使用OpenCV和Python掌握计算机视觉：深入探讨高级技术及代码演示

import cv2import numpy as npimport matplotlib.pyplot as plt# Load the image of the documentdocument_path = 'path/to/your/document.jpg'document_image = cv2.imread(document_path)# Convert the image to grayscalegray_document = cv2.cvtColor(document_image, cv2.COLOR_BGR2GRAY)# Apply Gaussian blur to reduce noise and improve edge detectionblurred_document = cv2.GaussianBlur(gray_document, (5, 5), 0)# Use Canny edge detection to find edges in the imageedges_document = cv2.Canny(blurred_document, 50, 150)# Find contours in the edged imagecontours, _ = cv2.findContours(edges_document, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)# Sort the contours by area and find the largest one (assuming it's the document)largest_contour = max(contours, key=cv2.contourArea)# Calculate the perimeter of the contourperimeter = cv2.arcLength(largest_contour, True)# Approximate the polygonal curves of the contourapprox = cv2.approxPolyDP(largest_contour, 0.02 * perimeter, True)# Ensure the approximated contour has four points (a rectangle)if len(approx) == 4:    # Apply perspective transformation to obtain a top-down view of the document    transformed_document = cv2.warpPerspective(document_image, cv2.getPerspectiveTransform(approx.reshape(4, 2), np.float32([[0, 0], [800, 0], [800, 1200], [0, 1200]])), (800, 1200))    # Display the original and transformed document side by side    plt.figure(figsize=(10, 5))    plt.subplot(1, 2, 1)    plt.imshow(cv2.cvtColor(document_image, cv2.COLOR_BGR2RGB))    plt.title('Original Document')    plt.axis('off')


    
    plt.subplot(1, 2, 2)    plt.imshow(cv2.cvtColor(transformed_document, cv2.COLOR_BGR2RGB))    plt.title('Transformed Document')    plt.axis('off')    plt.show()

Extracted Text:Tesseract at UB Mannheim
The Mannheim University Library (UB Mannheim) uses Tesseract to perform text recognition (OCR = optical characterrecognition) for historical German newspapers ( ' ). The latestresults with text from more than 700000 pages are available
Tesseract installer for Windows
Normally we run Tesseract on Debian GNU Linux, but there was also the need for a Windows version. That's why we have builta Tesseract installer for Windows.
WARNING: Tesseract should be either installed in the directory which is suggested during the installation or in a newdirectory. The uninstaller removes the whole installation directory. If you installed Tesseract in an existing directory, thatdirectory will be removed with all its subdirectories and files.
The latest installer can be downloaded here:e (64 bit)There are also available.
In addition, we also provide which was generated by Doxygen.

import cv2import pytesseractfrom PIL import Image# Path to the Tesseract executable (replace with your path)pytesseract.pytesseract.tesseract_cmd = r'C:\Program Files\Tesseract-OCR\tesseract.exe'# Load an image containing texttext_image_path = 'path/to/your/text_image.jpg'text_image = cv2.imread(text_image_path)# Convert the image to grayscalegray_text_image = cv2.cvtColor(text_image, cv2.COLOR_BGR2GRAY)# Use thresholding to emphasize the text_, thresholded_text = cv2.threshold(gray_text_image, 150, 255, cv2.THRESH_BINARY)# Use pytesseract to perform OCR on the thresholded imagetext = pytesseract.image_to_string(Image.fromarray(thresholded_text))# Display the original image and extracted textplt.figure(figsize=(8, 6))plt.imshow(cv2.cvtColor(text_image, cv2.COLOR_BGR2RGB))plt.title('Original Image')plt.axis('off')plt.show()print("Extracted Text:")print(text)

Extracted Text:Tesseract at UB Mannheim
The Mannheim University Library (UB Mannheim) uses Tesseract to perform text recognition (OCR = optical characterrecognition) for historical German newspapers ( ' ). The latestresults with text from more than 700000 pages are available
Tesseract 


    
installer for Windows
Normally we run Tesseract on Debian GNU Linux, but there was also the need for a Windows version. That's why we have builta Tesseract installer for Windows.
WARNING: Tesseract should be either installed in the directory which is suggested during the installation or in a newdirectory. The uninstaller removes the whole installation directory. If you installed Tesseract in an existing directory, thatdirectory will be removed with all its subdirectories and files.