使用 opencv 检测 object 后保存元数据

Question

I am fairly new to this topic but would like to safe the counts of "objects" found within my video, simply the raw counts of objects in each frame into a text file. I have the following code that runs well, but 1) it does not safe the objects as images to my folder, which I dont understand, and 2) it would not / or where are the objects saved as metadata. Any help in this regard?

Here is the code:

import cv2

#############################################
frameWidth = 640
frameHeight = 480
nPlateCascade = cv2.CascadeClassifier("Resources/haarcascades/haarcascade_fullbody.xml")
minArea = 200
color = (255, 0, 255)
###############################################

cap = cv2.VideoCapture("Resources/nyc.mp4")
cap.set(3, frameWidth)
cap.set(4, frameHeight)
cap.set(10, 150)
count = 0

while True:
    success, img = cap.read()
    imgGray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    numberPlates = nPlateCascade.detectMultiScale(imgGray, 1.1, 10)
    for (x, y, w, h) in numberPlates:
        area = w * h
        if area > minArea:
            cv2.rectangle(img, (x, y), (x + w, y + h), (255, 0, 255), 2)
            cv2.putText(img, "Object", (x, y - 5),
                    cv2.FONT_HERSHEY_COMPLEX_SMALL, 1, color, 2)
            imgRoi = img[y:y + h, x:x + w]
            cv2.imshow("ROI", imgRoi)

cv2.imshow("Result", img)

if cv2.waitKey(1) and 0xFF == ord('s'):
    cv2.imwrite("Resources/Output/" + str(count) + ".jpg", imgRoi)
    cv2.rectangle(img, (0, 200), (640, 300), (0, 255, 0), cv2.FILLED)
    cv2.putText(img, "Scan Saved", (150, 265), cv2.FONT_HERSHEY_DUPLEX,
                2, (0, 0, 255), 2)
    cv2.imshow("Result", img)
    cv2.waitKey(500)
    count += 1

Answer 1

if cv2.waitKey(1) and 0xFF == ord('s')

that's the issue right there.

and is a logical/boolean operator and has lower precedence than == . what's written there means

cv2.waitKey(1) and (0xFF == ord('s'))

I think you don't mean that.

You probably wanted the & operator which is a bitwise operator (operates on integers) and has higher priority than == .

cv2.waitKey(1) & 0xFF == ord('s') # is equivalent to
(cv2.waitKey(1) & 0xFF) == ord('s')