python opencv 3.3.0 video object detection

Question

problem

Now I am trying to detect the motional object in a 5 second video. I use python 3 with jupyter and opencv of the version 3.3.0

It seems I have some problems with the function cv2.imshow and the error was:

error: /Users/travis/build/skvark/opencv-python/opencv/modules/highgui/src/window.cpp:325: error: (-215) size.width>0 && size.height>0 in function imshow

Code

import cv2


def detect_video(video):
    camera = cv2.VideoCapture(video)
    history = 20    # 训练帧数

    bs = cv2.createBackgroundSubtractorKNN(detectShadows=True)  # 背景减除器，设置阴影检测
    bs.setHistory(history)

    frames = 0

while True:
    res, frame = camera.read()

    if not res:
        break

    fg_mask = bs.apply(frame)   # 获取 foreground mask

    if frames < history:
        frames += 1
        continue

    # 对原始帧进行膨胀去噪
    th = cv2.threshold(fg_mask.copy(), 244, 255, cv2.THRESH_BINARY)[1]
    th = cv2.erode(th, cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (3, 3)), iterations=2)
    dilated = cv2.dilate(th, cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (8, 3)), iterations=2)
    # 获取所有检测框
    image, contours, hier = cv2.findContours(dilated, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

    for c in contours:
        # 获取矩形框边界坐标
        x, y, w, h = cv2.boundingRect(c)
        # 计算矩形框的面积
        area = cv2.contourArea(c)
        if 500 < area < 3000:
            cv2.rectangle(frame, (x, y), (x + w, y + h), (0, 255, 0), 2)

    cv2.imshow("detection", frame)
    cv2.imshow("back", dilated)
    if cv2.waitKey(110) & 0xff == 27:
        break
camera.release()


if __name__ == '__main__':
    video = 'test.avi'
    detect_video(video)

note

I did not find a good way to solve this. Anyone can help? Thanks in advance.