如何以数组形式显示与 cv2 连接的多个窗口？

Question

我正在从各种摄像机实时捕捉帧。每个摄像机的输出都显示在一个带有 cv2.imshow 的窗口中。我现在想要实现的是所有窗口都连接在一起形成一个网格/矩阵，例如，如果我有 4 个摄像头，那么这些窗口会以 2x2 的形式显示给我。

下面我附上我所拥有的代码。这让我可以捕捉我拥有的不同相机的帧，但我无法做到以上。

cap = []
ret = []
frame = []
final = ""
i = 0

cap.append(cv2.VideoCapture(0))
cap.append(cv2.VideoCapture(1))
cap.append(cv2.VideoCapture(2))

number_cameras = len(cap)

# I initialize values
for x in range(number_cameras):
    ret.append(x)
    frame.append(x)

while(True):

    # I capture frame by frame from each camera
    ret[i], frame[i] = cap[i].read()

    if i == number_cameras-1:

        final = cv2.hconcat([cv2.resize(frame[x], (400, 400)) for x in range(number_cameras)])
        cv2.namedWindow('frame')
        cv2.moveWindow('frame', 0, 0)
        # I show the concatenated outputs
        cv2.imshow('frame', final)

        i = 0

    else:
        i = i + 1

    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# I release the cameras
for x in range(number_cameras):
    cap[x].release()

cv2.destroyAllWindows()

Answer 1

您可以通过将框架调整为宽度和高度的一半来构建一个由 4 个框架组成的框架。然后创建一个空框，根据调整后的宽高填充。

由于我目前没有 4 个摄像头，因此我使用单个摄像头进行模拟。

import numpy as np
import cv2

cap = cv2.VideoCapture(0)
while(True):
        ret, frame = cap.read()
        #find half of the width
        w = int(frame.shape[1] * 50 / 100)
        #find half of the height
        h = int(frame.shape[0] * 50 / 100)
        dim = (w, h)
        #resize the frame to half it size
        frame =cv2.resize(frame, dim, interpolation = cv2.INTER_AREA)
        #create an empty frame
        output = np.zeros((h*2,w*2,3), np.uint8)
        #place a frame at the top left
        output[0:h, 0:w] = frame
        #place a frame at the top right
        output[0:h, w:w * 2] = frame
        #place a frame at the bottom left
        output[h:h * 2, w:w * 2] = frame
        #place a frame at the bottom right
        output[h:h * 2, 0:w] = frame
        cv2.imshow("Output", output)
        key = cv2.waitKey(1) & 0xFF
        # if the `q` key was pressed, break from the loop
        if key == ord("q"):
            break
cv2.destroyAllWindows()