如何调整tesseract以更准确地识别汽车的车牌? [英] How to tune tesseract for identifying number plate of a car more accurately?
问题描述
我有一个代码可以检测和识别车牌，并使用tesseract将图像转换为文本. 我正在使用openCV本地化车牌. 我面临的问题是，tesseract无法准确识别号码.有什么方法可以改善tesseract的性能吗?
I have a code to detect and identify the car number plate and convert the image into text using tesseract. I am using openCV to localise the number plate. The problem that I am facing is that tesseract is not accurately identifying the number. Is there any way I can improve the tesseract performance?
我的代码(我从Internet下载的)是:
My code (which I downloaded from Internet) is:
import numpy as np
import cv2
# from copy import deepcopy
from PIL import Image
import pytesseract as tess
# plate = 0
def preprocess(img):
# print ('preprocessing image')
# cv2.imshow("Input", img)
imgBlurred = cv2.GaussianBlur(img, (5, 5), 0)
gray = cv2.cvtColor(imgBlurred, cv2.COLOR_BGR2GRAY)
sobelx = cv2.Sobel(gray, cv2.CV_8U, 1, 0, ksize=3)
cv2.imshow("Sobel",sobelx)
cv2.waitKey(0)
ret2, threshold_img = cv2.threshold(sobelx, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)
cv2.imshow("Threshold",threshold_img)
cv2.waitKey(0)
return threshold_img
def cleanPlate(plate):
# print ("CLEANING PLATE. . .")
gray = cv2.cvtColor(plate, cv2.COLOR_BGR2GRAY)
kernel = cv2.getStructuringElement(cv2.MORPH_CROSS, (3, 3))
thresh= cv2.dilate(gray, kernel, iterations=1)
_, thresh = cv2.threshold(gray, 150, 255, cv2.THRESH_BINARY)
im1, contours, hierarchy = cv2.findContours(thresh.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE)
if contours:
areas = [cv2.contourArea(c) for c in contours]
max_index = np.argmax(areas)
max_cnt = contours[max_index]
max_cntArea = areas[max_index]
x, y, w, h = cv2.boundingRect(max_cnt)
if not ratioCheck(max_cntArea, w, h):
return plate, None
cleaned_final = thresh[y:y + h, x:x + w]
# cv2.imshow("Function Test",cleaned_final)
return cleaned_final, [x, y, w, h]
else:
return plate, None
def extract_contours(threshold_img):
# print ('extracting contours')
element = cv2.getStructuringElement(shape=cv2.MORPH_RECT, ksize=(17, 3))
morph_img_threshold = threshold_img.copy()
cv2.morphologyEx(src=threshold_img, op=cv2.MORPH_CLOSE, kernel=element, dst=morph_img_threshold)
cv2.imshow("Morphed", morph_img_threshold)
cv2.waitKey(0)
im2, contours, hierarchy = cv2.findContours(morph_img_threshold, mode=cv2.RETR_EXTERNAL,
method=cv2.CHAIN_APPROX_NONE)
return contours
def ratioCheck(area, width, height):
# print ('checking ratio')
ratio = float(width) / float(height)
if ratio < 1:
ratio = 1 / ratio
aspect = 4.7272
min = 15 * aspect * 15 # minimum area
max = 125 * aspect * 125 # maximum area
rmin = 3
rmax = 6
if (area < min or area > max) or (ratio < rmin or ratio > rmax):
return False
return True
def isMaxWhite(plate):
# print ('is Max white')
avg = np.mean(plate)
if (avg >= 115):
return True
else:
return False
def validateRotationAndRatio(rect):
# print( 'validate the rotation and ratio')
(x, y), (width, height), rect_angle = rect
if (width > height):
angle = -rect_angle
else:
angle = 90 + rect_angle
if angle > 15:
return False
if height == 0 or width == 0:
return False
area = height * width
if not ratioCheck(area, width, height):
return False
else:
return True
def cleanAndRead(img, contours):
# print ('clean and read')
# count=0
for i, cnt in enumerate(contours):
min_rect = cv2.minAreaRect(cnt)
if validateRotationAndRatio(min_rect):
x, y, w, h = cv2.boundingRect(cnt)
plate_img = img[y:y + h, x:x + w]
if (isMaxWhite(plate_img)):
# count+=1
clean_plate, rect = cleanPlate(plate_img)
if rect:
x1, y1, w1, h1 = rect
x, y, w, h = x + x1, y + y1, w1, h1
cv2.imshow("Cleaned Plate", clean_plate)
cv2.waitKey(0)
plate_im = Image.fromarray(clean_plate)
plate_im.save('donald1.png')
text = tess.image_to_string(plate_im, lang='eng')
# print text
img = cv2.rectangle(img, (x, y), (x + w, y + h), (0, 255, 0), 2)
cv2.imshow("Detected Plate", img)
cv2.waitKey(0)
return text
numberplate = 0
img = cv2.imread("car_number_plate.jpg")
threshold_img = preprocess(img)
contours = extract_contours(threshold_img)
# if len(contours)!=0:
# print len(contours) #Test
# cv2.drawContours(img, contours, -1, (0,255,0), 1)
# cv2.imshow("Contours",img)
# cv2.waitKey(0)
plate = cleanAndRead(img, contours)
print ('plate information: ', plate)
如果我的车牌号是:MH01AV8866
If my number plate is: MH01AV8866
它将被识别为MH01AY8866
It will be recognised as MH01AY8866
任何建议将不胜感激.让我知道是否还需要其他信息.
Any suggestion will be appreciated. Let me know if any other information is required too.
推荐答案
您正在使用tesseract作为解决问题的通用模型，您可以为此调整模型，以便为此生成车牌的综合数据
You are using tesseract as a general model for your problem you can tune your model for that you need to generate synthetic data for your number plates with this
https://github.com/Belval/TextRecognitionDataGenerator
然后您可以按照提供的步骤调整模型
and then you can tune your model using the steps provided
https://github.com/tesseract-ocr /tesseract/wiki/TrainingTesseract-4.00---Finetune
https://github.com/tesseract-ocr/tesseract/wiki /TrainingTesseract-4.00
我已经对合成数据上的tesseract进行了调整，它就像一个魅力一样，尝试了CNN模型和tesseract两者，并且tesseract在较少的数据下训练得更好，并提供了更好的性能.
I've tuned the tesseract on synthetic data and it works like a charm, tried CNN models and tesseract both and tesseract trains better with lesser data and gives better performance.
这篇关于如何调整tesseract以更准确地识别汽车的车牌?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
