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一、什么是七段数码显示器
七段LCD数码显示器有很多叫法：段码液晶屏、段式液晶屏、黑白笔段屏、段码LCD液晶屏、段式显示器、TN液晶屏、段码液晶显示器、段码屏幕、笔段式液晶屏、段码液晶显示屏、段式LCD、笔段式LCD等。
如下图，每个数字都由一个七段组件组成。
七段显示器总共可以呈现 128 种可能的状态：
我们要识别其中的0-9，如果用深度学习的方式有点小题大做，并且如果要进行应用还有很多前序工作需要进行，比如要确认识别什么设备的，怎么找到数字区域并进行分割等等。
二、创建opencv数字识别器
我们这里进行使用空调恒温器进行识别，首先整理下流程。
1、定位恒温器上的 LCD屏幕。
2、提取 LCD的图像。
3、提取数字区域
4、识别数字。
我们创建名称为recognize_digits.py的文件，代码如下。仅思路供参考（因为代码中的一些参数只适合测试图片）
# import the necessary packagesfrom imutils.perspective import four_point_transformfrom imutils import contoursimport imutilsimport cv2# define the dictionary of digit segments so we can identify# each digit on the thermostat DIGITS_LOOKUP = {(1, 1, 1, 0, 1, 1, 1): 0,(0, 0, 1, 0, 0, 1, 0): 1,(1, 0, 1, 1, 1, 1, 0): 2,(1, 0, 1, 1, 0, 1, 1): 3,(0, 1, 1, 1, 0, 1, 0): 4,(1, 1, 0, 1, 0, 1, 1): 5,(1, 1, 0, 1, 1, 1, 1): 6,(1, 0, 1, 0, 0, 1, 0): 7,(1, 1, 1, 1, 1, 1, 1): 8,(1, 1, 1, 1, 0, 1, 1): 9} # load the example imageimage = cv2.imread("example.jpg")## pre-process the image by resizing it, converting it to# graycale, blurring it, and computing an edge mapimage = imutils.resize(image, height=500)gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)blurred = cv2.GaussianBlur(gray, (5, 5), 0)edged = cv2.Canny(blurred, 50, 200, 255) # find contours in the edge map, then sort them by their# size in descending ordercnts = cv2.findContours(edged.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)cnts = imutils.grab_contours(cnts)cnts = sorted(cnts, key=cv2.contourArea, reverse=True)displayCnt = None# loop over the contoursfor c in cnts:# approximate the contourperi = cv2.arcLength(c, True)approx = cv2.approxPolyDP(c, 0.02 * peri, True)# if the contour has four vertices, then we have found# the thermostat displayif len(approx) == 4:displayCnt = approxbreak # extract the thermostat display, apply a perspective transform# to itwarped = four_point_transform(gray, displayCnt.reshape(4, 2))output = four_point_transform(image, displayCnt.reshape(4, 2)) # threshold the warped image, then apply a series of morphological# operations to cleanup the thresholded imagethresh = cv2.threshold(warped, 0, 255, cv2.THRESH_BINARY_INV | cv2.THRESH_OTSU)[1]kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (1, 5))thresh = cv2.morphologyEx(thresh, cv2.MORPH_OPEN, kernel) # find contours in the thresholded image, then initialize the# digit contours listscnts = cv2.findContours(thresh.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)cnts = imutils.grab_contours(cnts)digitCnts = []# loop over the digit area candidatesfor c in cnts:# compute the bounding box of the contour(x, y, w, h) = cv2.boundingRect(c)# if the contour is sufficiently large, it must be a digitif w >= 15 and (h >= 30 and h <= 40):digitCnts.append(c) # sort the contours from left-to-right, then initialize the# actual digits themselvesdigitCnts = contours.sort_contours(digitCnts, method="left-to-right")[0]digits = [] # loop over each of the digitsfor c in digitCnts:# extract the digit ROI(x, y, w, h) = cv2.boundingRect(c)roi = thresh[y:y + h, x:x + w]# compute the width and height of each of the 7 segments# we are going to examine(roiH, roiW) = roi.shape(dW, dH) = (int(roiW * 0.25), int(roiH * 0.15))dHC = int(roiH * 0.05)# define the set of 7 segmentssegments = [((0, 0), (w, dH)),# top((0, 0), (dW, h // 2)),# top-left((w - dW, 0), (w, h // 2)),# top-right((0, (h // 2) - dHC) , (w, (h // 2) + dHC)), # center((0, h // 2), (dW, h)),# bottom-left((w - dW, h // 2), (w, h)),# bottom-right((0, h - dH), (w, h))# bottom]on = [0] * len(segments) # loop over the segmentsfor (i, ((xA, yA), (xB, yB))) in enumerate(segments):# extract the segment ROI, count the total number of# thresholded pixels in the segment, and then compute# the area of the segmentsegROI = roi[yA:yB, xA:xB]total = cv2.countNonZero(segROI)area = (xB - xA) * (yB - yA)# if the total number of non-zero pixels is greater than# 50% of the area, mark the segment as "on"if total / float(area) > 0.5:on[i]= 1# lookup the digit and draw it on the imagedigit = DIGITS_LOOKUP[tuple(on)]digits.append(digit)cv2.rectangle(output, (x, y), (x + w, y + h), (0, 255, 0), 1)cv2.putText(output, str(digit), (x - 10, y - 10),cv2.FONT_HERSHEY_SIMPLEX, 0.65, (0, 255, 0), 2) # display the digitsprint(u"{}{}.{} \u00b0C".format(*digits))cv2.imshow("Input", image)cv2.imshow("Output", output)cv2.waitKey(0)关于“如何创建opencv数字识别器”的内容就介绍到这里了，感谢大家的阅读。如果想了解更多行业相关的知识，可以关注编程网行业资讯频道，小编每天都会为大家更新不同的知识点。
