python - 打开 CV 断言失败，但文件名没有错误

问题描述

好的，所以我一直在做这个项目，我们从人行道上获取交通视频，检测汽车并读取他们的车牌。检测部分效果很好，我得到了满意的结果。现在我正在尝试提取汽车的边界框，并将它们保存为 jpg，并且我也只想要框架中某个区域的边界框。所以我写了这段代码，但每次在第 50 帧左右我都会收到一个断言错误。我认为视频没有任何问题，因为检测部分运行良好。我在第 54 行收到错误， cv2.imwrite("frames\\"+str(number)+'.jpg', frametosave) 我都尝试了frames\\，frames/但两个路径名都有错误。在我被解雇之前请帮帮我。

 import cv2
import numpy as np

video = cv2.VideoCapture("Resources/highway.mp4")
wh = 320
classpathname = 'Resources/coco.names'
classNames = []

videoWidth,videoHeight = int(video.get(3)), int(video.get(4))
size = (videoWidth, videoHeight)
result = cv2.VideoWriter('result.mp4', cv2.VideoWriter_fourcc(*'MJPG'),10, size)


with open(classpathname,'rt') as f:
    classNames = f.read().rstrip('\n').split('\n')

configFile = "Resources/yolov3.cfg"
weights = "Resources/yolov3.weights"

net = cv2.dnn.readNetFromDarknet(configFile, weights)
net.setPreferableBackend(cv2.dnn.DNN_BACKEND_OPENCV)
net.setPreferableTarget(cv2.dnn.DNN_TARGET_CPU)

def findObjects(output, img):
    h, w, c = img.shape
    boundingbox = []
    classIDs = []
    confidences = []

    for out in output:
        for det in out:
            scores = det[5:]


            classID = np.argmax(scores)

            confidence = scores[classID]
            if confidence> 0.6:

                width,height= int(det[2]*w), int(det[3]*h)
                x,y = int((det[0]*w )-width/2), int((det[1]*h) -height/2)
                boundingbox.append([x,y, width, height])
                classIDs.append(classID)
                confidences.append(confidence)


    indices = cv2.dnn.NMSBoxes(boundingbox, confidences, 0.6, 0.3)
    number = 1
    for i in indices:
        box = boundingbox[i]
        x,y,w,h = box[0],box[1],box[2],box[3]
        if(y+h>1000 and x+(w/2) <1000 ):
            frametosave = img[y:y+h, x:x+w]
            cv2.imwrite("frames/"+str(number)+'.jpg', frametosave)
            number+=1
        cv2.rectangle(img,(x,y), (x+w, y+h), (255,0,255),2)
        cv2.putText(img, f'{classNames[classIDs[i]].upper()} {int(confidences[i]*100)}%', (x,y-10), cv2.FONT_HERSHEY_SIMPLEX, 0.6, (255,0,255), 2)

framenumber = 1
while True:
    success, img = video.read()
    if success:
        blob = cv2.dnn.blobFromImage(img, 1 / 255, (wh, wh), [0, 0, 0], 1, crop=False)
        net.setInput(blob)
        print(framenumber)

        framenumber +=1
        layerNames = net.getLayerNames()

        outputLayerNames = [layerNames[i - 1] for i in net.getUnconnectedOutLayers()]
        outputs = net.forward(outputLayerNames)
        findObjects(outputs, img)
        if success:
            result.write(img)
        cv2.imshow("img", img)
        if cv2.waitKey(1) & 0xFF == ord('s'):
            break

video.release()
result.release()

这是我得到的错误

Traceback (most recent call last):
  File "C:\Users\chhet\PycharmProjects\opencv\objectDetection.py", line 72, in <module>
    findObjects(outputs, img)
  File "C:\Users\chhet\PycharmProjects\opencv\objectDetection.py", line 54, in findObjects
    cv2.imwrite("frames\\"+str(number)+'.jpg', frametosave)
cv2.error: OpenCV(4.5.4-dev) D:\a\opencv-python\opencv-python\opencv\modules\imgcodecs\src\loadsave.cpp:799: error: (-215:Assertion failed) !_img.empty() in function 'cv::imwrite'

OpenCV: FFMPEG: tag 0x47504a4d/'MJPG' is not supported with codec id 7 and format 'mp4 / MP4 (MPEG-4 Part 14)'
OpenCV: FFMPEG: fallback to use tag 0x7634706d/'mp4v'

Process finished with exit code 1

标签： pythonopencv

if(x<0): x=0 if(y<0): y=0 frametosave = img[y:y+h, x:x+w] if (x + w > videoWidth): if (y + h > videoHeight): frametosave = img[y:videoHeight, x:videoWidth] frametosave = img[y:y + h, x:videoWidth] if(y+h> videoHeight): frametosave = img[y:videoHeight, x:x+w] if frametosave.data: print(frametosave.data) cv2.imwrite("frames/" + str(number) + '.jpg', frametosave)

python - 打开 CV 断言失败，但文件名没有错误

问题描述

解决方案

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