需求分析: 车牌识别技术主要应用领域有停车场收费管理,交通流量控制指标测量,车辆定位,汽车防盗,高速公路超速自动化监管、闯红灯电子警察、公路收费站等等功能。对于维护交通安全和城市治安,防止交通堵塞,实现交通自动化管理有着现实的意义。 车牌自
车牌识别技术主要应用领域有停车场收费管理,交通流量控制指标测量,车辆定位,汽车防盗,高速公路超速自动化监管、闯红灯电子警察、公路收费站等等功能。对于维护交通安全和城市治安,防止交通堵塞,实现交通自动化管理有着现实的意义。
车牌自动识别系统应用的主要技术
车牌识别的技术难点
误定位一直是汽车牌照定位方面的研究重点。汽车牌照分割方面的研究方向一直是如何获得良好的汽车牌照分割,以及如何快速地实现汽车牌照倾斜度校正的基础。
之所以要进行预处理,主要是为了得到一个比较准确清晰的图像,以便于后期相关分析工作在图像中进行。
生成的灰度图
在汽车牌照定位之前,可以通过采用直方图均衡化的方法来实现车牌图像亮度接近化的转换处理。
通常情况下,首先,图像会因为采集时大气湍流、相对运动以及光学系统失真等因素的影响而变得模糊。
图像增强处理的一种常见的方法是图像滤波。
操作模板的形式为:
确定一个合适阈值,是对图像进行二值化处理的主要目的,待研究的区域经过二值化处理后将被分为背景以及前景两个部分。
两个灰度值不同的相邻区域之间总会存在边缘,也就是图像中亮度函数发生急剧变化的位置,边缘检测是图像分割、纹理和形状特征提取等图像分析的基础。
灰度映射是一种对像素点的操作,即根据原始图像中每个像素的灰度值,按照某种映射规则将其转化为另外一个灰度值,通过对原始图像中每个像素点赋予一个新的灰度值,来达到增强图像的目的。
基于识别基础的车牌字符分割法
垂直投影分割方法
自适应分割线聚类法
通常汽车牌照图像的倾斜校正主要分为垂直倾斜校正和水平倾斜校正两种,如此划分的依据是汽车牌照图像倾斜的类型。
我们采用基于行扫描的灰度值跳变点数目变化率来判断车牌是否水平。
该方法主要是运用两个坐标系之间的变换来实现的;对于倾斜角度在整幅图像上的设定,该方法主要是通过对图像中直线的倾斜角度进行判断来实现的。
对车牌图像进行逐行扫描,当扫描到某一行白色像素点宽度大于某一个阈值时,可以认为是字符边沿处,去除这一行以下或以上的所有行就可以消除铆钉和边框的干扰。
整个字符分割过程需要考虑如下问题:
计算垂直投影
初步垂直切分
在初步垂直切分中,字符的断裂和粘连现象先不被考虑,进行提取的只是在投影图中已经分离的那些区域。
在低质量车牌图像中,二值化处理后出现的字符粘连现象有时无法被任何一种分割方法所消除,有时利用垂直投影也无法分割那些粘连的字符,造成这种状况的主要原因是有时存在大量的噪声。
先将每两个相邻块之间的距离计算出来,在一定的阈值大于这个距离的情况下,可以认为这两个块属于同一个字符并执行块合并过程。
字符结果确认机制的具体实现步骤:
影响并导致汽车牌照内字符出现缺损、污染、模糊等情况的常见因素有照相机的性能、采集车辆图像时光照的差异、汽车牌照的清洁度。
模式就是一种对某种对象(一些敏感的客体)结构或者定量的描述,是一种集合(由具有某些共同特定性质的模式构成)。
目前模式识别主要有4种方法:
基于神经网络的识别方法
基于特征分析的匹配方法
基于模版的匹配方法
目前,小波识别法、模板匹配法与神经网络法等常被作为汽车牌照字符识别的主要方法。
相较于数字和英文字符的识别,汽车牌照中的汉字字符识别的难度更大,主要原因有以下4个方面:
字符笔画因切分误差导致非笔画或笔画流失。
汽车牌照被污染导致字符上出现污垢。
采集所得车辆图像分辨率低下导致多笔画的汉字较难分辨。
车辆图像采集时所受光照影响的差异导致笔画较淡。
import cv2import numpy as npdef stretch(img): ''' 图像拉伸函数 ''' maxi = float(img.max()) mini = float(img.min()) for i in range(img.shape[0]): for j in range(img.shape[1]): img[i, j] = (255 / (maxi - mini) * img[i, j] - (255 * mini) / (maxi - mini)) return imgdef dobinaryzation(img): ''' 二值化处理函数 ''' maxi = float(img.max()) mini = float(img.min()) x = maxi - ((maxi - mini) / 2) # 二值化,返回阈值ret 和 二值化操作后的图像thresh ret, thresh = cv2.threshold(img, x, 255, cv2.THRESH_BINARY) # 返回二值化后的黑白图像 return threshdef find_rectangle(contour): ''' 寻找矩形轮廓 ''' y, x = [], [] for p in contour: y.append(p[0][0]) x.append(p[0][1]) return [min(y), min(x), max(y), max(x)]def locate_license(img, afterimg): ''' 定位车牌号 ''' contours, hierarchy = cv2.findContours(img, cv2.RETR_EXTERNAL, cv2.CHaiN_APPROX_SIMPLE) # 找出最大的三个区域 block = [] for c in contours: # 找出轮廓的左上点和右下点,由此计算它的面积和长度比 r = find_rectangle(c) a = (r[2] - r[0]) * (r[3] - r[1]) # 面积 s = (r[2] - r[0]) * (r[3] - r[1]) # 长度比 block.append([r, a, s]) # 选出面积最大的3个区域 block = sorted(block, key=lambda b: b[1])[-3:] # 使用颜色识别判断找出最像车牌的区域 maxweight, maxindex = 0, -1 for i in range(len(block)): b = afterimg[block[i][0][1]:block[i][0][3], block[i][0][0]:block[i][0][2]] # BGR转HSV hsv = cv2.cvtColor(b, cv2.COLOR_BGR2HSV) # 蓝色车牌的范围 lower = np.array([100, 50, 50]) upper = np.array([140, 255, 255]) # 根据阈值构建掩膜 mask = cv2.inRange(hsv, lower, upper) # 统计权值 w1 = 0 for m in mask: w1 += m / 255 w2 = 0 for n in w1: w2 += n # 选出最大权值的区域 if w2 > maxweight: maxindex = i maxweight = w2 return block[maxindex][0]def find_license(img): ''' 预处理函数 ''' m = 400 * img.shape[0] / img.shape[1] # 压缩图像 img = cv2.resize(img, (400, int(m)), interpolation=cv2.INTER_CUBIC) # BGR转换为灰度图像 gray_img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) # 灰度拉伸 stretchedimg = stretch(gray_img) '''进行开运算,用来去除噪声''' r = 16 h = w = r * 2 + 1 kernel = np.zeros((h, w), np.uint8) cv2.circle(kernel, (r, r), r, 1, -1) # 开运算 openingimg = cv2.morphologyEx(stretchedimg, cv2.MORPH_OPEN, kernel) # 获取差分图,两幅图像做差 cv2.absdiff('图像1','图像2') strtimg = cv2.absdiff(stretchedimg, openingimg) # 图像二值化 binaryimg = dobinaryzation(strtimg) # canny边缘检测 canny = cv2.Canny(binaryimg, binaryimg.shape[0], binaryimg.shape[1]) '''消除小的区域,保留大块的区域,从而定位车牌''' # 进行闭运算 kernel = np.ones((5, 19), np.uint8) closingimg = cv2.morphologyEx(canny, cv2.MORPH_CLOSE, kernel) # 进行开运算 openingimg = cv2.morphologyEx(closingimg, cv2.MORPH_OPEN, kernel) # 再次进行开运算 kernel = np.ones((11, 5), np.uint8) openingimg = cv2.morphologyEx(openingimg, cv2.MORPH_OPEN, kernel) # 消除小区域,定位车牌位置 rect = locate_license(openingimg, img) return rect, imgdef cut_license(afterimg, rect): ''' 图像分割函数 ''' # 转换为宽度和高度 rect[2] = rect[2] - rect[0] rect[3] = rect[3] - rect[1] rect_copy = tuple(rect.copy()) rect = [0, 0, 0, 0] # 创建掩膜 mask = np.zeros(afterimg.shape[:2], np.uint8) # 创建背景模型 大小只能为13*5,行数只能为1,单通道浮点型 bgdModel = np.zeros((1, 65), np.float64) # 创建前景模型 fgdModel = np.zeros((1, 65), np.float64) # 分割图像 cv2.grabCut(afterimg, mask, rect_copy, bgdModel, fgdModel, 5, cv2.GC_INIT_WITH_RECT) mask2 = np.where((mask == 2) | (mask == 0), 0, 1).astype('uint8') img_show = afterimg * mask2[:, :, np.newaxis] return img_showdef deal_license(licenseimg): ''' 车牌图片二值化 ''' # 车牌变为灰度图像 gray_img = cv2.cvtColor(licenseimg, cv2.COLOR_BGR2GRAY) # 均值滤波 去除噪声 kernel = np.ones((3, 3), np.float32) / 9 gray_img = cv2.filter2D(gray_img, -1, kernel) # 二值化处理 ret, thresh = cv2.threshold(gray_img, 120, 255, cv2.THRESH_BINARY) return threshdef find_end(start, arg, black, white, width, black_max, white_max): end = start + 1 for m in range(start + 1, width - 1): if (black[m] if arg else white[m]) > (0.98 * black_max if arg else 0.98 * white_max): end = m break return endif __name__ == '__main__': img = cv2.imread('car.jpg', cv2.IMREAD_COLOR) # 预处理图像 rect, afterimg = find_license(img) # 框出车牌号 cv2.rectangle(afterimg, (rect[0], rect[1]), (rect[2], rect[3]), (0, 255, 0), 2) cv2.imshow('afterimg', afterimg) # 分割车牌与背景 cutimg = cut_license(afterimg, rect) cv2.imshow('cutimg', cutimg) # 二值化生成黑白图 thresh = deal_license(cutimg) cv2.imshow('thresh', thresh) cv2.imwrite("cp.jpg", thresh) cv2.waiTKEy(0) # 分割字符 ''' 判断底色和字色 ''' # 记录黑白像素总和 white = [] black = [] height = thresh.shape[0] # 263 width = thresh.shape[1] # 400 # print('height',height) # print('width',width) white_max = 0 black_max = 0 # 计算每一列的黑白像素总和 for i in range(width): line_white = 0 line_black = 0 for j in range(height): if thresh[j][i] == 255: line_white += 1 if thresh[j][i] == 0: line_black += 1 white_max = max(white_max, line_white) black_max = max(black_max, line_black) white.append(line_white) black.append(line_black) print('white', white) print('black', black) # arg为true表示黑底白字,False为白底黑字 arg = True if black_max < white_max: arg = False n = 1 start = 1 end = 2 while n < width - 2: n += 1 # 判断是白底黑字还是黑底白字 0.05参数对应上面的0.95 可作调整 if (white[n] if arg else black[n]) > (0.02 * white_max if arg else 0.02 * black_max): start = n end = find_end(start, arg, black, white, width, black_max, white_max) n = end if end - start > 5: cj = thresh[1:height, start:end] cv2.imshow('cutlicense', cj) cv2.waitKey(0) cv2.waitKey(0) cv2.destroyAllwindows()
运行效果:
可见车牌定位成功,下一步是识别字符。
安装步骤:
Tesseract Ocr 工具安装,下面是下载地址,下载后 用管理员安装,安装的时候注意 记住自己的安装路径。
https://www.aliyundrive.com/s/xHi1Y28LGjv
安装python pytesseract 库包
pip install pytesseract
pytesseract 配置。
找到pytesseract 刚才的安装路径,如下
然后打开这个文件,
这里填上你自己的安装路径地址,至此,字符识别开发环境就准备好了。
import cv2 as cvfrom PIL import Imageimport pytesseract as tessdef recoginse_text(image): """ 步骤: 1、灰度,二值化处理 2、形态学操作去噪 3、识别 :param image: :return: """ # 灰度 二值化 gray = cv.cvtColor(image, cv.COLOR_BGR2GRAY) # 如果是白底黑字 建议 _INV ret, binary = cv.threshold(gray, 0, 255, cv.THRESH_BINARY_INV | cv.THRESH_OTSU) # 形态学操作 (根据需要设置参数(1,2)) kernel = cv.getStructuringElement(cv.MORPH_RECT, (1, 2)) # 去除横向细线 morph1 = cv.morphologyEx(binary, cv.MORPH_OPEN, kernel) kernel = cv.getStructuringElement(cv.MORPH_RECT, (2, 1)) # 去除纵向细线 morph2 = cv.morphologyEx(morph1, cv.MORPH_OPEN, kernel) cv.imshow("Morph", morph2) # 黑底白字取非,变为白底黑字(便于pytesseract 识别) cv.bitwise_not(morph2, morph2) textImage = Image.fromarray(morph2) # 图片转文字 text = tess.image_to_string(textImage) n = 10 # 根据不同国家车牌固定数目进行设置 print("识别结果:") print(text[1:n])def main(): # 读取需要识别的数字字母图片,并显示读到的原图 src = cv.imread("cp.jpg") cv.imshow("src", src) # 识别 recoginse_text(src) cv.waitKey(0) cv.destroyAllWindows()if __name__ == "__main__": main()
运行结果:
识别结果:0226 F By
向校于数字和英文字符的识别,汽车车牌中的汉子字符识别的 难度更大。
import tkinter as tkfrom tkinter.filedialog import *from tkinter import ttkimport tkinter.messagebox as mBox#代码在下一个文件中import predictimport cv2from PIL import Image, ImageTkimport threadingimport timeclass Surface(ttk.Frame): pic_path = "" viewhigh = 600 viewwide = 600 update_time = 0 thread = None thread_run = False camera = None color_transfORM = {"green": ("绿牌", "#55FF55"), "yello": ("黄牌", "#FFFF00"), "blue": ("蓝牌", "#6666FF")} def __init__(self, win): ttk.Frame.__init__(self, win) frame_left = ttk.Frame(self) frame_right1 = ttk.Frame(self) frame_right2 = ttk.Frame(self) win.title("车牌识别") win.state("zoomed") self.pack(fill=tk.BOTH, expand=tk.YES, padx="5", pady="5") frame_left.pack(side=tk.LEFT, expand=1, fill=tk.BOTH) frame_right1.pack(side=tk.TOP, expand=1, fill=tk.Y) frame_right2.pack(side=tk.RIGHT, expand=0) ttk.Label(frame_left, text='原图:').pack(anchor="nw") ttk.Label(frame_right1, text='车牌位置:').grid(column=0, row=0, sticky=tk.W) from_pic_ctl = ttk.Button(frame_right2, text="来自图片", width=20, command=self.from_pic) from_vedio_ctl = ttk.Button(frame_right2, text="来自摄像头", width=20, command=self.from_vedio) self.image_ctl = ttk.Label(frame_left) self.image_ctl.pack(anchor="nw") self.roi_ctl = ttk.Label(frame_right1) self.roi_ctl.grid(column=0, row=1, sticky=tk.W) ttk.Label(frame_right1, text='识别结果:').grid(column=0, row=2, sticky=tk.W) self.r_ctl = ttk.Label(frame_right1, text="") self.r_ctl.grid(column=0, row=3, sticky=tk.W) self.color_ctl = ttk.Label(frame_right1, text="", width="20") self.color_ctl.grid(column=0, row=4, sticky=tk.W) from_vedio_ctl.pack(anchor="se", pady="5") from_pic_ctl.pack(anchor="se", pady="5") self.predictor = predict.CardPredictor() self.predictor.train_svm() def get_imgtk(self, img_bgr): img = cv2.cvtColor(img_bgr, cv2.COLOR_BGR2RGB) im = Image.fromarray(img) imgtk = ImageTk.PhotoImage(image=im) wide = imgtk.width() high = imgtk.height() if wide > self.viewwide or high > self.viewhigh: wide_factor = self.viewwide / wide high_factor = self.viewhigh / high factor = min(wide_factor, high_factor) wide = int(wide * factor) if wide <= 0: wide = 1 high = int(high * factor) if high <= 0: high = 1 im = im.resize((wide, high), Image.LANCZOS) # 在pillow的10.0.0版本中,ANTIALIAS方法被删除了,使用新的方法即可: imgtk = ImageTk.PhotoImage(image=im) return imgtk def show_roi(self, r, roi, color): if r: roi = cv2.cvtColor(roi, cv2.COLOR_BGR2RGB) roi = Image.fromarray(roi) self.imgtk_roi = ImageTk.PhotoImage(image=roi) self.roi_ctl.configure(image=self.imgtk_roi, state='enable') self.r_ctl.configure(text=str(r)) self.update_time = time.time() try: c = self.color_transform[color] self.color_ctl.configure(text=c[0], background=c[1], state='enable') except: self.color_ctl.configure(state='disabled') elif self.update_time + 8 < time.time(): self.roi_ctl.configure(state='disabled') self.r_ctl.configure(text="") self.color_ctl.configure(state='disabled') def from_vedio(self): if self.thread_run: return if self.camera is None: self.camera = cv2.VideoCapture(0) if not self.camera.isOpened(): mBox.showwarning('警告', '摄像头打开失败!') self.camera = None return self.thread = threading.Thread(target=self.vedio_thread, args=(self,)) self.thread.setDaemon(True) self.thread.start() self.thread_run = True def from_pic(self): self.thread_run = False self.pic_path = askopenfilename(title="选择识别图片", filetypes=[("jpg图片", "*.jpg")]) if self.pic_path: img_bgr = predict.imreadex(self.pic_path) self.imgtk = self.get_imgtk(img_bgr) self.image_ctl.configure(image=self.imgtk) resize_rates = (1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4) for resize_rate in resize_rates: print("resize_rate:", resize_rate) try: r, roi, color = self.predictor.predict(img_bgr, resize_rate) except: continue if r: break # r, roi, color = self.predictor.predict(img_bgr, 1) self.show_roi(r, roi, color) @staticmethod def vedio_thread(self): self.thread_run = True predict_time = time.time() while self.thread_run: _, img_bgr = self.camera.read() self.imgtk = self.get_imgtk(img_bgr) self.image_ctl.configure(image=self.imgtk) if time.time() - predict_time > 2: r, roi, color = self.predictor.predict(img_bgr) self.show_roi(r, roi, color) predict_time = time.time() print("run end")def close_window(): print("destroy") if surface.thread_run: surface.thread_run = False surface.thread.join(2.0) win.destroy()if __name__ == '__main__': win = tk.Tk() surface = Surface(win) win.protocol('WM_DELETE_WINDOW', close_window) win.mainloop()
在上述代码中,先使用图像边缘和车牌颜色定位车牌再识别字符。车牌字符识别使用的算法是OpenCV 的SVM,车牌字符识别在predict方法(perdict.py )中实现,代码如下:
import cv2import numpy as npfrom numpy.linalg import normimport sysimport osimport JSONSZ = 20 #训练图片长宽MAX_WIDTH = 1000 #原始图片最大宽度Min_Area = 2000 #车牌区域允许最大面积PROVINCE_START = 1000#读取图片文件def imreadex(filename):return cv2.imdecode(np.fromfile(filename, dtype=np.uint8), cv2.IMREAD_COLOR)def point_limit(point):if point[0] < 0:point[0] = 0if point[1] < 0:point[1] = 0#根据设定的阈值和图片直方图,找出波峰,用于分隔字符def find_waves(threshold, histogram):up_point = -1#上升点is_peak = Falseif histogram[0] > threshold:up_point = 0is_peak = Truewave_peaks = []for i,x in enumerate(histogram):if is_peak and x < threshold:if i - up_point > 2:is_peak = Falsewave_peaks.append((up_point, i))elif not is_peak and x >= threshold:is_peak = Trueup_point = iif is_peak and up_point != -1 and i - up_point > 4:wave_peaks.append((up_point, i))return wave_peaks#根据找出的波峰,分隔图片,从而得到逐个字符图片def seperate_card(img, waves):part_cards = []for wave in waves:part_cards.append(img[:, wave[0]:wave[1]])return part_cards#来自opencv的sample,用于svm训练def deskew(img):m = cv2.moments(img)if abs(m['mu02']) < 1e-2:return img.copy()skew = m['mu11']/m['mu02']M = np.float32([[1, skew, -0.5*SZ*skew], [0, 1, 0]])img = cv2.warpAffine(img, M, (SZ, SZ), flags=cv2.WARP_INVERSE_MAP | cv2.INTER_LINEAR)return img#来自opencv的sample,用于svm训练def preprocess_hog(digits):samples = []for img in digits:gx = cv2.Sobel(img, cv2.CV_32F, 1, 0)gy = cv2.Sobel(img, cv2.CV_32F, 0, 1)mag, ang = cv2.cartToPolar(gx, gy)bin_n = 16bin = np.int32(bin_n*ang/(2*np.pi))bin_cells = bin[:10,:10], bin[10:,:10], bin[:10,10:], bin[10:,10:]mag_cells = mag[:10,:10], mag[10:,:10], mag[:10,10:], mag[10:,10:]hists = [np.bincount(b.ravel(), m.ravel(), bin_n) for b, m in zip(bin_cells, mag_cells)]hist = np.hstack(hists)# transform to Hellinger kerneleps = 1e-7hist /= hist.sum() + epshist = np.sqrt(hist)hist /= norm(hist) + epssamples.append(hist)return np.float32(samples)#不能保证包括所有省份provinces = ["zh_cuan", "川","zh_e", "鄂","zh_gan", "赣","zh_gan1", "甘","zh_gui", "贵","zh_gui1", "桂","zh_hei", "黑","zh_hu", "沪","zh_ji", "冀","zh_jin", "津","zh_jing", "京","zh_jl", "吉","zh_liao", "辽","zh_lu", "鲁","zh_meng", "蒙","zh_min", "闽","zh_ning", "宁","zh_qing", "靑","zh_qiong", "琼","zh_shan", "陕","zh_su", "苏","zh_sx", "晋","zh_wan", "皖","zh_xiang", "湘","zh_xin", "新","zh_yu", "豫","zh_yu1", "渝","zh_yue", "粤","zh_yun", "云","zh_zang", "藏","zh_zhe", "浙"]class StatModel(object):def load(self, fn):self.model = self.model.load(fn) def save(self, fn):self.model.save(fn)class SVM(StatModel):def __init__(self, C = 1, gamma = 0.5):self.model = cv2.ml.SVM_create()self.model.setGamma(gamma)self.model.setC(C)self.model.setKernel(cv2.ml.SVM_RBF)self.model.setType(cv2.ml.SVM_C_SVC)#训练svmdef train(self, samples, responses):self.model.train(samples, cv2.ml.ROW_SAMPLE, responses)#字符识别def predict(self, samples):r = self.model.predict(samples)return r[1].ravel()class CardPredictor:def __init__(self):#车牌识别的部分参数保存在js中,便于根据图片分辨率做调整f = open('config.js')j = json.load(f)for c in j["config"]:if c["open"]:self.cfg = c.copy()breakelse:raise RuntimeError('没有设置有效配置参数')def __del__(self):self.save_traindata()def train_svm(self):#识别英文字母和数字self.model = SVM(C=1, gamma=0.5)#识别中文self.modelchinese = SVM(C=1, gamma=0.5)if os.path.exists("svm.dat"):self.model.load("svm.dat")else:chars_train = []chars_label = []for root, dirs, files in os.walk("train\\chars2"):if len(os.path.basename(root)) > 1:continueroot_int = ord(os.path.basename(root))for filename in files:filepath = os.path.join(root,filename)digit_img = cv2.imread(filepath)digit_img = cv2.cvtColor(digit_img, cv2.COLOR_BGR2GRAY)chars_train.append(digit_img)#chars_label.append(1)chars_label.append(root_int)chars_train = list(map(deskew, chars_train))chars_train = preprocess_hog(chars_train)#chars_train = chars_train.reshape(-1, 20, 20).astype(np.float32)chars_label = np.array(chars_label)self.model.train(chars_train, chars_label)if os.path.exists("svmchinese.dat"):self.modelchinese.load("svmchinese.dat")else:chars_train = []chars_label = []for root, dirs, files in os.walk("train\\charsChinese"):if not os.path.basename(root).startswith("zh_"):continuepinyin = os.path.basename(root)index = provinces.index(pinyin) + PROVINCE_START + 1 #1是拼音对应的汉字for filename in files:filepath = os.path.join(root,filename)digit_img = cv2.imread(filepath)digit_img = cv2.cvtColor(digit_img, cv2.COLOR_BGR2GRAY)chars_train.append(digit_img)#chars_label.append(1)chars_label.append(index)chars_train = list(map(deskew, chars_train))chars_train = preprocess_hog(chars_train)#chars_train = chars_train.reshape(-1, 20, 20).astype(np.float32)chars_label = np.array(chars_label)print(chars_train.shape)self.modelchinese.train(chars_train, chars_label)def save_traindata(self):if not os.path.exists("svm.dat"):self.model.save("svm.dat")if not os.path.exists("svmchinese.dat"):self.modelchinese.save("svmchinese.dat")def accurate_place(self, card_img_hsv, limit1, limit2, color):row_num, col_num = card_img_hsv.shape[:2]xl = col_numxr = 0yh = 0yl = row_num#col_num_limit = self.cfg["col_num_limit"]row_num_limit = self.cfg["row_num_limit"]col_num_limit = col_num * 0.8 if color != "green" else col_num * 0.5#绿色有渐变for i in range(row_num):count = 0for j in range(col_num):H = card_img_hsv.item(i, j, 0)S = card_img_hsv.item(i, j, 1)V = card_img_hsv.item(i, j, 2)if limit1 < H <= limit2 and 34 < S and 46 < V:count += 1if count > col_num_limit:if yl > i:yl = iif yh < i:yh = ifor j in range(col_num):count = 0for i in range(row_num):H = card_img_hsv.item(i, j, 0)S = card_img_hsv.item(i, j, 1)V = card_img_hsv.item(i, j, 2)if limit1 < H <= limit2 and 34 < S and 46 < V:count += 1if count > row_num - row_num_limit:if xl > j:xl = jif xr < j:xr = jreturn xl, xr, yh, yldef predict(self, car_pic, resize_rate=1):if type(car_pic) == type(""):img = imreadex(car_pic)else:img = car_picpic_hight, pic_width = img.shape[:2]if pic_width > MAX_WIDTH:pic_rate = MAX_WIDTH / pic_widthimg = cv2.resize(img, (MAX_WIDTH, int(pic_hight*pic_rate)), interpolation=cv2.INTER_LANCZOS4)pic_hight, pic_width = img.shape[:2]if resize_rate != 1:img = cv2.resize(img, (int(pic_width*resize_rate), int(pic_hight*resize_rate)), interpolation=cv2.INTER_LANCZOS4)pic_hight, pic_width = img.shape[:2]print("h,w:", pic_hight, pic_width)blur = self.cfg["blur"]#高斯去噪if blur > 0:img = cv2.GaussianBlur(img, (blur, blur), 0)#图片分辨率调整oldimg = imgimg = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)#equ = cv2.equalizeHist(img)#img = np.hstack((img, equ))#去掉图像中不会是车牌的区域kernel = np.ones((20, 20), np.uint8)img_opening = cv2.morphologyEx(img, cv2.MORPH_OPEN, kernel)img_opening = cv2.addWeighted(img, 1, img_opening, -1, 0);#找到图像边缘ret, img_thresh = cv2.threshold(img_opening, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)img_edge = cv2.Canny(img_thresh, 100, 200)#使用开运算和闭运算让图像边缘成为一个整体kernel = np.ones((self.cfg["morphologyr"], self.cfg["morphologyc"]), np.uint8)img_edge1 = cv2.morphologyEx(img_edge, cv2.MORPH_CLOSE, kernel)img_edge2 = cv2.morphologyEx(img_edge1, cv2.MORPH_OPEN, kernel)#查找图像边缘整体形成的矩形区域,可能有很多,车牌就在其中一个矩形区域中try:contours, hierarchy = cv2.findContours(img_edge2, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)except ValueError:image, contours, hierarchy = cv2.findContours(img_edge2, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)contours = [cnt for cnt in contours if cv2.contourArea(cnt) > Min_Area]print('len(contours)', len(contours))#一一排除不是车牌的矩形区域car_contours = []for cnt in contours:rect = cv2.minAreaRect(cnt)area_width, area_height = rect[1]if area_width < area_height:area_width, area_height = area_height, area_widthwh_ratio = area_width / area_height#print(wh_ratio)#要求矩形区域长宽比在2到5.5之间,2到5.5是车牌的长宽比,其余的矩形排除if wh_ratio > 2 and wh_ratio < 5.5:car_contours.append(rect)box = cv2.boxPoints(rect)box = np.int0(box)#oldimg = cv2.drawContours(oldimg, [box], 0, (0, 0, 255), 2)#cv2.imshow("edge4", oldimg)#cv2.waitKey(0)print(len(car_contours))print("精确定位")card_imgs = []#矩形区域可能是倾斜的矩形,需要矫正,以便使用颜色定位for rect in car_contours:if rect[2] > -1 and rect[2] < 1:#创造角度,使得左、高、右、低拿到正确的值angle = 1else:angle = rect[2]rect = (rect[0], (rect[1][0]+5, rect[1][1]+5), angle)#扩大范围,避免车牌边缘被排除box = cv2.boxPoints(rect)heigth_point = right_point = [0, 0]left_point = low_point = [pic_width, pic_hight]for point in box:if left_point[0] > point[0]:left_point = pointif low_point[1] > point[1]:low_point = pointif heigth_point[1] < point[1]:heigth_point = pointif right_point[0] < point[0]:right_point = pointif left_point[1] <= right_point[1]:#正角度new_right_point = [right_point[0], heigth_point[1]]pts2 = np.float32([left_point, heigth_point, new_right_point])#字符只是高度需要改变pts1 = np.float32([left_point, heigth_point, right_point])M = cv2.getAffineTransform(pts1, pts2)dst = cv2.warpAffine(oldimg, M, (pic_width, pic_hight))point_limit(new_right_point)point_limit(heigth_point)point_limit(left_point)card_img = dst[int(left_point[1]):int(heigth_point[1]), int(left_point[0]):int(new_right_point[0])]card_imgs.append(card_img)#cv2.imshow("card", card_img)#cv2.waitKey(0)elif left_point[1] > right_point[1]:#负角度new_left_point = [left_point[0], heigth_point[1]]pts2 = np.float32([new_left_point, heigth_point, right_point])#字符只是高度需要改变pts1 = np.float32([left_point, heigth_point, right_point])M = cv2.getAffineTransform(pts1, pts2)dst = cv2.warpAffine(oldimg, M, (pic_width, pic_hight))point_limit(right_point)point_limit(heigth_point)point_limit(new_left_point)card_img = dst[int(right_point[1]):int(heigth_point[1]), int(new_left_point[0]):int(right_point[0])]card_imgs.append(card_img)#cv2.imshow("card", card_img)#cv2.waitKey(0)#开始使用颜色定位,排除不是车牌的矩形,目前只识别蓝、绿、黄车牌colors = []for card_index,card_img in enumerate(card_imgs):green = yello = blue = black = white = 0card_img_hsv = cv2.cvtColor(card_img, cv2.COLOR_BGR2HSV)#有转换失败的可能,原因来自于上面矫正矩形出错if card_img_hsv is None:continuerow_num, col_num= card_img_hsv.shape[:2]card_img_count = row_num * col_numfor i in range(row_num):for j in range(col_num):H = card_img_hsv.item(i, j, 0)S = card_img_hsv.item(i, j, 1)V = card_img_hsv.item(i, j, 2)if 11 < H <= 34 and S > 34:#图片分辨率调整yello += 1elif 35 < H <= 99 and S > 34:#图片分辨率调整green += 1elif 99 < H <= 124 and S > 34:#图片分辨率调整blue += 1if 0 < H <180 and 0 < S < 255 and 0 < V < 46:black += 1elif 0 < H <180 and 0 < S < 43 and 221 < V < 225:white += 1color = "no"limit1 = limit2 = 0if yello*2 >= card_img_count:color = "yello"limit1 = 11limit2 = 34#有的图片有色偏偏绿elif green*2 >= card_img_count:color = "green"limit1 = 35limit2 = 99elif blue*2 >= card_img_count:color = "blue"limit1 = 100limit2 = 124#有的图片有色偏偏紫elif black + white >= card_img_count*0.7:#TODOcolor = "bw"print(color)colors.append(color)print(blue, green, yello, black, white, card_img_count)#cv2.imshow("color", card_img)#cv2.waitKey(0)if limit1 == 0:continue#以上为确定车牌颜色#以下为根据车牌颜色再定位,缩小边缘非车牌边界xl, xr, yh, yl = self.accurate_place(card_img_hsv, limit1, limit2, color)if yl == yh and xl == xr:continueneed_accurate = Falseif yl >= yh:yl = 0yh = row_numneed_accurate = Trueif xl >= xr:xl = 0xr = col_numneed_accurate = Truecard_imgs[card_index] = card_img[yl:yh, xl:xr] if color != "green" or yl < (yh-yl)//4 else card_img[yl-(yh-yl)//4:yh, xl:xr]if need_accurate:#可能x或y方向未缩小,需要再试一次card_img = card_imgs[card_index]card_img_hsv = cv2.cvtColor(card_img, cv2.COLOR_BGR2HSV)xl, xr, yh, yl = self.accurate_place(card_img_hsv, limit1, limit2, color)if yl == yh and xl == xr:continueif yl >= yh:yl = 0yh = row_numif xl >= xr:xl = 0xr = col_numcard_imgs[card_index] = card_img[yl:yh, xl:xr] if color != "green" or yl < (yh-yl)//4 else card_img[yl-(yh-yl)//4:yh, xl:xr]#以上为车牌定位#以下为识别车牌中的字符predict_result = []roi = Nonecard_color = Nonefor i, color in enumerate(colors):if color in ("blue", "yello", "green"):card_img = card_imgs[i]gray_img = cv2.cvtColor(card_img, cv2.COLOR_BGR2GRAY)#黄、绿车牌字符比背景暗、与蓝车牌刚好相反,所以黄、绿车牌需要反向if color == "green" or color == "yello":gray_img = cv2.bitwise_not(gray_img)ret, gray_img = cv2.threshold(gray_img, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)#查找水平直方图波峰x_histogram = np.sum(gray_img, axis=1)x_min = np.min(x_histogram)x_average = np.sum(x_histogram)/x_histogram.shape[0]x_threshold = (x_min + x_average)/2wave_peaks = find_waves(x_threshold, x_histogram)if len(wave_peaks) == 0:print("peak less 0:")continue#认为水平方向,最大的波峰为车牌区域wave = max(wave_peaks, key=lambda x:x[1]-x[0])gray_img = gray_img[wave[0]:wave[1]]#查找垂直直方图波峰row_num, col_num= gray_img.shape[:2]#去掉车牌上下边缘1个像素,避免白边影响阈值判断gray_img = gray_img[1:row_num-1]y_histogram = np.sum(gray_img, axis=0)y_min = np.min(y_histogram)y_average = np.sum(y_histogram)/y_histogram.shape[0]y_threshold = (y_min + y_average)/5#U和0要求阈值偏小,否则U和0会被分成两半wave_peaks = find_waves(y_threshold, y_histogram)#for wave in wave_peaks:#cv2.line(card_img, pt1=(wave[0], 5), pt2=(wave[1], 5), color=(0, 0, 255), thickness=2) #车牌字符数应大于6if len(wave_peaks) <= 6:print("peak less 1:", len(wave_peaks))continuewave = max(wave_peaks, key=lambda x:x[1]-x[0])max_wave_dis = wave[1] - wave[0]#判断是否是左侧车牌边缘if wave_peaks[0][1] - wave_peaks[0][0] < max_wave_dis/3 and wave_peaks[0][0] == 0:wave_peaks.pop(0)#组合分离汉字cur_dis = 0for i,wave in enumerate(wave_peaks):if wave[1] - wave[0] + cur_dis > max_wave_dis * 0.6:breakelse:cur_dis += wave[1] - wave[0]if i > 0:wave = (wave_peaks[0][0], wave_peaks[i][1])wave_peaks = wave_peaks[i+1:]wave_peaks.insert(0, wave)#去除车牌上的分隔点point = wave_peaks[2]if point[1] - point[0] < max_wave_dis/3:point_img = gray_img[:,point[0]:point[1]]if np.mean(point_img) < 255/5:wave_peaks.pop(2)if len(wave_peaks) <= 6:print("peak less 2:", len(wave_peaks))continuepart_cards = seperate_card(gray_img, wave_peaks)for i, part_card in enumerate(part_cards):#可能是固定车牌的铆钉if np.mean(part_card) < 255/5:print("a point")continuepart_card_old = part_card#w = abs(part_card.shape[1] - SZ)//2w = part_card.shape[1] // 3part_card = cv2.copyMakeBorder(part_card, 0, 0, w, w, cv2.BORDER_CONSTANT, value = [0,0,0])part_card = cv2.resize(part_card, (SZ, SZ), interpolation=cv2.INTER_AREA)#cv2.imshow("part", part_card_old)#cv2.waitKey(0)#cv2.imwrite("u.jpg", part_card)#part_card = deskew(part_card)part_card = preprocess_hog([part_card])if i == 0:resp = self.modelchinese.predict(part_card)charactor = provinces[int(resp[0]) - PROVINCE_START]else:resp = self.model.predict(part_card)charactor = chr(resp[0])#判断最后一个数是否是车牌边缘,假设车牌边缘被认为是1if charactor == "1" and i == len(part_cards)-1:if part_card_old.shape[0]/part_card_old.shape[1] >= 8:#1太细,认为是边缘print(part_card_old.shape)continuepredict_result.append(charactor)roi = card_imgcard_color = colorbreakreturn predict_result, roi, card_color#识别到的字符、定位的车牌图像、车牌颜色if __name__ == '__main__':c = CardPredictor()c.train_svm()r, roi, color = c.predict("car2.jpg")print(r)
运行第一个文件会弹出一个选择框;
选个图片
运行结果:
['京', 'A', 'D', '7', 'Z', '9', '7', '2']
看来还是需要在训练下模型。后续补充新模型验证测试。
代码中涉及的文件下载地址
下载
Https://download.csdn.net/download/hai411741962/88244933
来源地址:https://blog.csdn.net/hai411741962/article/details/132450880
--结束END--
本文标题: opencv 案例实战01-停车场车牌识别实战
本文链接: https://www.lsjlt.com/news/382633.html(转载时请注明来源链接)
有问题或投稿请发送至: 邮箱/279061341@qq.com QQ/279061341
下载Word文档到电脑,方便收藏和打印~
2024-03-01
2024-03-01
2024-03-01
2024-03-01
2024-03-01
2024-02-29
2024-02-29
2024-02-29
2024-02-29
2024-02-29
回答
回答
回答
回答
回答
回答
回答
回答
回答
回答
0