(cv2，capture) 对象不可调用

Question

基本上，此代码将检测场景中对象的运动。当检测到运动时，红色矩形框将跟踪对象的运动。但是，我在代码中添加了一个新函数，它是帧差异。一般来说，它是阈值。当我运行代码时，它说："cv2.capture"对象不可调用。

import cv2.cv as cv
class Target:
    def __init__(self):
        self.capture = cv.CaptureFromCAM(0)
        cv.NamedWindow("Target", 1)
    def run(self):
        # Capture first frame to get size
        ret, current_frame = self.capture()
        previous_frame = current_frame
        frame = cv.QueryFrame(self.capture)
        frame_size = cv.GetSize(frame)
        color_image = cv.CreateImage(cv.GetSize(frame), 8, 3)
        grey_image = cv.CreateImage(cv.GetSize(frame), cv.IPL_DEPTH_8U, 1)
        moving_average = cv.CreateImage(cv.GetSize(frame), cv.IPL_DEPTH_32F, 3)
        first = True
        while True:
            current_frame_gray = cv2.cvtColor(current_frame,cv2.COLOR_BGR2GRAY)
            previous_frame_gray = cv2.cvtColor(previous_frame, cv2.COLOR_BGR2GRAY)    
            frame_diff = cv2.absdiff(current_frame_gray,previous_frame_gray)
            closest_to_left = cv.GetSize(frame)[0]
            closest_to_right = cv.GetSize(frame)[1]
            color_image = cv.QueryFrame(self.capture)
            # Smooth to get rid of false positives
            cv.Smooth(color_image, color_image, cv.CV_GAUSSIAN, 3, 0)
            if first:
                difference = cv.CloneImage(color_image)
                temp = cv.CloneImage(color_image)
                cv.ConvertScale(color_image, moving_average, 1.0, 0.0)
                first = False
            else:
                cv.RunningAvg(color_image, moving_average, 0.020, None)
            # Convert the scale of the moving average.
            cv.ConvertScale(moving_average, temp, 1.0, 0.0)
            # Minus the current frame from the moving average.
            cv.AbsDiff(color_image, temp, difference)
            # Convert the image to grayscale.
            cv.CvtColor(difference, grey_image, cv.CV_RGB2GRAY)
            # Convert the image to black and white.
            cv.Threshold(grey_image, grey_image, 70, 255, cv.CV_THRESH_BINARY)
            # Dilate and erode to get people blobs
            cv.Dilate(grey_image, grey_image, None, 18)
            cv.Erode(grey_image, grey_image, None, 10)
            storage = cv.CreateMemStorage(0)
            contour = cv.FindContours(grey_image, storage, cv.CV_RETR_CCOMP, cv.CV_CHAIN_APPROX_SIMPLE)
            points = []
            while contour:
                bound_rect = cv.BoundingRect(list(contour))
                contour = contour.h_next()
                pt1 = (bound_rect[0], bound_rect[1])
                pt2 = (bound_rect[0] + bound_rect[2], bound_rect[1] + bound_rect[3])
                points.append(pt1)
                points.append(pt2)
                cv.Rectangle(color_image, pt1, pt2, cv.CV_RGB(255,0,0), 1)

            cv.ShowImage("Target", color_image)
            cv.ShowImage("frame_diff", frame_diff)

            # Listen for ESC key
            c = cv.WaitKey(7) % 0x100
            if c == 27:
                break
if __name__=="__main__":
    t = Target()
    t.run()

这是我想要从中传输的原始帧差异代码：

import cv2
cap = cv2.VideoCapture(0)
ret, current_frame = cap.read()
previous_frame = current_frame
while(cap.isOpened()):
    current_frame_gray = cv2.cvtColor(current_frame, cv2.COLOR_BGR2GRAY)
    previous_frame_gray = cv2.cvtColor(previous_frame, cv2.COLOR_BGR2GRAY)    
    frame_diff = cv2.absdiff(current_frame_gray,previous_frame_gray)
    cv2.imshow('frame diff ',frame_diff)      
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
    previous_frame = current_frame.copy()
    ret, current_frame = cap.read()
cap.release()
cv2.destroyAllWindows()

Answer 1

不能调用 capture 对象，但可以通过调用其 read 方法从中读取。将帧返回代码更改为：

ret, current_frame = self.capture.read()

应该解决这个问题。

编辑：

两行：

ret, current_frame = self.capture.read()
previous_frame = current_frame

将适用于VideoCapture但不适用于CaptureFromCAM.您显然不需要它们，因为您可以通过执行以下操作来获取帧：

frame = cv.QueryFrame(self.capture)