[英]Improving pytesseract correct text recognition from image
我正在嘗試使用pytesseract模塊讀取驗證碼。 它大部分時間都提供准確的文本,但並非總是如此。
這是讀取圖像、操作圖像和從圖像中提取文本的代碼。
import cv2
import numpy as np
import pytesseract
def read_captcha():
# opencv loads the image in BGR, convert it to RGB
img = cv2.cvtColor(cv2.imread('captcha.png'), cv2.COLOR_BGR2RGB)
lower_white = np.array([200, 200, 200], dtype=np.uint8)
upper_white = np.array([255, 255, 255], dtype=np.uint8)
mask = cv2.inRange(img, lower_white, upper_white) # could also use threshold
mask = cv2.morphologyEx(mask, cv2.MORPH_OPEN, cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (3, 3))) # "erase" the small white points in the resulting mask
mask = cv2.bitwise_not(mask) # invert mask
# load background (could be an image too)
bk = np.full(img.shape, 255, dtype=np.uint8) # white bk
# get masked foreground
fg_masked = cv2.bitwise_and(img, img, mask=mask)
# get masked background, mask must be inverted
mask = cv2.bitwise_not(mask)
bk_masked = cv2.bitwise_and(bk, bk, mask=mask)
# combine masked foreground and masked background
final = cv2.bitwise_or(fg_masked, bk_masked)
mask = cv2.bitwise_not(mask) # revert mask to original
# resize the image
img = cv2.resize(mask,(0,0),fx=3,fy=3)
cv2.imwrite('ocr.png', img)
text = pytesseract.image_to_string(cv2.imread('ocr.png'), lang='eng')
return text
為了處理圖像,我從這個stackoverflow帖子中得到了幫助。
這是原始的驗證碼圖像:
這個圖像是在操作后生成的:
但是,通過使用pytesseract ,我收到了文本: AX#7rL 。
任何人都可以指導我如何將成功率提高到 100% 嗎?
由於生成的圖像中存在小孔,因此形態變換,特別是cv2.MORPH_CLOSE
,用於關閉孔並平滑圖像應該在這里起作用
獲取二值圖像(黑白)的閾值
執行形態學操作以關閉前景中的小孔
反轉圖像以獲得結果
4X#7rL
在插入tesseract之前可能有一個cv2.GaussianBlur()
也會有幫助
import cv2
import pytesseract
# Path for Windows
pytesseract.pytesseract.tesseract_cmd = r"C:\Program Files\Tesseract-OCR\tesseract.exe"
# Read in image as grayscale
image = cv2.imread('1.png',0)
# Threshold to obtain binary image
thresh = cv2.threshold(image, 220, 255, cv2.THRESH_BINARY)[1]
# Create custom kernel
kernel = cv2.getStructuringElement(cv2.MORPH_RECT, (3,3))
# Perform closing (dilation followed by erosion)
close = cv2.morphologyEx(thresh, cv2.MORPH_CLOSE, kernel)
# Invert image to use for Tesseract
result = 255 - close
cv2.imshow('thresh', thresh)
cv2.imshow('close', close)
cv2.imshow('result', result)
# Throw image into tesseract
print(pytesseract.image_to_string(result))
cv2.waitKey()
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