如何使用 Pytesseract 提取图像中的小数

Question

Above is the image ,I have tried everything I could get from SO or google ,nothing seems to work. I can not get the exact value in image , I should get 2.10 , Instead it always get 210.

And it is not limited to this image only any image which have a decimal before number 1 tesseract ignores the decimal value.

 def returnAllowedAmount(self,imgpath):
        th = 127
        max_val = 255
        img = cv2.imread(imgpath,0) #Load Image in Memory
        img = cv2.resize(img, None, fx=2.5, fy=2.5, interpolation=cv2.INTER_CUBIC) #rescale Image
        img = cv2.medianBlur(img, 1)
        ret , img = cv2.threshold(img,th,max_val,cv2.THRESH_TOZERO)
        self.showImage(img)

        returnData = pytesseract.image_to_string(img,lang='eng',config='-psm 13 ' )
        returnData = ''.join(p for p in returnData if p.isnumeric() or p == ".") # REMOVE $ SIGN

Answer 1

Before throwing the image into Pytesseract, some preprocessing to clean/smooth the image helps. Here's a simple approach

• Convert image to grayscale and enlarge image
• Threshold
• Perform morphological operations to clean image
• Invert image

---

First we convert the image to grayscale, resize using the imutils library then threshold to obtain a binary image

Now we perform morphological transformations to smooth the image

Now we invert the image for Pytesseract and add a Gaussian blur

We use the --psm 10 config flag since we want to treat the image as a single character. Here's some additional configuration flags that could be useful

Results

$2.10

After filtering

2.10

import cv2
import pytesseract
import imutils

pytesseract.pytesseract.tesseract_cmd = r"C:\Program Files\Tesseract-OCR\tesseract.exe"

image = cv2.imread('1.png',0)
image = imutils.resize(image, width=300)
thresh = cv2.threshold(image, 150, 255, cv2.THRESH_BINARY_INV)[1]

kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (3,3))
close = cv2.morphologyEx(thresh, cv2.MORPH_CLOSE, kernel)

result = 255 - close 
result = cv2.GaussianBlur(result, (5,5), 0)

data = pytesseract.image_to_string(result, lang='eng',config='--psm 10 ')
processed_data = ''.join(char for char in data if char.isnumeric() or char == '.')
print(data)
print(processed_data)

cv2.imshow('thresh', thresh)
cv2.imshow('close', close)
cv2.imshow('result', result)
cv2.waitKey()

Answer 2

I was able to increase the number of correct decimals by using the methods mentioned in the other answers. Yet, a small share of the decimals were not recognized correctly.

The solution I found was to change the language setting for pytesseract.

I was using a non-English setting, but changing the config to lang='eng' fixed all remaining issues.

Not sure what the reason is, but with the new LSTM engine for Tesseract, the training data is probably mostly English.

Answer 3

Sometimes tesseract is oddly sensitive to image size. You can often get better results by scaling your image.

I scaled your image by a factor of 2 and I got good results.

import cv2
import pytesseract

# if windows
# pytesseract.pytesseract.tesseract_cmd = 'C:\\Program Files (x86)\\Tesseract-OCR\\tesseract.exe'

img = cv2.imread('twoten.png', 0)
img = cv2.resize(img, (0,0), fx=2, fy=2)

config = ("--psm 12")

data = pytesseract.image_to_string(img, lang='eng', config = config)

print(data)

which gave this in a console:

$2.10