自学教程：Python中OpenCV实现简单车牌字符切割

import cv2import numpy as npimport matplotlib.pyplot as pltfrom PIL import Image#读取原图片image1=cv2.imread("123456.jpg")cv2.imshow("image1", image1)#灰度化处理image1_1=cv2.cvtColor(image1,cv2.COLOR_BGR2GRAY)cv2.imshow("image1_1", image1_1)#图像反色h,w = image1_1.shapeimage1_2=image1_1.copy()for i in range(h):    for j in range(w):        image1_2[i,j] = 255-image1_2[i,j]cv2.imshow('image1_2', image1_2)#图像二值化ret,image2 = cv2.threshold(image1_2, 100, 255, cv2.THRESH_BINARY)cv2.imshow('image2', image2)#水平投影h1,w1=image2.shape #返回高和宽image3=image2.copy()a = [0 for z in range(0, h1)] #初始化一个长度为w的数组，用于记录每一行的黑点个数 #记录每一行的波峰for j in range(0,h1):      for i in range(0,w1):          if  image3[j,i]==0:             a[j]+=1             image3[j,i]=255            for j in range(0,h1):      for i in range(0,a[j]):           image3[j,i]=0            plt.imshow(image3,cmap=plt.gray())#灰度图正确的表示方法plt.show()cv2.imshow('image3',image3)  #垂直投影h2,w2=image2.shape #返回高和宽image4=image2.copy()b = [0 for z in range(0, w2)]  #b = [0,0,0,0,0,0,0,0,0,0,...,0,0]初始化一个长度为w的数组，用于记录每一列的黑点个数#记录每一列的波峰for j in range(0,w2): #遍历一列     for i in range(0,h2):  #遍历一行        if  image4[i,j]==0:  #如果该点为黑点            b[j]+=1  #该列的计数器加一，最后统计出每一列的黑点个数              image4[i,j]=255  #记录完后将其变为白色，相当于擦去原图黑色部分            for j in range(0,w2):      for i in range((h2-b[j]),h2):  #从该列应该变黑的最顶部的点开始向最底部涂黑        image4[i,j]=0   #涂黑        plt.imshow(image4,cmap=plt.gray())plt.show()cv2.imshow('image4',image4) #分割字符Position = []start = 0a_Start = []a_End = []#根据水平投影获取垂直分割位置for i in range(len(a)):    if a[i] > 0 and start ==0:        a_Start.append(i)        start = 1    if a[i] <= 0 and start == 1:        a_End.append(i)        start = 0#分割行，分割之后再进行列分割并保存分割位置for i in range(len(a_Start)):    #获取行图像    cropImg = image2[a_Start[i]:a_End[i], 0:w1]    #对行图像进行垂直投影    bstart = 0    bend = 0    b_Start = 0    b_End = 0    for j in range(len(b)):        if b[j] > 0 and bstart ==0:            b_Start =j            bstart = 1            bend=0        if b[j] <= 0 and bstart == 1:            b_End =j            bstart = 0            bend=1        if bend == 1:            Position.append([b_Start,a_Start[i],b_End,a_End[i]])            bend =0image2 = cv2.cvtColor(image2, cv2.COLOR_BGR2RGB)#将灰度图转为RGB彩图#根据确定的位置分割字符for m in range(len(Position)):    cv2.rectangle(image2, (Position[m][0],Position[m][1]), (Position[m][2],Position[m][3]), (0, 0, 255), 2)#第一个参数是原图；第二个参数是矩阵的左上点坐标；第三个参数是矩阵的右下点坐标；第四个参数是画线对应的rgb颜色；第五个参数是所画的线的宽度cv2.imshow('rect',image2)cv2.waitKey(0)