Python OpenCV:用于绘制矩形的鼠标回调 [英] Python OpenCV: mouse callback for drawing rectangle

问题描述

我想保存视频流中的图像，然后在显示的图像上绘制一个矩形以产生感兴趣的区域.以后，将该ROI保存到文件中.我使用opencv python抓取示例来使用setMouseCallback函数.但是我不知道我在做什么错，因为它没有给出我期望的结果.我想看到在mouse input窗口中显示的静态图像上绘制的绿色矩形，并且roi已保存到文件中.请帮助调试此代码或显示更好的方法:

I want to save an image from the video stream and then draw a rectangle onto the shown image to produce a region of interest. Later, save that ROI in a file. I used opencv python grabcut example to use the setMouseCallback function. But I don't know what I'm doing incorrect as it is not giving the result I expect. I would like to see the green rectangle drawn on the static image shown in mouse input window and the roi being saved to file. Please help debug this code or show a better approach:

import cv2

rect = (0,0,1,1)
rectangle = False
rect_over = False  
def onmouse(event,x,y,flags,params):
    global sceneImg,rectangle,rect,ix,iy,rect_over

    # Draw Rectangle
    if event == cv2.EVENT_LBUTTONDOWN:
        rectangle = True
        ix,iy = x,y

    elif event == cv2.EVENT_MOUSEMOVE:
        if rectangle == True:
            cv2.rectangle(sceneImg,(ix,iy),(x,y),(0,255,0),2)
            rect = (min(ix,x),min(iy,y),abs(ix-x),abs(iy-y))

    elif event == cv2.EVENT_LBUTTONUP:
        rectangle = False
        rect_over = True
        cv2.rectangle(sceneImg,(ix,iy),(x,y),(0,255,0),2)
        rect = (min(ix,x),min(iy,y),abs(ix-x),abs(iy-y))

        x1,y1,w,h = rect        
        roi = sceneImg[y1:y1+h, x1:x1+w]

        cv2.imwrite('roi.jpg', roi)

# Named window and mouse callback
cv2.namedWindow('video')
cv2.namedWindow('mouse input')
cv2.setMouseCallback('mouse input',onmouse)

camObj = cv2.VideoCapture(-1)
keyPressed = None
running = True
scene = False
# Start video stream
while running:
    readOK, frame = camObj.read()

    keyPressed = cv2.waitKey(5)
    if keyPressed == ord('s'):
        scene = True

        cv2.imwrite('sceneImg.jpg',frame)
        sceneImg = cv2.imread('sceneImg.jpg')

        cv2.destroyWindow('video')
        cv2.imshow('mouse input', sceneImg)

    elif keyPressed == ord('r'):
        scene = False
        cv2.destroyWindow('mouse input')

    elif keyPressed == ord('q'):
        running = False

    if not scene:
        cv2.imshow('video', frame)

cv2.destroyAllWindows()
camObj.release()

推荐答案

每次调用{event == cv2.EVENT_MOUSEMOVE:}时，您都需要重置图像.

You need to reset the image everytime when the {event == cv2.EVENT_MOUSEMOVE:} called.

您的代码应如下所示:

if event == cv2.EVENT_LBUTTONDOWN:
    rectangle = True
    ix,iy = x,y

elif event == cv2.EVENT_MOUSEMOVE:
    if rectangle == True:
        sceneImg = sceneImg2.copy()
        cv2.rectangle(sceneImg,(ix,iy),(x,y),(0,255,0),2)
        rect = (min(ix,x),min(iy,y),abs(ix-x),abs(iy-y))


elif event == cv2.EVENT_LBUTTONUP:
    rectangle = False
    rect_over = True

    cv2.rectangle(sceneImg,(ix,iy),(x,y),(0,255,0),2)
    rect = (min(ix,x),min(iy,y),abs(ix-x),abs(iy-y))

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