Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

Getting the bounding box of the recognized words using python-tesseract

I am using python-tesseract to extract words from an image. This is a python wrapper for tesseract which is an OCR code.

I am using the following code for getting the words:

import tesseract

api = tesseract.TessBaseAPI()
api.Init(".","eng",tesseract.OEM_DEFAULT)
api.SetVariable("tessedit_char_whitelist", "0123456789abcdefghijklmnopqrstuvwxyz")
api.SetPageSegMode(tesseract.PSM_AUTO)

mImgFile = "test.jpg"
mBuffer=open(mImgFile,"rb").read()
result = tesseract.ProcessPagesBuffer(mBuffer,len(mBuffer),api)
print "result(ProcessPagesBuffer)=",result

This returns only the words and not their location/size/orientation (or in other words a bounding box containing them) in the image. I was wondering if there is any way to get that as well

like image 608
Abtin Rasoulian Avatar asked Dec 30 '13 00:12

Abtin Rasoulian


People also ask

How do you extract text from an image using Tesseract OCR engine and Python?

Create a Python tesseract script Create a project folder and add a new main.py file inside that folder. Once the application gives access to PDF files, its content will be extracted in the form of images. These images will then be processed to extract the text.

What is bounding box in OCR?

A bounding box is an imaginary rectangle that are used to outline the object in a box as per as machine learning project requirement. They are the main outcomes of object detection model. The imaginary rectangle frame that surrounds an object in an image.

How does OCR Tesseract work?

Tesseract tests the text lines to determine whether they are fixed pitch. Where it finds fixed pitch text, Tesseract chops the words into characters using the pitch, and disables the chopper and associator on these words for the word recognition step.


2 Answers

Use pytesseract.image_to_data()

import pytesseract
from pytesseract import Output
import cv2
img = cv2.imread('image.jpg')

d = pytesseract.image_to_data(img, output_type=Output.DICT)
n_boxes = len(d['level'])
for i in range(n_boxes):
    (x, y, w, h) = (d['left'][i], d['top'][i], d['width'][i], d['height'][i])
    cv2.rectangle(img, (x, y), (x + w, y + h), (0, 255, 0), 2)

cv2.imshow('img', img)
cv2.waitKey(0)

Among the data returned by pytesseract.image_to_data():

  • left is the distance from the upper-left corner of the bounding box, to the left border of the image.
  • top is the distance from the upper-left corner of the bounding box, to the top border of the image.
  • width and height are the width and height of the bounding box.
  • conf is the model's confidence for the prediction for the word within that bounding box. If conf is -1, that means that the corresponding bounding box contains a block of text, rather than just a single word.

The bounding boxes returned by pytesseract.image_to_boxes() enclose letters so I believe pytesseract.image_to_data() is what you're looking for.

like image 113
stwykd Avatar answered Oct 07 '22 03:10

stwykd


tesseract.GetBoxText() method returns the exact position of each character in an array.

Besides, there is a command line option tesseract test.jpg result hocr that will generate a result.html file with each recognized word's coordinates in it. But I'm not sure whether it can be called through python script.

like image 19
lennon310 Avatar answered Oct 07 '22 03:10

lennon310