Python+OpenCV图像处理之对象测量
2020-12-13 04:11
标签：res numpy 选择图片 返回 out python实现 osi 面积 几何 OpenCV中经常会测量对象的面积，周长，质心，边界框等 求图形几何矩中心 并求最小外接矩形python实现 运行结果 多边形拟合（应用：选择图片中几何体形状）python实现 Python+OpenCV图像处理之对象测量 标签：res numpy 选择图片 返回 out python实现 osi 面积 几何 原文地址：https://www.cnblogs.com/qianxia/p/11103831.htmlimport cv2
import numpy as np
__author__ = "boboa"
def measure_demo(image):
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
ret, thresh = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)
print("threshold value", ret)
cv2.imshow("binary", thresh)
outImage,contours, hierarchy = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
for i, contour in enumerate(contours): # 遍历全部轮廓
area = cv2.contourArea(contour)
# cv2.boundingRect返回四个参数（x，y）为矩形左上角的坐标，（w，h）是矩形的宽和高
x, y, w, h = cv2.boundingRect(contour) # 外接矩形大小
rate = min(w, h) / max(w, h) # 宽高比
# 计算图像中的中心矩
mm = cv2.moments(contour)
cx = mm["m10"]/mm["m00"]
cy = mm["m01"]/mm["m00"] # 几何图形的中心位置 , mm是字典类型
cv2.circle(image, (np.int(cx), np.int(cy)), 2, (0, 255, 255), -1)
cv2.rectangle(image, (x, y), (x+w, y+h), (0, 0, 255), 2) # 外接矩形
print("contour area ", area)
cv2.imshow("measure contours", image)
if __name__ == "__main__":
img = cv2.imread("image/123.jpg")
cv2.namedWindow("input image", cv2.WINDOW_AUTOSIZE)
cv2.imshow("input image", img)
measure_demo(img)
cv2.waitKey(0)
cv2.destroyAllWindows()
"""
approxPolyDP(curve, epsilon, closed[, approxCurve]) -> approxCurve
curve-拟合曲线
epsilon-拟合曲线条数（int）
closed-拟合曲线是否闭合（True or False）
多边形拟合
"""
approxCurve = cv2.approxPolyDP(contour,10,True)
print(approxCurve.shape)
#画轮廓多边形拟合数目>6的图形轮廓为红
if approxCurve.shape[0] > 6:
cv2.drawContours(dst,contours,i,(0,0,255),2)
# 画轮廓多边形拟合数目=3的图形轮廓为蓝
elif approxCurve.shape[0] == 3:
cv2.drawContours(dst,contours,i,(255,0,0),2)
# 画其余数目的轮廓多边形拟合的图形轮廓为黄
else:
cv2.drawContours(dst,contours,i,(0,255,255),2)