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opencv+python识别七段数码显示器的数字(数字识别)

目录

一、什么是七段数码显示器

二、创建opencv数字识别器

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 packages from imutils.perspective import four_point_transform from imutils import contours import imutils import 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 image image = cv2.imread("example.jpg")## pre-process the image by resizing it, converting it to# graycale, blurring it, and computing an edge map image = 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 order cnts = 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 contours for c in cnts:# approximate the contour peri = cv2.arcLength(c, True) approx = cv2.approxPolyDP(c, 0.02 * peri, True)# if the contour has four vertices, then we have found# the thermostat display if len(approx) == 4:displayCnt = approx break

# extract the thermostat display, apply a perspective transform# to it warped = 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 image thresh = 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 lists cnts = cv2.findContours(thresh.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE) cnts = imutils.grab_contours(cnts) digitCnts = []# loop over the digit area candidates for 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 digit if w >= 15 and (h >= 30 and h <= 40):digitCnts.append(c)

# sort the contours from left-to-right, then initialize the# actual digits themselves digitCnts = contours.sort_contours(digitCnts, method="left-to-right")[0]digits = []

# loop over each of the digits for 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 segments segments = [((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 segments for (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 segment segROI = 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 image digit = 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 digits print(u"{}{}.{} \u00b0C".format(*digits)) cv2.imshow("Input", image) cv2.imshow("Output", output) cv2.waitKey(0)

原始图片

边缘检测

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