Python+Opencv实现数字识别的示例代码

# coding=utf-8
# 导入一些python包
from imutils.perspective import four_point_transform
from imutils import contours
import imutils
import cv2

# 定义每一个数字对应的字段
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
}

# 读取输入图片
image = cv2.imread("example.jpg")

# 将输入图片裁剪到固定大小
image = imutils.resize(image, height=500)
# 将输入转换为灰度图片
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
# 进行高斯模糊操作
blurred = cv2.GaussianBlur(gray, (5, 5), 0)
# 执行边缘检测
edged = cv2.Canny(blurred, 50, 200, 255)
cv2.imwrite('edge.png', edged)

# 在边缘检测map中发现轮廓
cnts = cv2.findContours(edged.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cnts = imutils.grab_contours(cnts)
# 根据大小对这些轮廓进行排序
cnts = sorted(cnts, key=cv2.contourArea, reverse=True)
displayCnt = None

# 循环遍历所有的轮廓
for c in cnts:
	# 对轮廓进行近似
	peri = cv2.arcLength(c, True)
	approx = cv2.approxPolyDP(c, 0.02 * peri, True)

	# 如果当前的轮廓有4个顶点，我们返回这个结果，即LCD所在的位置
	if len(approx) == 4:
		displayCnt = approx
		break

# 应用视角变换到LCD屏幕上
warped = four_point_transform(gray, displayCnt.reshape(4, 2))
cv2.imwrite('warped.png', warped)
output = four_point_transform(image, displayCnt.reshape(4, 2))

# 使用阈值进行二值化
thresh = cv2.threshold(warped, 0, 255, cv2.THRESH_BINARY_INV | cv2.THRESH_OTSU)[1]
cv2.imwrite('thresh1.png', thresh)
kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (1, 5))
# 使用形态学操作进行处理
thresh = cv2.morphologyEx(thresh, cv2.MORPH_OPEN, kernel)
cv2.imwrite('thresh2.png', thresh)

# 在阈值图像中查找轮廓，然后初始化数字轮廓列表
cnts = cv2.findContours(thresh.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cnts = imutils.grab_contours(cnts)
digitCnts = []

# 循环遍历所有的候选区域
for c in cnts:
	# 计算轮廓的边界框
	(x, y, w, h) = cv2.boundingRect(c)

	# 如果当前的这个轮廓区域足够大，它一定是一个数字区域
	if w >= 15 and (h >= 30 and h <= 40):
		digitCnts.append(c)

# 从左到右对这些轮廓进行排序
digitCnts = contours.sort_contours(digitCnts, method="left-to-right")[0]
digits = []

# 循环处理每一个数字
i = 0
for c in digitCnts:
	# 获取ROI区域
	(x, y, w, h) = cv2.boundingRect(c)
	roi = thresh[y:y + h, x:x + w]

	# 分别计算每一段的宽度和高度
	(roiH, roiW) = roi.shape
	(dW, dH) = (int(roiW * 0.25), int(roiH * 0.15))
	dHC = int(roiH * 0.05)

	# 定义一个7段数码管的集合
	segments = [
		((0, 0), (w, dH)),	             # 上
		((0, 0), (dW, h // 2)),           # 左上
		((w - dW, 0), (w, h // 2)),	         # 右上
		((0, (h // 2) - dHC) , (w, (h // 2) + dHC)), # 中间
		((0, h // 2), (dW, h)),	           # 左下
		((w - dW, h // 2), (w, h)),	         # 右下
		((0, h - dH), (w, h))	           # 下
	]
	on = [0] * len(segments)

	# 循环遍历数码管中的每一段
	for (i, ((xA, yA), (xB, yB))) in enumerate(segments): # 检测分割后的ROI区域，并统计分割图中的阈值像素点
		segROI = roi[yA:yB, xA:xB]
		total = cv2.countNonZero(segROI)
		area = (xB - xA) * (yB - yA)

		# 如果非零区域的个数大于整个区域的一半，则认为该段是亮的
		if total / float(area) > 0.5:
			on[i]= 1

	# 进行数字查询并显示结果
	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)

# 显示最终的输出结果
print(u"{}{}.{} \u00b0C".format(*digits))
cv2.imshow("Input", image)
cv2.imshow("Output", output)
cv2.waitKey(0)