config=pytesseract_config)
    print("after morph_img: " + captcha)
    cv2.waitKey(0)

    cv2.destroyAllWindows()


if __name__ == "__main__":
    argparser = argparse.ArgumentParser()
    argparser.add_argument('path', help='Captcha collection dir path')
    args = argparser.parse_args()
    path = args.path
    for entry in os.listdir(path):
        filename = os.path.join(path, entry)
        if os.path.isfile(filename):
            solve(filename)

以下是中间图像，后跟每个图像的文本输出打印：

调整大小后：e7rmp

模糊后：e7rmp

在thresh_img之后：ce7nmp

erode_img之后：ce7nap

morph_img之后：ce7nap

您可以看到thresh_img之后打印了正确的文本。腐蚀和变形后，情况变得更糟。

但是成功率几乎不到1％。在大多数情况下，我仍然会回答错误。

任何指针/想法真的会有所帮助吗？ Here is a sample collection of captcha's，如果有人想尝试我的代码。