cv2.imwrite() 没有将时间戳写入帧

Posted 2023-02-22

【中文标题】cv2.imwrite() 没有将时间戳写入帧

【英文标题】：cv2.imwrite() not writing the timestamp into frame

【发布时间】：2018-07-24 04:15:05

【问题描述】：

我有一个成功运行的图像识别脚本。我想要的是，在成功的图像识别中，它将捕获的帧与当前时间戳一起保存到文件名中。 这是我的代码

#!C:\Users\Gurminders\AppData\Local\Programs\Python\Python35-32\python.exe
print("Content-type: text/html\n\n");
# Import OpenCV2 for image processing
import cv2
import mysql.connector
import numpy as np
import os
import sys
import datetime
import time
import cgitb
cgitb.enable()
# put the database inputs here
cnx = mysql.connector.connect(user='root', password='', host='localhost', 
database='image')
cursor = cnx.cursor()
def assure_path_exists(path):
dir = os.path.dirname(path)
if not os.path.exists(dir):
    os.makedirs(dir)

# Create Local Binary Patterns Histograms for face recognization
recognizer = cv2.face.LBPHFaceRecognizer_create()

assure_path_exists("trainer/")

# Load the trained mode
recognizer.read('trainer/trainer.yml')

# Load prebuilt model for Frontal Face
cascadePath = "haarcascade_frontalface_default.xml"
# Create classifier from prebuilt model
faceCascade = cv2.CascadeClassifier(cascadePath);

# Set the font style
font = cv2.FONT_HERSHEY_SIMPLEX
# Initialize and start the video frame capture
cam = cv2.VideoCapture(0)
check = "1" #sys.argv[1]
int_check = int(check)
print(int_check + 5)
ts = time.time()
st = datetime.datetime.fromtimestamp(ts).strftime('%d-%m-%Y %H:%M:%S')
# Loop
while True:
# Read the video frame
ret, im =cam.read()

# Convert the captured frame into grayscale
gray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)

# Get all face from the video frame
faces = faceCascade.detectMultiScale(gray, 1.2,5)

# For each face in faces
for(x,y,w,h) in faces:

    # Create rectangle around the face
    cv2.rectangle(im, (x-20,y-20), (x+w+20,y+h+20), (0,255,0), 4)

    # Recognize the face belongs to which ID
    Id, confidence = recognizer.predict(gray[y:y+h,x:x+w])


    # Check the ID if exist 
    if(Id == int_check):
        confi = round(100 - confidence,2)

        if(confi >20):

            # create table face with two variables id and verified
            cursor.execute ("UPDATE face SET verified=%s WHERE id='%s' " % (confi, Id))


        elif(confi <20):
            cursor.execute ("UPDATE face SET verified='false' WHERE id='%s' " % (Id))






    # Put text describe who is in the picture
    cv2.rectangle(im, (x-22,y-90), (x+w+22, y-22), (0,255,0), -1)
    cv2.putText(im, str(Id), (x,y-40), font, 1, (255,255,255), 3)

# Display the video frame with the bounded rectangle
cv2.imshow('Live Camera Capturing',im)
file_name = str(Id) + " " + str(st)
print(file_name)
cv2.imwrite("face -" + str(file_name) + " frame.jpg", im)

# wait time in ms for camera quit
if cv2.waitKey(1000):
    break


cnx.close()

# Stop the camera
cam.release()

# Close all windows
cv2.destroyAllWindows()

变量 file_name 存储用户 ID 和当前时间戳，但是当我尝试在 cv2.imwrite() 中使用它以便它可以写入帧的名称时，它什么也不做。 这里有什么问题？

【问题讨论】：

当我使用 print(file_name) 时，它是时间戳的 concat 字符串，并且 Id 打印时没有任何错误。但是对于下一行，它没有给出任何错误，只是不使用文件名生成帧 jpg

如果你 cc2.putText 任何恒定的固定测试字符串，如“hello world”，它是否有效？

hello @Micka 解决方案是从时间戳中删除冒号 : 符号，因为文件名中不允许使用它。谢谢

【参考方案1】：

解决方案是从时间戳中删除冒号

st = datetime.datetime.fromtimestamp(ts).strftime('%d-%m-%Y_%H-%M-%S')

这解决了问题