StackOverflow OCR - Crop Letters - Python

In this topic, we will explore how to crop individual letters from an image using OCR (Optical Character Recognition) with the help of Python.

Introduction

OCR is a technology that recognizes printed or handwritten text in images and converts it into machine-readable text. In the context of this topic, we will focus on using OCR to extract individual letters from an image. This can be useful in various applications such as text recognition, document scanning, and more.

To achieve this task, we will be using the Tesseract OCR engine and the OpenCV library in Python.

Prerequisites

Before we begin, make sure you have the following prerequisites installed on your system:

• Python 3 (https://www.python.org/)
• Tesseract OCR (https://github.com/tesseract-ocr/tesseract)
• OpenCV (https://opencv.org/)

Once you have the prerequisites installed, let's proceed with the implementation.

Implementation

1. Import the necessary libraries:

import cv2
import pytesseract

2. Load the image using OpenCV:

image = cv2.imread('image.jpg')

3. Preprocess the image to enhance OCR results (optional):

gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray, (5, 5), 0)

4. Perform OCR to extract the text from the image:

text = pytesseract.image_to_string(blur)

5. Crop individual letters from the text:

letters = [char for char in text if char.isalpha()]

6. Save the cropped letters as separate images:

for i, letter in enumerate(letters):
    cropped_image = image.copy()
    mask = cv2.inRange(blur, 0, 255)  # Create a mask of the letter
    cropped_image[mask != 255] = (255, 255, 255)  # Set non-letter pixels to white
    x, y, w, h = cv2.boundingRect(mask)  # Get the bounding box of the letter
    cropped_letter = cropped_image[y:y+h, x:x+w]  # Crop the letter from the image
    cv2.imwrite(f'letter_{i}.png', cropped_letter)  # Save the cropped letter image

7. Display the cropped letters:

for i, letter in enumerate(letters):
    letter_image = cv2.imread(f'letter_{i}.png')
    cv2.imshow(f'Letter {i}', letter_image)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

Conclusion

In this topic, we have learned how to extract individual letters from an image using OCR with the help of Python. This technique can be useful in various applications such as text recognition, data extraction, and more. Experiment with different image preprocessing techniques and OCR parameters to achieve optimal results.