python - AttributeError: 'NoneType'对象没有属性 'shape'/从多个轮廓框转换为单数

Question

您好，早上好!

我是python和opencv的新手，所以如果我听起来不专业，就可以提前道歉。

我正在尝试检测MCB并确定其尺寸。但是，此错误不断弹出。
AttributError:“NoneType”对象没有属性“shape”。

我在这个论坛和其他网站上进行了几次搜索，并且大多数人都宣称视频路径是问题所在，因此我尝试从捕获到视频流进行调整或更改，但是没有结果。

代码在这里:

import cv2
from collections import deque

from scipy.spatial import distance as dist
from imutils import perspective
import numpy as np
import argparse
import imutils
import math
import time

font = cv2.FONT_HERSHEY_SIMPLEX

def midpoint(ptA, ptB):
    return ((ptA[0] + ptB[0]) * 0.5, (ptA[1] + ptB[1]) * 0.5)

ap = argparse.ArgumentParser()
ap.add_argument("-v", "--video", help="path to the (optional) video file")
args = vars(ap.parse_args())

sensitivity = 43
greyLower = np.array([96,0,176-sensitivity])
greyUpper = np.array([180,sensitivity,255])
pixelsPerMetric = None
KNOWN_WIDTH = 81

if not args.get("video", False):
    camera = cv2.VideoCapture(0)
else:
    camera = cv2.VideoCapture(args["video"])

while True:
    (grabbed, frame) = camera.read()

    if args.get("video") and not grabbed:
        break

    frame = imutils.resize(frame, width=600)
    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)

    mask = cv2.inRange(hsv,greyLower, greyUpper)
    mask = cv2.erode(mask, None, iterations=2)
    mask = cv2.dilate(mask, None, iterations=2)

    (_, contours, hierarchy) = cv2.findContours(mask.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
    center = None
    for pic, contour in enumerate(contours):

        if len(contours) > 0:
                    c = max(contours, key =cv2.contourArea)
                    x,y,w,h = cv2.boundingRect(contour)
                    rect = (x+w, y+h)
                    rect = cv2.minAreaRect(c)
                    box = cv2.boxPoints(rect)
                    box = np.int0(box)
                    box = perspective.order_points(box)
                    for (x, y) in box:
                        frame = cv2.rectangle(frame,(int(x),int(y)),(int(x+w), int(y+h)),(0,0,139),2)
                    # unpack the ordered bounding box, then compute the midpoint
                    # between the top-left and top-right coordinates, followed by
                    # the midpoint between bottom-left and bottom-right coordinates
                    (tl, tr, br, bl) = box
                    (tltrX, tltrY) = midpoint(tl, tr)
                    (blbrX, blbrY) = midpoint(bl, br)

                    # compute the midpoint between the top-left and top-right points,
                    # followed by the midpoint between the top-righ and bottom-right
                    (tlblX, tlblY) = midpoint(tl, bl)
                    (trbrX, trbrY) = midpoint(tr, br)

                    # draw the midpoints on the image
                    cv2.circle(frame, (int(tltrX), int(tltrY)), 5, (255, 0, 0), -1)
                    cv2.circle(frame, (int(blbrX), int(blbrY)), 5, (255, 0, 0), -1)
                    cv2.circle(frame, (int(tlblX), int(tlblY)), 5, (255, 0, 0), -1)
                    cv2.circle(frame, (int(trbrX), int(trbrY)), 5, (255, 0, 0), -1)

                    # draw lines between the midpoints
                    cv2.line(frame, (int(tltrX), int(tltrY)), (int(blbrX), int(blbrY)),
                            (255, 0, 255), 2)
                    cv2.line(frame, (int(tlblX), int(tlblY)), (int(trbrX), int(trbrY)),
                            (255, 0, 255), 2)
                    # compute the Euclidean distance between the midpoints
                    dA = dist.euclidean((tltrX, tltrY), (blbrX, blbrY))
                    dB = dist.euclidean((tlblX, tlblY), (trbrX, trbrY))

                    # if the pixels per metric has not been initialized, then
                    # compute it as the ratio of pixels to supplied metric
                    # (in this case, inches)

                    # compute the size of the object
                    dimA = dA / KNOWN_WIDTH
                    dimB = dB / KNOWN_WIDTH

                    if rect >300:
                            frame = cv2.rectangle(frame,(int(x),int(y)),(int(x+w), int(y+h)),(0,0,139),2)
                            cv2.putText(frame,"MCB",(x,y),cv2.FONT_HERSHEY_SIMPLEX, 0.7, (0,0,139))

                    # draw the object sizes on the image
                    cv2.putText(frame, "{:.1f}in".format(dimA),
                            (int(tltrX - 15), int(tltrY - 10)), cv2.FONT_HERSHEY_SIMPLEX,
                            0.65, (255, 255, 255), 2)
                    cv2.putText(frame, "{:.1f}in".format(dimB),
                            (int(trbrX + 10), int(trbrY)), cv2.FONT_HERSHEY_SIMPLEX,
                            0.65, (255, 255, 255), 2)
                    cv2.imshow("Frame", frame)
                    cv2.imshow("Mask", mask)

                    key = cv2.waitKey(10) & 0xFF

                    if key == ord("q"):
                        break

        camera.release()
        cv2.destroyAllWindows()

该代码通过检测MCB的hsv颜色代码(灰色)来进行，并使用中点声明尺寸(从pyimages引用)。

我遇到的另一个问题是，我试图创建一个矩形框进行检测而不是多个。因此，我尝试设置轮廓以检测hsv代码的最大区域，但是未实现所需的结果。

任何帮助或建议都将是有用的，并且对任何评论家都是开放的，因为我想了解有关python的更多信息并扩展此专业 Realm 。

谢谢。

编辑:
完整回溯:

Traceback (most recent call last):
File "/Users/mac/Desktop/Control EZ/Test/Detect box.py", line 37, in <module>
    frame = imutils.resize(frame, width=600)
  File "/usr/local/lib/python2.7/site-packages/imutils/convenience.py", line 69, in resize
    (h, w) = image.shape[:2]
AttributeError: 'NoneType' object has no attribute 'shape'

Answer 1

在这行上:

(grabbed, frame) = camera.read()

此处将变量frame设置为None，因此尝试调整(不存在)图像的大小失败。我对您的相机类别一无所知，但可能是在没有要读取的帧数据的情况下发生的。 None对象没有形状，甚至没有数据。基本上什么都没有。

看起来您正在检查grabbed变量，但仅在某些情况下。如果grabbed为false，也许您应该始终继续