仅检查OpenCV中视频供稿的特定部分 [英] Check only particular portion of video feed in OpenCV

问题描述

如何获取特定宽度和高度的网络摄像头视频提要?

How to get webcam video feed, for specific width and height?

我对OpenCV库的经验为零，因此在这方面我需要帮助.这段代码来自geeksforgeeks.com.这是我现在唯一的东西.

I have zero experience with OpenCV library, so I need help in this regard. This code is from geeksforgeeks.com. This is the only thing I have right now.

我想要实现的是，我只想检测视频Feed中指定区域的运动.

What I'm trying to achieve is that, I want to detect motion in only specified area of video feed.

import cv2, time, pandas



from datetime import datetime 



static_back = None
motion_list = [ None, None ] 
time = [] 
df = pandas.DataFrame(columns = ["Start", "End"]) 
video = cv2.VideoCapture(0) 



while True: 
    check, frame = video.read() 
    motion = 0
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY) 
    gray = cv2.GaussianBlur(gray, (21, 21), 0)



if static_back is None: 
    static_back = gray 
    continue

diff_frame = cv2.absdiff(static_back, gray) 

thresh_frame = cv2.threshold(diff_frame, 30, 255, cv2.THRESH_BINARY)[1] 
thresh_frame = cv2.dilate(thresh_frame, None, iterations = 2) 

(cnts, _) = cv2.findContours(thresh_frame.copy(),  
                   cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE) 

for contour in cnts: 
    if cv2.contourArea(contour) < 50000: 
        continue
    motion = 1

    (x, y, w, h) = cv2.boundingRect(contour) 
    # making green rectangle arround the moving object 
    cv2.rectangle(frame, (x, y), (x + w, y + h), (0, 255, 0), 3) 

motion_list.append(motion) 

motion_list = motion_list[-2:] 

if motion_list[-1] == 1 and motion_list[-2] == 0: 
    time.append(datetime.now()) 

if motion_list[-1] == 0 and motion_list[-2] == 1: 
    time.append(datetime.now()) 

cv2.imshow("Gray Frame", gray) 

cv2.imshow("Difference Frame", diff_frame) 

cv2.imshow("Threshold Frame", thresh_frame) 

cv2.imshow("Color Frame", frame) 

key = cv2.waitKey(1) 
if key == ord('q'): 
    # if something is movingthen it append the end time of movement 
    if motion == 1: 
        time.append(datetime.now()) 
    break


for i in range(0, len(time), 2): 
    df = df.append({"Start":time[i], "End":time[i + 1]}, ignore_index = True)

df.to_csv("Time_of_movements.csv") 
video.release() 
cv2.destroyAllWindows()

推荐答案

似乎您想获取每一帧特定区域的关注区域(ROI).要在OpenCV中执行此操作，我们可以使用边界框坐标裁剪图像.将(0,0)视为图像的左上角，从左至右作为x方向，从上至下作为y方向.如果我们将(x1, y1)作为ROI的左上角，而将(x2,y2)作为ROI的右下角，则可以通过以下方式裁剪图像:

It seems like you want to obtain the region of interest (ROI) for a particular area of each frame. To do this in OpenCV, we can crop the image using bounding box coordinates. Consider (0,0) as the top left corner of the image with left-to-right as the x-direction and top-to-bottom as the y-direction. If we have (x1, y1) as the top-left vertex and (x2,y2) as the bottom-right vertex of a ROI, we can crop the image by:

ROI = frame[y1:y2, x1:x2]

作为说明:

-------------------------------------------
|                                         | 
|    (x1, y1)                             |
|      ------------------------           |
|      |                      |           |
|      |                      |           | 
|      |         ROI          |           |  
|      |                      |           |   
|      |                      |           |   
|      |                      |           |       
|      ------------------------           |   
|                           (x2, y2)      |    
|                                         |             
|                                         |             
|                                         |             
-------------------------------------------

由于图像在OpenCV中存储为Numpy数组，因此我们能够做到这一点. 此处是Numpy数组索引和切片的重要资源.获得理想的投资回报率后，您就可以在该区域进行运动检测了.

We are able to do this since images are stored as a Numpy array in OpenCV. Here is a great resource for Numpy array indexing and slicing. Once you have the desired ROI, you can do your motion detecting in this region.

这篇关于仅检查OpenCV中视频供稿的特定部分的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！