OpenCv图像处理实战——银行卡卡号识别

图像处理项目

测试图片自取区
card1 card2

银行卡卡号识别

from imutils import contours
import numpy as np
import argparse
import imutils
import cv2
import myutils
#argparse这个库可以让我们直接在命令行中就可以向程序中传入参数并让程序运行。

#这两个方法在包中没有导出来，直接把源代码粘过来。
def sort_contours(cnts, method="left-to-right"):reverse = Falsei = 0if method == "right-to-left" or method == "bottom-to-top":reverse = Trueif method == "top-to-bottom" or method == "bottom-to-top":i = 1boundingBoxes = [cv2.boundingRect(c) for c in cnts] #用一个最小的矩形，把找到的形状包起来x,y,h,w(cnts, boundingBoxes) = zip(*sorted(zip(cnts, boundingBoxes),key=lambda b: b[1][i], reverse=reverse))return cnts, boundingBoxes
def resize(image, width=None, height=None, inter=cv2.INTER_AREA):dim = None(h, w) = image.shape[:2]if width is None and height is None:return imageif width is None:r = height / float(h)dim = (int(w * r), height)else:r = width / float(w)dim = (width, int(h * r))resized = cv2.resize(image, dim, interpolation=inter)return resized

#设置参数
ap=argparse.ArgumentParser()
ap.add_argument("-i","-image",required=True,help="path to input image")
ap.add_argument("-t","-template",required=True,help="path to template OCR-A image")
args=vars(ap.parse_args())

#指定信用卡类型
FIRST_NUMBER={"3":"American Express","4":"Visa","5":"MasterCard","6":"Discover Card"
}

#绘图展示
def cv_show(name,img):cv2.imshow(name,img)cv2.waitKey(0)cv2.destroyAllWindows()

#读取一个模板图像
img=cv2.imread("card2.jpg")
cv_show('img',img)
#灰度图
ref=cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
cv_show('ref',ref)

#二值图像
ref=cv2.threshold(ref,10,255,cv2.THRESH_BINARY_INV)[1]
cv_show("ref",ref)

#计算轮廓
#cv2.findContours()函数接收的是二值图像，即黑白的（不是灰度图），cv2.RETR_EXTERNAL 只检测外轮廓，cv2.CHAIN_APPROX_SIMPLE只保留终点坐标
#返回的list中每个元素都是图像中的一个轮廓
ref_,refCnts,hierarchy=cv2.findContours(ref.copy(),cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)cv2.drawContours(img,refCnts,-1,(0,0,255),3)
cv_show('img',img)
print(np.array(refCnts).shape)
refCnts=sort_contours(refCnts,method='left-to-right')[0]
digits={}

# 遍历每一个轮廓
for (i, c) in enumerate(refCnts):# 计算外接矩形并且resize成合适大小(x, y, w, h) = cv2.boundingRect(c)roi = ref[y:y + h, x:x + w]roi = cv2.resize(roi, (57, 88))# 每一个数字对应每一个模板digits[i] = roi

# 初始化卷积核
rectKernel = cv2.getStructuringElement(cv2.MORPH_RECT, (9, 3))
sqKernel = cv2.getStructuringElement(cv2.MORPH_RECT, (5, 5))

# 读取输入图像，预处理
image = cv2.imread('card1.jpg')
cv_show('image', image)
image = resize(image, width=300)
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
cv_show('gray', gray)

# 礼帽操作，突出更明亮的区域
tophat = cv2.morphologyEx(gray, cv2.MORPH_TOPHAT, rectKernel)
cv_show('tophat', tophat)
#
gradX = cv2.Sobel(tophat, ddepth=cv2.CV_32F, dx=1, dy=0,  # ksize=-1相当于用3*3的ksize=-1)gradX = np.absolute(gradX)
(minVal, maxVal) = (np.min(gradX), np.max(gradX))
gradX = (255 * ((gradX - minVal) / (maxVal - minVal)))
gradX = gradX.astype("uint8")print(np.array(gradX).shape)
cv_show('gradX', gradX)

# 通过闭操作（先膨胀，再腐蚀）将数字连在一起
gradX = cv2.morphologyEx(gradX, cv2.MORPH_CLOSE, rectKernel)
cv_show('gradX', gradX)
# THRESH_OTSU会自动寻找合适的阈值，适合双峰，需把阈值参数设置为0
thresh = cv2.threshold(gradX, 0, 255,cv2.THRESH_BINARY | cv2.THRESH_OTSU)[1]
cv_show('thresh', thresh)# 再来一个闭操作thresh = cv2.morphologyEx(thresh, cv2.MORPH_CLOSE, sqKernel)  # 再来一个闭操作
cv_show('thresh', thresh)

# 计算轮廓thresh_,threshCnts, hierarchy = cv2.findContours(thresh.copy(), cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)cnts = threshCnts
cur_img = image.copy()
cv2.drawContours(cur_img, cnts, -1, (0, 0, 255), 3)
cv_show('img', cur_img)
locs = []

# 遍历轮廓
for (i, c) in enumerate(cnts):# 计算矩形(x, y, w, h) = cv2.boundingRect(c)ar = w / float(h)# 选择合适的区域，根据实际任务来，这里的基本都是四个数字一组if ar > 2.5 and ar < 4.0:if (w > 40 and w < 55) and (h > 10 and h < 20):# 符合的留下来locs.append((x, y, w, h))# 将符合的轮廓从左到右排序
locs = sorted(locs, key=lambda x: x[0])
output = []

# 遍历每一个轮廓中的数字
for (i, (gX, gY, gW, gH)) in enumerate(locs):# initialize the list of group digitsgroupOutput = []# 根据坐标提取每一个组group = gray[gY - 5:gY + gH + 5, gX - 5:gX + gW + 5]cv_show('group', group)# 预处理group = cv2.threshold(group, 0, 255,cv2.THRESH_BINARY | cv2.THRESH_OTSU)[1]cv_show('group', group)# 计算每一组的轮廓group_,digitCnts, hierarchy = cv2.findContours(group.copy(), cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)digitCnts = contours.sort_contours(digitCnts,method="left-to-right")[0]# 计算每一组中的每一个数值for c in digitCnts:# 找到当前数值的轮廓，resize成合适的的大小(x, y, w, h) = cv2.boundingRect(c)roi = group[y:y + h, x:x + w]roi = cv2.resize(roi, (57, 88))cv_show('roi', roi)# 计算匹配得分scores = []# 在模板中计算每一个得分for (digit, digitROI) in digits.items():# 模板匹配result = cv2.matchTemplate(roi, digitROI,cv2.TM_CCOEFF)(_, score, _, _) = cv2.minMaxLoc(result)scores.append(score)# 得到最合适的数字groupOutput.append(str(np.argmax(scores)))# 画出来cv2.rectangle(image, (gX - 5, gY - 5),(gX + gW + 5, gY + gH + 5), (0, 0, 255), 1)cv2.putText(image, "".join(groupOutput), (gX, gY - 15),cv2.FONT_HERSHEY_SIMPLEX, 0.65, (0, 0, 255), 2)# 得到结果output.extend(groupOutput)

后面识别四位数都是这种方法，就不一一展示了。

# 打印结果
print("Credit Card Type: {}".format(FIRST_NUMBER[output[0]]))
print("Credit Card #: {}".format("".join(output)))
cv2.imshow("Image", image)
cv2.waitKey(0)
#Credit Card Type: Visa
#Credit Card #: 4000123456789010